Water securityThe combination of drought and warming climate places severe strain on California’s water supply
As stores of water in the West are reduced — whether by usage in drought, evapotranspiration in heat, or both — warming temperatures also see the snowpack on the wane. The two phenomena together could put severe strain on water supplies, with implications for ecosystems, industries, and people alike. Even at their most severe, the droughts of decades and centuries past did not occur in tandem with today’s degree of temperature change or have to contend with the demands of a population that in California alone now numbers above thirty-eight million residents. As needs for water grow ever greater, so, too, do the potential threats to its supply.
Growing danger of California water supply falling to critically low levels // Source: ca.gov
California being in the clutches of drought, as it is today, is nothing new. From prehistoric droughts to so-called “megadroughts” that strangled the state some 1,000 years ago, to more recent extreme dry periods in the late 1970s and early 1990s, drought happens.
A UCSB release reports that this time around, however, California has more than thirty-eight million residents with water needs and is grappling with a troubling trend that’s in play around the world: global warming.
“It’s not just that there is low precipitation but low precipitation in a warming climate,” said Frank Davis, director of the UC Santa Barbara-based National Center for Ecological Analysis and Synthesis. “The combination of warm and dry has a lot of ecological impactions. It puts greater physiological stress on, for example, forest trees. Also, when it’s dry and warm, we start to see really strong impacts on fresh-water systems, like those that spawn salmon. Being really dry plus warm is a one-two punch.”
An “alarming situation”
Along the makeshift path heading toward the bluffs at Coal Oil Point off the Santa Barbara coast, dirt grates underfoot; pale withering grasses crunch and crumble. In the nearby foothills east of town, the chaparral is behaving as if it’s summertime and some trees are starting to die.
“This is just weird,” said UCSB geography professor and department chair Dar Roberts on a recent trip to Coal Oil Point Reserve, one of six natural reserves administered by the campus and used as outposts for environmental research. “Normally at this time of year there is a nice, lush, green cover of plants at this site. … This isn’t January. This is August.”
The oceanfront reserve is home to one of five climate monitoring stations run by UCSB’s geography department to measure temperature, wind speed, precipitation, fog, and soil moisture as a means of studying climate change. These days they’re also providing insight into drought.
“From the point of view of drought, they’re some of the most important measurements we have,” said Roberts. “From a plant’s perspective, it’s the moisture in the soil that matters more than anything else. And we’re at a lower level of soil moisture right now than we have been in three years — drier than even a typical summer. Our other sites are telling the same story.”
