Southwestern North America is in the midst of "the driest 19-year span since the late 1500s and the second driest since [the year] 800," according to a new study in Science magazine. The area includes large areas of the western United States, extending from California, Arizona and New Mexico north to Oregon and Idaho, The Washington Post notes.
The researchers used hydrological modeling and new 1,200-year tree-ring reconstructions of summer soil moisture to produce their findings. The study argues that global warming has "pushed what would have been a moderate drought in southwestern North America into megadrought territory."
Bree Seville uses a small brush to sweep the stairs leading to burned out ruins of her fiancee's mother's home in the Keswick area of Redding, Calif., Thursday, Aug. 9, 2018. California is seeing earlier, longer and more destructive wildfire seasons because of drought, warmer weather attributed to climate change and home construction deeper into the forests. (AP Photo/John Locher)
The study of the ancient trees and their tree rings enabled the researchers to reconstruct what the climate looked like in the western U.S. in the past, according to Forbes magazine. With this method, the scientists were able to deduce the average soil moisture through time in a region then plot the soil moisture and compare historical megadroughts to current conditions.
"It seems to me that this is a very important study," said AccuWeather Senior Meteorologist Brett Anderson. "It makes sense that there is now clearly a human footprint that is already starting to have an influence on these megadroughts by making them more extreme and potentially longer-lasting. The researchers clearly did their homework on this one."
A megadrought is broadly defined as a severe drought that occurs across a broad region for a long duration, typically multiple decades, noted the Washington Post, which also said the megadrought in the late 800s is thought to have instigated the fall of the Mayan civilization.
Currently, drought conditions have led to "increased wildfires in the western U.S. and the need to rely on deep underground aquifers for water," according to Forbes. "As the drought conditions continue, we will continue to draw down these aquifers that in some instances can take decades to centuries to refill."
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