Unique Arctic habitats for flora and fauna, including sea ice, tundra, thermokarst ponds and lakes, and permafrost peatlands have been disappearing over recent decades.

 

Sea ice supports of vast array of life in the Arctic and represents a critical habitat for many species. Sea ice, however, is being lost at a faster rate than projected by even the most pessimistic of climate change scenarios, such as those reported by the Intergovernmental Panel on Climate Change (IPCC). Early warning signs of losses in the sea-ice food web include declines in populations of some species associated with sea ice, such as ivory gulls and polar bears.

The plant communities that make up tundra ecosystems – various species of grasses, sedges, mosses, and lichens – are, in some places, being replaced by species typical of more southern locations, such as evergreen shrubs. Trees are beginning to encroach on the tundra and some models project that by 2100 the treeline will have advanced north by as much as 500 km, resulting in a loss of 51% of the tundra habitat. Depending on the magnitude of change, the resulting ecosystems may no longer be considered “Arctic”. The result may be that many of the species that thrive in the Arctic today may not be able to survive there in the future.

Thermokarst lakes1 and ponds are the most biologically diverse aquatic ecosystems in the Arctic. While drainage and appearance of thermokarst lakes is a relatively common and natural occurrence, over the past 50 to 60 years, studies have shown a net loss of these lakes in some places such as the continuous permafrost zone of northern Alaska and northwestern Canada, and the discontinuous permafrost zone of Siberia. Meanwhile, a net gain of thermokarst lakes has been observed in the continuous permafrost zone of Siberia. The effects of these habitat shifts on local aquatic populations, migratory species, and vegetation are the subject of continuing investigations.

Permafrost peatlands represent unique ecosystem diversity, provide key habitats for some species, maintain hydrology and landscape stability, and hold an enormous stock of organic carbon. Climate change combined with other impacts is leading to a decrease in the extent and duration of permafrost in northern peatlands. Melting permafrost and peatland degradation release greenhouse gases that create a positive feedback for further climate change.

 

1. Thermokarst lakes and ponds are formed by the thawing of permafrost.