- Earth’s cryosphere — comprised of ice sheets, glaciers, permafrost and snowfall — is in a rapid state of flux due to escalating climate change, with numerous studies underlining the grave risks posed by the thaw.
- Today, that worldwide meltdown poses new threats to human lives — endangering freshwater supplies and food security while increasing the risks of natural disasters and disease outbreaks. Cryosphere loss poses immense dangers to the environment, agriculture, economy and society according to a new report.
- If emissions continue unabated, these problems will only worsen. Scientists warn of compounding risks as cryosphere melt escalates, including sea level rise, the slowing of ocean currents, and the triggering of feedbacks that will add to climate change.
- 2025 is designated the International Year of Glaciers’ Preservation. Experts are calling for drastic cuts to carbon emissions because each fraction of a degree of warming avoided counts toward the preservation of the cryosphere along with the ecosystem services that ice, snow and permafrost provide.
Earth’s frozen places — ice sheets, glaciers and permafrost — are melting: A clear sign of climate change and a planet quickly exiting the stable state that gave rise to human civilization. This great thaw is having far-reaching consequences for communities and individuals across the globe — from polar and mountainous regions to coastal areas.
In a recent landmark report, marking the World Day for Glaciers, UNESCO is ringing alarm bells: Cryosphere melt is putting freshwater accessibility at risk for more than one billion people living in mountainous regions and a further two billion living downstream as glaciers and snowpacks melt away and decline; most of those individuals live in developing countries. That same report finds that cryosphere melt is endangering two-thirds of irrigated agriculture across the globe.
“The melting and the changes in the cryosphere are a reality and we need to really start taking action,” Abou Amani, director of the Division of Water Sciences and secretary of the Intergovernmental Hydrological Programme, tells Mongabay in an interview.
That’s a stark warning, but only the tip of the iceberg when it comes to gauging the cryosphere’s importance to human wellbeing and evaluating potential harms as it shrinks away.
Amani lists the ever-increasing risks associated with shrinking mountain snowpacks and glaciers — melting that has downstream impacts on water quality and availability, harms food security, heightens disease risk, triggers catastrophic landslides and glacial lake outburst floods (or GLOFs), and threatens the long-term viability of hydropower. Those risks have already heightened — and will greatly intensify — if climate change isn’t curbed, Amani says.
The newly released report comes during the International Year of Glaciers’ Preservation. 2025 also marks the start of the Decade of Action for Cryospheric Sciences. But this is not the first cryosphere warning to humanity: Other international organizations and agencies have offered similar cautions in past years. The recent 2024 State of the Cryosphere report, for example, notes that Earth’s current climate trajectory could lock in “disastrous and irreversible” consequences for billions across the globe this century as ice and snows melt.
The scientific evidence is indisputable, experts say: The fate of Earth’s frozen regions is directly linked to human health and wellbeing.
“The cryosphere … touches on all sorts of aspects of human communities and human health,” says Pam Pearson, director of the International Cryosphere Climate Initiative. She reiterates a crucial message from the new report: Cryosphere melt is already rapid, with the rate of change accelerating. “The modeling is getting better and better and, for every year that goes by, unfortunately, the extremes are becoming the means,” she says.
Cryosphere warning signs
Unfolding events in the cryosphere are already touching the lives of people living far from frozen or snowy regions. What the cryosphere is telling us, scientists warn, is that the stable conditions in which humanity thrived for centuries are already out of balance.
Glaciers — often held up as a posterchild for climate change — are sending strong clear signals of global warming impacts. In a recent paper, researchers found that Earth’s glaciers (excluding Greenland and the Arctic) have lost about 5% of their mass since 2000; that amounts to a mindboggling 273 billion metric tons of ice melting per year. Of great concern is the second period under the study, 2012 to 2023, showed a jump in ice loss topping 36%.
This monumental loss has given rise to a spate of “glacier funerals” in recent years, as people mourn geographic features that hold significance as freshwater sources, but which also play crucial economic and cultural roles. Researchers are now tracking the demise of freshwater glaciers around the planet via a “Global Glacier Casualty List.”
Other cryosphere records have recently been breached. February 2025 marked a record low for global sea ice, according to the Copernicus Climate Change Service. One month earlier, the warmest January on record coincided with the lowest Arctic Sea ice extent ever for that month, while new records for surface melting of the Antarctic ice sheet were also set in January due to “widespread above-average air temperatures.”
Scientists have also detected signs that melting glaciers, failing ice sheets and thawing permafrost are driving climate feedbacks that add fuel to global warming, helping close the window on potentially catastrophic warming. Loss of ice and snow is now affecting Earth’s “albedo,” the planet’s capacity to reflect solar energy back into space, contributing to rising temperatures. Melting permafrost is directly releasing large amounts of CO2 and methane that had been stored for eons in frozen landscapes.
