Showing posts with label Arctic Melting. Show all posts
Showing posts with label Arctic Melting. Show all posts

Wednesday, August 20, 2025

Dramatic slowdown in melting of Arctic sea ice surprises scientists. Natural climate variation is most likely reason as global heating due to fossil fuel burning has continued

Melting is likely to start again at about double the long-term rate in the next five to 10 years, the scientists said. Photograph: Keren Su/China Span/Alamy

 

The melting of sea ice in the Arctic has slowed dramatically in the past 20 years, scientists have reported, with no statistically significant decline in its extent since 2005.

The finding is surprising, the researchers say, given that carbon emissions from fossil fuel burning have continued to rise and trap ever more heat over that time.

They said natural variations in ocean currents that limit ice melting had probably balanced out the continuing rise in global temperatures. However, they said this was only a temporary reprieve and melting was highly likely to start again at about double the long-term rate at some point in the next five to 10 years.

The findings do not mean Arctic sea ice is rebounding. Sea ice area in September, when it reaches its annual minimum, has halved since 1979, when satellite measurements began. The climate crisis remains “unequivocally real”, the scientists said, and the need for urgent action to avoid the worst impacts remains unchanged.

 The natural variation causing the slowdown is probably the multi-decadal fluctuations in currents in the Atlantic and Pacific oceans, which change the amount of warmed water flowing into the Arctic. The Arctic is still expected to see ice-free conditions later in the century, harming people and wildlife in the region and boosting global heating by exposing the dark, heat-absorbing ocean.


 

Dr Mark England, who led the study while at the University of Exeter, said: “It is surprising, when there is a current debate about whether global warming is accelerating, that we’re talking about a slowdown.

“The good news is that 10 to 15 years ago when sea ice loss was accelerating, some people were talking about an ice-free Arctic before 2020. But now the [natural] variability has switched to largely cancelling out sea ice loss. It has bought us a bit more time but it is a temporary reprieve – when it ends, it isn’t good news.”

The research, published in the journal Geophysical Research Letters, used two different datasets of Arctic sea ice levels from 1979 to the present day. The scientists analysed the sea ice area for every month of the year and the slowdown was seen in all cases.

To see if such a slowdown could be a result of natural variation, they examined the results of thousands of climate model runs. “This is not an extremely rare event – over a century, it should happen a couple of times,” said England, now at the University of California, Irvine. Furthermore, all the simulations showed sea ice loss accelerating again after the slowdown.

Prof Julienne Stroeve, of University College London, said: “We know climate records, be it in global temperatures or sea ice, can remain the same for several years in a row as a result of internal climate variability.”

Stroeve’s analysis of the long-term trend from 1979 to 2024 shows that about 2.5 sq metres of September ice is lost for every tonne of CO2 emitted.

 

Prof Andrew Shepherd, of Northumbria University, said: “We know that the Arctic sea ice pack is also thinning, and so even if the area was not reducing, the volume still is. Our data show that since 2010 the average October thickness has fallen by 0.6cm per year.”

The rate of the rise in global surface temperature has also slowed down in the past, before resuming a rapid rise. A major El Niño event in 1998 was followed by a decade or so of similar global temperatures, which was nicknamed “the pause”. However, the planet continued to accumulate heat throughout and global temperatures have since risen rapidly.

England rejected any suggestion the sea ice slowdown suggested climate change was not real. “Climate change is unequivocally real, human-driven, and continues to pose serious threats. The fundamental science and urgency for climate action remain unchanged,” he said.

“It is good to explain to people that [the slowdown] is happening, else they are going to hear it from someone who is trying to use it in bad faith as a way to undermine our very solid understanding of what’s happening with climate change.”

