After years of prolonged drought, the water level in Lake Mead has dropped significantly.Photo: Photo by CEBImagery 2014
Since the turn of the 21st century, researchers have explored evidence locked in tree rings and other clues from past climate conditions to build an increasingly troubling picture of southwestern North America prone to deep, long-term droughts .
A megadrought is an emerging term for the worst of these extreme droughts — lasting two decades or more. These scientists didn’t know until recently (that’s how long the drought lasted) that when they looked at the region’s drought history, the region was slipping into a powerful new megadrought — and unique because it didn’t exist without human Driven by the growing impetus of global warming.
The crisis is partly due to natural climate variability and man-made global warming. Decades of water-based population growth and economic development have created a classic”Expand the bullseye” mode turns natural disasters (in this case exacerbated by greenhouse gases) into unnatural disasters.
There is another reason why the West finds itself in such a profound hydrological dilemma on the grandest of time scales: long-term Great Drought Gap. While tree rings show a series of megadroughts since 800 (vertical pink bands in the chart at the top and bottom of this article), take a look at the yawning whitespace from about 1700 to 1900:
This is also a span in the early stages of Western colonial power. But if there was a megadrought, there would almost certainly be some history, including Indigenous history, to weigh in and plan for the future of water at the beginning of the 20th century.
Of course, that didn’t happen.
