§ Change of tone

This is the first progress report from the CCC to assess climate policy and action under the new Labour government, which took office in July 2024.

Last year’s edition had said that “urgent action is needed” and that the UK was “not on track” for its 2030 international climate goal, namely, a 68% reduction in emissions relative to 1990 levels.

In contrast, the 2025 report says: “This target is within reach, provided the government stays the course.”

Speaking at a pre-launch press briefing, CCC interim chair Prof Piers Forster said: “[This is] an optimistic report, [showing] that it is possible for the country to meet its climate commitments.”

Moreover, in comments aligned with the shift in language since last year, he said that the report was “more optimistic” than the 2024 edition. Forster explained:

“We are not a political organisation and our job as a committee is just to look at the evidence, but, in terms of looking at the evidence, we are more optimistic than we were this time last year.”

The reasons for this were a mixture of policies from the previous government starting to deliver and the impact of decisions taken by the new administration, he said.

While the tone is relatively optimistic, the latest progress report uses less prescriptive language than previous editions, according to Carbon Brief analysis shown in the figure below.

For example, the word “must” occurs once every 10 pages in this year’s report, down from seven times in 2021. Similarly, the word “should” only occurs four times per 10 pages, down from 13.

This shift in language appears to be a continuation of the approach taken by the committee in its advice on the UK’s seventh “carbon budget”, published in February.

(Under the Climate Change Act 2008, the government has until June 2026 to legislate for this budget, which is a legally binding emissions limit for the five-year period from 2038 to 2042.)

The committee has faced inaccurate criticism from some opponents of climate action, who have argued that it was, in effect, setting government policy.

Pushing back on this, Forster had reiterated in February: “[O]ur core responsibility…is to give…the very best non-partisan advice possible…It’s not up to us to make the policy, it’s up to government.”

Beyond the overall tone of the latest progress report, it also puts a stronger emphasis than last year’s on the need for action to reduce emissions.

It sets out the rationale for the world reaching net-zero carbon dioxide (CO2) emissions to stop global warming, but also asserts the benefits this would bring to the UK in terms of energy security, a more efficient economy and lower bills:

“[C]ontinued reliance on fossil fuels undermines UK energy security…[A] fossil-fuelled future would leave the UK increasingly dependent on imports, and energy bills would remain subject to volatile fossil fuel prices.”

In language that could be interpreted as pushback against the leader of the opposition, the Conservative’s Kemi Badenoch, who recently falsely claimed that reaching net-zero emissions by 2050 was both “impossible” and only possible “by bankrupting us”, the CCC report states:

“The science is unambiguous. Only by achieving net-zero CO2 emissions, with deep reductions in other greenhouse gases, can the UK stop contributing to an ever-warmer climate…The 2050 net-zero target for the UK remains deliverable and affordable, with whole-economy costs estimated at an annual average of 0.2% of GDP.”

Asked directly if he agreed that the net-zero by 2050 target was “impossible” and would come with “catastrophic” costs – as Badenoch has asserted – Forster said that on the contrary, it was “possible” and would, “ultimately, be good for the UK economy”. He told journalists:

“We think that, provided there is further government policy, it is possible both to reach our [2030 target], our carbon budgets and then, ultimately, get to net-zero…[and that] while the benefit doesn’t come instantly…it will, ultimately, be good for the UK economy.”

The report also makes the point that the UK is far from alone in its efforts, with global investments in clean-energy technologies reaching $2tn last year, double the sum going to fossil fuels. It adds:

“Most of the world is investing heavily in low-carbon technologies, driven by falling costs, energy security concerns and a realisation of the need to respond to rising climate impacts.”

(This is despite the Trump administration’s withdrawal from the Paris Agreement and a “period of uncertainty” in international relations since the US election, the report notes.)

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§ Overall progress

Last year’s report, published just days after Labour’s “landslide” election victory, had set the scene for the new administration, saying that it needed to “make up lost ground” to get back on track.

That report had called on the new government to “limit the damage” from Conservative climate policy rollbacks, which had been implemented ahead of the election.

This year’s report looks at how things have progressed since then, based on three sets of metrics:

• First, it looks at changes to the UK’s greenhouse gas emissions over the past year.
• Second, it looks at indicators of progress on the ground, such as the uptake of electric vehicles (EVs), the rollout of electric heat pumps and the rate of tree-planting.
• Third, it looks at policy changes introduced over the past year by the new government.

The assessment includes policy changes introduced up until 23 May 2025, meaning that it does not consider the June spending review or the industrial strategy published earlier this week.

Greenhouse gas emissions have more than halved since 1990, with a 50.4% reduction, making the UK “one of the leading economies in the world”, Forster said. The report adds:

“The UK should…be proud of its place among a leading group of economies demonstrating consistent and sustained decarbonisation.”

It says that UK emissions fell again during 2024, with a 2.5% reduction marking the tenth year of steady decline, excluding the Covid-19 pandemic and subsequent rebound.

Echoing Carbon Brief analysis published in March, the CCC says that the latest drop in emissions was due to the power sector, industry and transport, where EVs are starting to have an impact.

However, the report emphasises once again that progress to date has largely come in the electricity sector, where the UK became the first country in the G7 to phase out coal power in 2024.

Indeed, the CCC says that electricity supply is now only the UK’s sixth-largest source of emissions, after surface transport, buildings, industry, agriculture and aviation, as shown in the figure below.

In order to continue cutting emissions to meet UK climate goals, the CCC says that reductions will be needed across a broader range of sectors, including transport, buildings, industry and land-use.

The pace of emissions cuts outside the power sector – an average of 8m tonnes of CO2 equivalent (MtCO2e) per year since 2008 – is roughly on track for the fourth carbon budget covering 2023-27.

However, the report says this pace will need to “more than double” toward the end of the decade, hitting 19MtCO2e per year, in order to hit the UK’s NDC and sixth carbon budget.

Turning to the indicators of progress on the ground, the CCC says that there are some “clear signs” of such shifts starting to take place, in areas such as transport, buildings and land-use.

For example, the report points to “significant increases” in the rates of heat-pump rollout (up 56% year-on-year in 2024), tree-planting (+59%) and peatland restoration (+47%).

(See the sections below for further detail on policies and progress in each sector.)

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§ Policy gaps

Turning to its assessment of government climate policy, the CCC report says there has also been some “positive progress” since Labour came to office last year.

Specifically, it points to the removal of planning barriers for onshore wind and heat pumps, as well as implementation of the “clean heat market mechanism” to drive heat-pump sales, reinstatement of the 2030 combustion car ban and publication of the 2030 clean-power action plan.

As a result, the CCC says that there are now “credible policies” in place to make 38% of the emissions cuts needed to hit the UK’s 2030 target, up from 25% in 2023 and 32% last year.

At the same time, the share of emissions savings subject to policies facing “some” or “significant risks” has fallen from 53% in 2023 and 50% in 2024, down to 43% in the latest report.

These improvements are illustrated in the figure below, which shows that the credibility of UK climate policies towards the 2030 target has been steadily increasing.

Nevertheless, there are still “insufficient plans” to make 14% of the cuts needed by 2030, the same share as last year. The biggest policy gaps are around heat-pump rollout, the report says.

The CCC says: “With 39% of policies and plans needed to hit the 2030 NDC rated as having significant risks, or insufficient or unquantified plans, the government must act swiftly.”

The figure below illustrates the implications of falling to “act swiftly” more clearly.

If only the most “credible” policies actually deliver emissions savings (solid dark blue line) then the UK would miss its international targets for 2030 and 2035 (black circles) by significant margins.

The UK would get somewhat closer to its goals, if emissions cuts are successfully achieved as a result of policies subject to “some” (light blue) or “significant” delivery risks (grey line).

At the pre-launch briefing, Dr Emily Nurse, head of net-zero at the CCC, told journalists that further action was needed to get on track for the 2030 target. She said:

“Around three-fifths of what’s needed is covered by either credible plans or [those] having some risks…The UK can hit its upcoming emissions reduction targets and remain on track for net-zero, but only with further policy action.”

The government has the chance to fill these policy gaps when it publishes its updated “carbon budget delivery plan”, which has a deadline of 29 October this year.

This plan must set out how the government intends to meet the UK’s legally binding climate goals, after the previous administration’s plan was ruled unlawful by the High Court.

While there has been “good or moderate progress” on 20 of the 35 policy recommendations made last year, the CCC says there has been “no progress” on its top recommendation to make electricity cheaper.

The report says this remains its top recommendation for the second year in a row.

The reason for emphasising this, it says, is that electrification of transport, heat and industry will be the key to making required emissions cuts over the next decade, according to the CCC, with these shifts being facilitated by the expansion and continued decarbonisation of the power sector.

CCC chief executive Emma Pinchbeck told journalists that making progress in lowering electricity prices was “absolutely critical”, particularly relative to the price of gas. She said:

“The reason we keep banging on about [this], very simply, [is] that the evidence from every other country that’s had a successful rollout of electric technologies – particularly for heat – is that you need a three-to-one electricity-to-gas price ratio.”

(At present, domestic electricity prices are roughly four times higher than gas prices.)

Pinchbeck reiterated the committee’s call for the government to remove policy “levies” from electricity bills, adding that failing to do so would mean “slowing down” the transition. She said:

“If you’re effectively taxing your future fuel, you’re slowing down your energy transition, when the economy is going to become more and more dependent on electricity…It is just sensible economic policy to have cheap fuel going into your economy.”

While Pinchbeck welcomed plans in the government’s just-published industrial strategy to cut levies on industrial electricity bills, she said that it should do the same for households.

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§ Road transport

Road-transport emissions fell for a second consecutive year in 2024, says the report.

The number of electric vehicles (EVs) on UK roads is roughly doubling every two years.

If this trend continues, the road-transport sector will produce the emissions savings required for its contribution to the UK’s 2030 climate target, the CCC says (see below).

EVs made up 19.6% of new car sales in 2024, compared to 16.1% the previous year, according to the report. In the first quarter of 2025, this figure rose to 20.7%.

This represents “strong growth”, but is below the headline targets of the zero-emission vehicle (ZEV) mandate, a government regulation that requires car manufacturers to sell an increasing percentage of zero-emission vehicles each year, the CCC says.

The mandate targets a 22% market share for 2024 and a 28% share for 2025, according to the CCC.

The CCC notes that lower-cost EVs are becoming increasingly available. It adds that “price parity with petrol cars has already been reached in parts of the second-hand market”, with this milestone set to arrive for new cars by between 2026 and 2028.

Overall, there has been a “small improvement” in the UK’s policy efforts to decarbonise road transport since last year’s report, it says.

This is largely down to Labour’s decision to reinstate a 2030 ban on the sale of new petrol and diesel vehicles, which was weakened to 2035 under Conservative prime minister Rishi Sunak, explains the report.

The CCC describes the move as a “welcome market signal to accelerate the transition to EVs”.

As well as reinstating the 2030 ban, the government announced changes to the ZEV mandate.

The government essentially weakened the mandate by extending flexibilities and allowing the sale of hybrid vehicles between 2030 and 2035.

Ministers said this move was in response to import tariffs announced by Donald Trump. 

The CCC says the changes “risk allowing existing planned plugin hybrid vehicle sales to slightly reduce the emissions savings from EVs”, adding:

“It is also possible that manufacturers could divert investment towards [hybrids], diluting the consumer offer for EVs – we currently think that this risk is minimal due to progress in scaling up the EV market to date, but it is something that we will monitor closely.”

