Via The Guardian: California drought goes from bad to worse as state grapples with heat wave. Excerpt:
Spring is starting to feel a lot like summer in California, as a record-setting heat wave punishes the parched state now in its fourth year of what is said to be the worst drought in a millennium.
Experts say the scorching spring days are part of a long-term warming pattern – driven largely by human activity – that is increasing the chances that future droughts will be as bad as this one. The warm and dry weather exacerbates already dire conditions as soil dries, snow melts and water usage is driven up.
“It’s like a one-two punch,” said Jeanine Jones, deputy drought manager for the state Department of Water Resources (DWR). “Not having enough water to fill our reservoirs and having the hot weather evaporate the little that we do have.”
According to the most recent US drought report, moderately below-average precipitation, coupled with extremely above-average temperatures, has maintained or worsened drought conditions in California. The consequences have been devastating, from shriveling reservoirs to vanishing groundwater, dying crops, thinning herds and raging wildfires.
California relies on a series of massive storms during the winter months to drop snow on the Cascades and Sierra Nevada mountain ranges. During the spring and summer months the snowpack, acting like a natural reservoir, melts as water demand rises.
But the recent extremely warm weather has caused precipitation to fall as rain rather than snow. The effect is dramatically less snowpack melt from the state’s mountain ranges, which can provide as much as a third of California’s water supply.
This year, the mountain runoff will likely be just a trickle. Snow on the mountains has fallen to 12% of average levels, from 28% last year. In March, data collected from parts of the Cascade and Sierra Nevada mountains indicated that some sites were for the first time snow-free by the first of the month. Jones said the 1 April snowpack measurements, which will be reported next week, are expected to be the lowest on record.
“That does not at all bode well for our depleted reservoirs,” Jones said.
Hotter temperatures are predicted to be the new norm in California, the result of rising temperatures under climate change. This month, for the first time since record keeping began in the late 1880s, the temperature in Los Angeles peaked in the 90s fahrenheit for six consecutive days, according to the Los Angeles Times.
Based on the current warming trajectory, the likelihood that low rain years will coincide with high heat years is almost a certainty.
“California is in a climate regime where are much more likely to get this kind of drought event again because of the role of temperature rise,” said Stanford University professor Noah Diffenbaugh, who led a study examining the role of warm temperatures in California’s droughts.
That study, published earlier this month in Proceedings of the National Academy of Sciences, found that historically, California’s worst droughts occurred when conditions were both dry and warm, and that those conditions had occurred more frequently in the past two decades than in the last century.
Sitting here in Vancouver with yet another rainstorm pounding on my skylight, I can foresee a looming undocumented-Californian problem for Canada...even as we eventually face our own megadrought.