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In climate news, a new study from Columbia University's Earth Institute reveals that the western United States and northern Mexico are entering a mega-drought worse than any in more than a thousand years. The report in the journal Science concludes that human-induced greenhouse gas emissions are playing a key role in driving unprecedented drought conditions in southwestern North America.
The western United States and northern Mexico have experienced increasingly long dry seasons since the beginning of the 21st century, and some climatologists predict that this trend will cause extreme drought in the long term worse than any other documented, according to a study that publishes the journal Science this April 17.
This document classifies the phenomenon as “mega-drought” and relates it to human activity not only thanks to modern meteorological records, but also to the analysis of growth ringsin trees that are up to 1,200 years old.
The research covered a territory that spans nine US states, from Oregon and Montana to California and New Mexico, and extends into northern Mexico. Park Williams, a bioclimatologist at Columbia University and its lead author, states that “we are in the same trajectory as the worst prehistoric droughts“.
His team mapped dozens of droughts in that area from the year 800 and estimated that only four deserved the prefix 'mega' for presenting extreme aridity that lasted decades: the first at the end of the 9th century and the last at the end of the 16th century, 1575 to 1603.
What are the impacts of the mega-drought?
The authors say that the region's two most important water reservoirs, Lake Powell and Lake Mead, have been drastically reduced during the drought. Forest fires throughout the region are growing in area.
"In any given year, there is more than ten times more forest area burned than we would have expected in a given year, 40 years ago," said Dr. Williams.
What has helped mitigate the impact of the drought has been groundwater - the water that is held underground in aquifers.
This has increasingly been used to bolster supplies for agriculture.
The longer the drought lasts, the deeper the reserves that people are digging, and they take a long time to replenish.
-Is there complete agreement among scientists that a mega-drought is occurring at this time?
-Not. This new study is controversial, especially since the definition of what exactly a mega-drought means remains under discussion.
Some say that it is also too early to declare that a mega-drought is underway.
But even those who disagree with the idea acknowledge that there is water stress in the region and that this is likely to worsen in the future.
“Whether or not the western US has crossed the threshold of an event that is identified by a specific label, what has become clear this century is that water is an essential resource in the western US. .UU., And it is precarious, because the region can have long periods with little precipitation, "said Dr. Angeline Pendergrass, a scientist at the US National Center for Atmospheric Research (NCAR).
"And it looks like climate change will not make it better, in fact it will probably make it worse."