North America

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drought to have the worst of it, hits the Western United States in recorded history, is already, say scientists.

researchers say that the mega drought is a naturally occurring event that in the year 2000 started and is not yet complete.

Climate Change , though, a great impact rising temperatures are making The Drought more severe.

Some researchers are careful to say, to say that it is too early to see whether the region is drought a true mega.

So, what exactly is drought a mega?

According to the authors of this new paper, a mega-drought in North America refers to a multi-decade-event, contains periods of very high severity, which are observed more than anything, during the 19th or 20th century.

The authors say, there were about 40 of drought, over the period of 800-2018 in the West of the USA.

Of these, only drought four of the criteria for a mega.

These were. in the late 800s, the mid-1100s, the 1200s and the late 1500s

As a researcher, what drought know conditions were like in The Past ?

The Key to this new study, is to reconstruct the use of tree-ring records, the soil moisture data for The Past 1200 years.

The Team were also able to use evidence such as medieval tree stumps usually grows in wet river beds, the abandonment of settlements, the improvement of indigenous civilizations at The Peak of the 13Th Century drought, plus evidence from the lake deposits, indicating wildfire activity, during these drought periods.

What has the study? A graphic shows the soil moisture over the centuries, in the West of the USA. The Blue Line at the bottom shows the mean soil moisture 2000-2018

The researchers discovered that, when compared to the worst 19-year-drought-events in The Past included soil moisture records from 2000-2018, the current period is already worse than three of The Four mega-droughts.

The Fourth , ran from 1575 to 1603, was probably the worst of them all, but the difference with today's event is low.

"The First two decades of The Drought will look the same as The First two decades of the mega-droughts," said lead author Dr. Park Williams of Columbia University in New York .

"In fact, there is drought, mainly associated with the worst two decades of the worst of the mega. "

the current mega drought is a natural event or was it caused by Climate Change ?

The authors say that undoubtedly, the current drought situation is a natural event, but is made much worse by Climate Change .

The Key to be event seems to have been the El Niño/La Niña Weather phenomenon.

"We know from many lines of evidence, that if you get the La-Niña-Type conditions in the tropical Pacific, the southwestern United States and Northern Mexico is dry. And that is what we have seen in The Last two decades," said Dr. Williams .

Lake Mead saw a huge decline in water levels during the recent drought

But the Climate Change super-charged the current drought.

The authors say that in the Western US, the temperatures have risen to 1. 2C, since the year 2000. Warmer air contains more moisture, and the moisture is pulled out of the ground.

do you believe that Climate Change is responsible for approximately one-half of the Tempo and severity of the current event.

"It doesn't matter if this is the worst drought ever," said co-author Benjamin Cook , which is associated with Columbia University and the Nasa Goddard Institute For Space Studies.

"What matters is that it was made much worse than it would have been, because of Climate Change . "

What are The Drought , the impact of the mega?

The authors say that the two most important reservoirs in the region, Lake Powell and Lake Mead have both shrunk dramatically during The Drought . Forest fires in the region grow in the area.

"every year there are about ten times more forest area burns, as we would have expected that in a given year, 40 Years ago," said Dr. Williams .

What has helped to mitigate the effects of drought, the groundwater - the water held underground in the ground water was.

The amount of land influenced by wildfire in The Last few years in the United States rose

This was increasingly provided to strengthen for agriculture.

the longer The Drought lasts, the deeper into these reserves, the people dig and take a long time to replenish.

there is full agreement among scientists that a mega is taking place drought, just now?

no. This new study is controversial, especially as the definition of what exactly is drought a mega, is currently fighting yet.

Some say that it is much too early to declare that a mega drought is in progress.

But even those who do not agree with the idea to acknowledge it, it is water scarcity in the region and this is likely to be worse in The Future .

"whether or not the western US has exceeded a threshold, in an event that goes by a special label, what is already clear in This Century that the water is a vital resource in the Western US, and it is a precarious, because the region may have long periods with little precipitation," said Dr. Angeline Pendergrass, a scientist with the U.S. National Center for Atmospheric Research (NCAR).

"And it looks like Climate Change will not make it any better - in fact, it is probably even worse. "

published in the journal Science.

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Source of news: bbc.com