It adds that “for the transition to accelerate, further reductions in the cost of purchasing EVs, as well as improved access to, and reduced costs of, local public charging, are needed”.

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§ Buildings

Heat pump installations increased by 56% in 2024 compared to the year before, the report says. Some 98,000 heat pumps were installed.

A total of 23,000 heat pumps were installed under the Boiler Upgrade Scheme, which allows homeowners to claim grants for replacing fossil-fuel boilers. This is an increase of 83% on 2023 levels, says the CCC.

However, the speed at which heat pumps are rolled out remains one of the “biggest risks” to the UK meeting its 2030 climate target, it adds.

The UK’s heat pump market share is around 4%, much lower than comparable countries, such as Ireland (30%) and the Netherlands (31%), the CCC says.

The government has taken steps to “remove planning barriers” for heat pumps. This includes amending the planning policy in England to remove the requirement for planning permission for heat pumps located less than 1m from a property boundary.

However, the government has “not yet provided clarity on whether [it] will continue with the proposed phase-out of new fossil fuel boiler installations from 2035”, or “make alternative plans to ensure that low-carbon heating reaches the installation rates required”, the CCC says.

The report adds that the ratio of residential electricity to gas prices is “significantly off track”.

The ratio is important because it underpins the “underlying cost savings of switching to electric technologies are reflected in the bills paid by households and businesses”, the CCC says, continuing:

“Action has not been taken to remove policy costs from electricity prices which would address this, despite it being our first recommendation last year…Currently, a typical household with a heat pump is paying around £490 per year in policy costs, which inflate their bills above the underlying cost of the additional electricity used.”

Data from other nations suggests that the “market share of heat pump installations are correlated with more favourable electricity-to-gas price ratios”, says the CCC (see chart below).

Forster told the press briefing that the CCC’s “biggest recommendation” to government remains reducing the price of electricity in relation to gas:

“By far the most important recommendation we have for the government is to reduce the cost of electricity, both for households and for businesses and industry as well…If we want the country to benefit from the transition to electrification, we have to see it reflected in utility bills.” 

The report adds that, on efforts to increase the energy efficiency of residential buildings, the “proportion of homes with insulated cavity walls has steadily increased over recent years, but this will need to accelerate later in the decade” to be in line with net-zero.

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§ Industry

Industry emissions decreased by 4.7MtCO2e in 2024, compared to the year before, the CCC says. Emissions are now 48% lower than 2008 levels.

From 2023-24, annual emissions dropped quickly due to the removal of blast furnaces at Port Talbot steelworks in 2024. They are due to be replaced by electric arc furnaces by 2027, with the move leading to 2,500 job losses.

The government should have developed a “more proactive and decisive transition plan” for Port Talbot and the report describes the UK’s upcoming steel strategy as “an opportunity to set out plans for the low-carbon transition at Scunthorpe steelworks and other UK steel production”.

To deliver the emissions savings needed to meet the UK’s 2030 climate goal, companies will “increasingly need to switch to electric alternatives to fossil-fuelled technology”, the report says, adding:

“A high ratio of [industrial] electricity-to-gas prices currently presents a barrier to this.”

It adds that, currently, “there is now no major source of government support for manufacturers to invest in electrification”.

The CCC notes that the government did not launch the latest round of the Industrial Energy Transformation Fund, which was due in December 2024. It has “not clarified whether this or similar funding will continue”.

On 23 June, the UK government announced a 10-year industrial strategy, including measures to slash the price of electricity for energy-intensive businesses from 2027 by exempting them from green levies.

In the press briefing, Pinchbeck described the move as “good”, but urged the government to introduce similar measures for household electricity bills, too. (See: Buildings.)

On efforts to introduce carbon capture and storage (CCS) technologies to UK industries, the report says progress “is not on track to be deployed at the pace required” by government plans to reach net-zero.

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§ Fossil fuels and hydrogen

The report says that the UK’s “continued reliance on fossil fuels undermines energy security”, continuing:

“Household energy bills rose sharply following Russia’s invasion of Ukraine and have remained high since. It is the price of gas that has driven up both gas and electricity bills.”

(See Carbon Brief’s factcheck on what is causing high electricity bills in the UK.)

The report does not directly address the Labour government’s policies on oil and gas production in the North Sea.

Labour has ruled out new oil and gas licences. However, the government has indicated it might approve new projects that already have a licence, if they can pass a new environmental impact assessment that will consider the emissions from burning the oil and gas produced.

In regards to the North Sea, the report says:

“With North Sea resources largely used up, a fossil-fuelled future would leave the UK increasingly dependent on imports and energy bills would remain subject to volatile fossil fuel prices.”

The CCC adds that the “main progress in the fuel-supply sector in the past year has been around low-carbon hydrogen production”.

In the 2024 autumn budget, the government confirmed support for 11 “electrolytic”

hydrogen production projects, which are expected to start operating by the end of 2026. (These projects use electricity to split water into hydrogen and oxygen.)

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§ Electricity

The UK’s transition away from fossil fuels to renewable energy in its electricity supply continued to drive the bulk of emissions reductions in 2024, the CCC says. It accounted for 41% of the total in-year reduction in emissions.

From the 1990s until 2024, the power sector has transformed from the largest source of emissions to only the sixth largest, behind aviation. (See: Overall progress.)

The UK’s last coal-fired power plant, Ratcliffe-on-Soar, closed in October 2024. (See Carbon Brief’s detailed explainer on how the UK became the first G7 nation to phase out coal.)

Coal emissions from electricity generation were 99% lower in 2024 than in 2008 and will reach zero in 2025, the CCC says. It describes this as a “major milestone on the UK’s path to a decarbonised power system”.

Falling gas generation accounted for 72% of emissions reductions in the power sector in 2024, the CCC says. 

The electricity supplied by gas fell by 15% in 2024, compared to the previous year. This was “made up with roughly equal proportions of imports and low-carbon generation”.

The rollout of wind and solar capacity in 2024 was larger than in any of the previous six years, the report says.

But to achieve the government’s goal of “clean power” by 2030, total renewable capacity will need to more than double.

Based on projects in the pipeline, both offshore and onshore wind “appear on track” for the government’s goal, according to the CCC.

However, “roll-out of solar is significantly off track and will need to improve to deliver its contribution to a decarbonised electricity system”.

The report says that, overall, “positive policy progress has been made in decarbonising electricity supply over the past year”.

It continues that “concrete steps have been made to remove barriers and support the deployment of low-carbon technology”.

These steps include removing barriers facing onshore wind developments, “streamlin[ing]” the approval of nationally significant infrastructure, including renewable projects and introducing reforms to speed up connecting projects to the grid.

However, the CCC adds that there are “remaining uncertainties on the future electricity market arrangements and further challenges to deploying infrastructure to overcome”.

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§ Agriculture and land

There was a “significant increase” in both tree-planting and peatland restoration in 2024, the report says.

Some 20,700 hectares of new trees were planted, an increase of 59% on the year before and the highest rate in 20 years, it adds, as shown in the chart below.

Over the same period, the restoration of peatlands increased by 47%.

This “demonstrates that a rapid increase in rates is feasible” for the land-use sector, the CCC says.

However, woodland creation remains “slightly off track”. (Carbon Brief reported last year that successive UK governments have fallen so far short of their tree-planting targets since 2020 that they have failed to plant an area of forest nearly equivalent to the size of Birmingham.)

In addition, Scotland accounted for 73% of the total trees planted from 2023-24 and the CCC has “concerns that recent reductions in funding for woodland creation in Scotland could reverse this trend”.

A target to have 35,000 hectares of peat under restoration in England by 2025 is also “expected to be missed”.

Livestock numbers continued to fall in 2024, the report says.

Meat eating has declined steeply over the past couple of years. The average amount of meat eaten per person each week dropped by around 100g from 2020-22, according to CCC data.

Pinchbeck told the press briefing that meat-eating in the UK is now lower than what the CCC had anticipated in its central pathway for meeting net-zero:

“There’s lots of factors behind that, including the cost of living crisis. So we are not necessarily saying that trend will increase. Farming is facing a number of pressures, outside having to deal with a changing climate, reduced crop yields [and] difficulty making farms sustainable.”

Both the reduction in livestock and meat eating are “key to freeing up land required to increase tree-planting and peatland restoration”, the report says.

The government’s progress on addressing land-use sector emissions with policies has been “mixed” over the past year, according to the CCC.

The government is expected to produce a long-awaited land-use framework by the end of this year, but it “remains unclear how this framework will drive change on the ground”, the advisers say.

The government paused the sustainable farming incentive, part of the environmental land management (ELM) schemes, in March 2025.

This was due to all of the funding being allocated, which is “positive”, says the CCC. However, the decision has left a “gap in delivery grants for on-farm actions”.

The Nature for Climate Fund has been extended by one year, but is “unclear” what will happen to this scheme in the long term, it adds.

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§ Aviation and shipping

Emissions in the aviation sector increased by 9% year-on-year in 2024, “marking a return to pre-pandemic levels”, the report says.

In government and CCC scenarios for net-zero, emissions stay flat and start slowly decreasing over the rest of the decade, the report says, adding:

“Aviation emissions will likely exceed the trajectories assumed in all [these] pathways if they continue to increase, posing a risk to the UK’s emissions targets.”

The biggest driver of aviation emissions since 1990 has been “rising demand for international flights, particularly leisure”, it continues.

Aviation now causes more emissions than the UK’s entire power grid. In 1990, aviation emissions were 10 times lower than those from electricity, according to the report.

The CCC “recommends that the government should develop and implement policy that ensures the aviation sector takes responsibility for mitigating its emissions and, ultimately, achieving net-zero”, adding:

“This includes paying for permanent engineered removals to balance out all remaining emissions. Robust contingencies should also be in place to address any delays in decarbonisation, including through managing the forecasted increase in aviation demand.”

The share of sustainable aviation fuel (SAF) as a proportion of all jet fuel rose from 0.7% to 2.1% from 2023-24, the CCC says.

It notes that the SAF mandate came into force in January 2025 and the sustainable aviation fuel bill was introduced to parliament in May.

Achieving the government’s target of 10% of jet fuel from SAF by 2030 “remains uncertain as different types of SAF will need to scale up”, it adds.

There are currently no operational UK SAF plants, but some are under construction.

On shipping, the report notes that the UK has set out a maritime decarbonisation strategy, with an aim to reduce the domestic maritime sector’s fuel lifecycle emissions to zero by 2050 and interim goals of cutting pollution by 30% by 2030 and 80% by 2040, compared to 2008.

The targets are “broadly aligned” with government plans for net-zero, the CCC says.

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§ Other sectors

Another sector tracked by the CCC is “engineered removals”, technologies that suck CO2 out of the atmosphere.

Aside from small experiments, there is no deployment of such technologies in the UK. However, the government’s pathway for net-zero expects such methods to remove 6MtCO2e from the atmosphere by 2030, the report says, adding:

“This sector will need to develop and scale up notably over the coming five years.”

One of the CCC’s “top 10” priority actions is for the government to “finalise business models for large-scale deployment of engineered removals”.

On this, the advisers say:

“There has been little progress…This puts the contribution of engineered removals to the UK’s 2030 NDC at increasing risk.”

Another issue assessed by the CCC is waste, which produced 26.7MtCO2e in 2024, making it the eighth most polluting sector.

The report says there has been “some progress” on waste policy, but notes the government is “yet to confirm its intention to prevent biodegradable waste from going to landfill, a key measure to reduce emissions from waste”.

