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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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Milky Way’s neighbouring galaxy is of same size, not bigger

With Andromeda no longer considered the Milky Way's big brother

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UFO religion as a concept is now becoming a part of popular understanding.
Countless galaxies exist in the universe, each hiding secrets that humankind is yet to unearth. Pixabay
  • Astronomers discover that the other galaxy nearest to us is the same size as ours
  • The name of the other galaxy is Andromeda
  • It is heavier than sun but the same size as Milky Way

In what could put a galactic arms race to rest, astronomers have discovered that our nearest big neighbour, the Andromeda galaxy, is roughly the same size as the Milky Way.

It had been thought that Andromeda was two to three times the size of the Milky Way, and that our own galaxy would ultimately be engulfed by our bigger neighbour.

Galaxy nearest to Milky Way is not larger than it. VOA
Galaxy nearest to Milky Way is not larger than it. VOA

But the new study, published in the journal Monthly Notices of the Royal Astronomical Society, evens the score between the two galaxies.

It found the weight of the Andromeda is 800 billion times heavier than the Sun, on par with the Milky Way.

The research suggests scientists previously overestimated the amount of dark matter in the Andromeda galaxy.

Also Read: Planets Beyond Milky Way Galaxy Discovered For First Time

“We had thought there was one biggest galaxy and our own Milky Way was slightly smaller but that scenario has now completely changed,” said Prajwal Kafle from the University of Western Australia.

“By examining the orbits of high speed stars, we discovered that this galaxy has far less dark matter than previously thought, and only a third of that uncovered in previous observations,” he said.

Andromeda  is heavier than sun. VOA
Andromeda is heavier than sun. VOA

The study used a new technique to measure the speed required to escape a galaxy.

“When a rocket is launched into space, it is thrown out with a speed of 11 km per second to overcome the Earth’s gravitational pull,” he said.

“Our home galaxy, the Milky Way, is over a trillion times heavier than our tiny planet Earth so to escape its gravitational pull we have to launch with a speed of 550km/s,” Kafle said.

Andromeda is same size as the Milky way galaxy. Wikimedia Commons
Andromeda is same size as the Milky way galaxy. Wikimedia Commons

“We used this technique to tie down the mass of Andromeda,” he added.

The Milky Way and Andromeda are two giant spiral galaxies in our local Universe, and light takes a cosmologically tiny two million years to get between them.

With Andromeda no longer considered the Milky Way’s big brother, new simulations are needed to find out what will happen when the two galaxies eventually collide, suggests the study.