After five years of drought, California has been inundated by snow and rain. Good, right? Not necessarily, say climate experts.
The recent storms that have taken much of California out of a years-long drought have been welcome, no doubt. But climate experts are also saying that it’s a sign of problems to come because the two extremes of severe drought and torrential storms are no longer a rarity. Drastic swings between the two is the new norm.
And that of course will put stress on infrastructure if water and wastewater utilities aren’t prepared.
“These biggest events that cause the biggest problems are the ones we are pretty sure are going to become more common,” Daniel Swain, a climate scientist at UCLA, told E&E News. “We’re seeing the stresses of the current climate upon our infrastructure, and seeing in some cases it’s enough to cause really big problems. And we know that in the future, we’re going to add to those stresses at both ends of the spectrum.”
According to Swain, in short, warming is causing more evaporation off oceans and other water bodies, putting more moisture into the atmosphere. That vapor doesn’t always come back down in the form of precipitation, nor does it always fall in the same place where it went up. But when it does fall, it can be excessive. Case in point: California’s lengthy drought from 2012 through 2016, and then the last two extremely wet months.
The ramifications for infrastructure was seen recently at the Oroville Dam, where nearly 200,000 people in the surrounding communities had to be evacuated for two days when officials were concerned about the dam’s emergency spillway collapsing, stemming from erosion damage created by the massive water flows being released from the reservoir.
The Oroville incident also points to the problems of having a snowpack-dependent water system with a warming climate.
“Here in the West, we use the same dams and reservoirs for both water storage and flood control, so during the wet season, reservoir managers continuously balance the dual pressures of storing as much water as possible for the dry summer and releasing sufficient water to create room for the next storm,” Noah Diffenbaugh, a professor of earth system science at Stanford University, explained in a recent New York Times editorial.
It worked when warm years were less common and the snowpack could be relied on to stay in the mountains longer, leaving more room in reservoirs to help prevent flooding during the wet season then gradually melting to replenish reservoirs in the dry season. But with more precipitation coming in the form of rain rather than snow, and earlier melting of the snowpack, water managers must release water more frequently for flood control — and at the same lose the very resource that becomes so precious during drought periods.
“This is exactly what climate scientists have predicted for California since at least the 1980s: protracted periods of warm, dry conditions punctuated by intense wet spells, with more rain and less snow, causing both drought and floods,” writes Diffenbaugh. “Although California has greatly improved water-use efficiency in the last half-century, climate change is pushing our water system to the limit.”
One way to the combat the trend, he writes, is to build more infrastructure that allows excess runoff to recharge groundwater aquifers, instead of simply being lost during flood control measures. And infrastructure will have to be able to hold up to the weather extremes. There has been some movement in that direction. A law enacted last year requires California’s Natural Resources Agency to bring scientists and engineers together in order to turn climate science into information that can be used to better build infrastructure going forward.
“What’s happened at Oroville Dam, it’s an example for us and a warning to us of what we need to be thinking about,” Adrienne Alvord, Western states director for the Union of Concerned Scientists, said to E&E News. “We can try to mitigate how much climate change we see, but we also need to respond to what we believe will occur.”