Tuesday, May 20, 2025

Sea level rise will cause ‘catastrophic inland migration’, scientists warn. Rising oceans will force millions away from coasts even if global temperature rise remains below 1.5C, analysis finds

 

The loss of ice from the Greenland and Antarctic ice sheets has quadrupled since the 1990s. Photograph: Bernhard Staehli/Shutterstock

 

Sea level rise will become unmanageable at just 1.5C of global heating and lead to “catastrophic inland migration”, the scientists behind a new study have warned. This scenario may unfold even if the average level of heating over the last decade of 1.2C continues into the future.

The loss of ice from the giant Greenland and Antarctic ice sheets has quadrupled since the 1990s due to the climate crisis and is now the principal driver of sea level rise.

The international target to keep global temperature rise below 1.5C is already almost out of reach. But the new analysis found that even if fossil fuel emissions were rapidly slashed to meet it, sea levels would be rising by 1cm a year by the end of the century, faster than the speed at which nations could build coastal defences.



The world is on track for 2.5C-2.9C of global heating, which would almost certainly be beyond tipping points for the collapse of the Greenland and west Antarctic ice sheets. The melting of those ice sheets would lead to a “really dire” 12 metres of sea level rise.

Today, about 230 million people live within 1 metre above current sea level, and 1 billion live within 10 metres above sea level. Even just 20cm of sea level rise by 2050 would lead to global flood damages of at least $1tn a year for the world’s 136 largest coastal cities and huge impacts on people’s lives and livelihoods.

However, the scientists emphasised that every fraction of a degree of global heating avoided by climate action still matters, because it slows sea level rise and gives more time to prepare, reducing human suffering.

 

Sea level rise is the biggest long-term impact of the climate crisis, and research in recent years has shown it is occurring far faster than previously estimated. The 1.5C limit was seen as a way to avoid the worst consequences of global heating, but the new research shows this is not the case for sea level rise.

The researchers said the “safe limit” temperature for ice sheets was hard to estimate but was likely to be 1C or lower. Sea level rise of at least 1-2 metres was now inevitable, the scientists said. In the UK, just 1 metre of sea level rise would see large parts of the Fens and Humberside below sea level.

“What we mean by safe limit is one which allows some level of adaptation, rather than catastrophic inland migration and forced migration, and the safe limit is roughly 1cm a year of sea level rise,” said Prof Jonathan Bamber of the University of Bristol in the UK. “If you get to that, then it becomes extremely challenging for any kind of adaptation, and you’re going to see massive land migration on scales that we’ve never witnessed in modern civilisation.” Developing countries such as Bangladesh would fare far worse than rich ones with experience of holding back the waves, such as the Netherlands, he said.

Durham University’s Prof Chris Stokes, lead author of the study, said: “We’re starting to see some of the worst-case scenarios play out almost in front of us. At current warming of 1.2C, sea level rise is accelerating at rates that, if they continue, would become almost unmanageable before the end of this century, [which is] within the lifetime of our young people.”

The average global temperature hit 1.5C for the first time in 2024. But the international target is measured as the average over 20 years, so is not considered to have been broken yet.

 

The new study, published in the journal Communications Earth and Environment, combined data from studies of warm periods up to 3m years ago; observations of ice melting and sea level rise in recent decades; and climate models. It concluded: “Continued mass loss from ice sheets poses an existential threat to the world’s coastal populations.”

Prof Andrea Dutton of the University of Wisconsin-Madison, who was part of the study team, said: “Evidence recovered from past warm periods suggests that several metres of sea level rise – or more – can be expected when global mean temperature reaches 1.5C or higher.”

At the end of the last ice age, about 15,000 years ago, sea level was rising at 10 times the rate today, driven by self-reinforcing feedbacks that may have been triggered by only a small increase in temperature. The last time CO2 levels in the atmosphere were as high as today, about 3m years ago, sea level rise was 10-20 metres higher.

Even if humanity can bring the planet back to its preindustrial temperature by removing CO2 from the atmosphere, it will still take hundreds to thousands of years for the ice sheets to recover, the researchers said. That means land lost to sea level rise will remain lost for a long time, perhaps until the Earth enters the next ice age.

