Observations of sea ice concentrations and its seasonal as well as long-term changes in the Arctic and Antarctic provide important insights into the influence of climate change on the polar regions. Sea ice is an important indicator of global climate change. The sea ice is one of the most important components in Earth’s climate system: the white, snow covered ice reflects up to 90 percent of the solar radiation back into space. As a result, the ice and snow not only cool the North Pole region; they also form the basis for global wind and ocean currents, which distribute heat from the tropics over the entire globe and make the planet inhabitable for us humans.
Sea ice is an important part for the climate system and also plays a crucial role as habitat for various organisms, fish, birds or even seals and polar bears. At three to seven per cent, sea ice covers a considerable proportion of the Earths surface and is subject to strong seasonal fluctuations. This makes sea ice an essential factor for the Earths radiation balance and, due to its long-term change, also for global warming. The maps of sea ice concentration show that the Arctic and Antarctic sea ice is continuously changing. The sea ice concentration (level 3 data products) is based on the analysis of satellite data that has been collected for both hemispheres since 1979. White areas are indicating a sea ice concentration of 100 percent. Dark regions represent open sea water. The sea ice extent describes the area that is covered with at least 15 percent sea ice.
Is global warming affecting sea ice concentration?
Sea ice extent in the Polar Regions is subject to large seasonal fluctuations. While almost the entire Arctic Ocean is ice-covered in winter, the ice-covered area melts to about a quarter of the surface. At the beginning of continuous ice observations by satellites in 1979, the ice-covered area at the end of summer was still about half as large as in winter. In the Arctic, we are thus witnessing a strongly decreasing trend in summer ice extent of about 13 % per decade. If this trend continues, the Arctic will be ice-free in summer by the middle of the century (ice cover less than 1 million km²) with enormous consequences for the climate and ecosystem. In the Antarctic, on the other hand, we are seeing the opposite trend. Ice extent in winter is slightly increasing, while in summer it is only slightly decreasing. The cause of the strongly decreasing trend in the Arctic is the polar amplification, which is about twice to three times as large as the global average with 2 - 4 °C warming.
Last updated at: 13.06.2021