The term “global warming” is typically used to describe increasing global temperatures as a result of human emissions of carbon dioxide (CO2) and other greenhouse gases.
However, unusually cold events are often portrayed as being made worse by human activity, as a result of increased variability or a disruption of the “polar vortex” in a fast-warming world.
There is significant debate in the scientific community about whether rapid Arctic warming and sea ice loss could disrupt atmospheric circulation patterns and lead to cold-air outbreaks in the northern hemisphere mid-latitude regions.
In a new analysis, Carbon Brief shows that few places in the world have seen an increase in extreme cold days over the past 55 years.
If climate change is influencing atmospheric circulation, any effects on extreme cold appear to be more than compensated by the rapid winter warming the world has experienced.
A controversial hypothesis
In an episode of Marketplace’s How We Survive podcast last year, the host – US radio journalist Kai Ryssdal – noted that climate change is expected to cause “hotter hots [and] colder colds in unexpected parts of the world”.
This is not an uncommon sentiment, with the media commonly attributing extreme cold events to human activity, particularly during episodes of bitter cold or polar-vortex events.
Some researchers have argued that these extreme cold snaps might be becoming more frequent due to reduced sea ice and Arctic amplification – the phenomenon where the Arctic warms more quickly than the global average.
At the core of the hypothesis that Arctic warming could influence mid-latitude cold extremes is the fact that a rapidly warming Arctic changes the temperature difference between the poles and the equator.
Normally, the strong contrast in temperature between these regions drives key patterns of atmospheric circulation, including the jet stream. According to proponents of this theory, when Arctic temperatures rise faster than those farther south, atmospheric circulation can weaken, meander, or buckle more frequently. As a result, cold polar air can spill down into areas that are usually less frigid.
A related argument focuses on how diminished sea ice – particularly in the Barents and Kara seas – might disrupt the atmosphere. Less sea ice means more heat and moisture escapes from the ocean surface into the air, which can potentially alter weather patterns downstream. This can boost the odds of “blocking high” weather systems, or unusual circulation patterns that pull cold air into mid-latitudes.
However, there are relatively few studies that attribute an increase in cold extremes – or an individual extreme cold event – to human activity.
Carbon Brief’s attribution map – which charts extreme weather events around the world and their links to human-caused warming – includes 33 studies that examine extreme cold events specifically.
Of these, 24 studies found that the extreme cold was made less likely due to climate change, six found no discernible human influence and three found insufficient data to conclude either way. Only one extreme event attribution study in the database found that a cold extreme – severe frosts in Western Australia in 2016 – was made more likely due to climate change. However, even that study noted that “warmer temperatures may have offset or countered this effect of the circulation driver”.
Many climate scientists disagree with the hypothesis that warming could lead to increased cold outbreaks, arguing that cold extremes are decreasing overall in a warming world.
Others contend that causality cannot yet be proved and that both models and observations provide limited support for a significant role of climate change in mid-latitude cold events.
In addition, observed data reveals that, although cold spells still occur, they have become less frequent and less intense over recent decades. Most modeling studies do not consistently reproduce more frequent or severe cold outbreaks. Instead, they often show that the overall warming trend dominates, making cold extremes rarer over time.
This suggests that, if there were a connection between climate change and extreme cold events, the long-term warming trend will still likely lead to fewer, milder cold outbreaks – and that any effect from Arctic amplification would be relatively small.
Have any regions experienced increased cold events?
To help assess the effects of climate change on extreme cold events, Carbon Brief used gridded daily minimum global temperature data from Berkeley Earth to calculate how the temperatures of the coldest 5% of the days of the year have changed since the 1970s.
Minimum daily temperatures reflect the single coldest measurement taken over the course of the day. (While the coldest 5% of days is a somewhat arbitrary number, the results are largely similar for the coldest 10%, 5%, 2%, 1%, or the single coldest day of the year.)
The figure below shows the results for every one-by-one degree latitude-longitude grid cell on the Earth’s land (a size approximately equivalent to 100km by 100km). Grid cells coloured red experienced a decrease in extreme cold days, while those coloured blue had more extreme cold days.
The vast majority of the planet has seen a strong decrease in extreme cold events, with the largest declines seen in high-latitude northern hemisphere regions (which have also experienced the fastest rate of warming overall).
The few regions that have seen an increase in extreme cold events tend to be those with the slowest average rates of warming, including India, South Africa and Antarctica.
In India, this has likely been influenced by rapid increases in air pollution – particularly cooling sulfate aerosols – over this period. Causes of more extreme cold events in Antarctica are less clear, though it is possible that they could be linked to the seasonal loss of ozone layer over the past 50 years.
