Hot, dry future will mean more wildfires

With climate change, bad conditions more common

The horrific wildfires in California this fall may be more commonplace as the planet warms: Climate change has doubled the odds that a region will suffer the brutal combination of hot and dry weather at the same time, a new study said.

In addition to scorching and ruining crops, those hot, dry conditions can also worsen fire risk, drying out vegetation in the summer and fueling intense, fastspreading wildfires like those that burned through more than 375 square miles in California this month, killing dozens.

When those extremes occur at the same time, it exacerbates the impacts far beyond what they would have caused separately, according to lead author Ali Sarhadi of Stanford University.

The study makes intuitive sense since the Earth has warmed about 1.8 degrees Fahrenheit since the late 19th century: “If it's getting warmer everywhere, then it's more likely to be hot in two places at once,” study co-author Noah Diffenbaugh said in a statement. He added that “it's probably also more likely to be hot when it's also dry in two places at once.”

Specifically, the frequency of warm and dry conditions happening at the same time in the mid-20th century was around 20 percent, the study said. Now, early in the 21st century, it's about 40 percent.

“So, what used to be a rare occurrence can now be expected to occur with some regularity, and we have very strong evidence that global warming is the cause,” Diffenbaugh, also of Stanford University, added.

The study was published in the peerreviewed journal Science Advances.

Looking ahead, within the next several decades, there's as much as a 75 percent chance that average temperatures will rise well beyond what they were around 1950.

Food scarcity because of the hot, dry weather combination will likely affect China and India, both of which are particularly at risk: The probability of warm and dry years in these key crop and pasture regions will be substantially greater over the next 30 years if greenhouse gas emissions aren't reduced, the study authors say.

Harvests of staple food crops such as wheat, rice, corn and soybeans could be threatened.

Scientists say global warming is caused by the burning of fossil fuels such as oil, coal and gas, which release greenhouse gases such as carbon dioxide and methane into the atmosphere, and has caused global air and ocean temperatures to rise to levels that cannot be explained by natural factors.

The Stanford study follows a separate paper published by the American Geophysical Union that said extreme heat events are increasing across the U.S. and Canada.

EPA-EFE Firefighters battle the Camp Fire in northern California, the deadliest in the state’s history, this month. A study says the conditions that spark such fires occur twice as frequently as they did in the mid-20th century.