Climate change in the Arctic
Due to climate change in the Arctic, this polar region is expected to become "profoundly different" by 2050. The speed of change is "among the highest in the world", with warming occurring at 3-4 times faster than the global average. This warming has already resulted in the profound Arctic sea ice decline, the accelerating melting of the Greenland ice sheet and the thawing of the permafrost landscape. These ongoing transformations are expected to be irreversible for centuries or even millennia.
Natural life in the Arctic is affected greatly. As the tundra warms, its soil becomes more hospitable to earthworms and larger plants, and the boreal forests spread to the north - yet this also makes the landscape more prone to wildfires, which take longer to recover from than in the other regions. Beavers also take advantage of this warming to colonize the Arctic rivers, and their dams contributing to methane emissions due to the increase in stagnant waters. The Arctic Ocean has experienced a large increase in the marine primary production as warmer waters and less shade from sea ice benefit phytoplankton. At the same time, it is already less alkaline than the rest of the global ocean, so ocean acidification caused by the increasing concentrations is more severe, threatening some forms of zooplankton such as pteropods.
The Arctic Ocean is expected to see its first ice-free events in the near future - most likely before 2050, and potentially in the late 2020s or early 2030s. This would have no precedent in the last 700,000 years. Some sea ice regrows every Arctic winter, but such events are expected to occur more and more frequently as the warming increases. This has great implications for the fauna species which are dependent on sea ice, such as polar bears. For humans, trade routes across the ocean will become more convenient. Yet, multiple countries have infrastructure in the Arctic which is worth billions of dollars, and it is threatened with collapse as the underlying permafrost thaws. The Arctic's indigenous people have a long relationship with its icy conditions, and face the loss of their cultural heritage.
Further, there are numerous implications which go beyond the Arctic region. Sea ice loss not only enhances warming in the Arctic but also adds to global temperature increase through the ice-albedo feedback. Permafrost thaw results in emissions of and methane that are comparable to those of major countries. Greenland melting is a significant contributor to global sea level rise. If the warming exceeds - or thereabouts, there is a significant risk of the entire ice sheet being lost over an estimated 10,000 years, adding up to global sea levels. Warming in the Arctic may affect the stability of the jet stream, and thus the extreme weather events in midlatitude regions, but there is only "low confidence" in that hypothesis.
Impacts on the physical environment
Warming
The period of 1995–2005 was the warmest decade in the Arctic since at least the 17th century, with temperatures above the 1951–1990 average. Alaska and western Canada's temperature rose by during that period. 2013 research has shown that temperatures in the region haven't been as high as they currently are since at least 44,000 years ago and perhaps as long as 120,000 years ago. Since 2013, Arctic annual mean surface air temperature has been at least warmer than the 1981-2010 mean.In 2016, there were extreme anomalies from January to February with the temperature in the Arctic being estimated to be between more than it was between 1981 and 2010. In 2020, mean SAT was warmer than the 1981–2010 average. On 20 June 2020, for the first time, a temperature measurement was made inside the Arctic Circle of 38 °C, more than 100 °F. This kind of weather was expected in the region only by 2100. In March, April and May the average temperature in the Arctic was higher than normal. This heat wave, without human – induced warming, could happen only one time in 80,000 years, according to an attribution study published in July 2020. It is the strongest link of a weather event to anthropogenic climate change that had been ever found, for now.
Arctic amplification
Precipitation
Field studies in northwest Greenland have shown that increased summer rainfall can trigger large debris flows and slope failures in permafrost terrain. In 2016–2017, unprecedented rain events near Siorapaluk caused widespread mass movement processes that reshaped the landscape and damaged archaeological sites. Approximately a quarter of the surveyed archaeological landscape was affected, providing an indicator of long-term slope stability since the late Holocene and highlighting how shifts toward rain-dominated precipitation regimes are already altering Arctic geomorphology.An observed impact of climate change is a strong increase in the number of lightnings in the Arctic. Lightnings increase the risk for wildfires. Some research suggests that globally, a warming greater than over the preindustrial level could change the type of precipitation in the Arctic from snow to rain in summer and autumn.