Belize moved its capital inland in 1970 after a devastating hurricane, but its largest city is still on the coast and will be inundated with only 1 metre of sea level rise, Carlos Fuller, Belize’s longtime climate negotiator, said: “Findings such as these only sharpen the need to remain within the 1.5C Paris agreement limit, or as close as possible, so we can return to lower temperatures and protect our coastal cities.”




 

Monday, March 17, 2025

'The ice melted beneath our feet': The huskies that revealed the rapid shrinking of Greenland's ice


 

Isabelle Gerretsen

 

In 2019, climate scientist Steffen Olsen took a startling photo of huskies appearing to walk on water. The photo quickly went viral as it revealed the reality of Greenland's rapidly melting ice.

In June 2019, a striking image of husky dogs apparently walking on water in Greenland stunned the world and quickly went viral.

The photo was taken by Steffen Olsen, a climate scientist at the Danish Meteorological Institute and lead of Blue Action, a European project which investigates the effect of a changing Arctic on weather and climate.

"The reaction surprised me," says Olsen. "It surprised me that so many people saw this as a beautiful photo. I saw it as a scary situation."

That's because the dogs were in fact wading through ankle-deep meltwater on top of sea ice in Inglefield Bredning, an 80km-long (49.7 miles) system in northwestern Greenland.

 

"I learned to see the photo as an illusion. People don't see sea ice, but dogs walking on water," Olsen says. 

Olsen captured the photo while travelling with a team of scientists who were monitoring sea and ice conditions near the town of Qaanaaq, one of the world's most northerly towns. They were retrieving scientific instruments they had deployed during the winter. 

"We had been travelling for some hours and it became clear that the melting was very extreme… [the ice] more or less melted beneath our feet while we were travelling on it," says Olsen. "The local hunters and I were very surprised… we were searching for dry spots to get the dogs and the sleds out of the water and there were none in sight. We turned around and made it back to the coast."

It surprised me that so many people saw this as a beautiful photo. I saw it as a scary situation

The dogs are typically very hesitant to get their paws wet, says Olsen. "Usually when we meet water, it's because there are cracks in the sea ice and the dogs have to jump over the water…they hate it. But it was actually very warm so I think they were happy to have cold feet," he says, adding that temperatures reached 14C (57F) on the day.

 The scientists managed to retrieve their instruments a few days later once the water had drained away through small cracks in the ice sheet. "Then you have a short period of time when you can then travel again before the ice collapses and breaks up," says Olsen.

On average, Greenland loses 234 billion tonnes of ice per year (Credit: Alamy)


 

Olsen says he was extremely surprised by the rapid melting he witnessed when he took the photo on 13 June 2019. He has only experienced such an extreme event once during his 15 years carrying out research in Greenland. It's unusual for melting to occur that quickly, Olsen explains.

"It requires a sudden onset of warm air while you still have fresh snow on the ice and solid sea ice. So it's an example of an extreme event developing early in the season... The local community have told me: 'you will have to wait 100 years to see [such an event] again'." 

Melting events such as the one Olsen witnessed would normally not occur until later in the season, in late June and July, but in 2019 melting started in mid-April, around six to eight weeks before the 1981-2020 average, and affected roughly 95% of Greenland's ice sheet, according to the US' National Oceanic and Atmospheric Administration.

 

Such early melting events can have a "snowball effect" and lead to more melting as there is less snow and ice to reflect the Sun's rays back into space and keep the surface cool, explains Bianca Perren, a paleoclimatologist at the British Antarctic Survey (BAS), who studies sediment cores from polar regions to understand the long-term variability of the climate. 

Greenland experienced record ice loss in 2019, shedding a total of 532 billion tonnes from its giant ice sheet, according to a 2020 study. On average, Greenland loses 234 billion tonnes of ice per year – enough to pack into 6,324 Empire State Buildings.

