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Whats interesting to me is climate change has been shown to actually increase total annual rainfall on land[1], but I guess this means that its those areas wher

Whats interesting to me is climate change has been shown to actually increase total annual rainfall on land[1], but I guess this means that its those areas where farming was once feasible and where people now live are becoming more arid? [1] https://www.epa.gov/climate-indicators/climate-change-indicators-us-and-global-precipitation https://www.epa.gov/climate-indicators/climate-change-indica...

scythe 2y ago
The issue is that the increased temperatures increase evaporation at the same time that they increase precipitation, and in many places, the net effect on water availability is expected to be negative.
throwup238 2y ago
> but I guess this means that its those areas where farming was once feasible and where people now live are becoming more arid? Yep, it's an agricultural catch 22. Arid regions where people live are generally formed by mountains absorbing rainfall. When that water washes down, it carries nutrients and forms very agriculturally productive alluvial plains like in the Nile delta (although the reason for that desertification is Hadley cell circulation, not mountains, iirc). It's both why Egyptian civilization was so successful and why so many artifacts survived as long as they were stored away from the delta. The longer the region has been arid, the thicker the layer of usable nutrients and some areas like California are also on top of ancient oceans with thick layers of fossilized organisms providing calcium carbonate and phosphorus. These regions also tend to have favorable temperatures that support multiple growing seasons per year and without plentiful water, there are far fewer other plant species to compete with. In wetter regions, that water instead washes most of the nutrients into the ocean to the point where areas like the Amazon are so nutrient poor that organisms evolve unique adaptation like pitcher plants and the whole ecosystem depends on intercontinental dust that's carried all the way from the Sahara (the Bodélé Depression especially) [1]. Farming is still plenty feasible in wetter areas (Brazil and the PNW have plenty of agriculture for example and it's the whole basis for rice farming) but it's nowhere near as productive [1] https://www.nasa.gov/centers-and-facilities/goddard/nasa-satellite-reveals-how-much-saharan-dust-feeds-amazons-plants/ https://www.nasa.gov/centers-and-facilities/goddard/nasa-sat...
- jvanderbot 2y ago
  Just wanted to say that was a fascinating read thank you.
jauntywundrkind 2y ago
I feel like we get larger weather events, less frequently. So there'll be extended dry periods where normally rain would have been interspersed. In some terrain, the torrential rain often runs off too, flowing to rivers, where-as a more moderate rain would get absorbed.

scythe 2y ago

The issue is that the increased temperatures increase evaporation at the same time that they increase precipitation, and in many places, the net effect on water availability is expected to be negative.

throwup238 2y ago

> but I guess this means that its those areas where farming was once feasible and where people now live are becoming more arid? Yep, it's an agricultural catch 22. Arid regions where people live are generally formed by mountains absorbing rainfall. When that water washes down, it carries nutrients and forms very agriculturally productive alluvial plains like in the Nile delta (although the reason for that desertification is Hadley cell circulation, not mountains, iirc). It's both why Egyptian civilization was so successful and why so many artifacts survived as long as they were stored away from the delta. The longer the region has been arid, the thicker the layer of usable nutrients and some areas like California are also on top of ancient oceans with thick layers of fossilized organisms providing calcium carbonate and phosphorus. These regions also tend to have favorable temperatures that support multiple growing seasons per year and without plentiful water, there are far fewer other plant species to compete with. In wetter regions, that water instead washes most of the nutrients into the ocean to the point where areas like the Amazon are so nutrient poor that organisms evolve unique adaptation like pitcher plants and the whole ecosystem depends on intercontinental dust that's carried all the way from the Sahara (the Bodélé Depression especially) [1]. Farming is still plenty feasible in wetter areas (Brazil and the PNW have plenty of agriculture for example and it's the whole basis for rice farming) but it's nowhere near as productive [1] https://www.nasa.gov/centers-and-facilities/goddard/nasa-satellite-reveals-how-much-saharan-dust-feeds-amazons-plants/ https://www.nasa.gov/centers-and-facilities/goddard/nasa-sat...

jvanderbot 2y ago
Just wanted to say that was a fascinating read thank you.

jauntywundrkind 2y ago

I feel like we get larger weather events, less frequently. So there'll be extended dry periods where normally rain would have been interspersed. In some terrain, the torrential rain often runs off too, flowing to rivers, where-as a more moderate rain would get absorbed.