Climate Change and Sea Ice

Global warming signals are observed in the atmosphere, land, ocean, and ice from multiple instrumental and paleoclimatic sources. Data indicate regional warming and changes in precipitation patterns. The heat content of the ocean up to 700 m in depth has increased significantly while the contrast between wet regions and dry regions over the oceans has increased over the past 60 years. Among the strongest signals of warming are those from polar regions where climate change is amplified and increases in temperature have caused significant changes in the timing of the melt season, retreats in the snow cover, loss of mass in ice sheet and glaciers, and thawing of the permafrost. But among the most dramatic changes observed on a global scale have been the rapid decline of the perennial and multiyear ice cover in the Arctic during the period 1979–2017. Such decline can cause profound changes in the Arctic environment and the Earth's climate system.