"2019 was a really unusually warm year, but so was 2012," says Kelly Hogan, a marine geophysicist at BAS who studies the impacts of Greenland's melting ice sheet. In 2012, the summer period (June-August) was more than 2C (4F) warmer than the average for 1981-2010, and more than 1.5C (3F) warmer for the entire ice sheet. "Those extremes are coming round more frequently than we had thought they would. They're happening every few years," says Hogan.

"What's really distinctive about Greenland is how much melting you get on the surface in the summer, because you don't get anywhere near as much as that in Antarctica," says Hogan. "When you see huge volumes of water [on the ice], it is really shocking."

 But it's rare to see "giant pools of water" on the surface like in Olsen's photo, says Perren, as usually the water seeps through cracks in the ice. "It basically pops the ice sheet up and floats it out to the coast. So often you don't have this pooling of water, but instead you have warm water that's being sent down into the bowels of the Greenland ice sheet, basically warming the whole thing," she says.

Greenland's melting ice sheet is threatening local community's way of life (Credit: Getty Images)

The rapid melting of the ice is already affecting local communities' way of life. "They are having to adapt the way they hunt and fish," says Olsen.

If the ice is unsafe to travel on, it also makes it more difficult for scientists to carry out their research, Olsen adds. "We will have to adapt and rely more on automatic instruments instead of community-based monitoring." 

Safety is already a concern, says Perren, adding: "I have promised my son that I will not step foot on the ice sheet because it's so dangerous."

 

It looks like the dogs are skating on something without a bottom… it feels like they could just sink at any moment – Kelly Hogan

The photo has helped raise awareness of Greenland's vulnerability to climate change, says Olsen. "I have definitely found that you can get a lot of attention for the problem with a photo… so it has been very efficient.

"But I've also been challenged by people saying: 'how can you take a photo of climate change?' And I agree, you cannot take one photo and call it climate change, because that is something that unfolds over a longer time period," says Olsen. "We need to explain the photo and provide the right context."

Photos are useful tools for starting conversation about the environment and explaining scientific phenomena, says Perren. "Science has a communication problem," she says.

"When I first saw it in 2019 I remember thinking: 'oh my gosh, this is such a shocking image,'" adds Perren. "It's a symbolic image of what climate change looks like in Greenland. But there's also a scientific side to it: maybe this is unprecedented but it also [paints] a very good, kind of emblematic picture of what the future would look like."


 

Thursday, March 6, 2025

Global sea ice hit ‘all-time minimum’ in February, scientists say. Scientists called the news ‘particularly worrying’ because ice reflects sunlight and cools the planet

February was the lowest monthly level for sea ice in the Arctic, and the fourth-lowest in the Antarctic. Photograph: Bernhard Staehli/Shutterstock
 

Europe environment correspondent
 



 

Global sea ice fell to a record low in February, scientists have said, a symptom of an atmosphere fouled by planet-heating pollutants.

The combined area of ice around the north and south poles hit a new daily minimum in early February and stayed below the previous record for the rest of the month, the EU’s Copernicus Climate Change Service (C3S) said on Thursday.

“One of the consequences of a warmer world is melting sea ice,” said the C3S deputy director, Samantha Burgess. “The record or near-record low sea ice cover at both poles has pushed global sea ice cover to an all-time minimum.”


The agency found the area of sea ice hit its lowest monthly level for February in the Arctic, at 8% below average, and its fourth-lowest monthly level for February in the Antarctic, at 26% below average. Its satellite observations stretch back to the late 1970s and its historical observations to the middle of the 20th century.

Scientists had already observed an extreme heat anomaly in the north pole at the start of February, which caused temperatures to soar more than 20C above average and cross the threshold for ice to melt. They described the latest broken record as “particularly worrying” because ice reflects sunlight and cools the planet.

“The lack of sea ice means darker ocean surfaces and the ability of the Earth to absorb more sunlight, which accelerates the warming,” said Mika Rantanen, a climate scientist at the Finnish Meteorological Institute.