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§ Volcanic forcing in climate projections

Climate scientists refer to the influence volcanic eruptions have on the climate – largely through the release of sulphur dioxide gas into the atmosphere – as “volcanic forcing”.

Current climate models apply a constant volcanic forcing value when running future projections. This value is calculated based on the historical average of forcings from 1850 to the present day. 

This is the case with the Coupled Model Intercomparison Project (CMIP), the international modelling effort that feeds into the influential assessment reports from the Intergovernmental Panel on Climate Change (IPCC).

However, this approach has significant limitations. 

For starters, historically averaged forcing does not capture the episodic nature of eruptions. 

Large-magnitude volcanic eruptions happen sporadically – sometimes clustering within decades and other times leaving century-long gaps between events.

Meanwhile, the reference period of 1850 to the present day has seen a relatively low frequency of large-magnitude eruptions that emitted more than 3 teragrams (Tg) of sulphur dioxide (SO2), when compared to multimillennial records.

Finally, volcanic forcing reconstructions used in earlier generations of CMIP climate models did not include small-to-moderate magnitude eruptions that emitted less than 3Tg of SO2. 

This is because these eruptions went largely undetected before the satellite era began in 1980. Nonetheless, these smaller, but more frequent, eruptions contribute to 30-50% of long-term volcanic forcing.

§ Taking a new approach 

Traditionally, climate scientists have recognised three main sources of uncertainty in climate projections: internal variability, model uncertainty and scenario uncertainty. 

Here, “internal” variability refers to natural fluctuations that are generated within the climate system, such as by El Niño; model uncertainty refers to the differences in the results between multiple climate models; and scenario uncertainty refers to the different ways that the world could develop over the decades to come.

Our results show that volcanic eruptions should be specifically considered as a fourth significant source of uncertainty in climate projections. 

To explore how climate projections change when accounting for volcanic forcing uncertainty, our study uses a probabilistic approach that builds on a 2017 methodology developed by Bethke et al. 

To do this, we develop “stochastic forcing scenarios” – essentially, 1,000 different plausible timelines of volcanic activity extending to the end of the century. 

These scenarios draw from past volcanic activity recorded in ice cores going back 11,500 years, along with satellite measurements and geological evidence. Each scenario represents different combinations of eruption magnitudes, location, timing and frequency.

(In mathematics, “stochastic” systems involve randomness or uncertainty of outcome, making them unpredictable. This is in contrast to “deterministic” systems, which are characterised by having outcomes that are completely predictable based on initial conditions and a set of rules or equations.)

We then simulate climate projections using both stochastic and historically-averaged volcanic forcing between 2015 and 2100, exploring temperature rise under three different emissions scenarios drawn from the Shared Socioeconomic Pathways (SSPs). These are a low-emission scenario (SSP1-1.9), an intermediate scenario that is in line with current climate policies (SSP2-4.5) and a very-high emissions scenario (SSP5-8.5).

For this step, we use a simple climate model, or “emulator”, called FaIR.

By simulating 1,000 different volcanic futures, we find that the climate uncertainty caused by future 21st century eruptions could exceed the internal variability of the climate system itself over the same period. 

We also find that volcanic eruptions could account for more than one-third of total uncertainty in global temperature projections until the 2030s.

You can see these results in the plot below. It shows the contribution to the total uncertainty from the different sources. The colours represent volcanoes (orange), internal variability (dark blue), climate model response (yellow) and scenarios of future human emissions (green).

§ What this means for the 1.5C threshold

Our simulations demonstrate that incorporating possible timelines of volcanic activity slightly reduces the probability of crossing the Paris Agreement’s aspirational 1.5C temperature limit in the near term. 

We find that – depending on the emissions scenario – the probability of exceeding 1.5C decreases by 4-10%, compared to projections using constant volcanic forcing.

While this might sound encouraging, future volcanic activity does not provide any long-term mitigation of human-caused warming.

The eruption of Mount Tambora in 1815 offers a dramatic illustration of this point. While the event cooled global temperatures by an average of 0.8C, it led to a “year without a summer” and caused crop failures and widespread famine across Europe, North America and China.

Eruptions produce temporary cooling lasting just a few years. They do not alter the underlying warming trend driven by human emissions.

Our study finds that, taking into account a range of future volcanic activity, global warming will still exceed 1.5C within decades under all but the very lowest emissions scenarios. 

A high level of volcanic activity over the 21st century would help offset just a small fraction of global warming – meaning that emission reduction remains essential for meeting long-term climate goals. 

The charts below show the probability of scenarios exceeding 1.5C using stochastic volcanic forcing (solid lines) and constant volcanic forcing (dashed lines) under three emissions scenarios (top) and the difference in probability between the two forcing approaches (bottom).

§ Decadal-scale temperature variability

Another important insight from our research is that extreme warm and cold decades become more likely once the variability of volcanic forcing is accounted for.

We find that the chance of a negative decadal trend – a decade where global surface temperature cools on average – increases by 10-18% under the intermediate emissions scenario. 

We also find a corresponding increase in the probability of extremely warm decades, reflecting how volcanic forcing variability enhances the likelihood of both cooling and warming extremes.

This underscores how volcanic eruptions could introduce significant variability into the global temperature trends over decadal timescales. 

§ Toward better climate projections

Understanding volcanic effects on the climate is essential for comprehensively assessing future risks to agriculture, infrastructure and energy systems. 

Running thousands of volcanic scenarios with full-scale Earth system models is not practical as it requires too much computing power. On the other hand, current approaches have significant limitations, as described above.

However, there is a middle ground for future climate modelling efforts. 

The next phase of future climate modelling experiments – the Scenario Model Intercomparison Project for CMIP7 – can use a more representative “average” volcanic forcing baseline that incorporates the effects of small eruptions often missed in historical records. This bias has now been addressed in the historical volcanic forcing dataset that will underpin the next generation of climate model simulations. 

Additionally, modelling teams should run additional scenarios with high and low future volcanic activity to capture the range of volcanic uncertainty on climate projections.

While human-caused greenhouse gas emissions remain the dominant driver of climate change, properly accounting for volcanic uncertainty provides a more complete picture of possible climate futures and their implications for society. 

§ Solar and storage ‘gamechangers’

A solar panel generates most electricity when the sun is shining, meaning it cannot provide constant power throughout the year. Put another way, 100 watts (W) of solar capacity only generates around 20W on average – and that output will be concentrated in daylight hours.

Our report shows that battery energy storage can unlock solar’s full potential, by turning daytime generation into around-the-clock electricity.

Indeed, when paired with sufficient battery storage, that same 100W of solar capacity can provide electricity around the clock – up to 100% of the time.

This also means up to five times as much solar generation can be delivered using the same connection to the electricity network, reducing the need for costly grid upgrades.

Battery energy storage is now cheaper than ever, with global average prices falling by 40% in 2024 alone. The cost of a full battery system fell to a record-low $165 per kilowatt hour (kWh), according to BloombergNEF.

Additionally, there have been a number of technological improvements boosting battery energy storage. 

Recent innovations mean almost all grid batteries are now cobalt- and nickel-free, reducing the need for so-called “critical minerals”. They are longer-lasting than ever, with some batteries now having 20-year warranties. And they are safer than ever – with fire risk improving by a hundred-fold since 2019. 

Improved container design has also cut maintenance and installation costs. 

Our white paper shows that supply is ready to scale, with manufacturing capacity already exceeding demand. There is also significant new production capacity under construction outside of China. 

The next frontier is sodium-ion “salt” batteries, which would eliminate the need for lithium and drive prices down even further. One large salt-battery plant has already been commissioned in China.

These technological advances and declining costs mean the world’s first “24/365” battery and solar plants are now coming online:

• In Hawaii, several solar-plus-battery projects are providing electricity through the night after the decommissioning of the last coal power plant in 2022. 
• In the United Arab Emirates (UAE), at 100 megawatt (MW), Moro Hub is the world’s largest 100% solar-powered data centre, commissioned in 2022. 
• In Saudi Arabia, a tourist mega project, including 16 hotel resorts that are all powered entirely by solar electricity, was completed in 2023. 
• The first gigawatt-scale 24-hour solar project is already under development in the UAE. Emirati state-owned renewable energy company Masdar is leading the project, which was announced in January 2025 and will consist of a 5.2 gigawatt (GW) solar photovoltaic (PV) plant coupled with a 19 gigawatt hour (GWh) battery storage system to provide 1GW of uninterrupted solar electricity supply to the grid.

These examples show that 24/365 solar electricity has already been supplying customers and that it will increasingly start being used to power parts of the grid.

§ Cheaper in the sun 

In order to investigate the potential for 24/365 solar, Ember’s white paper modelled a hypothetical system, using real weather data, for a series of cities around the world.

The modelling is based on a system with 6GW of solar capacity and 17GWh of battery storage, because there are roughly 15 hours of darkness in winter in the mid-latitudes.

The modelling shows that solar and battery in the sunniest cities could already get more than 90% of the way to 24/365 solar generation, covering almost every hour of every day in the year.

For example, Muscat in Oman could draw on 1GW of continuous solar electricity for 99% of hours in the year, if it paired 6GW of solar panels with 17GWh of battery capacity. 

Las Vegas in the US, Mexico City in Mexico and Johannesburg in South Africa could all rely on such solar-plus-storage systems for at least 95% of hours in the year. 

Even Birmingham in the UK could achieve 1GW of solar output for 62% of hours annually. (This is lower than for sunnier cities due to a stronger seasonal cycle and cloudier weather.)

In the sunniest places, solar and storage could generate reliable output, close to 24/365, for around $100 per megawatt hour (MWh), based on average global costs for solar and batteries in 2024.

For each city, the yellow shading in the figure below shows the share of hours each year that it could rely on 1GW of solar output if it installed a 6GW solar plus 17GWh battery system, given historical weather conditions. 

Over the past year alone, the levelised cost of electricity (LCOE) for solar-plus-storage systems fell by 22%, driven by a 40% fall in battery prices. This is based on $165/kWh, which was BloombergNEF’s assessment of the global battery pack price at the end of 2024. The LCOE of solar and battery had fallen by 28% over the previous four years.

This makes solar with battery storage cheaper than both coal and nuclear when compared with US-based LCOE, as shown in the chart below. 

There is evidence that 2025 solar and battery prices will continue to fall again. Already in early 2025, tenders for large-scale battery storage projects in Tabuk and Hail, Saudi Arabia, reported battery prices as low as $72/kWh. 

§ Cloudy day challenges

Our modelling shows that the greatest challenge to generating constant, year-round electricity from solar plus storage is not nighttime, but clouds.

In the mid-latitudes, with around 15 hours of darkness in winter, around 17 hours of battery capacity is sufficient to bridge the period from sunset to sunrise.

This is because batteries typically do not fully charge and discharge to maintain high performance over time.

However, getting to 24/365 solar is harder, as while every day has daylight, not every day has full sunlight. Even though clouds do not reduce solar generation to zero – and despite batteries being cheaper than ever – extra battery storage is still not an economical option for bridging cloudy periods across multiple days.   

The graphic below illustrates this, based on the same 6GW solar plus 17GWh storage system as described before, generating electricity under the weather conditions and seasonal cycles of the same 12 cities around the world.

The chart for each city runs from January to December on the horizontal axis and across 24 hours of each day on the vertical axis. Direct use of solar power is shown in orange, with stored solar from the battery shown in yellow and periods with a shortfall in dark blue.

