M. L. Druckenmiller1, R. L. Thoman2,3, and T. A. Moon1
1National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA
2Alaska Center for Climate Assessment and Preparedness, University of Alaska Fairbanks, Fairbanks, AK, USA
3International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK, USA
To observe the Arctic is to take the pulse of the planet. The Arctic is warming several times faster than Earth as a whole, reshaping the northern landscapes, ecosystems, and livelihoods of Arctic peoples. Also transforming are the roles the Arctic plays in the global climate, economic, and societal systems. Arctic Report Card (ARC) 2025 marks the 20th annual installment of this report as a timely account of the state of the Arctic environment. Since its first publication in 2006, motivated by notable Arctic warming and change already underway, the Report Card has served as a peer-reviewed record of diverse environmental observations that together document an extraordinary, ongoing transformation. Its essays reveal the increasing pace, scale, and consequences of rapid environmental change across the Arctic’s Vital Signs (Fig. 1)—annually reported critical indicators of marine, terrestrial, and atmospheric processes—and other consequential parts of the Arctic system. This 20th anniversary edition reflects the Arctic’s trajectory, highlighting the persistence of long-term trends and the emergence of new and complex feedbacks and interactions (Figs. 2 and 3).
Arctic surface air temperatures during the past year (October 2024-September 2025; the annual period that aligns with the natural water cycle) were the highest on record since at least 1900. This included the Arctic experiencing its warmest autumn, second-warmest winter, and third-warmest summer since 1900, reinforcing the now well-established pattern of amplified regional warming. Over the past 20 years, Arctic autumn and winter air temperatures have each increased by more than twice the corresponding increases in global air temperatures.
An intensifying hydrologic cycle, driven by increased evaporation, precipitation, and meltwater production, continues to emerge as a central expression of persistent Arctic heating. The 2024/25 water year saw record-high precipitation averaged for the entire year and for spring, and ranked among the top five wettest years for all other seasons since 1950. These patterns are consistent with a more moisture-laden atmosphere and an increasing frequency of extreme precipitation events, including atmospheric rivers that can deliver heavy amounts of rain or snow to large regions. For example, an atmospheric river was responsible for heavy precipitation in the Aleutians and across Alaska in January 2025, contributing to an overall Arctic winter with more extreme precipitation events than any other season.
Snow cover on land is directly influenced by the observed increases in Arctic precipitation, while at the same time the reduction in snow cover duration amplifies Arctic warming. The year 2025 was a clear example of this, consistent with conditions over the last 15 years. While the winter snowpack was above average across much of the Arctic, rapid melting in late spring caused June snow extent to drop below normal, continuing a six-decade decline. June snow cover extent is now 50% of what it was in the 1960s, altering river discharge, vegetation processes, animal behavior, and fire risk. The loss of reflective snow surfaces in June, when incoming solar energy reaches its annual maximum, results in more heat absorbed at the surface, contributing to further Arctic warming trends.
The Arctic’s highly reflective surfaces are also diminishing in the ocean as sea ice cover shrinks. The annual maximum sea ice extent in March 2025 was the lowest in the 47-year satellite record, while the minimum ice extent in September was the 10th lowest. Compared with 2005—the year discussed in the first Arctic Report Card—the end-of-summer sea ice extent in 2025 was 28% smaller and considerably thinner and younger. Multi-year sea ice is now largely confined to the area north of Greenland and the Canadian Archipelago, and the thickest, oldest (> 4 years) ice has declined by more than 95% since the 1980s.
Loss of ice is also apparent on land. The Greenland Ice Sheet continued to lose mass in 2025, though the annual loss was less than the 2003-24 mean due to enhanced snowfall and below-average melt. However, the long-term trend remains consistent; Greenland continues to be a major contributor to global sea-level rise and a driver of freshwater and nutrient inputs that influence North Atlantic ocean circulation and marine productivity. Similarly, Arctic glaciers and ice caps outside of Greenland have rapidly thinned since the 1950s, also contributing steadily to rising global sea levels.
