But the drought had less obvious effects on climate and the environment, too: Low river flows drastically hampered the amount of carbon-free electricity that could be produced by the thousands of hydroelectric power plants dotted along rivers and reservoirs across the West.
They figured out that an extra 100 megatons of carbon ended up in the atmosphere because utilities had to use carbon-emitting power sources instead of hydroelectric power during drought, added up over the 15 years they studied.
In a normal year, a little more than 20 percent of the electricity produced across the western U.S. comes from hydroelectric plants.
If energy utilities can’t get the power they need from hydroelectric sources, they have to fill that gap with something else.
“Under drought conditions, the priority is to use water for people and cities, and managers might prefer to burn gas for energy,” he says.
In California, for instance, the extra carbon dioxide emitted because of the drought added up to more than seven percent of its total carbon emissions.
Many of the western states have set out plans for how to aggressively reduce their emissions over the next few decades.
Future megadrought?
And forecasts for the future predict that dry places are likely to get even drier, stressing out the hydroelectric system even further.
It’s way beyond what you may think.” But Diffenbaugh points out that with this study and a slew of others from the past few years, we’ve learned more and more about when and why carbon-free energy sources struggle.