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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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USA: Everything you want to know about Security Clearance; Find out here!

A security clearance allows a person access to classified national security information or restricted areas.

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Former CIA Director John O. Brennan speaks at the Council on Foreign Relations in Washington, March 11, 2014. President Donald Trump revoked Brennan's security clearance Wednesday. VOA
Former CIA Director John O. Brennan speaks at the Council on Foreign Relations in Washington, March 11, 2014. President Donald Trump revoked Brennan's security clearance Wednesday. VOA

U.S. President Donald Trump on Wednesday revoked the security clearance of former CIA Director John Brennan. We take a look at what that means.

What is a security clearance?

A security clearance allows a person access to classified national security information or restricted areas after completion of a background check. The clearance by itself does not guarantee unlimited access. The agency seeking the clearance must determine what specific area of information the person needs to access.

What are the different levels of security clearance?

There are three levels: Confidential, secret and top secret. Security clearances don’t expire. But, top secret clearances are reinvestigated every five years, secret clearances every 10 years and confidential clearances every 15 years.

All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance. VOA
All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance. VOA

Who has security clearances?

According to a Government Accountability Office report released last year, about 4.2 million people had a security clearance as of 2015, they included military personnel, civil servants, and government contractors.

Why does one need a security clearance in retirement?

Retired senior intelligence officials and military officers need their security clearances in case they are called to consult on sensitive issues.

Also Read: Governments Across The World Request Apple for 30,000 Device Information

Can the president revoke a security clearance?

Apparently. But there is no precedent for a president revoking someone’s security clearance. A security clearance is usually revoked by the agency that sought it for an employee or contractor. All federal agencies follow a list of 13 potential justifications for revoking or denying a clearance, which can include criminal acts, lack of allegiance to the United States, behavior or situation that could compromise an individual and security violations. (VOA)