The devastating impact of climate change on the southwest's rainfall is a stark reminder of our role in shaping the planet's future. The Colorado River Basin, a vital water source for seven states and Mexico, is facing an unprecedented megadrought that began in 1999. This crisis is a direct result of human-induced climate change, according to a recent report.
But here's where it gets controversial... While the link between climate change and rising temperatures is well-established, the cause of the declining precipitation has been less clear. However, researchers Jonathan Overpeck and Brad Udall are now certain that anthropogenic climate change is responsible for the drying up of the southwest.
Overpeck, the dean of the UM School for Environment and Sustainability, explains, "The drought has been relentless for over 25 years, with a consistent downward trend in precipitation. We initially thought it might be a natural fluctuation, but recent research confirms otherwise. Long-term, we're looking at more dry winters than wet ones, and that's a direct consequence of climate change."
Building upon a cornerstone study from 2017, Udall and Overpeck have been tracking the drought and its climate drivers through a series of detailed graphs. In their latest update, published as part of the Colorado River Research Group's annual report, they conclude that the decline in precipitation is also due to human activity, and it's unlikely to recover unless we take action.
"We understand the cause of this decline, and we know how to stop it. We just need to address climate change. It's not an impossible task; we have the solutions, and we still have time to act," Overpeck emphasizes.
The duo's conclusions are supported by two recent studies in climate science. One, led by Jeremy Klavans at the University of Colorado, Boulder, improved climate models for the region, while the other, led by Victoria Todd at the University of Texas at Austin, used paleoclimatology techniques to provide critical context by examining temperature trends from thousands of years ago.
Udall and Overpeck's contribution to the annual Colorado River Basin report is titled "Think Natural Flows Will Rebound in the Colorado River Basin? Think Again." They explain that the natural flow of the Colorado River should be around 16.5 million acre-feet to comfortably meet the basin's water needs, but it's currently closer to 12 million acre-feet.
Both researchers emphasize that there will be natural variations from year to year, with some winters wetter and others drier. However, their findings indicate a long-term trend towards drier conditions. Udall adds, "The near-term outlook is also concerning. We've depleted our reservoir storage over the past 26 years, and one more dry winter could lead to unprecedented water usage cuts."
Udall often fields questions about the consequences of not meeting international climate targets, like those set by the Paris Agreement. This precarious situation is one such consequence. While the region's farmers and water managers are acutely aware of the stakes, Udall stresses the global importance of the climate-water connection. Droughts are intensifying wildfires, and storms are carrying more water, leading to dangerous floods.
"The supercharging of the hydrological cycle is the essence of climate change. It's about water, and it's a global issue. We have the power to control our destiny, but we must act now," Udall concludes.
Source: University of Michigan
