A greenhouse in the desert

How will global warming affect the world’s deserts? Scientists in Nevada predict potentially heartbreaking outcomes.

Scientists believe that greenhouse gasses will increase plantproductivity in desert areas, which may increase the duration andintensity of rangeland fires, like this one that threatened the outskirts of Reno, Nev., in July 2007

Scientists believe that greenhouse gasses will increase plantproductivity in desert areas, which may increase the duration andintensity of rangeland fires, like this one that threatened the outskirts of Reno, Nev., in July 2007

Photo By D. Brian Burghart

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Imagine a future where hundreds of thousands of people in the more arid parts of the country flee wildfires. Imagine a future where many of those people never return home when the winds shift and the temperatures drop because the blazes have left their property smoldering husks. Imagine it happening with ever more increasing frequency until it’s hard to tell where one fire season ends and the next begins.

Hard to imagine a future like that?

Then maybe it’s easier to remember this summer’s fire season when the fires in the American West and Southwest forced the evacuation of more than a half-million people and burned thousands of homes. It’s a particularly frightening thought when you consider the fact that most of the land in the Southwest United States is arid or semi-arid.

Scientists generally don’t describe ecological changes in such apocalyptic terms. But it’s hard not to when faced with the early results of major experiments being conducted at the Nevada Desert Research Center. These experiments are designed to show the impacts of climate change caused by soaring levels of atmospheric carbon dioxide on desert environments.

“We need to see how natural ecosystems are responding to changes in the global climate,” Desert Research Institute scientist and project director Lynn Fenstermaker said. “In particular we are interested in how well certain ecosystems are going to be able to sequester (contain in the soil) the additional carbon that’s being produced by fossil-fuel burning.”

Rising CO2 levels in the atmosphere are one of the main causes of global warming and could cause all kinds of environmental mischief, particularly in sensitive desert ecosystems.

These changes could have devastating consequences, with effects including increased growth rates for plants, increased rain, and shifting varieties of plants and animals. These transformations may allow invasive, non-native species to gain footholds, warn scientists. And with the added fuel on the ground comes bigger and more destructive fires.

One project to study these effects is at the Nevada Desert FACE Facility. FACE is an acronym for Free-Air CO2 Enrichment. It’s a 10-year collaboration between Nevada’s universities, the Desert Research Institute, National Science Foundation, Brookhaven National Laboratory and the Department of Energy. The 2-square-kilometer desert facility is located on the Nevada Test Site, 65 miles north of Las Vegas.

FACE allows scientists to raise the CO2 level in large plots of land. For this project, the concentration of CO2 is raised by 50 percent above the present atmospheric levels in three plots in the Mojave Desert—North America’s driest ecosystem. It’s essentially done by fumigating the area with the greenhouse gas.

“Early results have shown that when we have a wet winter, an El Niño winter, we have invasive grass species producing a lot more and a lot bigger plants [including red brome, a relative of cheat grass]. This particular species leaves a lot of dead biomass [plant matter] on the surface, and then you get lightning strikes and then these nice rangeland fires. … So if we see an increase in the El Niño cycle, we may see an increase in the frequency of the fire cycle.”

The irony is that the wildfires also contribute to the carbon load in the atmosphere. In fact, large fire seasons can release more carbon into the air than all the vehicles in the state in a year.

Experiments like those at the Nevada Desert Research Center are necessary because some 40 percent of the Earth’s land surface is arid or semi-arid, with more land becoming desert each year. This process—the degradation of formerly productive land, often caused by humans—is called desertification. It’s already responsible for an unknown number of deaths. For example, according to U.S. Geological Survey documents, between 1968 and 1973 the desertification-caused Sahel drought in Africa led to the deaths of up to a quarter-million people and the collapse of the agricultural bases of five countries.

Can increasing carbon dioxide levels in the atmosphere cause devastating fires, more powerful hurricanes, decreased land productivity and inconceivable starvation? It’s hard to imagine that sort of future—maybe it’s easier just to remember it’s already happened.