John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Looming drought conditions will exceed anything seen since Medieval times, say scientists.
The climate's about to get more than medieval on us. Drought conditions in the 21st century could exceed those of the Medieval Climatic Anomaly, a period of sweltering heat some say sped the downfall of the ancient Pueblo Indians.
That's what researchers announced today in Science Advances, positing that America's Southwest and Central plains are facing a drought more horrid than any other in the last 1,000 years.
NASA's Benjamin Cook and others came to this cruddy conclusion after studying climate models and tree rings dating from the 12th and 13th centuries, the time of the warm-climate anomaly. Their findings of a looming "megadrought" are shocking in many ways, but here are two:
- Even in a scenario of moderate future emissions—and with an expected increase in cold-season rainfall over parts of the region—they believe conditions will deteriorate into unprecedented aridity. "Our results point to a remarkably drier future that falls far outside the contemporary experience of natural and human systems in Western North America," they write, "conditions that may present a substantial challenge to adaptation."
- They are linking global warming to the deepening of drought, a step many researchers have been reluctant to take. "Notably, the drying in our assessment is robust across models and moisture balance metrics," they say. "Our analysis thus contrasts sharply with the recent emphasis on uncertainty about drought projections for these regions, including the most recent Intergovernmental Panel on Climate Change assessment report."
One of the scientists, Cornell University's Toby Ault, said in a press release that he was "honestly surprised at just how dry the future is likely to be." He also added the obvious note that the time to prepare is today, if not last decade:
The metrics used in the study could be useful for future water resource management and agricultural planning. In further studies, the researchers plan to study in detail individual drought events in the 21st century projections to glean insight into their future severity, persistence and geographical scope.
"I look at these future megadroughts like a slow moving natural disaster. We have to put megadroughts into the same category as other natural disasters that can be dealt with through risk management," said Ault.