A 2025 study is the latest to show that glacial meltwaters contains methane — an extremely potent greenhouse gas — which is eventually released into the atmosphere, an effect scientists dubbed “glacial fracking.”
Gabrielle Kleber, a postdoctoral researcher in glaciology at the Arctic University of Norway, and lead author of the study, said that total methane releases from meltwater could be “substantial,” and are a previously unconsidered methane source.
“What we’re finding at least on Svalbard, is that the glacial environment may be releasing more methane than the permafrost environment, so that really shows that this is an important environment that needs to be included in climate models,” she explains.
Scientists are particularly concerned with tipping points in the Antarctic and Greenland ice sheets that, if triggered, could unleash, and lock in, enormous amounts of cataclysmic sea level rise over the coming centuries. At least one crucial tipping point may already have been breached in Antarctica, according to one study. It estimates that sea level rise combined with other climate effects — such as drought and heatwaves — could lead to more than 210 million people internally displaced and many millions more climate refugees by 2050.
The local and global reach of cryosphere melt
Humanity is already feeling the dire impacts of the global meltdown. The State of the Cryosphere echoes UNESCO’s findings, noting that the 1.2° C of warming we’ve already seen has caused an uptick in cryosphere triggered floods and landslides, along with snow and ice loss that has decreased freshwater availability.
Glacial melt is unleashing rapid change in mountainous regions, such as the Hindu Kush range in the Himalayas that was declared a “biosphere on the brink” last year. Rapidly decreasing snow and ice in this region could threaten freshwater for an estimated two billion people.
Abid Hussain, economist and food systems specialist at the International Centre for Integrated Mountain Development, says his organization has observed numerous impacts of climate change colliding with cryosphere melt.
That includes croplands moving upslope as temperatures rise, leading to land-use change and greater use of chemical fertilizers and pesticides. Cryosphere destabilization is also creating a snow melt situation with either “too much, [or] too little water,” says Hussain. In turn, that’s causing declines in agricultural production and a move away from farming traditional subsistence crops, such as barley, local beans and vegetables, with a shift towards cash crops that could cause nutritional deficiencies and adverse public health impacts.
“These [traditional] crops are disappearing from the food system, so it has clear impact on the food security and nutrition and health of the people at high altitude,” says Hussain.
“The water coming from glaciers is actually feeding the ecosystems, livelihoods and agriculture systems of 2 billion people in the Hindu Kush region,” he says. It’s estimated that the region could reach “peak water” around 2050; after that, supplies are projected to decline, with implications for health, livelihoods and key infrastructure such as hydropower.
“Any change in glacial patterns or availability of water from glaciers will impact the economy, livelihoods and industries downstream,” he says.
Then there is the threat of sudden disasters, including glacial lake overflow floods (or GLOFs for short). Research has assessed global GLOF risk, with some 15 million people now living in proximity to this danger today. A catastrophic flood in Pakistan in 2022 was triggered by extreme rainfall, combined with glacial melt, Hussain said. That event not only claimed lives and harmed food security, it also critically damaged infrastructure and spurred water-borne diseases in its aftermath.
A melting cryosphere has also raised concerns of pathogens long locked in ice being unleashed with the potential of pandemic-level spread. That’s a threat highlighted by a 2024 UNEP “foresight” report covering potential risks to ecosystems and human health. It cites one example of a cryosphere-related health impact — a 2016 outbreak of anthrax in Western Siberia linked to permafrost melt.
Future disease risk, says Pearson, is currently an “unknown unknown.”
An additional worry is that melting ice, permafrost and snowpack will release contaminants of concern, such as toxic heavy metals including mercury, into waterways. That’s already a concern for water supplies, riverine ecosystems and fisheries.
In the Arctic, researchers have raised the alarm over possible remobilization of hundreds of tons of toxic legacy pollutants locked in permafrost (such as radioactive waste from the Cold War, plastics and industrial chemicals), adding to already severe climate change consequences for Indigenous peoples in the region.
A 2012 review offers a sobering summation of what’s at stake if the cryosphere melts away: The Arctic alone helps determine Earth’s “energy balance, atmospheric and ocean circulation, freshwater storage, sea level, [and] the storage and release of large quantities of greenhouse gases,” while it also helps assure human wellbeing via, “the economy, infrastructure, health, and Indigenous and non-Indigenous livelihoods, culture and identity.”
Ocean current collapse: Low likelihood but high impact
Rising ever higher on the list of concerns linked to cryosphere melt is a possible slowdown, or catastrophic shutdown, of one of Earth’s crucial ocean currents due to climate change and ice melt.
Scientists continue trying to pin down when the already-weakening Atlantic Meridional Overturning Circulation (AMOC) might collapse completely. The AMOC acts as a conveyor belt transporting heat energy between the northern and southern hemispheres. One estimate suggest the current’s failure could come sometime in the next century, while another suggests imminent collapse by the mid-21st century.
