Scientists react: What are the key new insights from the IPCC’s WG2 report?

Carbon Brief Staff

A new report out this week by the UN’s Intergovernmental Panel on Climate Change (IPCC) details how climate change has “caused widespread adverse impacts and related losses and damages to nature and people”.

It forms the second part of the IPCC’s sixth assessment report (AR6) and follows the first element that was published in August 2021.

While the first part focused on the “physical science basis” of the Earth’s changing climate, the second report – by the IPCC’s Working Group II (WG2) – presents the latest evidence on the impacts of climate change and the ways of adapting to them.

It details how the “rise in weather and climate extremes has led to some irreversible impacts as natural and human systems are pushed beyond their ability to adapt”.

The full report was published on 28 February following a two-week online approval session where government delegates met to agree line-by-line the high-level summary for policymakers (SPM).

In this article, Carbon Brief has asked a mix of researchers who contributed to the new report what they think are its most important insights.

  • Prof Hans-Otto Poertner: “The science is unequivocal: any further delay will miss the brief window we have to secure a liveable and sustainable future for all.”
  • Dr Aditi Mukherji: “Effectiveness of most adaptation responses decreases drastically at global warming levels of 1.5C to 2C, showing that mitigation and adaptation efforts have to go hand in hand.”
  • Prof Lindsay Stringer: “Climate change doesn’t affect people and environments equally around the world; it’s often the poorest people who are least able to adapt.”
  • Dr Marie-Fanny Racault: “These new findings emphasise the narrowing window of opportunity for adaptation and mitigation actions to take place.”
  • Prof Maarten van Aalst: “For the first time, the IPCC notes that climate change is already contributing to humanitarian crises.”
  • Dr Lisa Schipper: “The development of the concept of ‘climate-resilient development’ is the most exciting part of the report.”
  • Prof Rachel Bezner Kerr: “The report indicates that involving marginalised and vulnerable groups in inclusive planning processes and drawing on Indigenous and local knowledge are other approaches that support effective adaptation.”
  • Prof Richard Betts: “Our report contains a lot of bad news, but also offers encouragement and motivation to step up our responses to climate change.”
  • Prof Rachel Warren: “The report finds that very high risks emerge in all reasons for concern over the range 1.2 to 4.5C global average warming.”
  • Dr Carol Franco: “A major take home message from the report is the urgent need to take action in order to achieve a sustainable and climate-resilient future. We can’t wait, we can’t postpone it, the costs of inaction are too great and we are not on track.”
  • Prof Kristie Ebi: “The future is in our hands. The adaptation, mitigation, and development choices we make will determine all of our futures.”
  • Prof David Viner: “We may not be able to stop the worst impacts of climate change and prevent the severe damage to key systems, but with adequate financing of adaptation and resilience, many systems and the most vulnerable can be afforded some protection.”
  • Dr Ruth Morgan: “This report gives long overdue recognition to the importance of Indigenous knowledge and local knowledge for more effective and culturally-appropriate climate adaptation.”
  • Dr Martina Angela Caretta: “The linkages between climate change induced water insecurity and migration and conflicts are, in a first, assessed in this report.”
  • Dr Jeff Price: “[The report] includes, for the first time, specific analyses of risks to biodiversity hotspots and to the terrestrial biodiversity of small islands.

Image - Prof Hans-Otto Poertner (note)

Prof Hans-Otto Poertner
Head of the section on integrated ecophysiology at the Alfred Wegener Institute
AR6 WG2 co-chair

This report provides the best understanding yet of climate change impacts, risks and options to adapt. It shows that climate risks are appearing faster and will get more severe sooner.  Climate change is combining with over-exploitation of natural resources, growing urbanisation and inequity to increase the threats to nature and society. Ecosystems and people are being pushed to their limits, and beyond. People who are most vulnerable are least able to cope. 

We are not prepared for the climate risks we face and urgent, accelerated action is required to avoid mounting losses. Key to this is a healthy planet. The science is unequivocal: any further delay will miss the brief window we have to secure a liveable and sustainable future for all. We know what to do, we just have to act.

Image - Dr Aditi Mukherji (note)

Dr Aditi Mukherji
Principal researcher at the International Water Management Institute (IWMI)
AR6 WG2 chapter 4 coordinating lead author

A key insight of AR6 is on the centrality of water in climate change adaptation. We find that  the majority (~60%) of all documented adaptations are occurring in response to water related-hazards, such as droughts and floods. A large share of adaptation responses, particularly in the agriculture sector, also involve water. Most common adaptation responses are irrigation, soil moisture conservation, rainwater harvesting, water storage, drought and flood resistant crop varieties and changing cropping patterns in response to changes in the water cycle. 

