Forty-five years ago, the eminent American scientist Roger Revelle laid out for a House of Representatives committee what was likely to happen to the region dependent on water from the Colorado River if the world failed to address the risks of human-induced climate change.
Revelle was not just any scientist. He was regarded by many as the most influential oceanographer of this time. His work with his colleague Dave Keeling at the Scripps Institution (now part of the University of California San Diego) had established the foundation for the modern science of climate change. He had chaired reports for the National Academy of Sciences and advised presidents from Eisenhower to Reagan. George H.W. Bush later awarded him the National Medal of Science.
A teacher at heart, Revelle sometimes dove into details of climate science others were neglecting. For instance, the impacts of rising accumulations of greenhouse gases in the atmosphere were usually expressed in global averages. In fact, Revelle and other scientists were already projecting differing impacts dependent on geography.
These scientists foresaw effects that appeared, at first glance, contradictory. Some people would experience more flooding because of global warming, a problem of too much water. Other regions would see changes in the water cycle that led to soil dehydration, a problem of too little water.
At a July 1981 House hearing on “Carbon Dioxide and Climate” co-chaired by Revelle’s former student at Harvard, Al Gore, the professor drew attention to the work of German climatologist Herman Flohn. Flohn had identified the expected effects of climate change by latitude, a more helpful gauge than global averages. He focused on latitude 40 degrees north because the impacts of climate change would appear there relatively early. Moreover, it was densely populated. Hotter temperatures at the latitude would increase evaporation and add to the stress of lower rainfall.
At latitude 40 degrees north, Revelle prophetically observed: “We westerners are most concerned about the Colorado River,” where eventually “less precipitation might cause as much as a 50-percent reduction in its flow.”
Revelle suggested planning infrastructure to transport water from areas with plenty. Such construction would prove difficult and time-consuming, but enough time remained to do it. He also recommended slowing the rise in atmospheric carbon dioxide by displacing projected increases in coal use with natural gas and nuclear power to slow the pace of rising temperatures.
Revelle’s warning to members of Congress about the Colorado River was not a one-off. In the mammoth 1983 report Changing Climate produced by the National Academy of Sciences, a chapter by Revelle amplified his warning about the Colorado River. The overall document reflected an effort by the Reagan White House and the Academy to downplay the urgency of action to slow global warming. Yet, Revelle provided evidence that many likely impacts of climate change, while not imminent, were real nonetheless and required proactive policies to avoid more painful choices down the road.
From Revelle’s testimony to 2007, U.S. carbon emissions from energy rose 30 percent. Since 2007, U.S. emissions have fallen 18 percent but remain well above what they were in 1981. Furthermore, the current administration’s hostility to renewable energy and subsidies for coal will slow efforts to reduce greenhouse gases.
Trends in U.S. emissions, combined with erratic American collaboration with other nations to reduce them, reflect, at best, a tepid response to Revell’s warnings about the Colorado River and other climate change impacts. Revelle’s other idea, bringing in additional water supplies with improved infrastructure, also suffered from neglect.
The story of the Colorado River is a cautionary tale for humanity, as it confronts the global warming it has created. In short, responses can be anticipatory. Or, humans can keep passing the buck to later generations.
