The drought in California has been killing trees at an unprecedented rate. Nate Stephenson, research ecologists for the U.S. Geological Survey, advises local land managers with these kind of problems.
“A lot of people have heard about the recent drought in California and it’s been exceptional," he said. "Trees have been dying at a frequency that’s not been seen before in the historical record, and that’s because this is what’s called a hotter drought. If all you had was a rain gauge, you would say ‘Yeah, this is a severe drought, but we’ve seen droughts like this before, like back in the 1920s.’ But the warmer temperatures increase the evaporative demand that the trees feel, and that’s what pushes them over the edge.”
For 37 years, Dr. Stephenson has been working at Sequoia and Kings Canyon National Parks in California. His mission is to provide the information that managers need to help them make decisions. But he was quick to point out that science does not tell us what should be done. That’s up to society to choose. Science’s job is to give an accurate account of what is actually happening, and to show us the way to achieve a desired outcome. In a time when science has become widely politicized, it’s important to point out what the role of science actually is.
“All science can give you, at its best, is facts, and that’s only half the equation," Stephenson said. "The other half is values, that’s what do you want, and the combination of those two is what allows you to actually do things. You need to know what you want, and you need to know how to get there. Science can tell you how to get there once you’ve defined what you want, and usually your definition of what you want comes from some combination of laws, policies, and public engagement.”