Another way to assess changes in cold events is to look at the change in the number of days where any hour of the day – that is, the daily minimum temperature – is below freezing (0C, 32F). The map below shows the change in average annual freezing days between 1970 and 2024.
The map shows dramatic shifts in the number of freezing days in much of the high-latitude northern hemisphere, with nearly a month fewer freezing days over the Himalayas, eastern Europe and parts of Canada and the western US over the past 50 years.
(White areas on the graph – such as much of the tropics and subtropics – represent regions of the world where temperatures below freezing almost never occur and thus changes over time cannot be calculated.)
Fewer cold outbreaks in the US
A sizable portion of the academic research on cold outbreaks has been focused on the contiguous US, as it is a region prone to occasional extreme cold conditions caused by intrusions of Arctic air.
The map below shows there has been a warming trend in the coldest days of the year across virtually the entire US over the past 50 years.
This suggests that the effect of Arctic amplification on cold-air patterns is smaller than the strong winter warming trend.
Almost no regions of the US have seen a cooling trend in the 5% coldest days of the year – and higher latitude regions have tended to experience the fastest winter warming.
There has been a slight cooling trend in the coldest days of the year in northern Mexico and slower warming in California, Arizona, southern New Mexico and southern Texas.
Similarly, the figure below examines the change in days where minimum temperatures are below freezing in the US.
It shows that there are, on average, 13 fewer days below freezing each year compared to the 1970s. Or, to put it another way, there is half a month where daily minimum temperatures are no longer cold enough for icy and snowy conditions to occur.
Increasingly rare cold spells
The latest climate models overwhelmingly project that cold extremes will continue to diminish as greenhouse gas concentrations rise.
This means that, even if certain patterns occasionally transport freezing polar air southward, winters on the whole are likely to be milder than in the past.
However, the scientific understanding of precisely how Arctic warming might – or might not – influence mid-latitude weather is still evolving.
Researchers continue to refine models, incorporate better reanalysis data and examine how changes in atmospheric circulation dynamics might play out under different scenarios. Additional data – especially over multiple decades – will help clarify whether the Arctic’s role in mid-latitude cold extremes is significant or overstated.
For now, observations over the past 50 years generally show a world with fewer cold extremes – and projections point toward increasingly rare cold spells in the future.
The post Factcheck: Climate change is not making extreme cold more common appeared first on Carbon Brief.
Factcheck: Climate change is not making extreme cold more common
Antarctic sea ice has recorded its third-smallest winter peak extent since satellite records began 48 years ago, new data reveals.
Provisional data from the US National Snow and Ice Data Center (NSIDC) shows that Antarctic sea ice hit its annual winter peak on 14 September, with an extent of 17.59m square kilometres (km2).
The organisation notes that the data is still preliminary, adding that “large fluctuations in extent are typical of Antarctic sea ice near the seasonal maximum”.
One expert tells Carbon Brief that it is “concerning to see these low values persisting”, but says that scientists need more time to determine whether this represents a “structural shift” in Antarctic sea ice extent.
Meanwhile, at the Earth’s other pole, Arctic sea ice reached its annual minimum on 12 September, ranking as the joint-10th lowest in the satellite record.
The NSIDC notes that the last 20 years have seen the lowest 20 Arctic sea ice extents in the satellite record.
Antarctic peak
Dr Lettie Roach, a polar climate scientist at the Alfred Wegener Institute in Germany, tells Carbon Brief that this year’s Antarctic sea ice maximum was “well below average for the season”. She warns that, “after several decades of stable or increasing winter Antarctic sea ice conditions, it is concerning to see these low values persisting”.
She adds:
“Compared with the Arctic, it’s less clear how recent changes in Antarctic sea ice are attributable to human-caused warming vs natural variability. We need more years of observations to better understand whether this is truly a structural shift.”
Dr Clare Eayrs, a postdoctoral researcher at the Korea Polar Research Institute (KOPRI), tells Carbon Brief that, since recording a “near-average February minimum” extent, Antarctic sea ice has “returned to unusually low winter coverage”.
She notes that Antarctic sea ice extent in July and August this year were the fifth and fourth lowest on record, respectively, adding that “all five of the lowest July extents have occurred since 2022 and all four of the lowest August extents since 2023”.
The chart below shows Antarctic sea ice extent in 2025 (dark blue) and 2026 (red) so far. For comparison, the chart shows decadal averages (dotted lines) as well as 2023 (mid blue), the year of the smallest winter sea-ice maximum on record.
Eayrs tells Carbon Brief that the regional pattern of Antarctic sea ice cover “changed substantially during the growth season”.
