Perspective

A colleague of ours was heard to say, “If I hear one more person say, ‘So much for global warming—’.”

She didn’t finish the sentence but the exasperation was familiar. A tiny shift in weather is regularly taken as meaningful when it’s not.

For instance, on Feb. 16, 1990, in the middle of a major multi-year drought, western Nevada was hit with a major snowfall. It was followed immediately by premature “Is the drought over?” news stories.

It is akin to a comment Donald Trump made in a New York Times interview during the campaign—“You know the hottest day ever was in 1890-something. Ninety-eight.”—as though it had meaning. As usual with Trump, he never provided any verification, but even if what he had said was true, scientists and fact-checkers quickly pointed out that one point in time is not a trend. It may, indeed, be an exception or anomaly.

Far from the snowfalls this year disproving climate change, University of Nevada, Reno scientist Glenn Miller said they are exactly “what you would expect to happen” with warming.

“This is one of the symptoms of global warming,” he said. “If you have a lot more water evaporate, that water is going to come down at some point. This is exactly consistent with global warming. You have more extreme events happening.”

Thus, hotter summers, colder winters. “Stronger events” also are a cause of shorter autumns and springs.

The Union of Concerned Scientists has said extreme events like flooding, heavy snowfalls and downpours can all be a sign of global warming. This winter’s downpours in western Nevada are relatively new. The region did not experience them in, say, the 1950s or ’60s.

“In fact, as the Earth gets warmer and more moisture gets absorbed into the atmosphere, we are steadily loading the dice in favor of more extreme storms in all seasons, capable of causing greater impacts on society,” said UCS scientist Jeff Masters in 2011.

It is possible to assess the year’s heavy snows without reading more into them than there is. Some have been trying to do that.

Heather Emmons, spokesperson for the Natural Resources Conservation Service, issued a statement that said what is significant about this winter is its resemblance to 1983.

“1983 is a winter talked about with awe and reverence by snow surveyors and water managers in the western United States,” the statement said. “Putting it in the same sentence as 2017 indicates that we have a real heavy hitter at bat this winter.”

The numbers across the state are impressive.

“The Truckee, Lake Tahoe, Carson and Walker river basins have snowpacks 200-218 percent of normal. These amounts break all previous March 1 [snow telemetry] records for snow water content. … It is not just the Sierra—other parts of Nevada are having a drought busting year, too. The snow on Mt. Charleston, near Las Vegas, is 182 percent of normal. Snowpacks are 146-156 percent of normal in the Humboldt Basin and 134 percent in Eastern Nevada. The Humboldt River experienced flooding in February. Springtime streamflow forecasts for the Humboldt River exceed the amount of space left in Rye Patch Reservoir, making it likely that Rye Patch will fill this year.”

Another place where there could be a jump to conclusions is in the Western drought. There have been a lot of headlines: “California snowpack could bring 5-year drought to its knees” and “Drought finally over in nearly every part of California.”

But no scientist has called an end to the 17-year drought. After all, an extreme winter could easily be followed by an extreme summer that undoes a lot of the gains made.

At Lake Mead, where the “bathtub ring” and the lake’s dramatic fall have been used incessantly to illustrate the drought, the winter has raised the lake a bit, but Bureau of Reclamation spokesperson Rose Davis still told KLAS News, “It’s a very important concept to remember that nobody’s out of drought. … I mean, regardless of what you’re seeing on the flooding in California and other places, one year doesn’t undo drought.”

And amid all the snow, the journal Water Resources Research last week issued a study that said, in part, “Fifteen years into the 21st century, the emerging reality is that climate change is already depleting the Colorado River water supplies at the upper end of the range suggested by previously published projections. Record-setting temperatures are an important and underappreciated component of the flow reductions now being observed.”

The study was done by hydrology researchers Brad Udall of Colorado State University and Jonathan Overpeck of the University of Arizona. Forty million people rely on the Colorado’s water, and its volume is down 19 percent as a result of the drought.

In a Wired essay, hydroclimatologist Peter Gleick wrote that there are two kinds of drought.

“But another key variable is temperature. Temperature determines, among other things, the demand for water by crops, vegetation, and people, and especially the ratio of snow to rain that falls in the mountains. The past five years were by far the driest and hottest in more than a century of recordkeeping—in part because of human-caused climate change—and those high temperatures played a key role on worsening the scarcity of water and devastating the snowpack. This combination of hot and dry led to massive groundwater overdraft, cutbacks to farmers, loss of snow storage in the mountains, reductions in hydropower production, and a range of voluntary and mandatory restrictions on urban water use. And while the wet year may end the ’precipitation drought,’ higher and higher temperatures and a persistent ’snow drought’ are here to stay.”