How Much Can We Blame the California Drought on Global Warming?

"With each passing year, human-caused global warming bullies California for more water. Each year, the heat squeezes more moisture from soils and ecosystems.

This is because, as the atmosphere warms, its demand for moisture rises. Just as a puddle evaporates more quickly on a warm day, soils dry out more quickly during warmer years, which are becoming increasingly frequent in most locations globally.

Currently, California is in the grips of a severe drought, which motivated my colleagues and me to conduct a study to determine how much of this drought can be blamed on natural climate variability. And how much can be blamed on the global warming shakedown? Our answer is 8-27 percent.

This finding, done using a model built on historical data, sheds light on California’s future and the effect higher temperatures have on the natural forces that drive California’s droughts.

California of buckets

Global warming is an emerging background effect on the year-to-year variations in drought caused by natural climate variations, such as El Niño and La Niña. This is especially true in California, where year-to-year precipitation varies wildly.

During most years, when natural climate variations cause wet or near-average conditions, the demands of the increasingly greedy atmosphere are still met with relative ease. During the last few years, however, natural climate variations have caused precipitation totals to be low and temperatures to be high.

Human-caused warming, meanwhile, demands additional atmospheric moisture, at a time when water resources for natural and human systems are already in short supply."

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