DeBriefed 6 June 2025: Nigeria’s deadly flash floods; UK’s record spring drives solar surge; Lessons from Japan’s ‘Cool Biz’

Joe Goodman

Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.

§ This week

Deadly extremes

FLOODING: Up to 700 people are believed to have been killed by flash floods in Nigeria, reported BBC News. Northern Nigeria has faced “prolonged dry spells worsened by climate change”, followed by “excessive rainfall”, which can cause flash flooding, reported the Associated Press. 

FIRES: In Canada, continuing wildfires forced the evacuation of more than 26,000 people, “with heavy smoke choking millions of Canadians and Americans and reaching as far away as Europe”, reported Le Monde. CBC News reported that authorities in the Canadian province of Saskatchewan have been “battling the worst wildfire [the state has] seen in decades”. Scientist Prof Colin Laroque told the broadcaster: “This is classic climate change…This is our new normal.”

DEVASTATION: In northeastern India, at least 48 people have been killed in flash floods, Al Jazeera reported. Meanwhile, in China’s southwestern Yunnan province, heavy rainfall over the weekend triggered “flash floods and mudslides”, damaging roads and disrupting power supplies to around 5,000 people, reported Reuters. 

Trumping at the bit

DRILL, BABY, DRILL: The Trump administration in the US announced plans to eliminate Biden-era protections across millions of acres of the Alaskan Arctic, opening the area up for drilling and mining “in some of the last remaining pristine wilderness in the country”, the New York Times reported. According to US energy secretary, Chris Wright, Trump wants to “double the amount of oil coursing through Alaska’s vast pipeline system” and build a “massive natural gas project as its ‘big beautiful twin’”, reported the Associated Press.

‘GOLD STANDARD’: Elsewhere, more than 6,000 scientists and academics signed an open letter opposing a new push by Trump to impose what he called a restoration of “gold standard science” across federal agencies and national laboratories, reported the the New York Times. It explained: “The executive order puts his political appointees in charge of vetting scientific research and gives them the authority to ‘correct scientific information’, control the way it is communicated to the public and the power to ‘discipline’ anyone who violates the way the administration views science.” Meanwhile, CNN reported that “NASA scientists describe ‘absolute sh*tshow’ at agency as Trump budget seeks to dismantle top US climate lab”.

§ Around the world

  • BIG TECH: Meta signed a 20-year deal with an Illinois nuclear plant for energy to power its AI and data centres, reported the Financial Times. 
  • BIG SOLAR: Builders will be required to fit solar panels to the “vast majority” of new-build homes in England under changes to be published this year, according to energy secretary Ed Miliband, said BBC News.
  • BIG TARGET: The EU’s climate science adviser warned the bloc against watering down climate targets, a day after it was reported that EU climate commissioner Wopke Hoekstra “successfully lobbied Germany’s coalition government to endorse a controversial measure that weakens the EU’s next climate target”, said Politico.
  • BIG PROBELÉM: Civil society groups raised the alarm on how the “exorbitant price of accommodation” and “high cost of flights” will undermine Brazil’s civil society participation at COP30 in Belém, reported Dialogue Earth.

§ $2.2 trillion

How much global investment in clean-energy technologies, including renewables, nuclear and energy storage, is expected in 2025, according to the International Energy Agency. This is “twice the amount expected for fossil fuels”, reported Reuters. 

§ Latest climate research

  • A study in Communications Earth & Environment warned that the world has “likely” already reached a tipping point in the West Antarctic ice sheet and that its collapse would result in four metres of sea level rise over a timescale that “could be millennia”. 
  • Nature Communications published research which found that poor air quality in Europe could lead to 282,000 premature deaths a year by 2100 under a low-ambition climate scenario – but drop to 67,000 if ambitious action is taken to cut emissions. 
  • Climate change-driven atmospheric evaporative demand – sometimes known as “atmospheric thirst” – caused around 40% of increased drought severity globally from 1981-2022, according to new research in Nature.

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

§ Captured

Image (note)

The UK’s sunniest spring generated a record amount of solar power, according to new Carbon Brief analysis. The data revealed that the nation’s solar sites generated a record 7.6 terawatt hours (TWh) of electricity from January to May 2025. This is 42% higher than the 5.4TWh generated in the same period last year, as well as marking a much larger 160% increase over the past decade, the analysis said. It added: “The solar electricity generated in 2025 to date has avoided the need to import gas costing around £600m, which would have released 6m tonnes of carbon dioxide (MtCO2) when burned.” The Times and BBC News covered the analysis.

§ Spotlight

§ Lessons from 20 years of Japanese ‘Cool Biz’

This week, Carbon Brief examines a “casual dress” policy that has been “surprisingly effective” at driving emissions savings in Japan.

