Humanity’s greenhouse gas emissions have overheated Earth’s atmosphere, unleashing punishing heat waves, hurricanes, and other extreme weather—that much is widely understood. The larger problem is that the overheated atmosphere has in turn overheated the oceans, assuring a catastrophic amount of future sea level rise. As oceans heat up, the water rises—in part because warm water expands, but also because the warmer waters have initiated a major melt of polar ice sheets. As a result, average sea levels around the world are now all but certain to rise by at least 20 to 30 feet. That’s enough to put large parts of many coastal cities, home to hundreds of millions of people, under water.
By Harold R. Wanless. The Nation.April 13, 2021.