In recent years, California and other parts of the American West have been forced to find ways to cut back on water usage in response to a prolonged period of drought. The New York Times wrote that “the drought, now in its fourth year, is by many measures the worst since the state began keeping records of temperature and precipitation in the 1800s.” California Governor Jerry Brown declared “This is the new normal, and we’ll have to learn to cope with it.”1
However, scientists are now saying that the present-day United States’ Western, Southwestern and Great Plains states (including Colorado) previously suffered through far more severe droughts that lasted decades, and in certain regions, even lasted for centuries. These extended periods of severe drought have been dubbed “megadroughts” by the scientific community.1
Researchers have long been puzzled by the disappearance of the Anasazi people who, until around 1300 A.D., lived in the famous cliff dwellings of Mesa Verde National Park in southwestern Colorado. By using thousands of tree ring records and radiocarbon dating techniques, scientists have identified a severe drought that lasted from 1276 until 1299 A.D., and are now convinced that this megadrought was largely responsible for their disappearance.2
While that may seem like ancient history, Ken Caldeira, a climate scientist at the Carnegie Institution for Science and Stanford University said “it looks like the droughts in store for us later this century will make the droughts that did in the Mesa Verde civilization look like child’s play.”2
Calderia is referring to a recent study that suggests that in the second half of this century, rising greenhouse gas concentrations and the warming that will result will “greatly increase the risk of a severe long-term drought in the Southwest and Plains that could rival or even exceed some of the ancient ones.”1
In other words, Governor Brown’s so-called “new normal,” may in fact be an ancient normal. This will hardly come as a comfort on the heels of climate experts’ recent prediction that in the second half of this century, the Great Plains and Southwest will endure megadroughts “worse by far than anything seen in the past 1,000 years.” 2
Climate experts have pegged the odds that these droughts will last 10 years or more at 50 percent, and 20 percent that the droughts would last 35 years or more. Caldera wrote in an email to the San Francisco Chronicle “When you stack these model projections against the reconstruction of past climates, the results are so sobering that they have me ready to go out for a drink.”2
Another study, published in Science Advances in February 2015 predicted that “the western U.S. would soon experience the worst drought it has experienced in 1,000 years. The chances of a 35-year or longer “megadrought” striking the Southwest and central Great Plains by 2100 are above 80 percent if the world stays on its current trajectory of greenhouse gas emissions.”3
“Future droughts will occur owing to significantly higher temperatures than ever recorded” in the Southwest and Great Plains regions, the scientists said, adding that these extremes are likely to cause “increased stress on natural ecosystems and agriculture.”2
Already, fifteen of the 16 hottest years on record have occurred since 2001, and 2015 marked the 39th consecutive year of above-average global temperatures.4 Toby R. Ault, a researcher at Cornell University, says that “climate change is really weighting the dice” in favor of future megadroughts.”1
In light of such dire warnings, special districts should be prepared to face an uncertain future marred by longer and more intense wildfire seasons and the repercussions of the potential water scarcity issues.
1 – http://www.emergencymgmt.com/disaster/Megadroughts-Predicted-Southwest.html
2 – http://www.nytimes.com/2015/04/14/science/californias-history-of-drought-repeats.html
