The retreat of sea ice in the Arctic has long been a prominent symbol of climate change.
Observations reveal that Arctic sea ice extent at the end of summer has halved, since satellite records began in the late 1970s.
Yet, since the late 2000s, the pace of Arctic sea ice loss has slowed markedly, with no statistically significant decline for about 20 years.
In new research, published in Geophysical Research Letters, my colleagues and I explore the reasons for the recent slowdown of Arctic sea ice – and turn to climate models to understand what might happen next.
Our findings show that, rather than being an unexpected or rare event, climate model simulations suggest we should expect periods like this to occur relatively frequently.
This current slowdown is likely caused by natural fluctuations of the climate system – just as they played a part in an acceleration of sea ice loss in the decades prior.
Were it not for human-caused warming, it is likely that sea ice would have increased over this period.
According to our simulations, the slowdown could even last for another five or 10 years – even as the world continues to warm.
Widespread slowdown
The changes in the Arctic are one of the most clear and well-known indicators of a warming climate.
With the Arctic warming up to four times the rate of the global average, the region has lost more than 10,000 cubic kilometres of sea ice since the 1980s. (The volume of ice lost is roughly equivalent to 4bn Olympic swimming pools).
Arctic sea ice reached its smallest extent on record in September 2012, dwindling to 3.41m square kilometres (km2). This triggered discussions of when the Arctic might see its first “ice-free” summer, where sea ice extent drops below 1m km2.
Research has shown that human-caused warming is responsible for up to two-thirds of this decline, with the remainder down to natural fluctuations in the climate system, also known as “internal climate variability”.
Despite the record low of 2012, satellite data reveals a widespread slowdown in Arctic sea ice loss over the past two decades.
Climate model simulations of Arctic sea ice thickness and volume further reinforce these observations, indicating little or no significant decline over the past 15 years.
This data is laid out in the charts below, which show average sea ice extent in September (left) and for the whole year (middle), as well as how annual average sea ice volume differs from the long-term average (right).
(September is typically the point in the year where sea ice reaches its annual minimum, at the end of the Arctic summer.)
The coloured lines indicate that the data originates from the National Snow and Ice Data Centre (NSIDC, orange), the Ocean and Sea Ice Satellite Application Facility (OSISAF, red) and the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, blue).
These observational records show how the precipitous decline in sea ice seen over much of the satellite data has slowed since the late 2000s.
It also shows that the slowdown is not limited to summer months, but is occurring year-round.
Our study is not the first to highlight this slowdown – several recent studies have also examined various aspects of this phenomenon. Meanwhile, a 2015 paper was remarkably prescient in suggesting such a slowdown could occur.
Is the slowdown surprising?
The loss of sea ice around the north pole is both a cause and effect of Arctic amplification – the term given to the rapid warming in the region.
Melting snow and ice reduces the reflectiveness, or “albedo”, of the Arctic’s surface, meaning less incoming sunlight is reflected back out to space. This causes greater warming and even more melting of ice and snow.
This “surface-albedo feedback” is one of several drivers of Arctic amplification.
Given global warming is caused by the continued rise in greenhouse gas emissions, it might seem puzzling – or even impossible – that Arctic sea ice loss could slow down.
However, the recent generations of climate models used for the Coupled Model Intercomparison Project (CMIP) – the international modelling effort that feeds into the influential reports from the Intergovernmental Panel on Climate Change (IPCC) – illustrate why this might be happening.
Models from CMIP5 and CMIP6, which simulate the historical period and explore different future warming scenarios, indicate that slowdowns in Arctic sea ice loss lasting multiple decades are relatively common – happening in roughly 20% of model runs.
This is due to natural variability in the climate system, which can temporarily counteract decline of sea ice – even under high-emission scenarios.
One way that climate scientists investigate natural variability is by running multiple simulations of a model, each with identical levels of human-caused emissions of carbon dioxide, aerosols and methane. These are known as “ensembles”.
Due to the chaotic nature of the climate system, which results in different phases of natural variability, the different model runs produce different outcomes – even if the long-term climate change signal from human activity remains constant.
Large ensembles help us to understand how to interpret the Earth’s observed climate record, which has been influenced by both human-induced climate change and natural variations.
In our research, we examine how many individual model runs within the ensemble exhibit a similar or greater slowdown in sea ice loss than the observed record over 2005-24.
The models show that natural climate variability can accelerate sea ice loss, as seen during the dramatic record-lows in 2007 and 2012. However, this natural variability can also temporarily slow the longer-term downward trend.
The primary suspects behind this multi-decade variability are natural fluctuations linked to the tropical Pacific and the North Atlantic, although the precise causes are yet to be quantified.
For example, a shift from the positive, warm phase to the negative, cool phase of a natural cycle in the Interdecadal Pacific Oscillation is associated with bringing much cooler waters close to the North American coastline and into the Arctic. This could potentially lead to sea ice growth.