Cryosphere loss
Sea ice
Greenland ice sheet
Lakes
A January 2025 study published in the Proceedings of the National Academy of Sciences reported an "abrupt, coherent, climate-driven transformation" from "blue" to "brown" states of lakes in Greenland after a season of both record heat and rainfall drove a state change in these systems. This change was said to alter "numerous physical, chemical, and biological lake features", and the state changes were said to be unprecedented.Biological environment
Impacts on Arctic flora
Climate change is expected to have a strong effect on the Arctic's flora, some of which is already being seen. NASA and NOAA have continuously monitored Arctic vegetation with satellite instruments such as Moderate Resolution Imaging Spectroradiometer and Advanced Very-High-Resolution Radiometer. Their data allows scientists to calculate so-called "Arctic greening" and "Arctic browning". From 1985 to 2016, greening has occurred in 37.3% of all sites sampled in the tundra, whereas browning was observed only in 4.7% of the sites - typically the ones that were still experiencing cooling and drying, as opposed to warming and wettening for the rest.This expansion of vegetation in the Arctic is not equivalent across types of vegetation. A major trend has been from shrub-type plants taking over areas previously dominated by moss and lichens. This change contributes to the consideration that the tundra biome is currently experiencing the most rapid change of any terrestrial biomes on the planet. The direct impact on mosses and lichens is unclear as there exist very few studies at species level, but climate change is more likely to cause increased fluctuation and more frequent extreme events. While shrubs may increase in range and biomass, warming may also cause a decline in cushion plants such as moss campion, and since cushion plants act as facilitator species across trophic levels and fill important ecological niches in several environments, this could cause cascading effects in these ecosystems that could severely affect the way in which they function and are structured.
The expansion of these shrubs can also have strong effects on other important ecological dynamics, such as the albedo effect. These shrubs change the winter surface of the tundra from undisturbed, uniform snow to mixed surface with protruding branches disrupting the snow cover, this type of snow cover has a lower albedo effect, with reductions of up to 55%, which contributes to a positive feedback loop on regional and global climate warming. This reduction of the albedo effect means that more radiation is absorbed by plants, and thus, surface temperatures increase, which could disrupt current surface-atmosphere energy exchanges and affect thermal regimes of permafrost. Carbon cycling is also being affected by these changes in vegetation, as parts of the tundra increase their shrub cover, they behave more like boreal forests in terms of carbon cycling. This is speeding up the carbon cycle, as warmer temperatures lead to increased permafrost thawing and carbon release, but also carbon capturing from plants that have increased growth. It is not certain whether this balance will go in one direction or the other, but studies have found that it is more likely that this will eventually lead to increased in the atmosphere.
However, boreal forests, particularly those in North America, showed a different response to warming. Many boreal forests greened, but the trend was not as strong as it was for tundra of the circumpolar Arctic, mostly characterized by shrub expansion and increased growth. In North America, some boreal forests actually experienced browning over the study period. Droughts, increased forest fire activity, animal behavior, industrial pollution, and a number of other factors may have contributed to browning.
Impacts on terrestrial fauna
Arctic warming negatively affects the foraging and breeding ecology of native Arctic mammals, such as Arctic foxes or Arctic reindeer. In July 2019, 200 Svalbard reindeer were found starved to death apparently due to low precipitation related to climate change. This was only one episode in the long-term decline of the species. United States Geological Survey research suggests that the shrinkage of Arctic sea ice would eventually extirpate polar bears from Alaska, but leave some of their habitat in the Canadian Arctic Archipelago and areas off the northern Greenland coast.As the pure Arctic climate is gradually replaced by the subarctic climate, animals adapted to those conditions spread to the north. For instance, beavers have been actively colonizing Arctic regions, and as they create dams, they flood areas which used to be permafrost, contributing to its thaw and methane emissions from it. These colonizing species can outright replace native species, and they may also interbreed with their southern relations, like in the case of the Grizzly–polar bear hybrid. This usually has the effect of reducing the genetic diversity of the genus. Infectious diseases, such as brucellosis or phocine distemper virus, may spread to populations previously separated by the cold, or, in case of the marine mammals, the sea ice.