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Humans to blame for Creation of World’s Largest hot Sahara Desert: Study

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Hot Sahara Desert, Credits: Wikimedia
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Seoul, March 15, 2017: Challenging a commonly held theory that changes in the Earth’s orbit triggered Sahara desertification, a new study suggests that humans may have played an active role in the transition of a lush green landscape into the world’s largest hot desert thousands of years ago.

The desertification of the Sahara has long been a target for scientists trying to understand climate and ecological tipping points.

Most studies done to date point to changes in the Earth’s orbit or natural changes in vegetation as the major driving forces.

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In a new paper published in the journal Frontiers in Earth Science, David Wright from Seoul National University in South Korea challenges the conclusions of these studies.

“In East Asia there are long established theories of how Neolithic populations changed the landscape so profoundly that monsoons stopped penetrating so far inland,” said Wright.

Evidence of human-driven ecological and climatic change has been documented in Europe, North America and New Zealand, said Wright who believed that similar scenarios could also apply to the Sahara.

To test his hypothesis, Wright reviewed archaeological evidence documenting the first appearances of pastoralism across the Saharan region, and compared this with records showing the spread of scrub vegetation, an indicator of an ecological shift towards desert-like conditions.

The findings confirmed his thoughts.

Beginning approximately 8,000 years ago in the regions surrounding the Nile River, pastoral communities began to appear and spread westward, increasing at the same time the spread of scrub vegetation, the study said.

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Growing agricultural addiction had a severe effect on the region’s ecology. As more vegetation was removed by the introduction of livestock, it increased the albedo (the amount of sunlight that reflects off the earth’s surface) of the land, which in turn influenced atmospheric conditions sufficiently to reduce monsoon rainfall.

The weakening monsoons caused further desertification and vegetation loss, promoting a feedback loop which eventually spread over the entirety of the modern Sahara, the study said. (IANS)

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A Warmer Winter For The United States Due To El-Nino And Climate Change

While El Nino is the biggest factor in the forecast, long-term warming from human-caused climate change is a factor.

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winter
A large cloud gathers over the skyline of San Francisco, California, Dec. 12, 2014. While the Pacific Northwest is expected to have a mild winter, California's forecast is unsure. VOA

Winter looks wet and especially mild for much of the country, thanks to a weak El Nino brewing, U.S. meteorologists said.

The National Weather Service on Thursday predicted a warmer than normal winter for the northern and western three-quarters of the nation. The greatest chance for warmer than normal winter weather is in Alaska, the Pacific Northwest, Montana, northern Wyoming and western North Dakota.

No place in the United States is expected to be colder than normal, said Mike Halpert, deputy director of the government’s Climate Prediction Center.

The Southeast, Ohio Valley and mid-Atlantic can go any which way on temperature, Halpert said.

Winter
Overall the winter looks a lot like the last few, Wamrer. Wikimedia Commons

Overall the winter looks a lot like the last few, Halpert said.

“The country as a whole has been quite mild since 2014-2015,” Halpert said.

Winter weather expert Judah Cohen, of the private company Atmospheric and Environmental Research, uses different indicators to predict winter for the National Science Foundation. He also forecasted a warm winter, heavily based on weak snowfall in Siberia.

Precipitation

Halpert said the southern one-third of the United States and much of the East Coast could be hunkering down for a wetter than normal December through January. The chances are highest in southeastern Georgia and much of northern and central Florida.

Hawaii, Montana, Michigan, parts of Idaho, Wisconsin, northern Illinois, Indiana and Ohio are forecast to be drier than normal, with the biggest likelihood in Hawaii, Montana and Michigan.

The middle belt of the nation and some of the north from California to New York can go any which way on precipitation.

Hurricane Florence, winter
A member of the North Carolina Task Force urban search and rescue team wades through a flooded neighborhood looking for residents who stayed behind as Florence continues to dump heavy rain in Fayetteville, N.C. VOA

The weather service’s forecast doesn’t look at snow likelihood.

El Nino

Halpert said the biggest factor in the forecast is a likely El Nino , the natural warming of parts of the central Pacific Ocean that influences weather worldwide.

The El Nino hasn’t quite formed yet, but it’s almost warm enough. Meteorologists predict there’s a 75 percent chance it’ll be around this winter. But it will be weak, not strong like the El Nino that helped lead to the record warm 2015-2016 winter, Halpert said.

Background warming

While El Nino is the biggest factor in the forecast, long-term warming from human-caused climate change is a factor, too, Halpert said.

Climate change, Australia
The coal-fired Plant Scherer, one of the nation’s top carbon dioxide emitters, stands in the distance in Juliette, Georgia. VOA

“All things being equal, the slight kick we get out of the climate signal does tilt things toward the warm side,” Halpert said.

Also Read: Balloon Mission By NASA May Lead To Improved Weather Forecasting

But it’s not enough to outweigh other factors if they push toward cold.

“Even on a warming planet,” he said, “it doesn’t mean winter goes away and it’s never cold again.” (VOA)