The figure shows that, even on the cloudiest day of the year in Muscat, this solar-plus-storage system would generate constant electricity for 18 hours. Madrid in Spain would see lower output on some shorter and cloudier days in November, December and January. In contrast, Hyderabad in India would be impacted in the summer by cloudy monsoon days. 

Overall, the figure shows that the sunniest cities would only fall slightly short of 24/365 solar electricity, but clouds would have a larger impact elsewhere.

§ The trade-off

The International Energy Agency (IEA) has described solar power as offering the “cheapest electricity in history”.

For example, solar power costs just $41/MWh in Las Vegas, according to Ember’s calculations using average global equipment and borrowing costs. However, this is only delivering electricity through daytime hours. As a result, on average around the world, solar has a “capacity factor” of 21% – meaning each unit of solar capacity generates 21% of its maximum theoretical output.

Raising this all the way to 97% raises the price to $104/MWh. However, this also substantially improves the value of solar, now that it is delivering close to 24/365. However, as the chart below shows, meeting the last few percent of demand from solar and storage alone significantly increases the price.

The best value between solar alone or solar with plentiful storage depends on the use case. 

It may be optimal to build solar without a battery, so long as a factory can access cheap grid electricity when the solar panels are not generating, for example. 

On the other hand, it may be optimal to build solar and batteries to get to 99.7% for an off-grid data centre that values reliability over price. Even in the most sunny places, exactly 100% supply will generally be uneconomic – but it is possible to get very close.

For many cases and based on current prices, the sweet spot may be to size the system for a constant supply of solar electricity for 60-90% of the time, our modelling suggests.

This provides cheap, low-carbon solar power most of the time. It would enable electricity to be used flexibly through the night or during high-price hours. 

If widely deployed, such systems would allow for a significantly downscaled need for grid investment, whether they are large-scale solar farms exporting more electricity to the grid or industrial sites drawing from public supplies less often.

§ This week

§ Three years to 1.5C

‘DOOMED TO BREACH’: At current carbon dioxide (CO2) emission levels, the world is “doomed to breach the symbolic 1.5C warming limit” in as little as three years, according to research by 60 climate scientists covered by BBC News. (Carbon Brief carried a guest post by two scientists involved in the study.) Co-author and Carbon Brief climate science contributor Dr Zeke Hausfather told the Washington Post: “Some reports, there’s a silver lining. I don’t think there really is one in this one.”

FLOODED AFRICA: South Africa declared a national disaster after floods killed more than 90 people in four of the country’s nine provinces, Bloomberg reported. This is the “second time in about seven months” that the government has invoked the measure to “free up funds for relief and reconstruction”, it added. Separately, 29 people were confirmed to have died “after heavy rains at the weekend triggered floods and landslides” in Kinshasa, the capital of the Democratic Republic of the Congo, the Associated Press reported.

CHINA DELUGE: Heavy rainfall fuelled by Typhoon Wutip has caused the “worst flood in a century” in China’s southern province of Guangdong, with the Sui river in the Huaiji county swelling to “over five metres above the official danger level…the highest on record”, reported state broadcaster CGTN. Local authorities have declared a “top-level emergency” as economic losses from the floods are estimated at $5.7m, the outlet added.

HURRICANE AND HEAT DOME: In North America, forecasters have warned that parts of the US could see “dangerously high temperatures and extreme humidity” from an incoming heat dome, the Wall Street Journal reported. The Associated Press reported that a “fast-moving brush fire” burned hundreds of acres and forced the evacuation of 50 Maui residents in Hawaii, even as 2023 wildfire survivors struggle with declining health, per the Guardian. Hurricane Erick made landfall on Mexico’s Pacific coast on Thursday “shortly after being downgraded slightly from an ‘extremely dangerous’ category 4” storm, noted BBC News.     

§ Bonn talks turn ‘bitter’

BEGIN AGAIN: The Bonn climate talks – the annual two-week preparatory talks held each June deemed “critical to thrash out differences” before each year’s COP – began on Monday “amid severe geopolitical turmoil and renewed tensions”, the Hindustan Times reported. It added that the meetings are shrouded by a “shadow of failed climate-finance talks” at COP29 in Baku, Azerbaijan last year and “divergent views” on a roadmap to raise climate finance to $1.3tn.

AGENDA FIGHT: The start of the talks was delayed by an “agenda row”, after Bolivia – on behalf of the Like-Minded Group of Developing Countries (LMDC) – sought to include items on climate finance from developed nations and “climate change-related trade-restrictive unilateral measures”, Climate Home News reported. Donald Trump’s administration “decided…not to send a delegation to the preparatory meetings” – meaning the US was absent in Bonn for the first time ever, it added. 
‘BITTER EXCHANGES’: After 30 hours of “bitter exchanges”, the agenda was adopted on Tuesday​​ “to polite applause and a bigger sense of discontent”, another Climate Home News article said. The Bonn chairs agreed to hold “substantive consultations” on climate finance and report back in Belém at COP30, it continued. Negotiators can now “turn their full attention to equally thorny discussions” on climate adaptation indicators and fossil fuels, it added. (Carbon Brief’s Josh Gabbatiss and Molly Lempriere will report live from Bonn next week.)

§ Around the world

• BRUSSELS BAN: The European Commission tabled a bill that, according to Euractiv, “would phase out the large volumes of Russian gas still flowing into the EU until the end of 2027”, adding that the ban would stand “irrespective of whether there is peace” in Ukraine. 
• UK-CHINA MEET: UK officials including energy secretary Ed Miliband, climate envoy Rachel Kyte and nature envoy Ruth Davies sat down with Chinese counterparts, including the head of China’s Ministry of Economy and Environment, in London this week to discuss the “next steps of climate cooperation”, according to Chinese business publication Jiemian News.
• AMAZON OIL BID: Brazil’s national oil agency has “auctioned off” several oil sites near the mouth of the Amazon river and two inland sites near Indigenous territories months before the country is due to host COP30, the Associated Press reported.
• BLACKOUT BLACK BOX: Spain announced the findings of a 49-day probe into the “catastrophic” Iberian blackout, the Financial Times reported, “spread[ing] the blame…between its grid operator and electricity companies”. (See Carbon Brief’s updated Q&A.) 
• MISINFORMATION MEASURED: A review of 300 studies found that action on climate change is being “obstructed and delayed by false and misleading information stemming from fossil-fuel companies, rightwing politicians and some nation states”, the Guardian said.
• OIL PEAK EARLY: According to the International Energy Agency (IEA), China’s oil demand will peak in 2027, two years earlier than previously forecast, Bloomberg reported. At the same time, India’s “thirst for oil will rise more than any other country” over the next five years, wrote the Times of India. 

§ 120 kcal

The amount of calories the average person could lose per day for every 1C of warming, due to climate change’s impact on six key crops, according to research covered by Carbon Brief.

§ Latest climate research

• New forests larger than the size of North America would need to be planted to offset the potential CO2 emissions from fossil fuel reserves held by the world’s top 200 fossil fuel companies, found new analysis in Communications Earth & Environment.
• According to new research in Science Advances, human-driven climate change will remove coral habitat faster than corals can expand into higher-latitude, cooler waters. It found that severe coral cover declines will likely occur over the next 40-80 years, while large-scale expansion “requires centuries”.
• New rapid analysis by World Weather Attribution estimated that climate change will make Saturday’s “widespread heat” of 32C in southeast England “about 100 times” more likely. 

(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)

§ Captured

Carbon Brief charted eight decades of the UK’s nuclear energy fleet – from setting up the world’s first commercial reactor in Cumbria in 1956 to UK chancellor Rachel Reeves greenlighting the Sizewell C reactor last week. The chart shows the contribution of each of the UK’s nuclear plants to the country’s overall capacity, according to when they started and stopped operating. It also shows timelines for new planned nuclear capacity yet to come on board, plus known planned closure dates.

§ Spotlight

Forecasting Mumbai’s fierce monsoon

This week, Carbon Brief visits Mumbai’s official monsoon monitoring centre and “war room” to examine how the city is responding to its earliest downpour on record.

If extreme weather had a poster-child capital, it would be Mumbai. The megacity has it all – catastrophic urban flooding every monsoon, sea level rise, landslides, climate-change induced tropical cyclones, heatwaves across all its seven islands – and, with further climate change, it will only get worse.

Famed for its “spirit”, Mumbai’s 26 million metropolis dwellers have come to loathe the term that valorises their resilience every monsoon, evident from the memes that flooded the internet on 26 May when the monsoon arrived earlier than ever before in the city’s history.

On its first monsoon day of the year, the city received 135.4mm of rainfall rather than its normal of 0.2mm – an excess of 67,600%. Visuals of a flooded metro line that opened only 17 days ago went viral. 

Faced with criticism, the state’s deputy chief minister Eknath Shinde equated the rains to a “cloudburst” and admitted that the country’s richest civic body – that he heads in the absence of elected representatives – was caught off-guard this year.

Despite having a year to prepare, Shinde admitted that pumps meant to remove water from a city that is barely above sea level were not working to full capacity. They stand in sharp contrast to the billion-dollar highways that have robbed the city of its natural flood defences and now dominate its skyline and waterfront, but are already being overwhelmed by extreme weather. 

In India’s financial capital – where 73% of all offices and commercial establishments are within 500m of a flood hotspot and 69% of all employees experience “hindered access” from waterlogging trying to get to or leave work – forecasting the monsoon is fraught, essential and getting trickier with climate change. 

Forecasting the monsoon

Dr Sushma Nair, a meteorologist with the India Meteorological Department’s (IMD) regional monitoring centre, has the unenviable job of getting it right. 

Nair and her team work out of the Colaba Observatory, at the southernmost tip of the city. Established in 1826 by the East India Company, it is one of world’s longest-running observatories and is older than the IMD itself – as well as many parts of the city that have been reclaimed from the sea. 

“As weather-in-charge, it’s a 24/7 job,” Nair told Carbon Brief during a visit to the observatory.

Nair’s day begins at 8:30am, when her team prepares a forecast, checks upper air observations, runs models and decides what colour – yellow, orange or red – to assign the region for the next 24 hours, before hopping on a video call with her regional contemporaries and the IMD HQ.

“No journalist will get a forecast from us before 11:30 or 12:30, because we are discussing the weather,” she said.

Meteorological Centre has a Nowcast that refreshes every three hours, allowing forecasters to account for sudden changes in the weather and upgrade the city to a red alert, based on satellite and radar warnings.

Nair confesses that she “normally” checks the Nowcast at 4am, “because I lose my sleep at 3am”, and has the city’s chief disaster manager on speed dial for a red nowcast, no matter what the hour. “I am an insomniac, so don’t take that as a regular forecaster’s sleep hours,” she joked.

Her biggest source of dread is two-hour intense downpours in which the island city receives more than 150mm of rain, caused by an offshore vortex that is a “very small-scale, sub-grid system” that weather models cannot capture. She said:

“Low-pressure cyclonic systems, we can see coming. [But] this is the goblin that I haven’t seen who rushes in usually at night, creates havoc and leaves. Climate change is already contributing to these types of events: a whole lot of rain in smaller spells.” 

As a coastal city, scientists told Carbon Brief that the city should be prepared to soak in 300mm of rain, but, because of choked drains, rivers and built infrastructure, it currently cannot even take in 100mm. 

Mumbai’s monsoon ‘war room’

Fifteen minutes away from the observatory, a whiteboard in the Brihanmumbai Municipal Corporation’s (BMC) “monsoon war room” shows the state of affairs: rivers that should have been desilted by May are still only 66% done.

In its disaster control room three flights down, the phones will not stop ringing. The city’s residents, police and fire brigades are calling to report waterlogging, fallen branches and landslides. 

