Description of Sea Ice Extent:
Unlike icebergs, glaciers, ice sheets, and ice shelves, which originate on land, sea ice forms, expands, and melts in the ocean. Sea ice influences global climate by reflecting sunlight back into space. In winter, incoming solar energy is not absorbed into the ocean because of the sea ice coverage resulting in temperatures remaining cool. In summer, when sea ice melts, the surface area reflecting sunlight decreases, allowing more solar energy to be absorbed by the ocean, causing temperatures to rise. This creates a positive feedback loop. Warmer water temperatures delay ice growth in the autumn and winter, and the ice melts faster the following spring, exposing ocean waters for longer periods the following summer.
Sea ice is an important element of the Arctic and Antarctic systems. For example, sea ice in the Arctic provides an important habitat for biological activity, e.g. algae grows on the bottom of sea ice, forming the basis of the Arctic food web. It also plays a critical role in the life cycle of many marine mammals such as seals and polar bears. Sea ice also serves a critical role in supporting the culture—and even survival—of Indigenous communities. We present the annual sea ice extent in millions of kilometers for the Arctic region.
Additionally, understanding the major effect of ice on the Great Lakes is crucial because it impacts a range of societal benefits provided by the lakes, from hydropower generation to commercial shipping to the fishing industry. The amount of ice cover varies from year to year, as well as how long it remains on the lakes. NOAA scientists are observing long-term changes in ice cover as a result of global warming. Studying, monitoring, and predicting ice coverage on the Great Lakes plays an important role in determining climate patterns, lake water levels, water movement patterns, water temperature structure, and spring plankton blooms. We present the annual maximum lake ice as a percentage of surface area for the Great Lakes region
Sea ice data was accessed from the NOAA National Centers for Environmental Information (NCEI) for the northern hemisphere. The data are plotted in units of millions of square km.
Great Lakes ice data was accessed from the NOAA Great Lakes Environmental Research Laboratory, Original ice charts from 1973 through 1988 are from the Canadian Ice Service. Beginning in 1989, the source was the U.S. National Ice Center (USNIC). Currently, data from both Canadian and U.S. sources are combined in USNIC's daily products. The data are plotted as a percentage of total lake surface area
For the most up to date data, please reference the original source above.