For example, she says that “in April, the Bellingshausen Sea remained almost entirely ice-free, while the neighbouring Amundsen Sea had more ice than usual”.
However, by late August, changes in atmospheric pressure and wind meant that “the Bellingshausen deficit had largely recovered, while ice was unusually scarce in the Amundsen Sea and across much of East Antarctica”.
Arctic minimum
Meanwhile, the Arctic recorded its minimum summer sea ice extent on 12 September. At 4.60m km2, this year ties with 2025, 2010 and 2008 as the 10th-lowest sea ice extent on record.
The chart below shows Arctic sea ice extent in 2025 (dark blue) and 2026 (red) so far. For comparison, the chart shows decadal averages (dotted lines) as well as 2012 (mid blue), the year of the smallest summer sea-ice minimum on record.
Roach tells Carbon Brief that although this minimum is not “record setting”, it is still “lower than any sea ice minimum before 2007”. She adds:
“Human-caused climate change has reduced Arctic sea ice cover and thickness, so the region is fundamentally different compared to a few decades ago.”
Scientists have been tracking Arctic sea ice thickness using a reanalysis produced called the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) since 1979.
In March 2026, the National Oceanographic and Atmospheric Administration (NOAA) terminated a global dataset of air pressure that scientists relied upon to produce PIOMAS, forcing both datasets to stop publishing updates.
The PIOMAS website says it will take “considerable effort and time” to find alternative data to use in their reanalysis. It adds that “we don’t yet have a good sense if that’s possible with available funds and if so, when we will be able to resume production of a new PIOMAS timeseries”.
Roach also notes that August saw record-breaking heat sweep across much of the world, explaining that high temperatures “extended into Arctic coastal regions, close to regions with substantial sea ice loss – particularly the Barents-Kara and East Siberian seas”.
Dr Zack Labe, a scientist at Climate Central, tells Carbon Brief that the absence of a new record does not mean that ice cover is becoming more “resilient”. He says:
“Local weather patterns across the Arctic play a really important role in year-to-year sea-ice extent, even as the long-term trend is clearly downward.”
Labe tells Carbon Brief that weather in the Arctic this summer was “influenced mainly by lower pressure toward the central Arctic, which brought cloudier and cooler conditions that limited surface melt and delayed the start of the melt season”.
He explains that this “was most obvious across parts of the Beaufort and Chukchi seas, where the melt season didn’t really kick off until after early July, which was more than two weeks later than normal”.
In contrast, he says, the Atlantic side of the Arctic “had a much more extreme summer”, with sea ice in the Barents Sea recording its “earliest melt-out on record”.
This was partly due to “unusually warm air and ocean temperatures”, Labe says. He notes, for example, that parts of western Siberia saw unusually persistent temperatures more than 5C above the 1981-2010 average for much of the summer, which extended out over the Kara Sea and contributed to substantial ice melt in this area”.
Labe tells Carbon Brief that, going forward, scientists need “more data and observations of other sea-ice metrics, like ice thickness, which may give us better insight into the overall condition of the ice pack, especially during years like 2026 when it is very fragmented”.
(In March 2026, Arctic sea ice reached its peak extent for this winter, clocking in as the joint-smallest in a satellite record going back almost half a century.)
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The post ‘Concerning’ low sea ice persists as Antarctic hits third-lowest winter peak appeared first on Carbon Brief.
‘Concerning’ low sea ice persists as Antarctic hits third-lowest winter peak
Participants at COP31 in Antalya will have a “duty” not to interfere in Türkiye’s internal affairs under the country’s hosting deal with the UN, reviving a clause dropped for last year’s climate summit in Brazil that human rights groups warn could put activists at risk.
Türkiye has faced growing criticism from human rights groups over the jailing of opposition figures, journalists and activists and imposed a blanket protest ban around July’s summit of the NATO military alliance in Ankara.
The contested provision is included in the binding agreement between the UN climate secretariat and the Turkish government that sets out responsibilities over logistical arrangements and details participants’ rights and obligations.
The document, signed in June but only made public on Wednesday, gives accredited COP31 attendees immunity from legal action over what they say, write or do in connection with the conference. Climate Home News understands that this safeguard can be applied to what takes place both inside and, in certain circumstances, outside of the UN-controlled COP “Blue Zone”. For the first time, this protection explicitly continues after the summit ends.
But participants enjoying these “privileges and immunities” also have a duty to respect Türkiye’s laws and regulations and not to interfere in its internal affairs, the agreement states. Rights groups fear its wide-ranging formulation could be used to discourage criticism of the host government.
