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
At Climate Home News, we found this year a pretty depressing one to cover, shaped as it was by Donald Trump’s attacks on climate science and action at home and abroad – and rounded off by the UN declaring global warming will break through the key 1.5C limit the world set itself in 2015.
But it wasn’t all bad. Nobody had decided to follow the US out of the Paris Agreement by the time it turned 10 this month. Anti-climate candidates in Canada and Australia, backed by Trump, lost elections convincingly. And 2025 may also have been the year carbon dioxide emissions fell for the first time.
What’s more, our reporting this year saw results in the real world. After we revealed that Chilean doctors believe pollution from copper mines in the northern hub of Calama is causing autism, campaigners sued state-owned mining company Codelco. The case is ongoing.
One of the lawyers representing the campaigners said “when [Climate Home News] revealed our silent suffering and our fight, we felt we had finally been heard and had entered the national conversation thanks to international media coverage. That was the final push to file the lawsuit.”
If you want to fund more impactful reporting like this in 2026, please subscribe and unlock all of our content for just the price of a coffee per week. Or to keep up with our latest coverage, you can sign up for our free newsletter and follow us on LinkedIn, Instagram, BlueSky and Facebook.
Below are nine of our best stories this year and, if that’s not enough, here’s nine more from 2024.
1. Solar squeeze: US tariffs threaten panel production and jobs in Thailand
In the year of trade wars, Trump extended Biden-era tariffs on solar panels from China to neighbouring countries. Nicha Wachpanich spoke to some of those workers who subsequently lost their jobs making panels at Chinese-run factories in Thailand and found that the US levies and bad behaviour by bosses had combined to crush their dreams of a better life.
2. Business-as-usual: Donors pour climate adaptation finance into big infrastructure, neglecting local needs
Trump being Trump, and axing US climate finance, is no reason to let other wealthy donor nations off the hook. We examined the latest spreadsheets for annual adaptation aid and found Japan is counting support for massive infrastructure projects in its figures, despite them having only a dubious role in helping people adapt to climate change.
Our reporter Tanbirul Miraj Ripon visited one such project – the Matarbari port in Bangladesh. He found that the port handles coal and gas imports and has destroyed locals’ homes and livelihoods. Despite this, on paper it represents $363 million in Japanese climate adaptation finance, the biggest single climate resilience project being funded by a wealthy country in 2023.
3. Ethiopia’s bold EV ambitions hit bumps in rural areas
Other nations are trying hard to go green but finding it tricky. This year, Ethiopia hosted the Africa Climate Summit, was selected as the host of COP32 and opened the continent’s biggest hydropower dam.
It plans to use some of this clean power to charge electric vehicles, after banning imports of cars with internal combustion engines (even as the European Union is softening its own 2035 ban on ICEs). While that will reduce Ethiopia’s already tiny emissions and its fossil fuel import bills, it won’t be easy in a nation where only half the population has electricity access, as Solomon Yimer and Vivian Chime reported.
4. Ending poverty and gangs: How Zambia seeks to cash in on the global drive for EVs
Other African governments are trying to cash in on their minerals, which big players like China, the US and increasingly Saudi Arabia want for green technologies and/or making equipment for wars.
Pamela Kapekele went to look at the situation in Zambia’s Copperbelt province – where you can probably guess what they produce! She found that good tax regulations and working conditions will be needed if locals are to see the benefits of surging demand for the metal.
Later in the year, an acid spill from a copper-mine tailings dam that contaminated the country’s main river showed the value of environmental regulation too. Reporting from Nigeria’s lithium and South Africa’s platinum mines also highlighted the challenges of making minerals mining and processing cleaner and fairer for communities.
5. Is the world’s big idea for greener air travel a flight of fancy?
Some sectors – like international aviation and shipping – tend to fall outside the scope of national media, and it’s a gap we’ve aimed to fill. Together with Singapore’s Straits Times, we tracked the supply chain for what the airline industry calls “Sustainable Aviation Fuel” (SAF) and found that virgin and barely used palm oil – which threatens rainforests – is being passed off as waste cooking oil and used to power planes in Europe.
