It's hard not to notice the weather these days: extreme heat spanning the country with bursts of thunderstorms. A new study by the Environment California Research & Policy Center aptly titled "When it Rains, it Pours" says we should take caution. Extreme downpours are up 35% in California since 1948, and scientists claim these erratic weather patterns are a sign of global warming.
The study analyzed 3,700 weather stations across the United States, noting that Southern California is experiencing a marked rise in unstable weather. "Southern California and parts of the Central Valley are experiencing up to 72% increase in the frequency of extreme storms with a 7% increase in the intensity of the storms as well," the Center claimed in their press release. The L.A. region is up 34%; San Diego, 64%; Santa Barbara, 72%; Ventura/Oxnard, 41%; Bakersfield, 63%; Riverside, 53%; and the Hanford region, 61%.
The Center reports that 4 out of 5 people in the state of California live in areas hit by recent weather disasters.
"There's certainly been an increase in the erratic rainfall in Southern California," Amalie Orme, Professor of Geography at CSUN, confirmed over the phone. For many years, scientists believed that weather worked in a 30-year cycle of varying patterns. Upon reaching the later 20th century, "the picture began to dissolve," she said. The weather has become unstable, with a particular intensification of monsoonal flow in the Southwest. "We've had an increasing number of extreme events."
The winter rainfall in Southern California is derived from the Gulf of Alaska and farther out in the Central Pacific. Warming surfaces cause more evaporation. Rising, warm air creates instability in the atmosphere. Extreme heating of the continental surface can simultaneously dry out soil. So, global warming can certainly be related to drought-like conditions in some areas, while being punctuated by storm events. Feels familiar in the U.S., particularly in the last six months.
However, Orme pointed out that there are more reliable ways than storm measurements to substantiate global warming, and emphasized the larger picture.
"The firmer evidence is in patterns of vegetation because that gives you perspective," Orme claimed, stating that there is ample proof of warming in the Northern Hemisphere. "I was just in the White Mountains, a range east of the Sierra, for five days. We were certainly seeing evidence of warming in the distribution of the sage. It is marching up hill. [The sage growth] has increased vertically, over 150 feet in the last 50 years. Very suggestive."
Still, inconclusive. "The long term perspective is that we're privileged to have that much data to work with, but that doesn't mean we haven't had incidents like this in the past," Orme emphasized.
As for the human contributions to global warming, Orme said human impact is "undeniable." Although there were natural upticks in carbon before the Industrial Revolution, after the 1930s there is a very clear spike, as seen in the readings from the Volcano Observatory in Hawaii and ice core studies in Greenland.
"We need to heed scientists' warnings that this dangerous trend is linked to global warming, and do everything we can to cut carbon pollution today," said Bernadette Del Chiaro, director of global warming programs with Environment California Research & Policy Center, in a call to action. "How serious this problem gets is largely within our control -- but only if we act now to reduce the pollution that fuels global warming."
In the meanwhile, bring your umbrella.