What might happen to Arctic sea ice cover next?
So how long could this current slowdown persist?
Climate model simulations suggest the current slowdown might continue for another five or 10 years.
However, there is an important caveat: slowdowns like this often set the stage for faster declines later.
Climate models suggest that when the slowdown inevitably ends, the rate of sea ice loss could rapidly accelerate.
Thousands of simulations analysed in our research reveal that September sea ice loss ramps up at a rate of more than 500,000km2 per decade after prolonged periods of minimal sea ice loss.
This would equate to more than 10% of current sea ice cover in September.
An analogy of Arctic sea ice extent behaving like a ball bouncing downhill – set out in a 2015 Carbon Brief article by Prof Ed Hawkins – is particularly apt here.
Just like the ball – which eventually reaches the bottom due to gravity, despite an erratic journey – Arctic sea ice loss may temporarily seem to defy expectations at present.
Ultimately, however, sea ice loss will resume, reflecting the underlying human-induced warming trend.
While it may seem contradictory that Arctic sea ice loss can slow even as global temperatures climb, climate models clearly show that such periods are expected parts of climate variability.
As a result, the recent slowdown in Arctic sea ice does not signal an end to climate change or lessen the urgency of cutting greenhouse gas emissions, if global goals are to be met.
While the current slowdown might persist for some years to come, when sea ice loss resumes, it could do so with renewed intensity.
The post Guest post: Why the recent slowdown in Arctic sea ice loss is only temporary appeared first on Carbon Brief.
Guest post: Why the recent slowdown in Arctic sea ice loss is only temporary
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US National Oceanic and Atmospheric Administration has said there is a 50-60% chance that the El Niño weather pattern could return this year, amplifying the effect of global warming and potentially driving temperatures to “record highs”, according to Euronews.
- FLAGSHIP FUND: The African Development Bank’s “flagship clean energy fund” plans to more than double its financing to $2.5bn for African renewables over the next two years, reported the Associated Press.
- NO WITHDRAWAL: Vanuatu has defied US efforts to force the Pacific-island nation to drop a UN draft resolution calling on the world to implement a landmark International Court of Justice (ICJ) ruling on climate, according to the Guardian.
98
The number of nations that submitted their national reports on tackling nature loss to the UN on time – just half of the 196 countries that are part of the UN biodiversity treaty – according to analysis by Carbon Brief.
Latest climate research
- Sea levels are already “much higher than assumed” in most assessments of the threat posed by sea-level rise, due to “inadequate” modelling assumptions | Nature
- Accelerating human-caused global warming could see the Paris Agreement’s 1.5C limit crossed before 2030 | Geophysical Research Letters covered by Carbon Brief
- Future “super El Niño events” could “significantly lower” solar power generation due to a reduction in solar irradiance in key regions, such as California and east China | Communications Earth & Environment
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
UK greenhouse gas emissions in 2025 fell to 54% below 1990 levels, the baseline year for its legally binding climate goals, according to new Carbon Brief analysis. Over the same period, data from the World Bank shows that the UK’s economy has expanded by 95%, meaning that emissions have been decoupling from growth.
Spotlight
Bristol’s ‘pioneering’ community wind turbine
Following the recent launch of the UK government’s local power plan, Carbon Brief visits one of the country’s community-energy success stories.
The Lawrence Weston housing estate is set apart from the main city of Bristol, wedged between the tree-lined grounds of a stately home and a sprawl of warehouses and waste incinerators. It is one of the most deprived areas in the city.
Yet, just across the M5 motorway stands a structure that has brought the spoils of the energy transition directly to this historically forgotten estate – a 4.2 megawatt (MW) wind turbine.
The turbine is owned by local charity Ambition Lawrence Weston and all the profits from its electricity sales – around £100,000 a year – go to the community. In the UK’s local power plan, it was singled out by energy secretary Ed Miliband as a “pioneering” project.
‘Sustainable income’
On a recent visit to the estate by Carbon Brief, Ambition Lawrence Weston’s development manager, Mark Pepper, rattled off the story behind the wind turbine.
In 2012, Pepper and his team were approached by the Bristol Energy Cooperative with a chance to get a slice of the income from a new solar farm. They jumped at the opportunity.
“Austerity measures were kicking in at the time,” Pepper told Carbon Brief. “We needed to generate an income. Our own, sustainable income.”
With the solar farm proving to be a success, the team started to explore other opportunities. This began a decade-long process that saw them navigate the Conservative government’s “ban” on onshore wind, raise £5.5m in funding and, ultimately, erect the turbine in 2023.
Today, the turbine generates electricity equivalent to Lawrence Weston’s 3,000 households and will save 87,600 tonnes of carbon dioxide (CO2) over its lifetime.