Malaysia is a particular hotspot for this fraud, as government subsidies there make virgin palm oil cheap in the shops – and it can be sold for a higher price as “used” cooking oil, providing a profit motive for flipping it. Our investigation was picked up by the Financial Times, Bloomberg and the Malaysian authorities, who have since launched a crackdown on this kind of fraud.
But with verification of the materials used for SAF relying on just a handful of commercial auditors conducting mainly paper-based checks, airlines currently cannot know for sure if their green jet fuel is actually sustainable. Their advertising to passengers should – but often doesn’t – reflect this uncertainty.
6. Brazil’s environment minister suggests roadmap to end fossil fuels at COP30
Our reporting was often prescient this year. We called it correctly that the US would leave the Paris Agreement but not the UNFCCC, that Argentina would not follow America out of Paris, that Ethiopia rather than Nigeria would be chosen as COP32 host and that petrostates would try to kill a new green shipping framework at the International Maritime Organization.
We are also pretty sure we were the first – at least in English – to pick up on Brazilian Environment Minister Marina Silva’s proposal for COP30 to agree on a roadmap away from fossil fuels, which she aired back in June at London Climate Week. That proposal was pushed by President Lula at the start of COP30, dominated much of the conversation at the summit and will continue to be discussed throughout 2026.
8. PR firm working for Shell wins COP30 media contract
In the summer of 2025, our crack investigative reporter Matteo Civillini got the scoop on how the Brazilian government, via a contract tendered by the UN, was working with Edelman on international media relations for the COP30 climate summit while the global PR giant was simultaneously engaged in promoting Shell’s fossil fuel interests in Brazil.
This story was picked up by a range of other media, and amplified calls for agencies whose clients include fossil fuel firms to be excluded from the climate negotiations. Advocacy group Clean Creatives was inspired by Matteo’s reporting to launch a campaign against Edelman’s COP involvement. That culminated in an open letter from influencers and creators with a combined audience of over 24 million calling for Edelman to be dropped. The drumbeat on this theme is likely to get louder in 2026.
8. “House of cards”: Verra used junk carbon credits to fix Shell’s offsetting scandal
And talking of smoke and mirrors, just when we thought the murky web of carbon offsetting linking oil and gas major Shell to sham rice-farming projects in China couldn’t get any more convoluted, it did exactly that.
By combing through the records of carbon-credit registry Verra – the world’s biggest – Matteo confirmed that nearly a million bogus offsets from 10 disqualified methane reduction projects had been compensated for with the same number of junk credits from another four such projects that were also axed by Verra.
“It’s frankly unbelievable that Verra considers it appropriate to compensate for hot air credits with other hot air credits,” Jonathan Crook, policy lead at Carbon Market Watch, told us. “To pretend this is a satisfactory resolution is both absurd and deeply alarming.”
Verra insists the replacement credits were technically available to plug the gap left by the first batch – even though the second set, too, now need to be swapped out. Shell is keeping its distance, saying it does not manage or operate “the projects in question” despite being earlier involved in the Chinese rice-farming programmes as their “authorised representative”. Mind-boggling indeed!
9. Self-taught mechanics give second life to Jordan’s glut of spent EV batteries
In what was on balance a bad year, we brought you some hope too. A landmark advisory opinion on climate change and human rights from the International Court of Justice in The Hague was stronger than anyone imagined and may open the door to lawsuits against polluting countries and companies in 2026.
Other good news stories included analysts suggesting China’s fossil fuel use could peak this year, the UN’s loss and damage fund launching its first call for proposals, South Korea and Morocco moving to phase out coal and a boom in imports of solar panels to Africa.
Hope came too from ordinary people and their ingenuity – like the untrained Jordanians interviewed by Yamuna Matheswaran, hooking up solar panels to old Tesla batteries, lowering both their electricity bills and their carbon emissions into the bargain.
The post Nine of our best climate stories from 2025 appeared first on Climate Home News.
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