Droughts spanning multiple years have become drier, hotter and more frequent over the past 40 years, according to new research.
The study, published in Science, finds that the global land surface affected by these extreme events has expanded at a rate of nearly 50,000 square kilometres (km2) per year in the past four decades – an area larger than Switzerland each year.
The authors identify multi-year droughts – which can last from years to decades – that occurred around the world between 1980 and 2018.
They find that multi-year droughts can cause significant declines in vegetation in ecosystems such as grasslands. These impacts can also translate into severe impacts for humans, including water scarcity.
Study author Dr Dirk Karger, a senior researcher at the Swiss Federal Research Institute (WSL), tells Carbon Brief:
“Everybody was talking about droughts, [that they] will be more [frequent] with climate change, but there [was] no clear database where we could look. We finally have a good baseline of what is happening…[and] provide a new way of thinking about the impact the [multi-year droughts have].”
Long-lasting drought
“Multi-year” droughts – those lasting at least two years and for as long as decades – can have dramatic impacts on nature and societies.
These long-lasting events can deplete soil moisture and leave rivers, lakes and reservoirs parched. This, in turn, can result in “devastating impacts”, such as massive crop failures, tree mortality or reduced water supply, according to the study.
(For more on the different ways that droughts can be defined, see Carbon Brief’s guest post.)
In recent years, multi-year droughts have occurred around the world, including Chile, the western US and Australia. For example, a 2015 study found that the so-called “megadrought” that persisted in Chile from 2010 to 2019 led to a “marked decline in water reservoirs and an extended forest fire season”.
The new study maps the distribution of multi-year drought events between 1980 and 2018. It identifies droughts by looking at a “drought index” based on changes in rainfall and potential evapotranspiration, which measures the amount of water that escapes the soil and plants into the atmosphere.
The researchers also rank the drought events by their severity – based on a combination of the extent and duration, along with the magnitude of the drought index. Then, they use the index to estimate the impact of multi-year droughts on global vegetation.
They identify more than 13,000 multi-year drought events during the four-decade study period, spanning every continent except Antarctica.
The map below shows the location and characteristics of the 10 most severe events, with the colours representing each individual drought and its length.
The longest multi-year drought occurred in the eastern Congo basin. It lasted for almost a decade, from 2010 to 2018, and affected an area of almost 1.5m square kilometres (km2).
The study finds that the most affected ecosystems by these extreme events are temperate grasslands.
However, not all multi-year droughts result in significant damage to ecosystems.
In the humid tropics, which are home to rainforests such as the Amazon, the lack of rainfall is not strong enough to diminish vegetation. This suggests that plants in those regions might have a “greater resistance” to drought conditions, the authors write.
Boreal forests in the far-northern hemisphere and tundra ecosystems also had a “minor response” to these events. The authors say this is because their vegetation productivity is more dependent on temperature than on the presence or absence of rainfall.
The drought with the most severe vegetation impacts occurred in Mongolia from 2000 to 2011 and reduced vegetation “greenness” by almost 30%.
For Karger, it is difficult to pinpoint the strongest multi-year drought ever because it depends on what aspect is considered: the drought that had the largest extent or the one that lasted the longest. He continues:
“With our database we can easily answer any of these questions, it’s just a matter of what we sought for, since we provide that open source and open data”.
Drivers of droughts
The research reveals that multi-year droughts have increased in size, temperature, dryness and duration.
The global land area affected by this kind of drought increased at a rate of 49,279km2 per year during that time – equivalent to a size larger than Switzerland per year.
The factors behind the intensification of multi-year droughts are increased potential evapotranspiration, decreased rainfall and rising temperatures, the study says.
The researchers note that during multi-year drought events, the “precipitation deficit” – the difference in the amount of rain compared to a baseline over a certain period and region – has surged over time.
For the 10 most severe multi-year droughts, the precipitation deficit has increased, on average, by 7mm per year over nearly four decades.
At the same time, the temperature during these events has increased by 0.26-0.35C per decade.