AR6 in general – and the water chapter in particular – also finds that current adaptation responses have several beneficial impacts, such as increases in incomes, higher crop productivity, and better ecological and socioeconomic outcomes. However, these benefits of adaptation do not necessarily translate into climate risk reduction. Even more importantly, effectiveness of most adaptation responses decreases drastically at global warming levels of 1.5C to 2C, showing that mitigation and adaptation efforts have to go hand in hand.

Image - Prof Lindsay Stringer (note)

Prof Lindsay Stringer
Professor in environment and development at the University of York
AR6 WG2 chapter 8 lead author and lead for the cross-chapter paper on deserts, semi-arid areas and desertification

Two interlinked things stand out in the AR6 WG2 report to me: urgency and climate justice. 

Evidence is clear that we need to be acting faster and linking adaptation with mitigation and sustainable development if we are to be taking climate resilient development pathways. At the same time, climate change doesn’t affect people and environments equally around the world; it’s often the poorest people who are least able to adapt. 

The window of opportunity for climate-resilient development action is closing faster for people and environments where, for example, rising sea levels are already problematic (e.g. small islands, coastal settlements), water supplies are insecure (e.g. some deserts and semi-arid areas) and where the benefits people get from the environment are already disrupted by climate change (e.g. forests, grasslands and mountainous areas). 

Tardy responses mean adaptation options are being lost. We really have to get a move on, reduce the barriers to adaptation, mitigate urgently and work in a more integrated, inclusive, equitable way towards sustainable development.

Image - Dr Marie-Fanny Racault (note)

Dr Marie-Fanny Racault
Research fellow in the School of Environmental Sciences at the University of East Anglia
AR6 WG2 chapter 3 lead author and lead author on the SPM, technical summary and four cross-chapter boxes in chapters 2, 5 and 7

The report emphasises much more on the interconnection between climate, human and nature. New evidence strongly shows that climate-related impacts on ecosystems and biodiversity loss increases the vulnerability of people and reduces their ability to adapt to climate change, and that some human activities – such as unsustainable use of natural resources and pollution – exacerbate current ecosystems vulnerability to climate change, by limiting their autonomous adaptive capacity and the services (such as food source, health, coastal protection and carbon storage) that they provide.

A further important and new aspect presented in this report is the risks associated with overshoot. Evidence shows that reaching and temporarily exceeding 1.5C global warming in the coming decades or later, will cause additional and more severe impacts on nature and human systems, some of which will be irreversible – including species extinctions and loss of coral reefs – even if global warming is reduced. 

These new findings emphasise the narrowing window of opportunity for adaptation and mitigation actions to take place. Further strengthening evidence on the risks-associated with overshoot will be important to inform policy decisions.

Image - Prof Maarten van Aalst (note)

Prof Maarten van Aalst
Princess Margriet chair in climate and disaster resilience at the University of Twente, and director of the international Red Cross Red Crescent Climate Centre
AR6 WG2 chapter 16 coordinating lead author

All risks we were concerned about in the past are now approaching much faster. This is not just because the world is already getting warmer, but also because at the same level of warming, we face higher risks.

For the first time, the IPCC notes that climate change is already contributing to humanitarian crises. In addition, climate and weather extremes are increasingly driving displacement in every region of the world. This is our daily reality in the Red Cross Red Crescent.

However there are clear limits to adaptation; we’re already facing some of those now and they’ll be increasingly prominent as warming continues. This means we’ll face increasing losses and damages, even if we implement effective adaptation.A new focus is the risk of responses to climate change – a new addition to the risk definition used in the IPCC. Risk is still mainly framed as the result of climate hazards interacting with exposure and vulnerability. However, in AR6 we have explicitly added the notion that responses to climate change can generate significant risks of their own: maladaptation inadvertently creating or aggravating risks (such as a sea wall causing coastal erosion further down the coast, or irrigation upstream aggravating water scarcity downstream); some mitigation and carbon dioxide removal (such as some bioenergy competing with food production and threatening biodiversity) and even solar-radiation modification if it were to be deployed.

Image - Dr Lisa Schipper (note)

Dr Lisa Schipper
Environmental social science research fellow at the Environmental Change Institute at the University of Oxford, and visiting researcher at the University of Vienna
AR6 WG2 Chapter 18 coordinating lead author

The development of the concept of “climate-resilient development” is the most exciting part of the report. While climate resilience was discussed in AR5, it was never framed as an explicit critical goal. The reason it has a more prominent role now is because the 2018 IPCC special report on 1.5C set the tone on urgency. Consequently, the AR6 cycle has had greater emphasis on what we call the “solution space”.

