Recent climate models have forecast significant temperature increases for the Arctic region over the course of the 21st century. In fact, the Arctic region seems to be particularly affected by warming brought about by increased concentrations of atmospheric greenhouse gases. While a recent climate model predicts that global average temperatures will have risen by 1.5 degrees Celsius by the end of the 21st century, temperatures in the Arctic region will have increased by between 5 and 7 degrees Celsius in the same time span
This increase in temperatures, more than twice that of the global mean, is modelled as being accompanied by a substantial reduction in sea-ice levels. The ice of the Arctic is in a constant state of flux, as the warmer summer months naturally lead to a reduced amount of sea-ice. In the previous several decades, however, scientists have noted that there have been substantial reductions in the amount of ice that exists year-round in the Arctic. This type of ice, termed multi-year ice, can reveal broader changes that analysis of seasonal ice would not consider. Satellite analysis indicates that multi-year sea-ice decreased in area by an average of 7% per decade between the years 1978 and 2003
. The depth of sea-ice has also been undergoing significant change. It is thought that while average sea-ice depth in the Arctic is currently 2.5 to 3 meters during the summer months, this could change to perhaps only 1 meter by the end of this century. The melting of sea ice directly impacts the consequences and rate of global warming: since ice is more reflective than is water, the melting of the ice leads to more of the sun's energy being absorbed by the ocean. A warmer ocean then leads to a warmer atmosphere.
The warming of the Arctic not only has implications for the physical landscape of the Arctic, but also for the flora and fauna which inhabit the region. Arctic warming changes the structure of the region's permafrost, the layer of soil that normally remains frozen throughout the year. As temperatures rise and permafrost melts, the vast forests which border the northernmost Arctic regions are undergoing rapid changes. Some forests are advancing northwards into previously inhospitable terrain, while more southern regions are experiencing a drop in vegetation levels as plants struggle to adapt to new environmental conditions. The Arctic Climate Impact Assessment (ACIA), a key piece of research into the issues confronting the Arctic today and in the years ahead, notes that while warming temperatures will serve to increase overall vegetation levels - and thus increase the Arctic's ability to moderate rising greenhouse gas levels - this benefit will be mitigated by the de-icing of other regions. Without the reflectiveness of ice, the region will likely end up causing further warming
As the forests undergo changes, the ecosystems they support will shift as well. The ACIA notes that warmer forests will likely lead to an influx of non-native species. As with any such occurrence, this will lead to a period of chaos in which native and non-native species interact in an unnatural and destructive way. This non-native invasion, coupled with the increased risk of forest fires and devastating insect swarms, will translate to radical change by which the fauna of the Arctic forests may be permanently altered. The animals that inhabit the region north of the Arctic forests will face similar existential threats. Much scrutiny in the popular media has been directed towards the plight of polar bears whose migration habits have been altered by the gradual disappearance of sea ice. The ACIA claims that caribou, seals, whales, and other Arctic animals will be similarly stressed by the effects of rising temperatures.
All climate models carry with them a considerable amount of uncertainty. This is especially true when the models attempt to explain climate behavior in a region as unpredictable and mysterious as the Arctic. Yet even given the inherent variability in modelling long-term climate change, the data accumulated by the global scientific community suggests that the Arctic of the coming decades will be substantially different than the one we know today.