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The Sahara might not be the best choice, it has seen wetter periods in the past. Other deserts have been stable for far longer time spans.
by the8472 10y ago
The Sahara might not be the best choice, it has seen wetter periods in the past. Other deserts have been stable for far longer time spans.
- JoeAltmaier 10y agoI had understood that all deserts (save Antarctica) were man-made. So none have been stable for vast time spans.
- ComputerGuru 10y agoHow exactly did humans create the likes of the Saharan, Arabian, Gobi, Kalaharian, or Patagonian deserts?
- JoeAltmaier 10y agoDeforestation
- RugnirViking 10y agoThat's quite an extraordinary claim. Do you have a source I can read on that?
- JoeAltmaier 10y agoOne source is the satellite radar of the Sahara for instance - all the hidden roads, rivers and towns swallowed by the desert. Then the American Southwest was grasslands, until gold rush and westward expansion including cattle and sheep, resulting in overgrazing and irreversible changes. The Gobi was widely inhabited in prehistoric times. People arrived and wham! desert. Its still expanding today, one of the fastest-growing deserts in the world. Because, people. The Namib is indeed old. Its also almost the smallest desert - #25 on a list of 27 worldwide. So lets grant an exception there.
- the8472 10y agoFirst of all: correlation != causation. People do live in semi-arid regions bordering on deserts, so if the local climate was even slightly better than it is today people would have lived there and as things changed they would have given up settlements. People living there previously is not proof of them causing desertification. Also roads going through deserts does not prove much since they could just connect oasis or move goods across the desert without people living within it. The Sahara itself also is fairly old[0]. Of course its total extent is variable and subject to natural and man-made climate change and other human influence. But there is a huge difference between human activity creating a desert and influencing its extent or aridity. Most deserts are naturally created through the rain shadow[1] and other precipitation-reducing effects of geographic features. [0] https://www.researchgate.net/profile/Zhongshi_Zhang/publication/265791589_Aridification_of_the_Sahara_desert_caused_by_Tethys_Sea_shrinkage_during_the_Late_Miocene/links/5458b7120cf2cf5164833037.pdf https://www.researchgate.net/profile/Zhongshi_Zhang/publicat... [1] https://en.wikipedia.org/wiki/Rain_shadow https://en.wikipedia.org/wiki/Rain_shadow
- JoeAltmaier 10y agoRegions get less rain because of rain shadow. They can become deserts because of removal of water-conserving ground cover. Its a delicate balance, and wholesale deforestation or grazing can unbalance it with effects lasting for thousands of years.
- the8472 10y agoSo you're saying that the majority of the world's deserts only exist due to human activity?
- the8472 10y agoNo, there are many deserts far older than human agriculture. Humans are reponsible for some desertification, but often that's just making existing deserts worse/larger. https://en.wikipedia.org/wiki/Namib_Desert https://en.wikipedia.org/wiki/Namib_Desert
- flukus 10y ago> Having endured arid or semi-arid conditions for roughly 55–80 million years, the Namib may be the oldest desert in the world[1][3] Wow. Just to put that in perspective, it was a desert when North America was still joined to Europe, India wasn't and Australia was an Antarctic appendage: http://www.bobspixels.com/kaibab.org/geology/gc065mya.htm http://www.bobspixels.com/kaibab.org/geology/gc065mya.htm