The record-breaking drought in California is not chiefly the result of low precipitation. Three factors – rising temperatures, groundwater depletion, and a shrinking Colorado River – mean the most populous U.S. state will face decades of water shortages and must adapt. The Lake Oroville reservoir in Northern California was at less than 25 percent capacity last month. Image via raybouk/flickr. Creative Commons 2.0. The current drought afflicting California is indeed historic, but not because of the low precipitation totals. In fact, in terms of overall precipitation and spring snowpack, the past three years are not record-breakers, according to weather data for the past century. Similarly, paleoclimate studies show that the current drought is not exceptional given the natural variations in precipitation of the past seven centuries. Nor can it be confidently said that the current drought bears the unequivocal imprint of climate change driven by increasing greenhouse gases, since […]