Caves in Nevada can tell scientists about the history of the climate in the West and what it might look like in the future.
Matthew Lachniet, a geosciences professor at the University of Nevada Las Vegas, said the composition of stalagmites, or deposits of material on cave floors, tells scientists about the climate when they were formed.
"Stalagmites grow upwards from cave floors over time and the reason that's useful for us is that we're able to date how old that material is," said Lachniet. "The change in the material's chemistry is linked to how climate has varied in the past."
Compared to decades-long droughts that are often called mega-droughts, Lachniet said what he found is much worse.
"In our stalagmite records [and] in our lake records that we've integrated into our study, they show persistent aridity for thousands of years," said Lachniet. "It's even more severe than the so-called mega-droughts."
Lachniet said this drought was about 4,000 years long. It may have come from a warmer arctic region, changing ocean temperatures, or both. In a worst case scenario, he said global warming could bring about a drought in the West that is just as severe.
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