Contraction of the Arctic Sea Ice
Definitions Contraction of the Arctic Sea Ice
The Arctic is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenland), northern Finland (Northern Ostrobothnia, Kainuu and Lappi), Iceland, northern Norway (Nordland, Troms, Finnmark, Svalbard and Jan Mayen), Russia (Murmansk, Siberia, Nenets Okrug, Novaya Zemlya), northernmost Sweden (Västerbotten, Norrbotten and Lappland) and the United States (Alaska). Land within the Arctic region has seasonally varying snow and ice cover, with predominantly treeless permafrost (permanently frozen underground ice) under the tundra. Arctic seas contain seasonal sea ice in many places.
The Arctic is characterized by cold winters and cool summers. Its precipitation mostly comes in the form of snow and is low, with most of the area receiving less than 50 cm (20 in). High winds often stir up snow, creating the illusion of continuous snowfall. Average winter temperatures can go as low as −40 °C (−40 °F), and the coldest recorded temperature is approximately −68 °C (−90 °F). Coastal Arctic climates are moderated by oceanic influences, having generally warmer temperatures and heavier snowfalls than the colder and drier interior areas.
The Arctic is affected by current global warming, leading to Arctic sea ice shrinkage, diminished ice in the Greenland ice sheet, and Arctic methane release as the permafrost thaws. The melting of Greenland's ice sheet is linked to polar amplification. Due to the poleward migration of the planet's isotherms (about 56 km (35 mi) per decade during the past 30 years as a consequence of global warming), the Arctic region (as defined by tree line and temperature) is currently shrinking. Perhaps the most alarming result of this is Arctic sea ice shrinkage. There is a large variance in predictions of Arctic sea ice loss, with models showing near-complete to complete loss in September from 2035 to some time around 2067.
procesc(contraction,climate_change,Pollar Ice Arctic)
Sea ice in the Arctic has declined in recent decades in area and volume due to climate change. It has been melting more in summer than it refreezes in winter. Global warming, caused by greenhouse gas forcing is responsible for the decline in Arctic sea ice. The decline of sea ice in the Arctic has been accelerating during the early twenty‐first century, with a decline rate of 4.7% per decade (it has declined over 50% since the first satellite records). It is also thought that summertime sea ice will cease to exist sometime during the 21st century.
The region is at its warmest in at least 4,000 years and the Arctic-wide melt season has lengthened at a rate of five days per decade (from 1979 to 2013), dominated by a later autumn freeze-up. The IPCC Sixth Assessment Report (2021) stated that Arctic sea ice area will likely drop below 1 million km2 in at least some Septembers before 2050. In September 2020, the US National Snow and Ice Data Center reported that the Arctic sea ice in 2020 had melted to an area of 3.74 million km2, its second-smallest area since records began in 1979.
Sea ice loss is one of the main drivers of Arctic amplification, the phenomenon that the Arctic warms faster than the rest of the world under climate change. It is hypothesized that sea ice decline also makes the jet stream weaker, which would cause more persistent and extreme weather in mid-latitudes. Shipping is more often possible in the Arctic now, and expected to increase further. Both the disappearance of sea ice and the resulting possibility of more human activity in the Arctic Ocean pose a risk to local wildlife such as polar bears.
Arctic Sea Ice news & Analysis (National Snow and Ice Data Center, at University of Colorado)
Climate of the Arctic (Wikipidia)
Cryo (Norwegian Metereologic Institute)