As permafrost thaws, riverbanks in Alaska are slumping, releasing long-sequestered carbon. Water, liquid and frozen, occupies most of Earth’s surface, with oceans covering two-thirds of it and ice another 10th. All is being transformed by climate change, posing greater threats to life and human society than scientists had realized, according to a special assessment of climate science focused on oceans and ice released today by the United Nations. The report, from the Intergovernmental Panel on Climate Change (IPCC), comes during a week when the world is fixated on what many now call the climate crisis. The planet has already warmed 1°C since preindustrial times, and July was the hottest month in the modern record. Last week, crowds including many schoolchildren turned out in cities worldwide to demand action. And in New York City, the United Nations convened its first climate summit since 2014, calling on nations to commit to more ambitious carbon cuts than they did under the 2015 Paris agreement. Without such commitments—followed by action—the world could experience 2.5°C of warming above preindustrial levels, or more, in coming decades. The new Special Report on the Ocean and Cryosphere in a Changing Climate stresses that the watery parts of […]

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