The warming of ocean waters is also extremely consequential to the Arctic region. August mean sea surface temperatures (SSTs) show warming trends during 1982-2025 in almost all Arctic Ocean regions that are ice-free in August, with increases of ~0.3°C (~0.54°F) per decade in the region north of 65° N. This warming alters ecosystems and is a prime driver of sea ice loss. In 2025, August SSTs in most Arctic regions ranked among the warmest on record. Yet, stark regional differences were observed. While the Atlantic sector of the Arctic Ocean was anomalously warm, with SSTs as high as 7°C (12.6°F) above the 1991-2020 average, the Beaufort and northern Chukchi Seas in the Pacific sector were 1-2°C (1.8-3.6°F) cooler than average.
Yet waters in the Pacific sector’s Bering Sea were well above normal throughout summer, and these warm conditions continued into early October 2025. This contributed to the devastating strength of Ex-Typhoon Halong that traveled northward over these waters before inundating Alaska’s southwestern coast, delivering hurricane-force winds, storm surge, and catastrophic flooding. More than 1,500 residents from across the region had to be evacuated, and some villages, notably Kipnuk and Kwigillingok, were almost entirely destroyed. At the time of ARC 2025’s release, communities across the region are still assessing damage and whether many will ever be able to return to their communities. This storm, following Ex-Typhoon Merbok in 2022 that caused extensive damage in western Alaska, provides a somber account of the risks that many coastal communities face in a warming Arctic and without climate-resilient infrastructure and adequate disaster response capabilities (ANTHC 2024).
The long-term warming of the Arctic Ocean is also influenced by ocean currents bringing oceanic heat northward from lower latitudes. Continued atlantification—a northward influx of warmer, saltier Atlantic water—has transformed large areas of the Eurasian Basin, weakening the stratification that has historically insulated sea ice from underlying warm water. Atlantification, which links Arctic Ocean and North Atlantic processes, illustrates how regional and global system changes are closely intertwined. ARC 2025 describes how atlantification has diminished winter sea-ice formation over the past decade, while also lifting nutrient rich waters to be available for increased ocean primary productivity, which is the rate at which marine algae produces organic material. These changes are not confined to the Arctic’s Atlantic sector; atlantification has already been detected at the North Pole and is advancing toward Alaska, where warming and Pacific-origin waters are also causing change.
While higher primary productivity may benefit food webs in some cases, ecosystem health is often threatened. Misalignments between when food is available and when those species that depend on it are able to feed (i.e., trophic mismatches) hinder the movement of carbon through the food chain. Harmful algal blooms also present health risks to subsistence-based coastal communities. During 2003-25, primary productivity across the Arctic continued to exhibit positive trends in eight of the nine analyzed regions, with increases as large as 80% in the Eurasian Arctic.
The ARC 2025 essay on Warming Waters and Borealization further explores ecological shifts underway in the marine environment, detailing how warming waters, declining sea ice, and shifting productivity in the northern Bering Sea and Chukchi Sea are driving the northward expansion of southern species. As boreal species increase over time, Arctic species in the northern Bering and Chukchi Seas have declined by two-thirds and one-half, respectively.
Borealization is also happening on land as large swaths of Arctic tundra become more like the boreal forest due to warming temperatures. Tundra greening refers to the long-term increase in tundra vegetation productivity and abundance that began to be observed in the 1990s. In 2025, circumpolar mean maximum tundra greenness was the third highest in the 26-year modern satellite record, with the five highest values all reported in the last six years.
While greening has dominated across the Arctic throughout recent decades, tundra vegetation dynamics are complex as some causes of browning (i.e., declines in vegetation productivity) have also increased due to extreme events and disturbances, such as wildfires (York et. al 2020). While wildfires are not featured in ARC 2025, summer 2025 marked the fourth consecutive year in which northern North America experienced an area burned that was above the median based on analysis since 1988, with over 1 million acres burned in both Alaska and the Northwest Territories (Thoman 2025).