While one giant screen streams live CCTV footage from 25 of the city’s worst traffic chokepoints, another screen shows live Doppler radar footage – when it is working. 

“Whatever resources an emergency needs, we mobilise them from this control room,” a senior BMC disaster management official told Carbon Brief:

“If we get an orange alert from the IMD, all of our agencies, the navy, army: all of them get an alert message from us asking them to stand by.” 

Many fault the BMC for delayed alerts, desilting and a city dug up beyond recognition. Officials say they are using all platforms – from X to SMS – to warn people about monsoon impacts. They blame TV channels that have “stopped carrying the news” – and people who have stopped watching it for weather updates – for a lack of awareness. The official told Carbon Brief:

“We have sufficient funds. You can’t reduce natural hazards and, in such a crowded city, to survive, the only thing that can save you is your wits.”

§ Watch, read, listen

ET TU, PETROSTATE? A Foreign Affairs essay by two US professors argued that, as the US’s energy exports have grown, it has “begun to behave more like a classic petrostate”, less likely to “embrace multilateralism and cooperate on international rules”. 

ADRIAN VS ADANI: BBC World Service’s Life at 50C had a new documentary following Indigenous Queenslander Adrian Burragubba’s “battle against Adani[‘s]” coal mine in Australia’s Galilee Basin. 

NO SHADE: Adaptation policy researcher Aditya Valiathan Pillai spoke to the Migration Story about heat stress and the “politics of shade”.

§ Coming up

• 16-26 June: SB42 climate talks, Bonn
• 16-20 June: 79th meeting of the World Meteorological Organization’s Executive Council, Geneva
• 23 June-4 July: International Seabed Authority legal and technical commission meeting (Part II), Kingston
• 23-27 June: States parties to the United Nations Convention on the Law of the Sea, 35th meeting, New York

§ Pick of the jobs

• Bruegel, energy and climate economist | Salary: Unknown. Location: Brussels
• The Economist, editorial intern for the digital department | Salary: £30,000. Location: London
• Bertha Foundation, fellowship for filmmakers, lawyers and jouranalists | Fellowship: Up to $64,900 for a year. Location: Remote 

DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to debriefed@carbonbrief.org.

This is an online version of Carbon Brief’s weekly DeBriefed email newsletter. Subscribe for free here.

§ Who are you calling old?

How do you tell how old carbon is? We employ the same technique that is used to determine the age of an archaeological relic or to verify the age of a vintage wine – that is, radiocarbon dating.

Radiocarbon is the radioactive isotope of carbon, which decays at a known rate. This enables us to determine the age of carbon-based materials dating back to a maximum age of about 60,000 years old.

We know that some of the carbon that rivers release is very young, a product of recent CO2 uptake by plants.

We also know that rivers can receive carbon from much older sources, such as the decomposition of deep soils by microbes and soil organisms or the weathering and erosion of ancient carbon in rocks.

Soil decomposition can release carbon ranging from a few years to tens of thousands of years. An example of very old soil carbon release is from thawing permafrost.

Rock weathering and erosion releases carbon that is millions of years old. This is sometimes referred to as “radiocarbon-dead” because it is so old all the radiocarbon has decayed.

§ Rivers are emitting old carbon

In our new study, we compile new and existing radiocarbon dates of the CO2 emissions from around 700 stretches of river around the world.

We find that almost 60% of the carbon being released to the atmosphere by rivers is from older sources (hundreds to thousands of years old, or older), such as old soil and ancient rock carbon.

In the figure below, we suggest how different processes taking place within a landscape can release carbon of different ages into rivers, driving its direct emission to the atmosphere.

So, while rivers are leaking some modern carbon from plants and soils as part of the landscape processes that remove CO2 from the atmosphere, rivers are also leaking carbon from much older landscape carbon stores.

One major implication of this finding is that modern plants and soils are leaking less carbon back to the atmosphere than previously thought, making them more important for mitigating human-caused climate change.

We find that the proportion of old carbon contributing to river emissions varies across different ecosystems and the underlying geology of the landscapes they drain.

In the figure below, we show that landscapes underlain by sedimentary rocks, which are the most likely to contain substantial ancient (or “petrogenic”) carbon, also had the oldest river emissions. We also show that the type of ecosystem (biome) was also important, although the patterns were less clear.

What is obvious is that at least some old carbon was common across most of the rivers we observed, regardless of size and location.

We provide evidence that there is a geological control on river emissions. And the variability in the ecosystem also indicates important controlling factors, such as soil characteristics, vegetation type and climate – especially rainfall patterns and temperature which are known to impact the rate of carbon release from soils and rock weathering.

§ Are old carbon stores stable?

Long-term carbon storage in soils and rocks is an important process regulating global climate.

For example, the UK’s peatlands are important for regulating climate because they can store carbon for thousands of years. That is why restoring peatlands is such a great climate solution.

Rivers emit more than 7bn tonnes of CO2 to the atmosphere each year – that’s equivalent to about 10-20% of the global emissions from fossil fuel burning annually.

If 60% of river carbon emissions are coming from old carbon stores, then this constitutes a significant leak of carbon from old stores we thought were safely locked away.

Another major implication of our study is that these old carbon stores can be mobilised and routed directly to the atmosphere by rivers, which would exacerbate climate change if these stores are further destabilised.

As can be seen in the figure below, we found that river carbon emissions appeared to be getting older since measurements first began in the 1990s (lower F14Catm means older radiocarbon ages).

We found that river carbon emissions appeared to be getting older since measurements first began in the 1990s.

While there are several caveats to interpreting this trend, it is a warning sign that human activities, especially climate change, could intensify the release of carbon to the atmosphere via rivers.

Given the strong link between soil carbon and river emissions, if this trend is a sign of human activity disturbing the global carbon cycle, it is likely due to landscape disturbance mobilising soil carbon.

§ Using rivers to monitor global soil carbon storage

Rivers collect waters from across the landscapes they flow through and therefore provide a tool to track processes happening out of sight. 

A drop of water landing in a landscape travels through soils and rock before reaching the river, and its chemistry, including its radiocarbon age, reflects the processes occurring within the landscape.

Monitoring the age of carbon in rivers can therefore tell you a lot about whether their landscapes are storing or releasing carbon.

This has been shown to help identify carbon loss in degraded tropical peatlands, thawing Arctic permafrost and due to deforestation.

River radiocarbon is sensitive to environmental change and could therefore be a powerful monitoring tool for detecting the onset of climate tipping points or the success of landscape restoration projects, for example.

While we present data spread out across the world, there are quite a few gaps for important regions, notably where glacier change is happening and others where droughts and flood frequencies are changing. 

These include areas with low amounts of data in Greenland, the African continent, the Arctic and Boreal zones, the Middle East, eastern Europe, western Russia, Central Asia, Australasia and South America outside of the Amazon. 

All these regions have the potential to store carbon in the long-term and we do not yet know if these carbon stores are stable or not under present and future climate change.

River radiocarbon offers a powerful method to keep tabs on the health of global ecosystems both now and into the future.

§ An ‘unexceptional’ record high

Last year likely saw global average surface temperatures hit at least 1.5C above pre-industrial levels. This aligns with other major assessments of the Earth’s climate.  

Our best estimate is a rise of 1.52C (with a range of 1.39-1.65C), of which human activity contributed around 1.36C. The rest is the result of natural variability in the climate system, which also plays a role in shaping global temperatures from one year to the next.

Our estimate of 1.52C differs slightly from the 1.55C given by the World Meteorological Organisation (WMO) state of the global climate 2024 report, published earlier this year. This is because they make slightly different selections on which of the available global land and ocean temperature datasets to include. (The warming estimate has varied by similar amounts in past years and future work will aim to harmonise the approaches.)

The height of 2024’s temperatures, while unprecedented in at least the last 2,000 years, is not surprising. Given the high level of human-induced warming, we might currently expect to see annual temperatures above 1.5C on average one year in six. 

However, with 2024 following an El Niño year, waters in the North Atlantic were warmer than average. These conditions raise this likelihood to an expectation that 1.5C is surpassed every other year.

From now on, we should regard 2024’s observed temperatures as unexceptional. Temperature records will continue to be broken as human-caused temperature rise also increases.

§ Longer-term temperature change

Despite observed global temperatures likely rising by more than 1.5C in 2024, this does not equate to a breach of the Paris Agreement’s temperature goal, which refers to long-term temperature change caused by human activity.

IGCC also looks at how temperatures are changing over the most recent decade, in line with IPCC assessments.

Over 2015-24, global average temperatures were 1.24C higher than pre-industrial levels. Of this, 1.22C was caused by human activity. So, essentially, all the global warming seen over the past decade was caused by humans.

Observed global average temperatures over 2015-24 were also 0.31C warmer than the previous decade (2005-14). This is unsurprising given the high rates of human-caused warming over the same period, reaching a best estimate of 0.27C per decade.

This rate of warming is large and unprecedented. Over land, where people live, temperatures are rising even faster than the global average, leading to record extreme temperatures.  

But every fraction of a degree matters, increasing climate impacts and loss and damage that is already affecting billions of people. 

§ Driven by emissions

Undoubtedly, these changes are being caused by GHG emissions remaining at an all-time high.

Over the last decade, human activities have released, on average, the equivalent of around 53bn tonnes of CO2 into the atmosphere each year. (The figure of 53bn tonnes expresses the total warming effect of CO2 and other greenhouse gases, such as methane and nitrous oxide, using CO2 as a reference point.) 

Emissions have shown no sign of the peak by 2025 and rapid decline to net-zero required to limit global warming to 1.5C with no or limited “overshoot”.  

Most of these emissions were from fossil fuels and industry. There are signs that energy use and emissions are rising due to air conditioning use during summer heatwaves. Last year also saw high levels of emissions from tropical deforestation due to forest fires, partly related to dry conditions caused by El Niño.  

Notably, emissions from international aviation – the sector with the steepest drop in emissions during the Covid-19 pandemic – returned to pre-pandemic levels.

The amount of CO2 in the atmosphere, alongside the other major GHGs of methane (CH4) and nitrous oxide (N2O), is continuing to build up to record levels. Their concentrations have increased by 3.1, 3.4 and 1.7%, respectively, since the 2019 values reported in the last IPCC assessment.   

At the same time, aerosol emissions, which have a cooling effect, are continuing to fall as a result of important efforts to tackle air pollution. This is currently adding to the rate of GHG warming. 

Notably, cutting CH4 emissions, which are also short-lived in the atmosphere, could offset this rise. But, again, there is no real sign of a fall – despite major initiatives such as the Global Methane Pledge.

The effect of all human drivers of climate change on the Earth’s energy balance is measured as “radiative forcing”. Our estimate of this radiative forcing in 2024 is 2.97 Watts per square metre (W/m2), 9% above the value recorded in 2019 that was quoted in the last IPCC assessment.

This is shown in the figure below, which illustrates the percentage change in an array of climate indicators since the data update given in the last IPCC climate science report.

Continued emissions and rising temperatures are meanwhile rapidly eating into the remaining carbon budget, the total amount of CO2 that can be emitted if global warming is to be kept below 1.5C. 

Our central estimate of the remaining carbon budget from the start of 2025 is 130bn tonnes of CO2. 

This has fallen by almost three-quarters since the start of 2020. It would be exhausted in a little more than three years of global emissions, at current levels.

However, given the uncertainties involved in calculating the remaining carbon budget, the actual value could lie between 30 and 320bn tonnes, meaning that it could also be exhausted sooner – or later than expected.  

