The Third Pole—Mountain Ice

• Main Author: Summerhayes, Colin
• Format: Book Part
• Language: English
• Published: Oxford University PressNew York 2023
• Subjects: New Zealand; Ice cap
• Online Access: http://dx.doi.org/10.1093/oso/9780197627983.003.0007; https://academic.oup.com/book/chapter-pdf/58048005/oso-9780197627983-chapter-7.pdf

Abstract Melting mountain ice contributes to sea level rise. During the last glacial maximum an ice cap covered the Alps. Major glaciers formed ice streams that carved deep U-shaped valleys. The most recent Alpine advance occurred between 1820–1865 at the end of the Little Ice Age, followed by glacier retreats of 1–2 km. Advances and retreats reflect the influence of tropical volcanic eruptions and sunspot cycles (e.g., the Maunder Minimum). Sunspots do not explain modern warming—being as abundant in 1980 as in colder periods (1780 and 1855). Except locally (e.g., New Zealand), the snow line has climbed 400–500 m. Himalayan glaciers lost 25% of their mass in the last 40 years. Retreats reverse advances that began 5,000 years ago as Earth moved into a neoglacial period. Collapses of mountain ice fronts and meltwater lake dams cause major floods. Loss of glacial ice will diminish summer water supplies in arid regions.