Across Arctic watersheds, biogeochemical changes are also becoming more visible, influenced by multidecadal permafrost warming. In 2024, permafrost monitoring sites in North America and Svalbard saw their highest temperatures on record (Smith et al. 2025). One impact is the rusting rivers phenomenon—rivers appearing visibly orange as oxidized iron from thawing permafrost enters the water. This year’s Report Card documents satellite observations from more than 200 discolored streams and rivers across the Arctic, finding that these rusting rivers degrade water quality and habitat, with increased acidity and toxic trace metal concentrations. Mounting evidence illuminates the need for ongoing research to better understand influences on water quality, especially as related to rural community drinking water and subsistence fisheries.
Given the pervasive, high-impact environmental changes, maintaining Arctic observing and data-sharing infrastructure, along with specialized scientific expertise, is critical to ensure that necessary information is available to support decision-making at local to global scales. ARC 2025 includes an assessment of the Arctic Observing Network’s ability to support Arctic scientific assessments, like the Report Card itself, and discusses some of the vulnerabilities and risks facing nationally and internationally coordinated observing programs, especially amid risks of diminishing U.S. investments in climate and environmental observations.
At the same time, Arctic communities are increasingly establishing and leading monitoring programs to serve local information needs, shaping a more resilient and responsive Arctic observing system. ARC 2025 includes an essay from the Indigenous Sentinels Network (ISN), based on St. Paul Island in Alaska’s Bering Sea. Founded and led by the Aleut Community of St. Paul Island (ACSPI) Tribal Government, ISN empowers local observers to systematically record environmental conditions—from mercury contamination in harvested subsistence foods to coastal erosion and fish river habitat—using custom software tools and mobile apps, a community-owned database, and observing protocols designed for community relevance and scientific rigor. ISN has established lab space for local sample testing, information products for the community, and capacity building and mentoring programs that grow Indigenous leadership in Arctic observing.
Taken together, the findings of Arctic Report Card 2025 underscore that components of the Arctic system are both rapidly changing and closely connected—permafrost thaw influencing river chemistry, northward ocean heat transport reshaping Arctic marine ecosystems, and widespread warming leading to borealization of Arctic waters and landscapes. After twenty years of continuous reporting (e.g., Table 1), the Report Card stands as a chronicle of change and a caution for what the future will bring. Transformations over the next twenty years will reshape Arctic environments and ecosystems, impact the wellbeing of Arctic residents, and influence the trajectory of the global climate system itself, which we all depend on. Sustained, long-term observations and research and monitoring partnerships that remain nimble to emerging phenomena are essential foundations upon which understanding and adaptation depend.
References
ANTHC [Alaska Native Tribal Health Consortium], 2024: Unmet needs of environmentally threatened Alaska native villages: Assessment and recommendations. Available at: https://anthc.org/resource/unmet-needs-report/.
Smith, S. L., V. E. Romanovsky, K. Isaksen, K. E. Nyland, N. I. Shiklomanov, D. A. Streletskiy, and H. H. Christiansen, 2025: Permafrost [in “State of the Climate in 2024”]. Bull. Amer. Meteor. Soc., 106(8), S338-S341, https://doi.org/10.1175/BAMS-D-25-0104.1.
Thoman, R., 2025: Summer 2025 northern North America wildfire: Above median, but less than 2022-2024. Alaska and Arctic Climate Newsletter, https://alaskaclimate.substack.com/p/summer-2025-northern-north-america.
York, A., U. S. Bhatt, E. Gargulinski, Z. Grabinski, P. Jain, A. Soja, R. L. Thoman, and R. Ziel, 2020: Wildland fire in high northern latitudes. Arctic Report Card 2020, R. L. Thoman, J. Richter-Menge, and M. L. Druckenmiller, Eds., https://doi.org/10.25923/2gef-3964.
December 23, 2025