Sunday, March 19, 2017

Humans Can Change the Climate; We Have Done it Before | Science

Maybe you wonder how the Sahara Desert got that way and, yep, we did that.  The prevailing theory was it came due to changing global weather patterns but scientists have reviewed that further for a new explanation of how the Sahara Desert came to be.  (Science Daily: Did humans create the Sahara desert?)

Dunes of the Sahara Desert

Credit: © Andrea / Fotolia

Pictures of dunes because why not.

The researchers bring a little revolution to the matter.

New research investigating the transition of the Sahara from a lush, green landscape 10,000 years ago to the arid conditions found today, suggests that humans may have played an active role in its desertification.

The desertification of the Sahara has long been a target for scientists trying to understand climate and ecological tipping points. A new paper published in Frontiers in Earth Science by archeologist Dr. David Wright, from Seoul National University, challenges the conclusions of most studies done to date that point to changes in the Earth's orbit or natural changes in vegetation as the major driving forces.

- SD

We will want to see the case for that.

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, in each case at the same time as an increase in scrub vegetation.

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.

- SD

Here at the Rockhouse, that looks legitimate, mates.

Despite taking place several thousands of years ago, the implications of humans being responsible for environmental and climatic degradation are easy to see. With approximately 15% of the world's population living in desert regions, Wright stresses the importance of his findings: "the implications for how we change ecological systems have a direct impact on whether humans will be able to survive indefinitely in arid environments."

- SD

That part is editorial and fair enough but we're still asking about validity.  How do we know this was the Dominator relative to parallel physical changes such as a theorized (?) orbit change, etc.  The research looks excellent but I don't see a relative perspective to balance which effect was the Dominator or if it required both, most likely the last.

Note:  I haven't quoted the entirety of the article so the interested student is invited ...

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