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That's quite an extraordinary claim. Do you have a source I can read on that?

JoeAltmaier 10y ago
One 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 ago
  First 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 ago
    Regions 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 ago
      So you're saying that the majority of the world's deserts only exist due to human activity?

One 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 ago
First 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 ago
  Regions 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 ago
    So you're saying that the majority of the world's deserts only exist due to human activity?