The study attributes the higher temperatures during multi-year droughts to climate change, noting that the warming “align[s] well” with global changes. It also notes that the years with the largest areas under multi-year drought have followed the El Niño events of 1998, 2010 and 2015.
Dr Maral Habibi, a researcher at the University of Graz, in Austria, and who was not involved in the study, tells Carbon Brief:
“The study clearly illustrates how rising temperatures amplify drought through increased evapotranspiration, precipitation deficits and vicious feedback loops (such as reduced cloud cover exacerbating heat).”
‘More regular’ multi-year droughts
The research says that the most severe multi-year droughts identified in the study “represent valuable case studies to prepare for similar events that may occur more regularly in the 21st century”.
It also says that analysing droughts at a global level, rather than focusing on a single drought event, “paves a more realistic way to develop adequate and fair mitigation strategies”.
Dr Ruth Cerezo-Mota, a researcher at the National Autonomous University of Mexico (UNAM) who was also not involved in the study, tells Carbon Brief that the world needs more data, including high-quality and continuous observations, and more investment in science to “understand these dynamic processes”.
Habibi agrees on the need for “enhanced monitoring tools and predictive climate models”. She adds that “investments in AI-driven drought forecasting and cross-border water resource management are also vital” to “mitigate and adapt to the challenges of a warming, drying world”.
The post ‘Multi-year’ droughts have become more frequent, drier and hotter over past 40 years appeared first on Carbon Brief.
‘Multi-year’ droughts have become more frequent, drier and hotter over past 40 years
Climate Change
DeBriefed 15 August 2025: Raging wildfires; Xi’s priorities; Factchecking the Trump climate report
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Blazing heat hits Europe
FANNING THE FLAMES: Wildfires “fanned by a heatwave and strong winds” caused havoc across southern Europe, Reuters reported. It added: “Fire has affected nearly 440,000 hectares (1,700 square miles) in the eurozone so far in 2025, double the average for the same period of the year since 2006.” Extreme heat is “breaking temperature records across Europe”, the Guardian said, with several countries reporting readings of around 40C.
HUMAN TOLL: At least three people have died in the wildfires erupting across Spain, Turkey and Albania, France24 said, adding that the fires have “displaced thousands in Greece and Albania”. Le Monde reported that a child in Italy “died of heatstroke”, while thousands were evacuated from Spain and firefighters “battled three large wildfires” in Portugal.
UK WILDFIRE RISK: The UK saw temperatures as high as 33.4C this week as England “entered its fourth heatwave”, BBC News said. The high heat is causing “nationally significant” water shortfalls, it added, “hitting farms, damaging wildlife and increasing wildfires”. The Daily Mirror noted that these conditions “could last until mid-autumn”. Scientists warn the UK faces possible “firewaves” due to climate change, BBC News also reported.
Around the world
- GRID PRESSURES: Iraq suffered a “near nationwide blackout” as elevated power demand – due to extreme temperatures of around 50C – triggered a transmission line failure, Bloomberg reported.
- ‘DIRE’ DOWN UNDER: The Australian government is keeping a climate risk assessment that contains “dire” implications for the continent “under wraps”, the Australian Financial Review said.
- EXTREME RAINFALL: Mexico City is “seeing one of its heaviest rainy seasons in years”, the Washington Post said. Downpours in the Japanese island of Kyushu “caused flooding and mudslides”, according to Politico. In Kashmir, flash floods killed 56 and left “scores missing”, the Associated Press said.
- SOUTH-SOUTH COOPERATION: China and Brazil agreed to “ensure the success” of COP30 in a recent phone call, Chinese state news agency Xinhua reported.
- PLASTIC ‘DEADLOCK’: Talks on a plastic pollution treaty have failed again at a summit in Geneva, according to the Guardian, with countries “deadlocked” on whether it should include “curbs on production and toxic chemicals”.
15
The number of times by which the most ethnically-diverse areas in England are more likely to experience extreme heat than its “least diverse” areas, according to new analysis by Carbon Brief.
