IPCC Sixth Assessment Report in the context of "Effects of climate change on biomes"

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). Summertime sea ice will likely cease to exist sometime during the 21st century.

The region is at its warmest in at least 4,000 years. 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. The IPCC Sixth Assessment Report (2021) stated that Arctic sea ice area will likely drop below 1 million km 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 extent of 3.74 million km, its second-smallest extent since records began in 1979. 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.