Climate change undoubtedly poses a potent — even existential — threat to the planet. But the current approach to mitigating it, which reflects a single-minded focus on cutting carbon dioxide emissions, may end up doing serious harm, since it fails to account for the energy sector's depletion of water resources — another major contributor to climate change.

"Water is at the heart of both the causes and effects of climate change," a National Resource Council report declares. And, indeed, the water cycle — the processes of precipitation, evaporation, freezing, melting and condensation that circulate water from clouds to land to the ocean and back — is inextricably linked to the energy exchanges among the land, ocean and atmosphere that determine Earth's climate. Just as the accumulation of carbon in the atmosphere contributes to climate change, so does the degradation and depletion of water resources. And these processes are mutually reinforcing, with each propelling and intensifying the other.

Energy extraction, processing (including refining) and production is highly water-intensive. The energy sector is the largest consumer of water in every developed country except Australia, where, like in most developing countries, agriculture comes out on top. In the European Union, electricity-generating plants alone account for 44 percent of all freshwater consumed each year; in the United States, that figure is 41 percent.