The urgency of climate-resilient development was made even clearer by WG1’s conclusion in August last year that we are quickly nearing 1.5C. Coupled with the WG2 findings that, while we have made great gains in adaptation, they are not sufficient and we are hitting both hard and soft limits in natural and human systems, and have evidence of maladaptation, it’s clear that we cannot adapt our way out of climate change.

As a result, we need to think strategically about combining adaptation and mitigation with sustainable development, and this is what we call climate-resilient development.

Image - Prof Rachel Bezner Kerr (note)

Prof Rachel Bezner Kerr
Professor of global development at the Cornell University College of Agriculture and Life Sciences
AR6 WG2 Chapter 5 coordinating lead author

Since AR5, we have significantly more evidence of observed impacts including from human-induced climate change. One important new area of scientific evidence is the ways in which climate-related hazards are impacting food security. Increased warming, heatwaves and droughts are hindering efforts to achieve the UN sustainable development goals of “zero hunger” and “water for all”. 

Increasing climate extreme events have exposed millions of people to acute food security, particularly in Africa, Asia, Central and South America, on small islands and in the Arctic. Our assessment shows that climate change is slowing the growth of agricultural productivity. There is also considerably more evidence of projected risks from climate change – such as droughts, floods and heatwaves – causing sudden food production losses and limiting access to diverse and nutritious food. 

At the same time, our report highlights a significantly greater amount of evidence of effective adaptation options in food systems. Food security and nutrition, health and wellbeing, livelihoods and biodiversity can all be enhanced using approaches such as agroecology, community-based adaptation and adopting stress-tolerant crops and livestock. The report indicates that involving marginalised and vulnerable groups in inclusive planning processes and drawing on Indigenous and local knowledge are other approaches that support effective adaptation.

Finally, the report provides unequivocal evidence of the urgency of strong action now to minimise severe impacts. While there are many adaptation options being implemented in food systems, much more needs to be done to avoid severe impacts from climate change. Harmonised actions can be taken not just for mitigation but for adaptation. In food systems, such as agroforestry, forest restoration and shifting to balanced diets.

Image - Prof Richard Betts (note)

Prof Richard Betts
Head of climate impacts research at the UK Met Office and chair in climate impacts at the University of Exeter
AR6 WG2 chapter 4 lead author

Our report contains a lot of bad news, but also offers encouragement and motivation to step up our responses to climate change.

For the first time, the IPCC is able to draw a direct connection between human-caused climate change and observed impacts. Humans have transformed our planet’s climate, and this is causing harm – this is now clear from a vast body of evidence. And huge numbers of people across the world are vulnerable.

Even more seriously, with global warming on track to exceed 1.5C, severe climate risks will continue to emerge. Some will bring irreversible impacts.

But encouragingly, the report also shows that we can reduce many of these risks if we prepare better for more extreme weather and other aspects of an altered climate. This becomes more difficult if we allow global warming to continue, so this knowledge motivates urgent action to reduce emissions from fossil fuel burning and deforestation.

Image - Prof Rachel Warren (note)

Prof Rachel Warren
Professor of global change and environmental biology at the University of East Anglia
AR6 WG2 chapter 16 lead author

IPCC has reviewed new scientific information about observed climate change impacts and projected risks for human and natural systems. It looked at five “reasons for concern” about climate change. 

An example is “risks from extreme weather events”, which are already high with the present level of global warming of ~1.2C. If the globe continues to warm, the risks will increase in all the reasons for concern, and this increase in risk has been assessed to be much greater than previously thought. 

Specifically, the report finds that very high risks emerge in all reasons for concern over the range 1.2 to 4.5C global average warming. Very high risks emerge for unique and threatened systems and extreme weather events over the range 1.2 to 2.5C global average warming. Limiting global average warming to 1.5C would limit many risks to a moderate level.

Image - Dr Carol Franco (note)

Dr Carol Franco
Senior research associate in the Department of Forest Resources and Environmental Conservation at Virginia Tech
AR6 WG2 chapter 2 review editor

The threat of climate change to the well-being of people and ecosystems is unequivocal. The increase of 1.1C in average global temperatures has already caused serious impacts to people and nature and some of these are irreversible – such as species extinctions. If global average temperatures continue to increase, the capacity of people, ecosystems, and species to adapt and the rate at which they are able to do so, could be seriously compromised.