The strong winter warming event in the Arctic in early February had prevented sea ice from growing normally, he added. “I believe that this meteorological event, combined with the long-term decline of sea ice due to anthropogenic climate change, was the primary cause of the lowest Arctic sea ice extent on record.”

Global sea ice extent varies throughout the year but typically reaches its annual minimum in February, when it is summer in the southern hemisphere

C3S said February 2025 was the third hottest February it had seen. Global temperatures were 1.59C hotter than preindustrial levels, making it the 19th month in the past 20 that was more than 1.5C above preindustrial levels.

Earth observation programmes such as C3S rely on the reanalysis of billions of measurements from satellites, ships, aircraft and weather stations to create snapshots of the state of the climate. The agency cautioned that the margins above 1.5C were small in several months, and could differ slightly in other datasets.



 

The broken sea ice record comes after last year was confirmed as the hottest year on record and a Guardian analysis of C3S data revealed that two-thirds of the world’s surface was seared by record-breaking monthly heat in 2024. The El Niño weather pattern in the first half of the year added to the background heating effect of fossil fuel pollution, which traps sunlight.

El Niño has since subsided and morphed into a weak form of its cooler counterpart, La Niña. The World Meteorological Organization said on Thursday they expected the La Niña that emerged in December to be short-lived.

Richard Allan, a climate scientist at the University of Reading, said the long-term prognosis for Arctic sea ice was grim.

“The region continues to rapidly heat up, and can only be saved with rapid and massive cuts to greenhouse gas emissions,” he said. “That will also limit the growing severity of weather extremes and long-term sea level rise across the world.”

 

Tuesday, January 21, 2025

A third of the Arctic’s vast carbon sink now a source of emissions, study reveals. Critical CO2 stores held in permafrost are being released as the landscape changes with global heating, report shows

 

Near Newtok in Alaska, melting permafrost is causing the Ninglick River to widen and erode its banks. Photograph: Andrew Burton/Getty Images

 

 

A third of the Arctic’s tundra, forests and wetlands have become a source of carbon emissions, a new study has found, as global heating ends thousands of years of carbon storage in parts of the frozen north.

For millennia, Arctic land ecosystems have acted as a deep-freeze for the planet’s carbon, holding vast amounts of potential emissions in the permafrost. But ecosystems in the region are increasingly becoming a contributor to global heating as they release more CO2 into the atmosphere with rising temperatures, a new study published in Nature Climate Change concluded.

More than 30% of the region was a net source of CO2, according to the analysis, rising to 40% when emissions from wildfires were included. By using monitoring data from 200 study sites between 1990 and 2020, the research demonstrates how the Arctic’s boreal forests, wetlands and tundra are being transformed by rapid warming.


“It is the first time that we’re seeing this shift at such a large scale, cumulatively across all of the tundra. That’s a pretty big deal,” said Sue Natali, a co-author and lead researcher on the study at the Woodwell Climate Research Center.

The shift is occurring despite the Arctic becoming greener. “One place where I work in interior Alaska, when the permafrost thaws, the plants grow more so you can sometimes can get an uptick in carbon storage,” Natali said. “But the permafrost continues to melt and the microbes take over. You have this really big pool of carbon in the ground and you see things like ground collapse. You can visually see the changes in the landscape,” she said.

 


 The study comes amid growing concern from scientists about the natural processes that regulate the Earth’s climate, which are themselves being affected by rising temperatures. Together, the planet’s oceans, forests, soils and other natural carbon sinks absorb about half of all human emissions, but there are signs that these sinks are under strain.

The Arctic ecosystem, spanning Siberia, Alaska, the Nordic countries and Canada, has been accumulating carbon for thousands of years, helping cool the Earth’s atmosphere. In a warming world, the researchers say that the carbon cycle in the region is beginning to change and needs better monitoring.