Latest climate research
- As many as 13 minerals critical for low-carbon energy may face shortages under 2C pathways | Nature Climate Change
- A “scoping review” examined the impact of climate change on poor sexual and reproductive health and rights in sub-Saharan Africa | PLOS One
- A UK university cut the carbon footprint of its weekly canteen menu by 31% “without students noticing” | Nature Food
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
Factchecking Trump’s climate report
A report commissioned by the US government to justify rolling back climate regulations contains “at least 100 false or misleading statements”, according to a Carbon Brief factcheck involving dozens of leading climate scientists. The report, compiled in two months by five hand-picked researchers, inaccurately claims that “CO2-induced warming might be less damaging economically than commonly believed” and misleadingly states that “excessively aggressive [emissions] mitigation policies could prove more detrimental than beneficial”80
Spotlight
Does Xi Jinping care about climate change?
This week, Carbon Brief unpacks new research on Chinese president Xi Jinping’s policy priorities.
On this day in 2005, Xi Jinping, a local official in eastern China, made an unplanned speech when touring a small village – a rare occurrence in China’s highly-choreographed political culture.
In it, he observed that “lucid waters and lush mountains are mountains of silver and gold” – that is, the environment cannot be sacrificed for the sake of growth.
(The full text of the speech is not available, although Xi discussed the concept in a brief newspaper column – see below – a few days later.)
In a time where most government officials were laser-focused on delivering economic growth, this message was highly unusual.
Forward-thinking on environment
As a local official in the early 2000s, Xi endorsed the concept of “green GDP”, which integrates the value of natural resources and the environment into GDP calculations.
He also penned a regular newspaper column, 22 of which discussed environmental protection – although “climate change” was never mentioned.
This focus carried over to China’s national agenda when Xi became president.
New research from the Asia Society Policy Institute tracked policies in which Xi is reported by state media to have “personally” taken action.
It found that environmental protection is one of six topics in which he is often said to have directly steered policymaking.
Such policies include guidelines to build a “Beautiful China”, the creation of an environmental protection inspection team and the “three-north shelterbelt” afforestation programme.
“It’s important to know what Xi’s priorities are because the top leader wields outsized influence in the Chinese political system,” Neil Thomas, Asia Society Policy Institute fellow and report co-author, told Carbon Brief.
Local policymakers are “more likely” to invest resources in addressing policies they know have Xi’s attention, to increase their chances for promotion, he added.
What about climate and energy?
However, the research noted, climate and energy policies have not been publicised as bearing Xi’s personal touch.
“I think Xi prioritises environmental protection more than climate change because reducing pollution is an issue of social stability,” Thomas said, noting that “smoggy skies and polluted rivers” were more visible and more likely to trigger civil society pushback than gradual temperature increases.
The paper also said topics might not be linked to Xi personally when they are “too technical” or “politically sensitive”.
For example, Xi’s landmark decision for China to achieve carbon neutrality by 2060 is widely reported as having only been made after climate modelling – facilitated by former climate envoy Xie Zhenhua – showed that this goal was achievable.
Prior to this, Xi had never spoken publicly about carbon neutrality.
Prof Alex Wang, a University of California, Los Angeles professor of law not involved in the research, noted that emphasising Xi’s personal attention may signal “top” political priorities, but not necessarily Xi’s “personal interests”.
By not emphasising climate, he said, Xi may be trying to avoid “pushing the system to overprioritise climate to the exclusion of the other priorities”.
There are other ways to know where climate ranks on the policy agenda, Thomas noted:
“Climate watchers should look at what Xi says, what Xi does and what policies Xi authorises in the name of the ‘central committee’. Is Xi talking more about climate? Is Xi establishing institutions and convening meetings that focus on climate? Is climate becoming a more prominent theme in top-level documents?”
Watch, read, listen
TRUMP EFFECT: The Columbia Energy Exchange podcast examined how pressure from US tariffs could affect India’s clean energy transition.
NAMIBIAN ‘DESTRUCTION’: The National Observer investigated the failure to address “human rights abuses and environmental destruction” claims against a Canadian oil company in Namibia.