§ Beyond global temperatures

Our assessment also shows how surplus heat is accumulating in the Earth’s system at an accelerating rate, becoming increasingly out of balance and driving changes around the world.

The data and their changes are displayed on a dedicated Climate Change Tracker platform, shown below.

The radiative forcing of 2.97 W/m2 adds heat to the climate system. As the world warms in response, much of this excess heat radiates to space, until a new balance is restored. The residual level of heating is termed the Earth’s “energy imbalance” and is an indication of how far out of balance the climate system is and the warming still to come.   

This residual rate of heat entering the Earth system has now approximately doubled from levels seen in the 1970s and 1980s, to around 1W/m2 on average during the period 2012-24.  

Although the ocean is storing an estimated 91% of this excess heat, mitigating some of the warming we would otherwise see at the Earth’s surface, it brings other impacts, including sea level rise and marine heatwaves. 

Global average sea level rise, from both the melting of ice sheets and thermal expansion due to deep ocean warming, is included in the IGCC assessment for the first time. 

We find that it has increased by around 26mm over the last six years (2019-24), more than double the long-term rate. This is the indicator that shows the clearest evidence of an acceleration. 

Sea level rise is making storm surges more damaging and causing more coastal erosion, having the greatest impact on low-lying coastal areas. The 2019 IPCC special report on the oceans and cryosphere estimated that more than one billion people would be living in such low-lying coastal zones by 2050.

§ Multiple indicators

Overall, our indicators provide multiple lines of evidence all pointing in the same direction to provide a clear and consistent – but unsurprising and worsening – picture of the climate system.

It is also now inevitable that global temperatures will reach 1.5C of long-term warming in the next few years unless society takes drastic, transformative action – both in cutting GHG emissions and stopping deforestation.

Every year of delay brings reaching 1.5C – or even higher temperatures – closer.  

This year, countries are unveiling new “nationally determined contributions” (NDCs), the national climate commitments aimed at collectively reducing GHG emissions and tackling climate change in line with the Paris Agreement.

While the plans put forward so far represent a step in the right direction, they still fall far short of what is needed to significantly reduce, let alone stop, the rate of warming.

At the same time, evidence-based decision-making relies on international expertise, collaboration and global datasets. 

Our annual update relies on data from NASA and the National Oceanic and Atmospheric Administration (NOAA) and input from many of their highly respected scientists. It is this type of collaboration that allows scientists to generate well-calibrated global datasets that can be used to produce trusted data on changes in the Earth system. 

It would not be possible to maintain the consistent long-term datasets employed in our study if their work is interrupted. 

At a time when the planet is changing at the fastest rate since records began, we are at risk of failing to track key indicators – such as greenhouse gas concentrations or deep ocean temperatures – and losing core expertise that is vital for understanding the data.

§ Key developments

Ocean warming woes

NEAR-RECORD HIGHS: Global ocean temperatures remain “near record temperatures”, according to data from the EU’s Copernicus Earth-monitoring service, which was covered by the Financial Times. Dr Julien Nicolas, a senior scientist at Copernicus, said the warmer-than-usual oceans of 2023 and 2024 were “partly driven” by the El Niño phenomenon, but that the continued highs “underscore the long-term warming trend”. Meanwhile, the Sydney Morning Herald said that a marine heatwave currently stretching across 40m km2 of the south-western Pacific Ocean was “bringing intense heat, extreme rainfall and sea level rise” to the region.

‘UNUSUALLY INTENSE’: The New York Times carried an interactive looking at how marine heatwaves have increased in frequency over the past few decades. It noted that the UK and Irish coasts have “experienced an unusually intense marine heatwave, one of the longest on record” in recent months. It also pointed out that most studies of marine heatwaves focus on a very small number of countries. Dr Dan Smale, a community ecologist at the UK’s Marine Biological Association, told the newspaper: “There are lots of regions around the world where monitoring isn’t as good as other places and so we don’t really know what’s happening.”

‘UNPRECEDENTED HEATWAVE’: Western Australia’s Ningaloo reef has been hit by an “unprecedented heatwave” since August 2024, “turning corals white” across a 1,500km span of reef, the Guardian said. It added that “government scientists are reporting widespread coral death, which they say is the worst bleaching to hit the state…The scale of mortality has left many shocked.” Temperatures on western Australia’s reefs have “reached as high as or higher than ever recorded”, according to Dr James Gilmour, a research scientist at the Australian Institute of Marine Science. The Guardian delved into the emotions affecting the scientists who study the reef.

New deforestation rates in Latin America

SETBACK IN BRAZIL: Deforestation in the Brazilian Amazon surged 92% in May compared to the same period last year, according to official monitoring data covered by the Associated Press. The data showed 960km2 of forest loss, an area “slightly larger than New York City”, the newswire added. João Paulo Capobianco, executive secretary of Brazil’s ministry of the environment, told the outlet that wildfires have become one of the major drivers of deforestation in the Amazon. He called on countries to support the Tropical Forests Forever fund, a scheme proposed by Brazil to compensate for forest conservation, the article noted. 

PERU NOT FALLING BEHIND: Peru lost 4.1m hectares (41,000km2) of forest – an area the size of Switzerland – in the last 40 years, according to a report released by the MapBiomas Peru platform and covered by Mongabay. Agricultural activities lead the list of drivers of deforestation, especially with oil palm and rice plantations, followed by mining, the outlet noted. The report found that the Amazon and the equatorial dry forest are the ecosystems most affected by deforestation, with the latter losing 9% of its territory compared to the 1985 level.

COLOMBIA REDUCES DEFORESTATION: Colombia’s environment ministry announced a decrease in deforestation of 33% early this year, compared to the same period in 2024, the Washington Post reported. The outlet cited Colombia’s environment minister, Lena Estrada, who said deforestation fell from 40,219 hectares (402km2) in early 2024 to 27,000 hectares (270km2) so far this year. The biggest reductions took place in Amazon national parks, due to “community coordination and a crackdown on environmental crime”, the ministry said. The outlet added that the Colombian Amazon holds the highest levels of deforestation in Colombia, accounting for 69% of the country’s deforestation.

§ Spotlight

Three key takeaways from the UN ocean summit 

In this Spotlight, Carbon Brief highlights three key takeaways of the third UN ocean summit.

The third UN Ocean Conference ended last Friday (13 June) after a week of negotiations covering various aspects of the problems faced by the world’s oceans – including pollution, overfishing and the share of the benefits from the use of genetic resources in the high seas.

The summit took place in the French port of Nice and was co-hosted by France and Costa Rica. It brought together 15,000 attendees, including more than 60 heads of state and government.

High Seas Treaty ratifications 

The agreement on Biodiversity Beyond National Jurisdiction (BBNJ), also known as the High Seas Treaty, was adopted in 2023 after 20 years of negotiations. 

The treaty aims to “safeguard marine life in international waters”.

During the conference, 19 countries ratified the treaty, taking the total to 50 of the 60 countries required for the treaty to enter into force. According to BBC News, dozens of other countries also indicated their intent to ratify the treaty in the near future.

Sara Zelaya, a biologist and the senior advocacy officer for the ecosystems programme at the Inter-American Association for Environmental Defence, said that she hopes the treaty will complement other global governance mechanisms and allow for the fairer use of the “common heritage of mankind” that is the ocean. 

She told Carbon Brief:

“For the global south, it brings a little bit of justice – or at least a hope of justice – in the sense of how we are using the resources in the high seas”.

José Julio Casas, technical secretary of the Eastern Tropical Pacific Marine Corridor (CMAR) encompassing Costa Rica, Panama, Colombia and Ecuador, told Carbon Brief that ratification of the agreement would see countries able to restrict the activities that can be implemented in specific areas of the high seas, according to their economic, ecological and social relevance.

New commitments 

The conference saw several countries commit to ocean conservation funding.

The European Commission announced the largest investment of the summit, worth €1bn, for ocean conservation, science and sustainable fishing. Germany and New Zealand committed to allocate $115m and $52m, respectively, for conserving and strengthening the ocean governance of their territorial waters.

Several countries also committed to protecting large swathes of their ocean. French Polynesia pledged to create the world’s largest marine protected area, which will encompass around 5m km2 of ocean. Spain said it will establish five new marine protected areas.

Panama and Canada jointly announced the formation of a 37-country coalition called the High Ambition Coalition for a Quiet Ocean, which will focus on addressing ocean noise pollution.

Zelaya said that to make sure that these commitments translate into effective conservation of marine ecosystems, countries should include and prioritise oceans in their public policies and allocate specific budgets for ocean conservation.

The UN Ocean Declaration

At the summit, more than 170 countries adopted the Nice Ocean Action Plan, comprising a political declaration to commit to “urgent action” to protect the world’s oceans and a list of voluntary commitments. 

The declaration calls on countries to boost ocean protection, reduce marine pollution, regulate the high seas and provide finance for vulnerable countries and island nations. 

Alongside the political declaration are more than 800 voluntary commitments from a range of stakeholders, such as governments, scientists, civil society and UN agencies.

Mongabay reported that the Nice declaration is not legally binding, but “is intended to reflect the willingness of countries to invest more in ocean protection”. However, it added, reducing the use of fossil fuels was left out of the discussions. 

Casas told Carbon Brief that governments now need to demonstrate “political commitment”. He said that such commitments are “improving”, but they “must be accompanied by financial support”.

The fourth UN Ocean Conference is to take place in 2028 and will be co-hosted by Chile and South Korea. 

§ News and views

HARVEST AT RISK: UK farmers could face “another terrible harvest” after the country registered its “hottest spring on record and the driest conditions in decades”, according to an analysis by the Energy and Climate Intelligence Unit thinktank, covered by the Press Association. It found that the production of crops, such as wheat, barley, oats and oilseed rape, “could once again be near all-time lows”. This year, the UK saw its driest spring in the last 50 years, with rainfall 40% lower than average, the outlet added. 

WHALE, WHALE, WHALE: Angelika Lātūfuipeka Tukuʻaho, the princess of Tonga, called for the “recognition of whales as legal persons” during the UN Ocean Summit in Nice, France, last week, Inside Climate News said. Lātūfuipeka Tukuʻaho told the conference: “The time has come to recognise whales not merely as resources, but as sentient beings with inherent rights.” The outlet added that the Pacific island nation could move forward with legislation ensuring this recognition and allowing for “appointing human guardians to represent [whales] in court”. The bill would also seek to ensure whales’ “rights to life, migration, a healthy habitat and cultural protection”, Inside Climate News added.

RED LINES: India has staked out “clear red lines” on certain agricultural export items in its ongoing trade negotiations with the US, Business Standard reported. The outlet outlined three categories for the country’s commodities: “non-negotiable, very sensitive and liberal – based on their economic and political sensitivity”. The outlet said that “no tariff concessions will be entertained” in India on agricultural staples, such as wheat and rice, while “high-value” crops primarily consumed by the higher-income portion of the population would fall under the “liberal” categorisation.

FROM PLEDGES TO ACTION: Experts interviewed by the Brazilian outlet ((o))eco stressed the need to implement Brazil’s national biodiversity strategy and action plan (NBSAP). The NBSAP, which is a plan submitted to the UN Convention on Biological Diversity, aims to increase funding and political support for the conservation and sustainable use of Brazil’s biodiversity. Prof Alexander Turra from the Oceanographic Institute of the University of São Paulo said that although the NBSAP is aligned with international agreements, Brazil has not “necessarily succeeded” in achieving its strategy, adding that the country “[needs] to make a huge effort to implement it”.