Climate Home News understands that whether an action is covered by the immunity or infringes on the host’s internal affairs would be evaluated on a case-by-case basis, with close coordination between the country’s authorities and the UN climate change body.
A separate provision states that immunity shall be waived where the UN believes it would “impede the course of justice”.
‘Chilling effect’
Those same provisions featured in the host country agreements for COP28 in the United Arab Emirates and COP29 in Azerbaijan, both regarded as authoritarian regimes, before being dropped for COP30 in Brazil.
Ann Harrison, climate justice policy advisor at Amnesty International, said it is “extremely disappointing” that the COP31 agreement re-introduced clauses that could “hinder the ability of human rights defenders and civil society organisations to conduct their work safely”.
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She added the provisions could have a “wider chilling effect” on rights to freedom of expression and peaceful assembly, given concerns over the human rights situation in Türkiye, including laws that “have shrunk civic space” and their “abusive” implementation by authorities.
The UN climate change body declined to comment.
Rights groups have documented blanket protest bans, unlawful use of force by the police and prosecutions of journalists, human rights defenders and lawyers across Türkiye in the last year.
Arrests and protest bans
Last July, environmental activist Esra Işık was sentenced to more than two years for “resisting” a public official over what Amnesty International described as a peaceful protest against an urgent expropriation order linked to the expansion of coal mining in south-western Türkiye. She is appealing the conviction.
Ahead of a summit of the NATO alliance in the capital Ankara in July, authorities put in place a 13-day blanket ban on demonstrations, citing “national security”, and arrested over 200 people. Human Rights Watch said the crackdown showed Türkiye’s “ruthless intolerance of freedom of speech and assembly”.
Earlier this month, Turkish police detained dozens of people as part of what rights groups described as the government’s widening crackdown on LGBTQ+ activists and venues.
Questioned by media as to how he would guarantee the right to protest at COP31, Kurum said earlier in September that his team would “try to meet” any request they receive from civil society and give them “a free space to express themselves”.
“Don’t worry, thinking you will not be able to voice your opinions or really share your thoughts,” he said in an attempt to reassure campaigners, adding that he had put former deputy environment minister Mehmet Birpinar in charge of liaising with civil society.
Civic space needed
Camilla Pollera, human rights and climate change campaigner at the Center for International Environmental Law (CIEL), said meaningful participation at COP31 is fundamental to the legitimacy of climate action.
“At a climate summit, civil society participation necessarily includes being present, speaking out, scrutinising governments’ decisions and climate policies, and advocating for communities most vulnerable to climate change,” she added.
At last year’s COP30 summit, thousands of Indigenous people and climate activists peacefully marched through the Amazonian city of Belém in the first major demonstration outside the UN venue in four years. Smaller-scale demonstrations were largely confined to the “Blue Zone” at COP27 in Egypt, COP28 in the UAE and COP29 in Azerbaijan.
In two other separate incidents in Belém, members of the Munduruku tribe blocked access to the conference centre for hours, demanding an end to development projects in their ancestral land, and protesters stormed through the venue clashing with UN security officials.
The COP31 hosting agreement keeps some of the safeguards previously hailed by civil society groups. The government and the UN secretariat commit to upholding “the fundamental human rights” of all participants in the agreement’s preamble.
Under the deal, Türkiye also needs to ensure that security personnel follow “the highest ethical and professional standards and are expected to behave with integrity and respect”.
The post COP31 attendees told not to interfere in Türkiye’s “internal affairs” appeared first on Climate Home News.
COP31 attendees told not to interfere in Türkiye’s “internal affairs”
As rising seas submerge growing swathes of land, countries that lose territory should still keep their national boundaries, sovereign rights and UN membership, according to a political declaration adopted at the UN General Assembly in New York on Thursday.
The declaration, which was championed by climate-vulnerable small island states, affirms “the presumption in favour of continued statehood” in the face of sea level rise fuelled by climate change, and urges countries to work together to assist communities affected by encroaching oceans.
Speaking at a high-level UN meeting to address the existential threats posed by sea level rise, Cabo Verde’s Prime Minister Francisco Carvalho, one of the initiative’s co-facilitators along with Australia, said the adoption of the text by consensus sends “a message of hope”.
“This declaration has a very special meaning. For us, sea level rise is neither a distant threat nor a theoretical concern,” he said, adding that rising seas put at risk key infrastructure, water resources and economic growth in small island states.
In the Pacific, sea levels have risen at twice the global rate, dramatically increasing coastal flooding events from two to 20 a year in the Republic of the Marshall Islands, and from zero to 102 events per year in American Samoa, according to the World Meteorological Organization (WMO).
