We’ll need to mitigate and adapt to global warming to avoid massive costs from sea level rise
Ocean waters are rising because of global warming. They are rising for two reasons. First, and perhaps most obvious, ice is melting. There is a tremendous amount of ice locked away in Greenland, Antarctica, and in glaciers. As the world warms, that ice melts and the liquid water flows to the oceans.
The other reason why water is rising is that warmer water is less dense – it expands. This expansion causes the surface of the water to rise.