Southwest Drought: Are We Facing a Permanent Reality?

The Southwestern United States experiences a climate marked by a complex interplay of precipitation patterns and drought conditions. Historical data indicates that the region may eventually encounter heavy rainfall akin to the deluge seen nearly 30 years ago. Nevertheless, experts debate the timelines and causes of current climatic shifts, with many concluding that the last three decades have ushered in a new norm characterized by hotter and drier weather.

While the exact onset of the drought remains contentious among scientists, a prevailing opinion points to a timeframe between 1994 and 1999. Since then, the Southwest has recorded average or above-average precipitation in only 10 out of the last 31 years, harking back to 1993—a year of torrential rains that led to extensive infrastructure damage in Arizona. This prolonged dry spell is largely attributed to climate change, which diminishes storm frequency and accelerates evaporation, preventing effective water replenishment to underground aquifers and the Colorado River.

The Colorado River, a critical water source for the semi-arid region, is now receding faster than the ecosystem can adapt. Experts like Erin Saffell, Arizona’s State Climatologist, hold out hope for a return to non-drought conditions following several years of heavy rainfall. However, contrasting views arise from other scientists who argue the severity of the current drought is here to stay.

Jay Famiglietti, a climate researcher at Arizona State University, expressed skepticism about the prospects of relief, stating, “I don’t think we should be looking for any break in the severity of what we’re experiencing.” According to Famiglietti, the ongoing drought is distinctly driven by climate change, a departure from past patterns. The region, encompassing parts of Arizona, New Mexico, and southern Utah, has seen cyclical droughts. The 20th century alone witnessed three major dry spells, the longest lasting from 1942 to 1964.

Most experts acknowledge a clear correlation between rising temperatures and a decrease in moisture levels, despite the absence of a direct cause-and-effect relationship between climate change and annual rainfall. Rising temperatures lead to heightened evaporation and reduced soil moisture, compounding the challenges faced by the ecosystem. Famiglietti emphasized that increased heat exacerbates these conditions through a feedback loop, leading to drier soil and further desiccation.

According to a U.S. Geological Survey study in 2020, increased evapotranspiration accounts for at least half of the water loss from the Colorado River. Researchers found that 61% of the drought affecting the Colorado River Basin—spanning several states including Arizona and California—is heat-related. Consequently, Nolie Templeton, a hydrologist with the Central Arizona Project, views the situation as indicative of a permanent shift toward aridification, rather than a temporary drought.

The Central Arizona Project, a vital canal system delivering Colorado River water to millions, highlights the region’s dependence on reliable water sources. Unfortunately, climate change reduces snowfall in the Rocky Mountains, subsequently limiting runoff and exacerbating water shortages. Famiglietti described snowpack as a natural reservoir, emphasizing that when warming alters precipitation from snow to rain, it leads to rapid runoff, increasing flood risks and depleting reservoir levels.

While recent winters have yielded acceptable snowfall levels, the runoff has not met historical averages. Mark O’Malley, a meteorologist at the National Weather Service, noted discrepancies between expected snowfall and actual runoff, as soil moisture influences the efficiency of snowmelt. Dry conditions leading into winter can deplete soil moisture, resulting in runoff shortages during critical spring melt periods.

Climate patterns such as the El Niño-Southern Oscillation affect precipitation in the Southwest. El Niño events typically bring wetter winters, while La Niña conditions can lead to dryness. Despite a prediction for a dry winter predicted by analysts, Saffell emphasized that climate models serve as statistical tools rather than definitive forecasts.

Recent trends showcase a potentially easing drought; five of the past eight winters have been wetter than average. Nevertheless, skepticism remains regarding the permanence of these improvements. Famiglietti underscored the need for adaptive strategies in water management, stressing that the evolving climate requires a fundamental shift in lifestyle and resource use.