Anna Virkkala, the lead author of the study, said: “There is a load of carbon in the Arctic soils. It’s close to half of the Earth’s soil carbon pool. That’s much more than there is in the atmosphere. There’s a huge potential reservoir that should ideally stay in the ground.

“As temperatures get warmer, soils get warmer. In the permafrost, most of the soils have been entirely frozen throughout the full year. But now the temperatures are warmer, there’s more organic matter available for decomposition, and carbon gets released into the atmosphere. This is the permafrost-carbon feedback, which is the key driver here.”

 

Tuesday, December 17, 2024

Worrying signs from the Arctic

 

The Russell Glacier descending toward a lake of its own meltwater near Kangerlussuaq, Greenland, in July. Sean Gallup/Getty Images

 



Author Headshot

By David Gelles

 

In a year full of troubling signs that Earth’s climate is rapidly changing, some of the most alarming signals came from the Arctic.

The thawing tundra has become a source of greenhouse gas emissions, instead of locking away carbon. Sea ice levels are near historic lows. Fires are getting worse. Surface air temperatures are near record highs. And, yes, the polar bears are in trouble.

“There’s a lot going on in the Arctic,” said Brendan Rogers, an Arctic scientist at the Woodwell Climate Research Center in Falmouth, Mass. “There’s big changes in the rivers, and with salmon, and big changes in the atmosphere, and with sea ice, and ocean productivity, and the fauna.”

One area of particular concern to Rogers is the increase in wildfires. Fire season is getting longer, the fires are burning bigger and hotter, and more fires are being ignited by lightning strikes.

“The primary reasons are all directly tied to climate change,” he said.

Some fire activity is natural, of course. But Rogers said that, because of climate change, “the fires are happening too quickly, too much; they’re also increasing in severity and intensity.”

Another point of acute concern: Parts of the Arctic that have long stored carbon are now turning into sources of carbon.

Last week, the National Oceanic and Atmospheric Administration announced that the Arctic tundra has in recent decades been “adding more carbon dioxide to the atmosphere than it has removed, a reversal from the usual state of affairs since the peak of the last ice age,” my colleague Raymond Zhong wrote.

What happens in the Arctic doesn’t stay in the Arctic

A warmer Arctic has the potential to alter global weather patterns. It’s the temperature gradient between the polar regions and the Equator that drives air currents that move high and low pressure systems around the globe.

Major changes to the Arctic will most likely have far-reaching consequences, though scientists can’t yet predict exactly what they will be.

“There’s a lot about the Arctic that does very directly affect the rest of the world,” Zhong told me.

The thawing Arctic is also shaking up geopolitics.

With sea ice melting, new shipping lanes are opening up. As a result, Russia and China have sought to project their influence in the region in recent years.

That has led Canada to step up its military presence in the region and seek to work more closely with the United States. Announcing the move, the Canadian government called climate change “the overarching threat” to control of its Arctic territories.

Meanwhile, tensions between Russia and the West have resulted in scientists being shut out of the Russian Arctic, compromising efforts to collect reliable data on one of the largest and most significant swaths of the Arctic on Earth.

It’s too early to say we’ve hit a tipping point

Scientists can’t yet say that the changes being observed in the Arctic are irreversible, or that they are accelerating and compounding.

And while the tundra is now a carbon source, other permafrost areas, including beneath boreal forests, are still net carbon sinks, or natural reservoirs that store more carbon than they emit. (Though the forests are burning at an alarming rate.)

Still, things are moving fast up north.

The Arctic is warming four times as fast as the rest of the planet. In the waters that connect the Atlantic and the Pacific Oceans in northern Canada, sea ice was the lowest ever recorded in the period from October of 2023 to September.

In Canada’s Western Arctic, thawing permafrost is triggering landslides and making it a near certainty that some villages will have to move. This summer, the eastern half of Hudson Bay, home to the world’s most-studied polar bears, was ice-free a month earlier than usual.