‘RED AI’: The Network for the Digital Economy and the Environment studied the state of current research on “Red AI”, or the “negative environmental implications of AI”.
Coming up
- 17 August: Bolivian general elections
- 18-29 August: Preparatory talks on the entry into force of the “High Seas Treaty”, New York
- 18-22 August: Y20 Summit, Johannesburg
- 21 August: Advancing the “Africa clean air programme” through Africa-Asia collaboration, Yokohama
Pick of the jobs
- Lancaster Environment Centre, senior research associate: JUST Centre | Salary: £39,355-£45,413. Location: Lancaster, UK
- Environmental Justice Foundation, communications and media officer, Francophone Africa | Salary: XOF600,000-XOF800,000. Location: Dakar, Senegal
- Politico, energy & climate editor | Salary: Unknown. Location: Brussels, Belgium
- EnviroCatalysts, meteorologist | Salary: Unknown. Location: New Delhi, India
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.
The post DeBriefed 15 August 2025: Raging wildfires; Xi’s priorities; Factchecking the Trump climate report appeared first on Carbon Brief.
DeBriefed 15 August 2025: Raging wildfires; Xi’s priorities; Factchecking the Trump climate report
Climate Change
New York Already Denied Permits to These Gas Pipelines. Under Trump, They Could Get Greenlit
The specter of a “gas-for-wind” compromise between the governor and the White House is drawing the ire of residents as a deadline looms.
Hundreds of New Yorkers rallied against new natural gas pipelines in their state as a deadline loomed for the public to comment on a revived proposal to expand the gas pipeline that supplies downstate New York.
New York Already Denied Permits to These Gas Pipelines. Under Trump, They Could Get Greenlit
A “critical assessment” report commissioned by the Trump administration to justify a rollback of US climate regulations contains at least 100 false or misleading statements, according to a Carbon Brief factcheck involving dozens of leading climate scientists.
The report – “A critical review of impacts of greenhouse gas emissions on the US climate” – was published by the US Department of Energy (DoE) on 23 July, just days before the government laid out plans to revoke a scientific finding used as the legal basis for emissions regulation.
The executive summary of the controversial report inaccurately claims that “CO2-induced warming might be less damaging economically than commonly believed”.
It also states misleadingly that “excessively aggressive [emissions] mitigation policies could prove more detrimental than beneficial”.
Compiled in just two months by five “independent” researchers hand-selected by the climate-sceptic US secretary of energy Chris Wright, the document has sparked fierce criticism from climate scientists, who have pointed to factual errors, misrepresentation of research, messy citations and the cherry-picking of data.
Experts have also noted the authors’ track record of promoting views at odds with the mainstream understanding of climate science.
Wright’s department claims the report – which is currently open to public comment as part of a 30-day review – underwent an “internal peer-review period amongst [the] DoE’s scientific research community”.
The report is designed to provide a scientific underpinning to one flank of the Trump administration’s plans to rescind a finding that serves as the legal prerequisite for federal emissions regulation. (The second flank is about legal authority to regulate emissions.)
The “endangerment finding” – enacted by the Obama administration in 2009 – states that six greenhouse gases are contributing to the net-negative impacts of climate change and, thus, put the public in danger.
In a press release on 29 July, the US Environmental Protection Agency said “updated studies and information” set out in the new report would “challenge the assumptions” of the 2009 finding.
Carbon Brief asked a wide range of climate scientists, including those cited in the “critical review” itself, to factcheck the report’s various claims and statements.
The post Factcheck: Trump’s climate report includes more than 100 false or misleading claims appeared first on Carbon Brief.
https://www.carbonbrief.org/factcheck-trumps-climate-report-includes-more-than-100-false-or-misleading-claims/
Apple: $94 Billion Record Earnings and the Breakthrough Climate Solutions Fueling Growth
U.S. DOE Reveals $1B Funding to Boost Critical Minerals Supply Chain
DeBriefed 15 August 2025: Raging wildfires; Xi’s priorities; Factchecking the Trump climate report
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