From Floods to Drought: What Lizards Can Tell Us About Our Changing Desert
“I don't see the desert as barren at all; I see it as full and ripe. It doesn't need to be flattered by rain. It certainly needs rain, but it does with what it has and creates amazing beauty.” — Robert Edison Fulton Jr.
By DR. CAMERON BARROWS
That pumping carbon dioxide and methane into the Earth’s atmosphere will increase global temperatures is basic physics. For 2024, January - July temperatures in the Northern and Southern Hemispheres had their warmest January - July periods on record, and the contiguous U.S. had its second-warmest January - July period on record.
However, climate change entails more than just warming; understanding how a warming planet will impact weather patterns is far more complicated. How many times has a weather forecast for an upcoming weekend turned out to be wrong? Multiply that complexity and error to worldwide climate patterns and weather events and our ability to predict the future becomes muddled. Yes, it is getting warmer and will continue to do so until carbon dioxide and methane emissions are reduced. But will it be warmer and drier or warmer and wetter? Will there be prolonged droughts punctuated by massive flooding? Or higher humidity but less rain? More hurricanes, more tornados? Yes, probably, maybe, possibly, all the above. There just aren’t clear answers for these questions, but the possible outcomes will determine what happens to the biodiversity of our planet, and along with that our quality of life.
Our community science-based research is at least giving us a glimpse as to what those outcomes might look like for our desert and sky islands. We count lizards, not just because lizards are cool (they are) and relatively easy to observe, but because the lizards eat plants and insects, and require shade and sunlight. When we survey lizards, we indirectly also measure changes in the lizards’ food supply and the availability of thermal refugia. If the lizards’ food and/or places to bask or shelter from the sun change, the change will be expressed by changes in the abundance of lizards. In a sense we can use lizards as indicators of the broader health of our deserts, much like miners brought songbirds deep into their underground mines to be an indicator of air quality. If the bird suddenly died it meant that the miners needed to leave quickly or suffer the same result. What we have found so far is that there are some upslope shifts occurring. Side-blotched lizards are occurring at higher elevations above any previous records. We have also found that at the lowest elevations, lizards are scarcer than before. Except when it rains.
When a hurricane, like Hilary in 2023, tracks up through the Gulf of California and reaches our deserts we get flooding. We also get verdant hillsides and spectacular wildflower displays. The lizards then find abundant food at even the lowest elevations and their numbers swell. A warmer climate means warmer seas, and warmer seas often spawn hurricanes. That could mean more hurricanes and more summer monsoon rain. If it does, it means more summer humidity, and more flooding. It could also mean healthy lizard populations at lower elevations. So far, however, hurricanes and monsoon rains do not appear to be any more frequent than they have been across the past century. There was a major hurricane that caused flooding in Desert Hot Springs in the late 1930s. Then another one that impacted Palm Desert and Thousand Palms in the latter 1970s. Then Hilary. Hardly a pattern from which to predict increasing hurricanes in the eastern Pacific Ocean making landfall on our desert.
Because warmer temperatures evaporate water faster, rainfall amounts need to be more intense and more frequent to be able to sufficiently soak the ground to catalyze seeds to germinate and sustain those seedlings long enough for them to flower, attract pollinators and plant eaters (lizard food), and set seed. But there is no clear pattern, not yet, that would indicate that desert rainfall is becoming more intense or more frequent. Was Hilary an anomaly or the harbinger of a pattern yet to unfold? If heavy rainfall years continue to be rare exceptions, then we may see lizards begin to disappear from the lowest elevation portions of their distributions. Answering these unknowns is why continuing to survey lizards across the elevation gradients that characterize our desert is important.
Nullius in verba – Go outside, tip your hat to a chuckwalla (and a cactus), and think like a mountain