For many people, the thought of Japan conjures up images of thronging cities, bright lights and smartly dressed “salary-men” unwinding in an “izakaya” (Japanese pub) after a gruelling day at the office. 

Every morning, in cities around Japan, some 38 million office workers put on a uniform of suits and ties and make their way to work.

Come summer, however, and the morning commute adopts a laid-back Friday feel. Men’s suit jackets and neckties are replaced by open collars and short sleeves. Venture to the southern island of Okinawa and you might spot a salary-man in a Hawaiian-style “kariyushi” shirt. 

This was not always the case. Twenty years ago this month, then-environment minister Yuriko Koike introduced Japan – and the world – to the term “Cool Biz”.

“Cool Biz” – literally Cool Business – is an enduring campaign aimed at reducing energy consumption from air conditioning in the hot summer months when temperatures routinely exceed 30C.

‘No necktie’

Introduced in 2005, the same year the Kyoto protocol finally “entered into force”, Cool Biz mandated that government office buildings turn down the air conditioning to 28C and encourage employees to cool off by wearing less formal clothing. The campaign was characterised by the pithy slogan: “No jacket, no necktie.” 

The impact was near immediate. By official estimates, nearly half a million tonnes of CO2 were saved in the first year of Cool Biz. The following year the savings tripled.
In 2012, the policy was estimated to have saved Japan 2.2 MtCO2 of emissions. (This is equivalent to the emissions of Montenegro that year.)

Image - Japanese prime minister Fumio Kishida (centre) and other ministers in 2023 wearing “kariyushi” summer shirts to promote the annual “Cool Biz” light clothing campaign. Credit: Newscom / Alamy Stock Photo - Japanese prime minister Fumio Kishida (centre) and other ministers in 2023 wearing "kariyushi" summer shirts to promote the annual "Cool Biz" light clothing campaign. (note)

While temperature regulations were only mandated in government buildings, the impacts of the campaign extended far wider. 

Thanks to a widespread publicity campaign – which included a Cool Biz fashion show of Japanese public figures and business leaders – name recognition reached 96% in its first year, according to a survey by the Ministry of Environment.

Uniqlo, Japan’s largest clothes retailer, recorded a 14% sales bump – which it attributed to its range of Cool Biz-appropriate casual workwear. And the Federation of Japanese Necktie Unions petitioned the government, after it forecast a 30% sales slump worth approximately £1bn.

‘Accidental steering’

Twenty years on, working in relaxed attire in summer has become “firmly established in Japanese society”, Atsushi Watabe, programme director of sustainable consumption and production at Japan’s Institute for Global Environmental Strategies, told Carbon Brief.

But research into its popularity revealed that concerns about climate change are unlikely to have played a major role in the uptake. 

Surveys with members of the public found that Cool Biz had little or no impact on peoples’ reported environmental awareness or commitment, according to Prof Elizabeth Shove, an emeritus professor of sociology at Lancaster University,

Cool Biz’s actual success was a case of “accidental steering” through a combination of social, material and historical factors, said Shove.

Government officials led by example, she said. Japan’s then prime minister Junchiro Koizumi insisted that Cool Biz be worn for cabinet meetings and appeared in interviews in open-collar shirts.

“If the ministers are wearing a tie, their subordinates would feel uneasy about not wearing it,” prime minister Koizumi said at the time. “So the ministers should not wear a tie.”

Turning down the air conditioning in government buildings, likewise, set a standard for other businesses to follow.  

Timing also played a role, according to Watabe. Women working in Japanese offices were some of the earliest to support Cool Biz, having been subjected to cooling conventions adapted for male workers, he said, adding:

“Gradually, men who had always considered wearing suits outside as the norm also accepted the change and began to feel its benefits.”

A key lesson is that the success of Cool Biz came from shifting societal norms rather than targeting the behaviour of individuals, said Shove:

“Norms and values don’t just exist – they come from histories of standards, regulations and building research… [Cool Biz] was surprisingly effective by not changing individual behavior, but by just setting a new standard in the government’s own buildings and in industry.”

§ Watch, read, listen

DRILLED: A new podcast series explored how ”Greenpeace, which was only tangentially involved in the Standing Rock [oil pipeline] protests, has been slapped with a $666m bill for damages”.

REPUBLICANS ‘SCARED’: The Guardian interviewed former Democratic presidential candidate Bernie Sanders on a wide range of issues, including his thoughts on why some Republicans are “scared” to speak about the reality of climate change.
SELLING NEGATIVE EMISSIONS: A feature in the Financial Times examined the “battle to create a carbon trading market for negative emissions” in the UK. 

§ Coming up

§ Pick of the jobs

DeBriefed is edited by Daisy Dunne. Please send any tips or feedback to [email protected].

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