§ Watch, read, listen

ALREADY MANDATORY: In a video, Deutsche Welle explained how New York City is composting organic waste, now that it has made it mandatory for residents to separate it from their rubbish.

‘SPONGE PARKS’: A NPR podcast addressed how Copenhagen has converted 20 green areas into “sponge parks” to hold rainfall as part of efforts to adapt to climate change.

JUST NATURE: A France24 video reported on how farmers and scientists are working together in western France to re-establish its biodiversity by avoiding chemical fertilisers and pesticides.

BEYOND ELECTRIC VEHICLES: A BBC News article shared drone images revealing the impacts of nickel mining, used for electric vehicle batteries, in one of the most marine-biodiverse zones in Indonesia.

§ New science

• Sharks are remaining in their summer habitats longer as surface ocean temperatures rise, according to a new study in Conservation Biology. The authors warned that these delays in the sharks’ migrations “may alter local ecosystem dynamics and challenge current management strategies”. 
• New research, published in Nature Ecology and Evolution, found that the indicators contained within the Kunming-Montreal Global Biodiversity Framework’s (GBF) monitoring framework cover less than half of the elements of the GBF. The paper also highlights “important next steps to progressively improve the efficacy of the monitoring framework”.
• According to new research in Science Advances, human-driven climate change will remove coral habitat faster than corals can expand into higher-latitude, cooler waters. It found that severe coral cover declines will likely occur over the next 40-80 years, while large-scale expansion “requires centuries”.

§ In the diary

• 16-26 June: Preparatory meetings ahead of the COP30 climate conference | Bonn, Germany 
• 22 June: World Rainforest Day
• 21-29 June: London Climate Action Week | London
• 7-25 July: 30th session of the International Seabed Authority | Kingston, Jamaica

Cropped is researched and written by Dr Giuliana Viglione, Aruna Chandrasekhar, Daisy Dunne, Orla Dwyer and Yanine Quiroz. Please send tips and feedback to cropped@carbonbrief.org

§ ‘Partially protective’ adaptation

Globally, agriculture is projected to be one of the industries that is hit hardest by the impacts of climate change.

Along with rising average temperatures and changing rainfall patterns, increasingly frequent and severe weather extremes threaten planted crops.

However, large uncertainties remain around how farmers will adapt to future climate change. 

Most previous research on the yield impacts of climate change either assumes that farmers will not adapt to the changes at all or that they can adapt infinitely, explains Dr Andrew Hultgren, an environmental economist at the University of Illinois Urbana-Champaign. 

Hultgren, who led the new study, tells Carbon Brief:

“The question is: ‘What do real world farmers actually do?’ So that’s what we really set out to tackle…And what we find is that, essentially, neither of these extreme stories is really accurate. Farmers do adapt, but that adaptation is partially protective – not fully protective.”

The researchers model the impacts on crop yields under two emissions scenarios – moderate (RCP4.5) and very high (RCP8.5) – for two time periods – 2050 and 2098. They select six staple crops for their study: cassava, maize, rice, sorghum, soya bean and wheat.

For both emissions scenarios, the researchers apply projected future incomes consistent with SSP3 socioeconomic pathway. This portrays a “rocky road” of global development in the future due to rising geopolitical tensions driven by “regional rivalry”.

Under the moderate-emissions scenario, they find an overall decrease in staple crop yield of 8.3% in 2050 and 12.7% in 2098. 

However, they find that these losses can be reduced somewhat by the introduction of adaptive measures, such as switching to different varieties of a crop or adjusting irrigation levels. 

In order to account for adaptation, the researchers use data on crop yields from 12,658 sub-national regions to create a model that links changes in yields to exposure to extremely hot days. 

This allows the researchers to project the impacts of adaptive measures without having to prescribe what, exactly, those measures would be, Hultgren says. Relatively lower losses on extreme heat days are “reflective of adaptation”, he adds. 

In other words, if two regions with similar baseline climates and yields both experience a season of extreme heat, the one that has lower yield losses has more adaptations to climate change.

Factoring in adaptation and income growth, they find that the yield losses fall to 7.8% in 2050 and 11.2% in 2098 under moderate emissions. While these changes are relatively small, they are not insignificant, Hultgren argues:

“Twelve percent mitigation of losses is still a globally important amount of gains from adaptation.” 

Dr Jyoti Singh, a climate-crop modeller at Columbia University’s Center for Climate Systems Research, tells Carbon Brief that the dataset assembled for the new study is its “most noteworthy strength”. Singh, who was not involved in the new work, adds that it “significantly contributes to empirical agricultural impact modelling”.

However, she says, there is a “big limitation” of the study in that empirical models are based only on past data – they cannot account for the full range of potential futures. Therefore, the results from the new study cannot be compared directly to results from models that more explicitly represent the processes that influence crop growth, she says.

§ Regional loss patterns

The losses are not equal across all six staples. The end-of-century losses range from just over 1% loss for rice yields to 22.4% loss for soya bean yields. This is because each of the crops has a different response to changes in temperature and rainfall. 

The change in rice yield is particularly low, Hultgren explains, because the losses associated with overall warming are somewhat counterbalanced by yield increases due to rising nighttime temperatures.

In addition to the differences between crops, the researchers identify strong regional differences in the amount of future losses – as well as the extent to which adaptation will offset these losses.

In Africa, for example, the researchers project an overall yield decrease of 16% by 2098 with no adaptive measures in place. Adding in these adaptations reduces that yield loss to 11.6%. By contrast, adding adaptation to projections of staple yields in North America makes almost no change – reducing the losses from 21.0% to 20.8%. 

The maps below show the percentage of yield losses for (clockwise from top-left) maize, soya bean, wheat, sorghum, cassava and rice in 2098 under a moderate-warming scenario that factors in adaptation. 

The maps show that many of the staple crops studied suffer the most significant losses in current “breadbasket” regions of the world that produce much of the world’s calories, such as the US and Europe. In contrast, many lower-income, tropical regions see more modest losses. The authors write:

“Because such a large fraction of agricultural production is concentrated in these wealthy-but-low-adaption regions, they dominate projections of global calorie production, generating much of the global food security risk we document.”

However, Hultgren points out, subsistence farmers – particularly those who rely on cassava – will also be significantly impacted by climate change. The researchers identify the highest losses among the top two deciles of the global income distribution and the bottom decile. 

This result was “surprising”, Hultgren says. Typically, he explains, research has shown that poorer areas are the hardest-hit by climate change. 

He adds that the finding is reflective of the trade-off between average yields and adaptive measures. In high-producing regions, farmers have generally relied on planting the highest-yielding varieties, instead of crop varieties that might have lower average yields, but are more resilient to changes in climate. 

Hultgren tells Carbon Brief:

“Adaptation is costly…That’s why losses in the breadbasket portion of the world are so large, because farmers have to essentially pay a high price. Either in terms of actual financial inputs or in terms of just average yield losses, they have to pay a high price in order to get the adaptation they need.”

§ ‘Giving up breakfast’

By combining the projected yields for all six crops, the researchers also estimate the total impact of warming on global calories. 

They find a “nearly linear” decrease in global calorific output of 554tn kilocalories per 1C of warming – equivalent to about 120 kcal per person per day per 1C. (The recommended daily intake is typically around 2,000kcal for women and 2,500kcal for men.)

Hultgren tells Carbon Brief:

“If you think about a 3C warmer future, that’s like a population that is giving up breakfast every day – that would be the level of the caloric output loss.”

That result “should raise questions” about global food security and international political stability, Hultgren says. 

The study’s method of linking global calories to changes in temperature is one of the “key innovations” of the new study, Singh says. She adds that it “improve[s the] policy relevance” of the work.

Singh tells Carbon Brief:

“Real-world adaptation decisions, from changing crop types to investing in irrigation or adopting resilient varieties, vary significantly depending on policies and farmers’ knowledge, resource access and financial capacity.

“Studies like this one, even if not fully comprehensive, are essential steps toward understanding and incorporating adaptive capacity into yield projections, moving us closer to more realistic agricultural impact assessment efforts.”

§ 农机相关排放

粮食系统大约占人类温室气体排放的三分之一。

这一数字涵盖了与粮食生产相关的所有排放——从因森林砍伐或土地使用变化导致的排放，到奶牛打嗝或粪便释放的甲烷。

这项新研究的数据来自《中国统计年鉴》，后者提供了各种社会经济指标的年度统计数据。研究者从中提取了中国农业机械的数量与功率、机械所用的燃料属性、耕地面积、人口等信息。

除了CO2排放量外，研究者还计算了三种与农业机械相关的空气污染物排放量：PM2.5（细颗粒物）、NOx（氮氧化物）和THC（总烃）。

研究者将农业机械分为四类：小型拖拉机、大型拖拉机、田间管理机械和收割机械。然后，他们计算了每类机械在每一年的CO2、PM2.5、NOx和THC排放量。

下图展示了1985年至2020年研究期间的CO2排放量。图中柱状表示不同类型农业机械的排放量：收割机械（浅蓝色）、田间管理机械（粉色）、小型拖拉机（浅绿色）和大型拖拉机（深绿色）。

他们发现，农业机械CO2排放总量已从1985年的约23MtCO2（1MtCO2=百万吨二氧化碳），增长到2020年的近160MtCO2，年均增长率为5.7%。

这相当于2020年中国总排放量的约1.5%。虽然比例不高，但作者指出，这一排放量实际上超过了部分国家的年排放总量，如荷兰、菲律宾和尼日利亚。

尤其是，大型拖拉机所带来的排放量自2005年以来平稳增长，作者将此归因于“一系列推动大型机械化的政策”。

未参与该研究的中山大学教授覃章才表示，该研究将农业机械排放从更广泛的食品系统中拆分出来“提供了独特的视角”。覃教授表示，该做法“使政策制定者能够在不影响农业生产力的情况下，设计有针对性的干预措施”。

§ 区域分布

研究者还将排放数据细化到省级层面，发现不同地区农业机械排放量差异很大。排放量最低省份仅有约0.1MtCO2，而排放最高的省份则达到17.5MtCO2。

他们发现，中国东部和东北的五个省份——山东、河南、黑龙江、河北和安徽，占农业机械排放总量的40%以上。这些省份合计拥有全国三分之一的耕地面积和约46%的农机总动力。

然而，即使在这些高排放地区之间，机械类型的构成也存在差异，有些省份更依赖大型拖拉机，有些则以田间管理机械为主。

未参与该研究的《Our World in Data》副主编汉娜·里奇（Hannah Ritchie）博士表示，这种次国家级排放分析是该研究的关键进展之一。

里奇博士解释说：“这种排放估算的空间分辨率极具价值，因为在中国这样幅员辽阔的国家，各地排放差异显著。它还为未来在不同机械化程度和低碳技术采纳率下的潜在排放路径，提供了重要的洞见。”

§ 增长因素

研究人员确定了四个推动排放增加的社会经济因素：人口增长、人均耕地面积变化、机械化水平以及排放强度。

下图展示了由排放强度（深蓝色）、机械化水平（浅蓝色）、人均耕地面积（黄色）和人口（橙色）的变化所导致的CO2排放量变化（黑色）。

论文指出，在这些因素中，机械化水平的提升“主导”了排放变化。仅这些变化就导致1985年至2000年间排放量增加了约100%。

研究指出，人口增长也是研究区间早期农业机械排放量增长的重要驱动力，但自2000年以来，这一因素的影响有所减弱。

相比之下，作者指出，排放强度的上升总体上反而促使排放减少；而“耕作压力”在研究初期推动了排放上升，但自2000年起则转而起到抑制排放的作用。

§ 碳排放目标

作者指出，根据现行政策，中国致力于“到2035年主要农作物生产实现全过程机械化”。

因此，他们警告称，若农业机械化持续增长且未加遏制，可能会对中国实现“双碳”目标构成挑战。（“双碳”目标指的是中国承诺在2030年前实现碳达峰，并在2060年前实现碳中和。）

作者指出，有效减排需在短期和长期分别采取不同策略，并强调从短期可用性来看，“生物燃料和天然气将在未来十年发挥重要作用”。

作者还认为，从长远来看，可再生能源以及绿氢“具有最大的减排潜力”。

此前研究表明，使用自动化设备、电动拖拉机和可再生能源可以减少90%的农业排放。

里奇表示，她“对农业机械的相对（排放量占比）在2050年能达到20%持一定怀疑态度”。

她补充道：“这基于一个假设，即这些排放大多不会减少，而其他大多数行业排放迅速下降。但如果中国在减少其他排放源，包括卡车等更大型的道路运输排放和其他农业排放方面取得快速进展……那么我预计在农业机械的脱碳方面也会取得显著成效。”

§ Opposing net-zero

Reform UK’s leaders are openly sceptical about the causes and consequences of human-caused climate change. The party is also explicitly opposed to the UK’s net-zero target, which, at a global level, is the only way to stop warming from getting worse, according to scientists.

