October 2019

Arctic surface air temperature is an indicator of both regional and global climate change. Although there are year-to-year and regional differences in air temperatures, driven by natural variability, the magnitude, persistence, and Arctic-wide patterns of recent temperature increases are indicators of global climate change from increasing concentrations of atmospheric greenhouse gases. Warming atmospheric temperatures also act as a driver of Arctic changes in the ocean and on land. 

Snow covers the Arctic land surface (land areas north of 60° N) for up to 9 months each year, and influences the surface energy budget, ground thermal regime, and freshwater budget of the Arctic.

The Greenland ice sheet sits atop the largest island in the world and, as the second largest ice sheet on the Earth, contains the equivalent of roughly 7.4 m of global mean sea level rise. While the ice sheet was likely in balance (i.e., ice mass gain was balancing ice mass loss) during the 1970s, 1980s, and early 1990s, it began to lose mass in earnest beginning in the mid- to late-1990s. 

Sea ice is an important element of the Arctic system because it (1) acts as a barrier between the underlying ocean and the atmosphere, (2) limits the amount of absorbed solar energy during the summer due to its high albedo, (3) provides a habitat for biological activity, (4) limits human access to the Arctic Ocean, and (5) serves as a platform for Indigenous community hunting and travel.

Summer sea surface temperatures in the Arctic Ocean are driven mainly by the amount of incoming solar radiation absorbed by the sea surface. 

Autotrophic single-celled algae living in sea ice (ice algae) and water column (phytoplankton) are the main primary producers in the Arctic Ocean. Through photosynthesis, they transform dissolved inorganic carbon into organic material. Consequently, primary production provides a key ecosystem service by providing energy to the entire food web in the oceans.

Arctic lands and seas have experienced dramatic environmental and climatic changes in recent decades. These changes have been reflected in progressive increases in the aboveground quantity of live vegetation across most of the Arctic tundra biome-the treeless environment encircling most of the Arctic Ocean. This trend of increasing biomass is often referred to as “the greening of the Arctic.”