The Arctic

• Main Author: Summerhayes, Colin
• Format: Book Part
• Language: English
• Published: Oxford University PressNew York 2023
• Subjects: Arctic; Greenland; Ice; Ice Sheet; permafrost; Sea ice; Siberia
• Online Access: http://dx.doi.org/10.1093/oso/9780197627983.003.0006; https://academic.oup.com/book/chapter-pdf/58047935/oso-9780197627983-chapter-6.pdf

Abstract The Arctic has had sea ice for 40 million years. There have been small ice sheets in the Arctic since Miocene time (5–10 million years ago). Major ice sheets formed in Pleistocene time, covering northern Europe and North America. Declining Milankovitch insolation cooled the Arctic over the past 12,000 years. Through polar amplification, it is now warmer than it has been for 40,000 years and summer sea ice has declined since 1978. Glaciers are retreating everywhere. Ice cores show that in mid-glacial periods the climate oscillated rapidly with up to 10°C (18°F) warming in as little as 50 years. In the long warm interglacial 400,000 years ago, Greenland’s ice sheet was confined to the northeast coast. Since 1900, Greenland experienced warm events driven by changes in the Atlantic Multidecadal Oscillation. These explain the warming of the 1930s. Siberia now has heat waves and wildfires. Melting permafrost may become a major source of methane.