[throwaway41597]

Trees excel at harvesting water. When you water a tree, there is evaporative cooling like an artificial cooler but during the night, the dew falls back on the leaves and the ground where some of it finds its way back to the trees (possibly via an invertebrate first). Also the reflectiveness of leaves helps. Then there's the soil where layers of dead leaves, wood and others accumulate, sequester CO2 and create a sponge. Finally, by virtue of making the region cooler, rain is more likely to fall. Humans can probably engineer something better but the bar is high.

[gsf_emergency_2]

>Trees excel at harvesting water.

Specifically, some kind of giant succulent would be best for arid climes

https://en.wikipedia.org/wiki/Aloidendron_dichotomum

[flakeoil]

But they probably don't evaporate water and cool as much as other plants and trees.

[gsf_emergency_2]

Right, but as pointed out in TFA & below the cooling from evaporation is almost negligible compared to that from the shade. Maybe Vegas would be okay with conserving their water too

It's counterintuitive..

[thimkerbell]

For reader clarification: accumulating carbon in soil from decaying plant matter still leaves it part of short term carbon cycling, not to be confused with geological-time carbon sequestration. As you know.

[throwaway41597]

Not that simple. When carbon in the soil rises beyond a certain percentage (a tree falls) it'll convert back to CO2 because of the bugs eating it. But if the percentage starts at zero (in a desert) and an ecosystem settles there, the percentage will rise and stay above zero for as long as the ecosystem survives. Basically the plants generate matter as fast as wildlife eats it.

This sequestration can be long term if things go well or it can be short term if plants die in large numbers (because of climate change, diseases...).