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When Dr. Rebecca Finger-Higgens and her colleagues perform their work, they must jump into the future. But it’s not science fiction. It’s the science of climate change. And the future Colorado, according to their recent findings, could look less green, more arid, and more unstable. Finger-Higgens and a team of fellow scientists with the U.S. Geological Survey (USGS) Southwest Biological Science Center in Moab, Utah recently examined results from a decade-long study simulating predicted decreases in soil moisture in the Colorado Plateau region by the year 2100. Their resulting research, which was published in the peer-reviewed journal Global Change Biology in March, predicts a drastic reduction in plant cover and other consequences to dryland ecosystems in the coming decades.
As CO2 emissions continue to rise and the world braces for an intensification of already severe climate change effects, researchers are scrambling to predict what we will face next. But to simulate the future climate is no easy task. “Unlike other types of science that you can do in a laboratory, [ecology] is a lot more complicated [since] it is just a much larger scale [with more variables] like weather and climate,” Finger-Higggens explains. So understanding the potential future of the Colorado Plateau—the 150,580-square-mile geographic province spanning the Four Corners region—required the USGS team to manipulate the desert and make it even drier.
Starting in 2011, the scientists set up 40 plots for drought manipulation, building three-foot-tall PVC shelters over each plot of land to keep out 35 percent of rainfall, while allowing UV light in and keeping temperature and other variables intact. (They also left uncovered plots, to act as a control variable.) Then, every two minutes, probes measured the soil temperature and moisture at 10 centimeters deep. Each spring, researchers calculated vegetation growth in each plot, and at the end of the study, the team took foliage samples to calculate carbon and nitrogen in the plants, as well as calculated nitrogen availability in the soil.
The shelters were intact long before Finger-Higgens’s time on the project. “The study started while I was in graduate school, even before I started my Ph.D.” She says, demonstrating the time-consuming nature of ecological experiments. Finger-Higgen’s joined the team in 2020 after graduating from Dartmouth College with a Ph.D. in Ecology, Evolution, Environments, and Society, just in time to analyze the results, which were startling, she says—and not in a good way.
In fact, the scientists hardly needed their test plots to see the damaging effects of drought. “The real-life drought conditions were almost worse than what we were modeling,” Finger-Higgens says. Since 2000, the Southwest has been experiencing a megadrought, or a severe drought that lasts for many years over a wide area. While we may have gotten used to the extent of the heat, the Southwest megadrought is nothing normal, found to be the driest megadrought in a millennium. And we are largely to blame: Researchers estimate that 42 percent of the extended drought is thanks to human-caused climate change. When Finger-Higgens and her colleagues looked at their experimental data, the difference between the experimental plots and control plots was not striking. “A lot of the plants we found were declining,” Finger-Higgens says. “Even in our control plots that we did not remove any precipitation in.” Translation: If the views have already seemed less green on your hikes lately, you should expect the plant life in Colorado’s deserts to become even more sparse.
Coining their project “Droughting the Megadrought,” the team did find differences in the plant nutrient status between the megadrought-ed and extra-megadrought-ed plots. “It looks like the [current] ecosystem is still functioning,” Finger-Higgens says of the higher nutrient levels in untouched control plots, “but even at a certain point, water will be a limiting factor to those microbes and in soil organisms.” Particularly alarming to Finger-Higgens and her colleagues were the declines in biocrusts on the drought treatment plots. Biocrusts provide important soil stability and biogeochemical cycling. Losses to them, mean losses to ecosystem services like water retention and soil fertility, which Southwest residents rely on for everything from agriculture to recreation.
Finger-Higgens suspects that Colorado residents will likely start noticing the changes on the slopes first, if they haven’t already. “Those soils become more vulnerable to erode into dust, and that dust can actually end up in the Colorado snowpack, making the snow a darker color that will melt quicker,” she says. But more is at risk than just skiing, as Finger-Higgens suspects the drought conditions will endanger industries—and with them, livelihoods—that depend on the state’s southwest land, like open-range cattle ranching. Other research suggests that the drought will cause worsening air quality akin to the Dust Bowl. The USGS team also worries that the continued drought will lead to heightened consequences, writing “late successional biocrust communities might fail to survive, ultimately reshaping the landscape composition and increasing the risk of erosion and invasion by non-native plants.”
Looking ahead, Finger-Higgens has been charged with leading spin-off projects in the Colorado Plateau. “Instead of intercepting water,” Finger-Higgens explains about another current study, “we actually have heating lamps above [experimental plots], so they are a manipulation of increasing air temperature [rather than decreased precipitation.]” They also want to learn more about the changes to the biocrust, asking “if these ecosystems start to really dry out, are we seeing that they are more vulnerable to erosion?”
Questions like these keep Finger-Higgens out in the field, trying to predict our planet’s future. But while the U.S. Geological Survey’s research may try to look forward 80 years, Finger-Higgens and her fellow researchers assert that the question should no longer be about how we prepare for extreme drought, nor how we survive extreme drought until the next rainy season. Instead, it is: How do we cope with the reality that the drought is not going anywhere?