Such an event would cause rapid cataclysmic temperature drops in Northern Europe and a ripple effect around the globe, raising sea levels on the U.S. East Coast, and bringing an increase in severe storms. Many experts frame this as a “low likelihood, high impact” event
Last year, more than 40 scientists raised an alarm saying that the AMOC could collapse within decades, arguing that “this risk has so far been greatly underestimated.” They urge Nordic nations to prepare.
Other researchers suggest the Antarctic Circumpolar Current (ACC), which spans the southern hemisphere, is also slowing. One recent modeling study found that under high carbon emission scenarios, the ACC could slow by as much as 20% by 2050, bringing sea level rise and further ice sheet melt.
“There’s still a lot of uncertainty about whether the AMOC will collapse or not, so it might be best to hold off sounding the alarm until we have better evidence,” Nicholas Foukal, a researcher at Woods Hole Oceanographic Institution (WHOI), writes in an email. “Probably the most pressing question is how close we are to a tipping point in the AMOC given our current climate system.”
An added danger: The complexities of accurately monitoring these vast ocean currents is so challenging, we may only recognize a crossed tipping point after the fact, when it’s too late to act.
Foukal and other experts also worry that, even if we don’t see a total AMOC collapse soon, a slowdown or weakening of the current is more probable — though still uncertain. The latest Intergovernmental Panel on Climate Change reports deem this “very likely” over the next century. Research suggests the AMOC may have slowed by 15% since the 1950s. But even that is debated. Another study by Foukal and his team suggests there is little evidence of recent weakening. However, there is broader agreement among scientists that decline will occur over the course of this century, but the extent is unclear.
An AMOC slowdown will still have consequences for Europe and elsewhere, potentially affecting temperature and weather patterns as far away as Australia and New Zealand. Foukal says that, for him, the most concerning possibility is a potential shift of the Intertropical Convergence Zone — a band of low pressure where trade winds from both hemispheres converge, leading to high rainfall.
“That would affect the largest amount of global human population, driving intense rainfall in currently dry areas (landslides, mosquito-borne illnesses) and removing rainfall from currently wet areas (reducing biodiversity in tropical rainforests),” he says. “The impacts on human migration patterns, agriculture, political stability, and war/conflicts would have far-reaching effects.”
Every fraction of a degree counts
Current emissions and climate trajectories put the world on course for a warming of 2°C (3.6° F) or more in this century. If that happens, Earth’s frozen regions will be transformed beyond recognition, with an incalculable loss of ecosystem services felt round the globe, according to The State of the Cryosphere report. High temperatures could bring the demise of nearly half the world’s glaciers by 2100, including the loss of all those in the tropics and at mid-latitudes, make the Arctic Ocean ice-free several months every summer, and lock in huge rises in sea level over coming centuries.
The picture is bleak, especially considering humanity’s carbon emissions hit their highest levels ever in 2024 with no decline in sight, imposing dramatic impacts on people everywhere.
Two degrees Celsius, or more, of warming will bring dramatic intensified threats to human communities in regions where streams are glacially fed, slashing freshwater availability during parts of the year, while cryosphere-caused sea level rise in coastal regions will become a chronic concern. Taken all together, cryosphere loss is expected to impact “a huge percentage of the global population,” Pearson says.
But, experts continue emphasizing that the extent of these dramatic cryosphere changes — and the human suffering they cause — will hinge on emission reductions made today.
Achieving the Paris Agreement target of staunching warming at 1.5°C (2.7°F) would still mean the loss of many of Earth’s glaciers by 2100; it would still incur significant sea level rise and a host of community consequences. But it would mean avoiding the most devastating effects and allowing more time for adaptation.
Each fraction of a degree of warming prevented means less glacier melt and sea ice loss. “It’s quite clear that if we want to preserve the glaciers, we need to reduce our greenhouse gas emissions,” says David Rounce, an assistant professor at Carnegie Mellon University. “Every … decrease in temperature can have a huge impact in preserving and saving these glaciers.”
Further research is needed to deepen knowledge of crucial tipping points, particularly with AMOC and ice sheet tipping points, say experts. But those with eyes on preserving the cryosphere, along with its benefits to humanity, say that emissions must be slashed today to preserve the cryosphere’s crucial functions.
“This isn’t the year of studying glaciers or observing them. It’s about preserving them. And the only way to preserve them is through cuts to greenhouse gas emissions,” says Pearson.
Banner image: A ceremonial glacier graveyard in Iceland. In Iceland, as elsewhere in the world, glaciers are an important part of cultural and national identity, as well as a source of revenue through tourism, says Guðfinna Th Aðalgeirsdóttir, a researcher and glaciologist at the University of Iceland. Image by Josh Okun.
Polar warning: Warming temperatures mean more than melted ice
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