Surangel Whipps Jr., president of the Pacific island of Palau, said the summit in New York represents a “moment of international solidarity”, and highlighted that small island states will remain permanent members of the UN.
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Declaration recognises statehood
An advisory opinion by the world’s top maritime court, the International Tribunal on the Law of the Sea (ITLOS), first upheld in 2024 that countries do not have to shrink their maritime borders even if they lose land territory due to sea level rise. This was reiterated by the International Court of Justice in last year’s landmark ruling on the climate obligations of states.
The new declaration endorsed by all governments at the UN General Assembly stresses that sea level rise “is not a distant scenario but a real and lived experience for many”, and notes that international law must be implemented in global responses to rising seas.
UN Secretary-General António Guterres said the “milestone must now be translated into action”, adding that the declaration should encourage an “ongoing dialogue” at the “highest possible level” leading to practical outcomes. Pacific islands have proposed an international treaty on sea level rise that would provide more legal certainty.
“Those on the frontlines must be front and centre on every decision. We cannot allow countries and cultures to vanish beneath the waves,” he said. “The SOS has gone out. The world must answer.”
At regional summit, Pacific islands ask for COP31 support for clean energy and finance
Goodwin Friday, prime minister of St. Vincent and the Grenadines, said measures to protect vulnerable states will require adequate finance. “Investing in resilience now is more cost-effective than paying the far greater price for loss and damage later,” he added.
Championed by Australia’s COP31 co-presidency, Pacific islands have sought to put adaptation to sea level rise and ocean conservation at the top of the political agenda by inviting world leaders to attend the pre-COP31 summit co-hosted by Fiji and Tuvalu in October.
Tuvalu will also host the second global fossil fuel phase-out summit in April 2027, after around 60 governments met this year in Santa Marta, Colombia, to discuss ending their dependence on coal, oil and gas.
“Our coastlines, our reefs and our communities are living with the consequences of fossil fuel dependence every day, and our people have earned the right to help shape the way forward,” Lynda Tabuya, Fiji’s climate minister, said in a statement announcing details of the conference.
Ocean monitoring gets a boost in New York
Amid record-breaking marine heat and seas rising at unprecedented speed, governments in New York announced new commitments to protect the world’s ocean, as efforts to bolster marine ecosystems and coastal communities rise up the political agenda.
On Wednesday, the EU and Canada announced more funding for a new Europe-led ocean monitoring system called OceanEye, launched in the aftermath of a failed attempt by the Trump administration to dismantle the largest existing network of deep-sea observatories.
During an event at UN headquarters in New York, EU President Ursula von der Leyen and Canadian Prime Minister Mark Carney announced around $163 million in new funding for the initiative, with the EU pledging €92 million ($105m) on top of existing seed funding and Canada pledging C$82 million (US$58m) over five years.
According to an EU statement, while OceanEye will collaborate with the Global Ocean Observing System, that network “remains vulnerable to financial shortfalls and geopolitical disruptions”. A group of 30 countries from Europe, Africa and the Americas joined an international initiative in support of OceanEye, including large coastal nations like Brazil, Namibia and Mexico.
Von der Leyen said OceanEye “can make us the leading ocean data provider in a matter of years”, including by launching new satellites and installing new observatories in the deep ocean. “From outer space to the deepest ocean, our funding helps us keep watch beneath the waves,” she added.
Carney said the initiative would help protect Canada’s Arctic region with real-time monitoring operating year-round. “We can’t protect what we can’t see,” he said, also highlighting that Canada had expanded conservation of its ocean territory from 1% a decade ago to 15% now.
In New York, a group of 19 countries said they are either developing or implementing plans to sustainably manage all of their ocean territory, with 12 new nations joining the initiative. In a joint communiqué, they called on more countries to sign up ahead of COP31.
Warnings of El Niño-fuelled extreme heat
Scientists and world leaders have raised the alarm over this year’s record-breaking marine temperatures, which have persisted above historical peaks for more than 100 days as the naturally occurring El Niño phenomenon intensifies in the Pacific.
Extreme ocean heat could become a threat to coastal ecosystems and communities, experts fear. Water temperatures 1.5C above normal levels have also rapidly fuelled a strong hurricane in the Pacific in recent days.
Despite scientific calls for additional ocean conservation efforts, a report launched this week in New York warned that efforts to protect ocean ecosystems are lagging behind, with only 10% of the global ocean covered by conservation areas and just 3.5% designated as “effectively protected”.
The post Threatened by rising seas, small islands secure right to keep their statehood appeared first on Climate Home News.
Threatened by rising seas, small islands secure right to keep their statehood
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