Thirsty Cities

The cities shown here -- with apologies for Google's deplorable use of the U.S.-centric version of the Mercator projection -- are featured in a recent article by Mark Herman, simply entitled Thirsty Yet?

A greatly reduced Thames is just one of the changes to which urban dwellers may need to adjust.

Based on the United Nations World Water Development Report, the article is a reminder that the perils of climate change vary considerably from place to place. While much of our focus is on rising seas caused by the thermal expansion of the upper layer of ocean water and the melting of ice stored above sea level, lack of fresh water is an equally serious risk, and in some cases will be a problem in the very same places affected by sea-level rise.

More broadly, the article reminds us that environmental problems operate at varying scales and interact with each other in complicated ways.