That video is horrifying.

We learned last year that many of the effects of climate change are irreversible. Sea levels have been rising at a greater rate year after year, and the Intergovernmental Panel on Climate Change estimates they could rise by another meter or more by the end of this century.

As National Geographic showed us in 2013, sea levels would rise by 216 feet if all the land ice on the planet were to melt. This would dramatically reshape the continents and drown many of the world's major cities.