By Marlene Cimons
Botanist Lynn Sweet regularly treks through California's Joshua Tree National Park, nearly 800,000 acres that lie at the intersection of the Mojave and Colorado deserts. She likes to photograph the gnarly, spikey-limbed trees, which look — as some have observed — like a picture from a Dr. Seuss children's book.
Joshua tree flowers in Red Rock Canyon, Nevada.
Lynn Sweet, center, measures a dead Joshua Tree with two volunteers.
Ecosphere<p>Her calculations suggest that addressing climate change could save 19 percent of the trees after 2070. If nothing is done, however, the park likely only would keep a scant 0.02 percent. The <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.2763?source=post_page---------------------------" target="_blank">study</a> appears in the journal Ecosphere.</p><p>The work builds upon an <a href="https://www.academia.edu/27980913/Modeling_impacts_of_climate_change_on_Joshua_trees_at_their_southern_boundary_How_scale_impacts_predictions?source=post_page---------------------------" target="_blank">earlier study</a> in 2012, also by UC Riverside researchers, which found the trees would begin to vanish if temperatures rose 3 degrees C. The newest study considered additional factors, such as soil moisture estimates and precipitation, among others.</p><p>The trees already have begun drifting to higher areas in the park, where they might escape the heat and have a better chance at producing younger plants, she said. In hot areas, however, tress reproduce less — and those that do are dying, the study said. Older trees, which can live as long as 300 years, can store large amounts of water, which helps them cope with <a href="https://www.ecowatch.com/tag/drought">drought</a>. But younger trees lack this capacity, and are less likely to survive.</p>
A Joshua tree.
Pink clouds over the Mjoave desert.