DENVER, the United States, April 17 (Xinhua) -- Scientists on Thursday released a study showing America's West is experiencing its worst drought in more than 1,000 years.

"Global warming has pushed what would've been a moderate drought in southwestern North America into mega-drought territory," scientists at Columbia University said in the report, published in the journal Science.

"This appears to be just the beginning of a more extreme trend towards mega-drought as global warming continues," the study noted, saying that the period from 2000 to 2018 was "the driest 19-year span since the late 1500s and the second driest since 800 CE."

The scientists studied tree rings from around 30,000 trees in 1,586 locations to measure the amount of rainfall and soil moisture over the centuries, according to the study.

"Across the broad American West, the last two decades have looked as bad as the worst in the last millennium," said Park Williams, a Columbia bioclimatologist and lead author of the study.

"The severity varies throughout the region," he added. "But when you look at the region as a whole this is truly a monumental event."

Ironically, the study found that the 20th century was the wettest century in the entire 1,200-year record.

However, in the new millennium, California's devastating five-year drought was called over in 2017 by former Governor Jerry Brown, when reservoirs filled after huge storms.

Until recently, scientists thought that over the past 20 years, California has had three stretches of short-term droughts: between 2000-2003, 2007-2009, and 2012-2016.

"In California, it looks more like three individual droughts, but when we look at the larger scale we can see it's really one," Williams said.

The most severe conditions over the past two decades have occurred in the states of Arizona and California, according to research.

The droughts have produced record numbers of wildfires, hundreds of millions of dead trees, declining ground water levels, and drying soil moisture levels, the researchers said. Enditem

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