Summit County Citizens Voice

It's getting warmer ...

Snowpack changes, fires, vegetation mortality all signs of regional climate change

By Summit Voice

SUMMIT COUNTY — The Southwest is showing more signs of climate change than any other part of the country, a pair of climate experts say, calling for a no-regrets strategy in the face of global warming. The strategy was detailed in the journal Science to prepare residents for hotter and drier conditions.

The article was written by Jonathan Overpeck, principal investigator with the Climate Assessment for the Southwest at the University of Arizona, and Bradley Udall, director of the Western Water Assessment at the University of Colorado.

Signs of documented climate changes in the region include rising temperatures, earlier snowmelt, northward-shifting winter storms, increasing precipitation intensity and flooding, record-setting drought, plummeting Colorado River reservoir storage, widespread vegetation mortality and more large wildfires.

“The West, and especially the Southwest, is leading the nation in climate change – warming, drying, less late-winter snowpack and drought – as well as the impacts of this change,” said Overpeck, professor of geosciences and atmospheric sciences and co-director of the Institute of the Environment at the University of Arizona.

In the past 10 years, temperatures across western North America have surpassed the 20th century average, in many cases by more than 1 or even 2 degrees. Warming and shifting precipitation patterns, along with other factors like more desert dust deposition, have decreased late-season snowpack and the annual flow of the Colorado River, the researchers said.

As a result, water storage in Lake Powell and Lake Mead fell nearly 50 percent between 1999 and 2004 and has not risen significantly since.

Some studies suggest that Colorado River flow could decrease by another 20 percent by 2050.
Other University of Arizona researchers have mapped vegetation changes in the region, showing that more than 1 million acres of piñon pine have died in the Southwest in the last few decades from a lethal combination of record-high temperatures and uncommonly severe drought. In addition, the frequency of large wildfires has increased as snowpack has decreased.

Overpeck said researchers are confident that the higher temperatures and resulting changes in snowpack, Colorado River flow, vegetation mortality and wildfires are human-caused. But they don’t know if the drought that has plagued the West for the last 10 years – the worst since record- keeping began – is because of humans, Overpeck said.

“It’s critical to determine the causes of the observed change, including the drought, because then we will have a much improved ability to say what’s coming next, in the future,” Overpeck said.

“One thing is for sure,” Overpeck said. “The best strategy now – the no-regrets strategy – is to prepare for a hotter and drier West, Southwest and Arizona, and to make sure we don’t commit water to things now in ways that could make water shortages in the future more difficult to deal with.”

Fortunately, Overpeck said, scientists have a better understanding about potential future climate change in western North America than for many other regions around the globe, making it easier for policy makers to plan coping strategies.

The researchers also point to the region’s potential wealth of solar, wind and geothermal renewable energy production.

“That offers a way to make up economically for the costs that will be incurred in adapting to the warmer, drier conditions,” Overpeck said. “And it will have the side benefit of decreasing the chances, through reducing greenhouse gas emissions, for potentially greater human-caused climate change.”

Filed under: climate and weather, global warming, Summit County Colorado Tagged: | climate change, Colorado River, Environment, global warming, Lake Mead, Lake Powell, Southwest and Arizona, Summit County News