Sea ice loss in recent decades in the Arctic Ocean
Decline in arctic sea ice extent (area) from 1979 to 2022
Decline in arctic sea ice volume from 1979 to 2022
Sea ice in the Arctic region 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).[1][2][3] Summertime sea ice will likely cease to exist sometime during the 21st century.[4]
The region is at its warmest in at least 4,000 years.[5] Furthermore, 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.[6] 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.[7]: 1249 In September 2020, the US National Snow and Ice Data Center reported that the Arctic sea ice in 2020 had melted to an extent of 3.74 million km2, its second-smallest extent since records began in 1979.[8] Earth lost 28 trillion tonnes of ice between 1994 and 2017, with Arctic sea ice accounting for 7.6 trillion tonnes of this loss. The rate of ice loss has risen by 57% since the 1990s.[9]
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 plausible that sea ice decline also makes the jet stream weaker, which would cause more persistent and extreme weather in mid-latitudes.[10][11] Shipping is more often possible in the Arctic now, and will likely 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.
One important aspect in understanding sea ice decline is the Arctic dipole anomaly. This phenomenon appears to have slowed down the overall loss of sea ice between 2007 and 2021, but such a trend will probably not continue.[12][13]
Monthly averages 1979–2021. Data source via the Polar Science Center (University of Washington).
^Fisher, David; Zheng, James; Burgess, David; Zdanowicz, Christian; Kinnard, Christophe; Sharp, Martin; Bourgeois, Jocelyne (March 2012). "Recent melt rates of Canadian arctic ice caps are the highest in four millennia". Global and Planetary Change. 84: 3–7. Bibcode:2012GPC....84....3F. doi:10.1016/j.gloplacha.2011.06.005.