ShareThisOver several months during fall and winter, dozens of volunteers fanned out across the Mojave Desert in search of the smallest Joshua tree they could find.
They were part of a project to determine whether Joshua Tree National Park will lose its namesake plants to global warming within the next century -- a problem that park officials have been grappling with.
Previous studies painted a dire picture about the Joshua trees' future. But scientist Cameron Barrows found the park's plants are better adapted to handle drought and are less likely to give up so easily; he expects them to be reproducing in the park 100 years from now.
In all, the citizen scientists found 800 baby Joshua trees. They narrowed the field to about 80 of the newest plants that were a foot tall or less, so Barrows could chart their distribution in relation to rising temperatures.
Barrows was not surprised to find evidence that Joshua trees have stopped reproducing in the hotter areas of the park, where yearly low temperatures in the south have increased 3.2 degrees in the past 36 years. But enough recent offspring were found to give him hope for the future.
"What this indicates is more of a hopeful scenario, in that if we as a world of people who consume carbon and expel it, start living more sustainably, then things like protecting Joshua trees in the boundaries of Joshua Tree National Park are possible," said Barrows, a research ecologist at the University of California-Riverside's Palm Desert campus.
His findings veer from a 2005 study by Ken Cole of the U.S. Geological Survey showing that Joshua trees likely will be gone from 90 percent of their current range in the next 60 to 90 years.
The spiky trees, plentiful throughout the Southwest and Mexico in the Ice Age, now are limited to Joshua Tree National Park; eastern San Bernardino, Los Angeles and Kern counties; Inyo County; southern Nevada; extreme southwestern Utah; and northwest Arizona.
Cole predicts that all of the Joshua trees in San Bernardino and Riverside counties will migrate to Nevada and the higher elevations of Death Valley by the next century.
The difference, Barrows said, is that Cole's work covered the entire southwestern United States, while Barrows looked specifically at Joshua Tree National Park.
The park's location at the southern boundary of their habitat has allowed the plants there to better adapt to drought and high temperatures than those living in less extreme climates, he said.
"What this research says is, climate change is happening and it is going to have an impact on these species unless we are able to find a way to reduce the emission of carbon into the environment," Barrows said.
The National Park Service is planning for the changes that come with a warming planet. The agency also introduced a climate-change response strategy last fall that called for recycling, use of alternative fuels, energy efficiency and sustainable design. Park service Director Jonathan Jarvis said efforts have been inconsistent.
Under a federal initiative known as Climate Friendly Parks, Joshua Tree staff and visitors are urged to lower greenhouse gas emissions and energy use. But such efforts are not likely to alter the Joshua trees' slow decline.
Reach Janet Zimmerman at jzimmerman(at)PE.com. For more stories visit scrippsnews.com
Must credit The Press-Enterprise of Riverside, Calif.