The WG2 report acknowledges the increase in awareness and the incorporation of adaptation measures in national development and climate agendas, but points out that there are still many gaps in the implementation of these measures that are slowing down the adaptation process. 

The report provides a direct link and more evidence to support the Glasgow Climate Pact call for action and support for adaptation and the urgency to scale up adaptation finance. 

The report also stresses the untapped potential of nature to reduce climate impacts and improve people’s livelihoods as well as the importance and potential of nature-based solutions, which are also recognised as important for adaptation and mitigation in the Glasgow Climate Pact.

Finally, a major take home message from the report is the urgent need to take action in order to achieve a sustainable and climate-resilient future. We can’t wait, we can’t postpone it, the costs of inaction are too great and we are not on track.

Image - Prof Kristie Ebi (note)

Prof Kristie Ebi
Professor of global health at the University of Washington
AR6 WG2 chapter 7 lead author

People are suffering and dying right now from climate change, with the risks projected to increase with additional warming. More than half of the worldwide disease burden is climate sensitive, with clear risks to mental health as well. 

There are many effective adaptation options that can increase the resilience of our health systems and health care infrastructure, as well as strengthen the capacity of communities, particularly when these options reduce social inequities and other factors that drive vulnerability. The major constraint is insignificant investment in health systems – catch-up investments are needed that at least keep pace with climate change. 

Nearly all mitigation options benefit the health of our families, friends and colleagues. The economic value of avoided hospitalisations and avoided premature deaths from reducing emissions from coal-fired power plants, increasing walking and biking, and eating healthier diets meets or may exceed the costs of these mitigation policies. 

The future is in our hands. The adaptation, mitigation, and development choices we make will determine all of our futures.

Image - Prof David Viner (note)

Prof David Viner
Head of environmental science at CGG
AR6 WG2 chapter 17 coordinating lead author

This report highlights and demonstrates the increasing knowledge that we have about the human attribution of current and future climate impacts. Across the world we are witnessing the increasing frequency and severity of climate events upon human and natural systems.

The original outline of the WG2 made little if any reference to climate finance. However, by the time we reached the plenary, finance was covered across most sections of the SPM and was high on the agendas of many governments. The cross-chapter box on finance draws out the key statements and issues:

We may not be able to stop the worst impacts of climate change and prevent the severe damage to key systems, but with adequate financing of adaptation and resilience, many systems and the most vulnerable can be afforded some protection.

Image - Dr Ruth Morgan (note)

Dr Ruth Morgan
Associate professor in the College of Arts and Social Sciences at the Australian National University
AR6 WG2 chapter 4 lead author

This report gives long overdue recognition to the importance of Indigenous knowledge and local knowledge for more effective and culturally-appropriate climate adaptation. We worked closely with Indigenous contributors to glean their insights, and canvassed both scholarly and grey literature to better represent the ways that Indigenous peoples are understanding, experiencing and adapting to a warmer world. 

For instance, in the water chapter, we were able to assess the ways that climate change is impacting cultural uses and understandings of freshwater and freshwater ecosystems, particularly those of significance to Indigenous peoples and local peoples in high mountain and polar areas, and low-lying islands. This is just one example from the report that demonstrates its emphasis on more inclusive, equitable and ethical approaches to climate adaptation.

Image - Dr Martina Angela Caretta (note)

Dr Martina Angela Caretta
Senior lecturer in the Department of Human Geography at Lund University
AR6 WG2 chapter 4 coordinating lead author

There are several novel elements in chapter 4 on water as compared to its predecessor in AR5. 

Image - Dr Jeff Price (note)

Dr Jeff Price
Associate professor in biodiversity and climate change at the University of East Anglia
AR6 WG2 chapter 2 lead author and author on the cross-chapter paper on biodiversity hotspots

Key insights include far better estimates of extinction risk to species and the benefits of constraining warming to <2C. This includes, for the first time, specific analyses of risks to biodiversity hotspots and to the terrestrial biodiversity of small islands. 

The evidence for changes in ranges and timing of events in species being attributable to climate change is now assessed with very high confidence. Globally, the percentage of species at high risk of extinction will be 9%-14% at 1.5C, 10%-18% at 2C, 12%-29% at 3.0C, 13%-39% at 4C. 

Among groups containing the greatest numbers of species at high risk of extinction are invertebrates (especially pollinators); amphibians (especially salamanders) and flowering plants. All groups fare substantially better at 2C than 3C. Even the lowest estimates of species’ extinctions are 1000-times natural background rates. Within biodiversity hotspots, the risk of species extinction is approximately 10-times greater for endemic species than other native species.

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