deglaciation

Deglaciation is the transition from glacial to interglacial conditions, marked by the retreat of continental ice sheets and mountain glaciers as global or regional mean temperatures rise. It involves melting, thinning, and volume loss of ice, changes in albedo, and often rising sea levels as stored water is released into the oceans.

Main drivers include long-term climate warming due to natural orbital variations (Milankovitch cycles) and, in recent periods, human-induced increases in greenhouse gases. Feedbacks such as lower albedo from ice loss, changes in ocean circulation, and meltwater input can amplify the process. Regional patterns vary with geography and ice dynamics.

Evidence comes from geological and geochemical records, including moraines, varves, isotopic proxies in ice cores and marine sediments, and shoreline deposits. The most famous global deglaciation occurred at the end of the last glacial maximum about 26,500 to 19,000 years ago, with rapid ice retreat and sea level rise during the early to mid-Holocene.

Today, deglaciation is under way in many regions due to anthropogenic warming, with widespread retreat of mountain glaciers and thinning of ice sheets in Greenland and Antarctica. This modern deglaciation contributes to sea level rise and can impact freshwater resources, ecosystems, and hazards such as glacial lake outburst floods.

Deglaciation is not a uniform, monotonic process; regional advances can occur and feedbacks can temporarily slow or accelerate retreat. Long-term trends are inferred from multiple proxies and models.