A group of scientists recently warned that the Arctic could experience its first day that is practically ice-free by 2027. And, for the 11th year in a row, the Arctic was more abnormally warm than the world as a whole.

In a recent guest essay for the Times’ Opinion section, a former park ranger, Jon Waterman, revisited Arctic landscapes he first encountered 40 years ago and witnessed a world transformed by fires, landslides, new vegetation and melting permafrost.

When Waterman asked a villager, sweating in the heat, what could be done about climate change, he replied, “Maybe people down south could reduce their emissions.”

      
  

Sunday, December 15, 2024

Arctic Tundra Has Long Helped Cool Earth. Now, It’s Fueling Warming.

 

 
A hill with an ice core, known as a pingo, in the Mackenzie River Delta, Northwest Territories. Credit...Renaud Philippe for The New York Times

 


 Wildfires and thawing permafrost are causing the region to release more carbon dioxide than its plants remove, probably for the first time in thousands of years.

 

For thousands of years, the shrubs, sedges, mosses and lichens of the Arctic have performed a vital task for the planet: gulping down carbon dioxide from the air and storing the carbon in their tissues. When the plants die, this carbon is entombed in the frigid soil, where it no longer helps warm Earth’s surface.

But as fossil fuel emissions heat the planet, balmier air temperatures are thawing Arctic tundra, activating carbon-hungry microbes, and more vegetation is being burned up by wildfires.

The result, for the past two decades or so, is that the tundra has been adding more carbon dioxide to the atmosphere than it has removed, a reversal from the usual state of affairs since the peak of the last ice age.

It’s one of many signs of rapid change in the National Oceanic and Atmospheric Administration’s Arctic Report Card, the agency’s yearly checkup on the polar region. The 2024 report card was issued on Tuesday in Washington at the annual meeting of the American Geophysical Union, an association of earth and space scientists.


                                   Arctic Methane Release

 

 For the 11th year in a row, the Arctic this year was more abnormally warm than the world as a whole, the report card said. The period from October 2023 to September was the second-warmest for the region since 1900. In the Northwest Passage, the sea route that links the Atlantic and the Pacific through the islands of northern Canada, the area covered by sea ice this summer was the lowest since records began. Parts of Arctic Canada had their shortest snow season on record.

“The Arctic today, year after year, looks vastly different than the Arctic did 20 years ago,” said Twila Moon, an editor of the report card and the deputy lead scientist at the National Snow and Ice Data Center in Boulder, Colo.

In the Arctic tundra, there have long been signs of a shift in how much carbon is moving between the land and the air. But by incorporating more data and better methods of analysis, scientists can now describe the trend with confidence: Between 2001 and 2020, wildfires and thawing permafrost caused the tundra to release more carbon dioxide than its plants removed from the air, probably for the first time in many millenniums.

How much this gap widens depends in large part on how much nations rein in greenhouse warming, said Brendan Rogers, an Arctic scientist at the Woodwell Climate Research Center in Falmouth, Mass., who contributed to the report card.

“The more we can do to lower the overall temperature changes globally, the better we’re going to be able to deal with permafrost emissions,” Dr. Rogers said.


Gathering data in the vast Arctic environment is always a challenge, but Russia’s war in Ukraine has compounded the difficulties, including for scientists assessing the carbon cycle. “There are large parts of Siberia that we just don’t have any data from,” Dr. Rogers said.

Not all of the news in this year’s report card was bad.

In the seas around Alaska, ice seal populations challenged by rising temperatures were deemed healthy. And a cool winter helped Greenland’s vast ice sheet shed the smallest volume of ice since 2013, around 55 billion tons, though the long-term trend is still that melting ice from the island is adding enormously to rising sea levels worldwide.


 

Summer 2025 was hottest on record in UK, says Met Office. Unprecedented average temperature made about 70 times more likely by human-induced climate change, says agency

The water levels at Broomhead reservoir in South Yorkshire have been low this summer. Photograph: Richard McCarthy/PA by   Damien Gayle The...