The party has pledged to “scrap net-zero” if it ever takes power at the national level, falsely asserting that this would free up billions of pounds of public money for tax cuts and welfare programmes. 

(Its assertions ignore the fact that the large majority of the investments needed to reach net-zero are expected to come from the private sector, rather than government funds. They also do not account for the economic benefits of lower fossil fuel use or avoided climate impacts. The party’s misleading claims have been widely dismissed by economists.)

Reform UK has also said it would “ban” battery storage projects and impose new taxes on solar and wind power installations.

As it stands, the party only has five MPs in parliament. However, its success in the recent English local elections and favourable polling numbers have raised its profile in UK politics and given it new powers in some areas.

To assess the potential impact of these new powers on clean-energy expansion, Carbon Brief looked at data for 10 local councils where Reform UK won overall control, shown in the map below, including Durham, Kent and Derbyshire, as well as two mayoralties.

(The analysis does not include Warwickshire, where no party gained a majority in the elections. However, a subsequent vote saw the party’s local head selected to lead the county council. He has announced plans to “dumb down” net-zero initiatives in the county.)

Following the election, Richard Tice, Reform MP and deputy leader, said the party would use “every lever” available to block new renewable-energy projects in the areas it now controls.

At the heart of this commitment is Lincolnshire, the location of Tice’s own constituency, Boston and Skegness, which now also has a Reform-run council and a Reform mayor.

The rural county is the site of several large-scale solar project proposals, which have faced a strong backlash from some local people.

This mirrors a wider trend of opposition to solar and battery projects by campaigners, who say they are concerned about, what they allege, could be the impact on the local countryside and farmers. 

However, such views are not the norm. Survey data shows overwhelming public support for solar and other renewables across the UK, even if projects are built in people’s local areas.

Analysis by thinktank the Energy and Climate Intelligence Unit also noted that by rejecting net-zero-related projects, Reform UK could threaten thousands of jobs and millions of pounds of investment in areas such as Lincolnshire.

§ Capacity at risk

In total, some 5,862MW of solar and storage capacity is currently seeking local planning authority planning approval across the 10 Reform-controlled councils, Carbon Brief’s analysis shows. This is broken down by council area in the figure below. 

This includes a series of smaller proposed solar farms, each with a capacity of less than 50MW, meaning they need local planning approval.

(The threshold for local planning approval, currently 50MW, is set to rise to 100MW in 2026.)

Solar farms above this capacity threshold go through the “nationally significant infrastructure planning” (NSIP) process. These large-scale projects are then assessed by energy secretary Ed Miliband, who can grant or deny a development consent order. 

Local planning authorities (LPAs) are guided by the national planning policy framework (NPPF), rather than the politics of the county councils under which they sit. 

However, the Reform-controlled councils overseeing these authorities will likely attempt to assert influence over approvals. 

Gareth Phillips, partner at Pinsent Masons law firm and specialist in renewable energy planning and project development, tells Carbon Brief that, while county councils are not responsible for determining planning applications, they do have influence over the outcome.

He tells Carbon Brief:

“[Councils are an] important consultee, required to respond to statutory consultation…which gives the opportunity for county-council members to influence the planning decision…In the case of Reform, it is possible that its elected members may seek to rally support for opposing planning applications, perhaps leading campaigns against the proposals. The risk here is that it may give the perception of credence to opposing views.”

Phillips says that in addition to influencing planning authority decisions, county councils could issue new strategic planning guidelines for their areas. He explains:

“It will be for the LPA to decide what, if any, weight to place on the county council’s views, when determining the planning application. Over time, it’s possible that Reform-led county councils may propose so-called ‘core strategies’, i.e. planning documents setting out strategic level requirements and policy applicable to development proposals in its jurisdiction. Similarly, that policy would be a matter for the LPA to consider and decide how much weight to apply when determining planning applications.”

This risk is mitigated to some extent by the core strategies within the NPPF and the “national policy statements” for energy, he notes. 

As such, while local planning authorities will be required to determine the approval or rejection of an application on the basis of wider policy considerations, Reform-led councils could still affect the decision. “Reform-led county councils would have a voice and opportunity to influence planning decisions,” says Philips. 

Stand-alone battery energy-storage projects do not have a capacity cap for being processed by local planning authorities, following changes to the regulations in 2020.

However, a number of storage projects that are co-located with solar will be judged under the NSIP process, meaning councils will be unable to block their construction.

§ Solar strife

Carbon Brief’s analysis looks at projects that have submitted planning permission requests in the 10 Reform-controlled counties, using Solar Energy UK’s SolarPulse database for solar and storage. 

The analysis also covers relevant onshore wind projects, based on data from the government’s renewable energy planning database. 

(Solar Energy UK notes that the SolarPulse database does not include solar projects with a capacity of less than 5MW.)

The analysis shows that there is 1,866MW of proposed solar capacity awaiting planning permission in Lincolnshire, by far the largest pipeline, as shown in the chart below. 

The majority of this capacity is subject to national-level approval as it is above the NSIP threshold. Nevertheless, the county still has the most solar-power projects awaiting permission from the local planning authority, some 166MW. 

(A key reason Lincolnshire dominates this picture for solar power development is due to grid capacity. The county was home to several large-scale coal-fired power plants, such as West Burton, which have shuttered in recent years as part of the UK’s transition away from coal. This means there is more capacity for new generators to connect to the grid in the county than in many others, where the system is currently more constrained.) 

Overall, the bulk of the proposed capacity at risk is battery storage, which has seen a surge in applications and installations in recent years. 

There was 5,013MW of battery storage capacity in operation as of December 2024 and another 5,115MW under construction, according to trade association RenewableUK. It says an additional 40,223MW had planning approval and a further 77,354MW was under development.

§ Impact of rejection 

Overall, even if local planning authorities under the 10 Reform UK-run councils were to reject all of the nearly 6GW of proposed solar and storage capacity in their areas, it would have a limited impact on the UK’s wider solar, storage and wind targets. 

If built, the 786MW of proposed solar would generate 757 gigawatt hours (GWh) of electricity. On average, a household in the UK uses 2,700 kilowatt hours (kWh) of electricity each year, meaning these solar farms would be able to power the equivalent of around 280,000 homes – some 1% of the national total. 

If all of this proposed solar were rejected and the electricity were generated from gas-fired power stations instead, it would result in an extra 0.3m tonnes of carbon dioxide (CO2) emissions per year. (This is equivalent to less than a tenth of 1% of the UK’s annual total.) 

In total, the potential 757GWh of solar power could help displace around £60m of gas per year, based on wholesale prices in 2025 to date.

Private investment could also be impacted. Each 1MW of solar would attract around £1m of investment, meaning the 786MW of capacity would bring roughly £786m into the Reform-led counties. This would have an impact on local supply chains and “community benefit” schemes. 

Similarly, battery schemes with four hours of storage capacity also require around £1m of investment per megawatt. This means another £5bn of investment – some 5,076MW of capacity – could be at risk under Reform-led councils.

The total investment at risk for solar and storage is, therefore, close to £6bn.

While a large amount of potential new solar and storage capacity is being proposed in the Reform-led council areas and some could be put at risk as a result, it is also the case that some of these developments could fail for other reasons.

According to research from consultancy Cornwall Insight in February, the current battery storage “connection queue” is double the grid’s requirement for 2030. This means there are many more projects in the queue to gain access to the electricity network than needed.

The government’s plan for reaching its target of “clean power 2030” sets a guideline of 27GW of storage capacity by the end of this decade, whereas some 61GW of battery projects are seeking a grid connection over the same period. 

This means the UK would have enough options to meet its 2030 storage requirements even if some proposed battery projects fail due to Reform-led councils, says Ed Porter, global director of industry for battery analysts Modo Energy. He tells Carbon Brief: 

“With more than 50GW of battery projects with planning consent, projects could be targeted in Reform areas, but the UK would still have sufficient options to meet clean-power 2030 targets, subject to the achievable build out rate of storage projects.”

The main outcome of Reform-led refusals would be to block profitable projects that could reduce consumer costs and cut CO2 emissions, Porter adds.

Still, there is no guarantee that all of these projects – and the solar proposals – would have received planning permission if Reform UK had not been elected in the relevant areas. 

According to figures from Solar Media Market Research, the local authority refusal rate for proposed solar-power projects rose to almost 25% in 2024, the highest on record. This is up from 15% in 2022 and 20% in 2023. 

However, the majority of projects that are refused by local authorities still end up being approved. Over the past five years, some 80% of projects that went to appeal were subsequently approved, according to Solar Media. At the time of writing, all 12 of the solar projects that have gone to appeal in 2025 to date have been approved.

Battery energy-storage refusals hit a high of 22% in 2024, according to Solar Media. However, in 2025 so far, this has dropped to 9%.

§ Connections challenge 

Even if Reform UK-led councils are unable to block clean-energy developments outright, the party’s pledge to “fight [developers] every step of the way” could still make the process more challenging. 

One key way this could hamper the development of renewable energy technologies is by forcing them to go through the appeals process, extending the time it takes to gain planning permission by as much as a year. 

Following changes to the grid connections queue, new connection agreements include strict delivery deadlines for obtaining planning permission.

As such, if a project ends up going to appeal – and is, therefore, delayed – it could risk missing deadlines and having its grid connection agreement terminated. 

Additionally, with the capacity limit for NSIPs set to change in December, more projects – solar projects between 50MW and 100MW – will go to local planning authorities for approval. This will increase the number that could be threatened by Reform UK’s influence. 

Ultimately, though, there is limited renewable-energy capacity seeking planning permission in Reform-controlled counties, more than enough capacity in planning nationally to meet targets, plus the role of the council in what is – or is not – approved is limited.

Planning lawyer Philips concludes that Reform-led councils are only likely to cause a “nuisance”, with “limited effect”. He says: 

“In summary, there is the potential for Reform-led county councils to cause a nuisance for renewable energy projects in the planning process, but this will be limited in effect. 

“I’m not concerned about this because of the weight of policy support there is for those projects, which should serve to mitigate the influence Reform could otherwise have.”