Fierce warnings surface from a recent study conducted by researchers at UCLA, enlightening us on the toll that the human-propelled climate crisis is exacting on the Colorado River Basin. Spanning across seven western states, the River provides potable and irrigation water to approximately 40 million people. The study discovered that over 10 trillion gallons of water, approximating the size of Lake Mead, have evaporated from the Basin due to global warming between 2000 and 2021.
A staggering reduction of roughly 10% in the river's flow has been recorded over the past two decades. The researchers attribute this decline exclusively to the soaring temperatures in the West. They argue that this entrenched climate crisis has been so significant that without its debilitating impact, no water shortage would have ever been declared for the River.
The early part of 2022 marked the outset of the first-ever Tier 1 shortage, owing to the alarming situation. Thereafter, the situation deteriorated further, leading to the implementation of a more critical Tier 2 shortage in January 2023. This was largely due to the appreciable drop in water levels at Lake Mead, the largest reservoir in the U.S.
The lead author of the study, Benjamin Bass, shed light on the team's primary motivation at the inception of the study. They were cognizant of the severe drought and were eager to delve into its profound impacts on Lake Mead's water levels. The team sought to provide a comprehensive study that considered both the unprecedented, extensive drought phenomena and the ramifications of anthropogenic climate change.
An urgent scramble to curtail water usage has dominated activities along the Colorado River in the past two years. This arises from state leaders and water users alike, largely triggered by the spiraling system reaching uncomfortably low signals.
While the escalated temperatures are of grave concern in all states, they appear to wreak the most havoc in snow-laden regions like Colorado, where the River commences. This is owed to the increased evaporation from the melting snow due to rising temperatures, causing darker earth to be exposed, which in turn absorbs even more heat. This is referred to as a positive albedo effect.
Bass and his team approached this crisis by designing a model that simulated stream flow in the Basin. They considered two conditions - historical temperature conditions and the removal of anthropogenic warming effects. Their finding was stark - climate change-driven temperatures are substantially reducing the flow of the River over time.
The team unearthed that this reduction of roughly 10% has been unwavering, regardless of whether the years were categorically wetter. The reductions persisted even during periods of higher snowpack and rainfall. This led to the chilling realization that these reductions appear to be stubbornly regardless of other climatic conditions.
An identification of an 11.7% decrease in the annual stream flow by the National Center for Atmospheric Research and the National Oceanic and Atmospheric Administration echoed these findings. The two separate studies, despite utilizing different modeling methods, invariably arrived at the same conclusion.
The long-term forecast is sobering - an unavoidable surge in temperature and the continuous decrease in runoff. This possibility was flagrantly emphasized by NCAR's Ethan Gutmann. Yet, a recent spike in snowfall has helped raise Lake Mead's levels slightly, offering some temporary respite.
Nevertheless, formal negotiations to examine further reduction possibilities in the Basin's water use will soon commence. This battle against time and tide involves federal officials and state water users. Only by drastic water-use reductions can the Basin combat the future of high temperature and dry conditions in the West, all whilst attempting to reverse the harsh consequences of past overuse.
Bass finished by cautioning about the inescapable repercussions that will follow if greenhouse gases are not reined in. Unless drastic steps are taken to curb them, water reductions will persistently follow the trajectory of temperature increases.
