There is a lot being talked about in terms of water vapor and 'new water paradigm' ideas. Here's a small webinar series that goes into a collaborative effort to draft 'water principles' to understand water vapor more: https://earth-regenerators.mn.co/events/how-to-restore-the-w...
Basically there are some concepts around atmospheric river 'heart pumps' associated with forests, evapotranspiration and it's role in the 'small water cycle', how moisture can 'hop' from coast further inland (or not), and how urbanization & modern agriculture has impacted water (urban heat dome effect, water drainage, etc.). There's probably some interesting opportunities/research in seeing this better.
This means that there may be a way to change the net water balance in desert areas to enhance plant growth. One effective method is a water barrier(black plastic) with a few inches of sand to weight it down. Then every 10-15 feet you make a slope graded round are 5.7.5 feet across and make small hole(3-5 inches) in this plastic and you plant a desert tree in that hole. Next you kill all goats in the area and make them extinct in that wide area.(Goats create deserts by cropping all tree branches/leaves/roots and are felt by many to have contributed to the desertification of North Africa(and other places).
Deserts get some rain - whatever they get is directed to the graded holes and the cover limits evaporation. Drip irrigation to each tree will help it to establish.
The drop in evaporation will add to the retained water budget and tree transpired water will contribute to potential cloud formation and rain as the process is continued. One of the desert elimination projects now underway to plant tree in this area need to adopt these practices over a wide area.
https://www.greatgreenwall.org/about-great-green-wall
One meta question is whether this problem is worth solving at all ? There are places where forests are much easier to grow, and we are cutting them down by the thousands on a daily basis.
For carbon capture, it is much easier to densify regions with already suitable conditions than trying to plant a few trees in inhospitable regions.
Food is a solved problem in the modern era. High cost agriculture is unsustainable in a global market. If non-mechanized farmers in highly arable places (India) are being priced out, then what hope does harsh desert agriculture have ?
Given other 'low hanging fruit' solutions, is the opportunity cost of pursuing such a solution too high ?
Solved problem? We've hardly even identified the actual problem.
As it it stands now farming is an open loop system and input supplies are becoming constrained and expensive. We have killed our soils and the dirt that is left behind requires external inputs to produce current crop numbers.
In addition to this, we grow a large portion of our food in the United States in areas with active droughts and impending water shortages.
Fortunately there are better ways to do things, I just don't know that we can change fast enough.
To address the greater point of your comment though, I agree.
For about six thousand years (at least), turning deserts and other marginal terrain into croplands is what tends to distinguish civilizations from non-civilizations: cities being a byproduct of the scale of agriculture activities water movement processes make possible.
Which is not me saying it is good or bad.
Just me saying ‘it is.’
With the point being it is worth deciding if there is a baby in the bath water. Or irrigation canal so to speak before deciding which moral high ground is rocky and which is silty.
Trees are good not only for carbon capture, but for soil protection, water capture, and biodiversity.
It makes sense to plant trees where they will make the most good, not where it is the easiest. Otherwise you propose to look for the keys under the lamp and not in the dark alley where they fell.
That said, planting trees the wrong place could be counterproductive as well.
The idea is to enlarge the arable/growth area or all those people will die or move and transfer the crowding to another area - which might then get depleted...
We are in such great danger that we need to do many positive moves in parallel to save our collective asses...
This stupidity in Ukraine endangers millions.
The problem is humans usually displace or kill the predators at the top of the food chain (since we are the top) which then allows the stuff below it to grow beyond what it should.
So for example if something like a large cat was normally hunting these goats it is very possible humans would have been threatened by the presence of the cats (or been annoyed that the cats were killing domesticated animals) and then hunted those to extinction. Very common throughout human history.
Something that will never cease to amaze me is how damp desert land tends to be just feet below the surface. Even months since the last rain event, I'll go dig a hole on my land in the Mojave and with little effort I'm digging through sand that's damp-smelling and visibly darker and cooler from retained moisture. Return to the hole a day later and its a lighter shade of brown, all dried up from exposure.
In a weird way this makes sense to me. A lot of what takes water out of the ground is plants with their roots that extend way, way down. No plants means no roots and no shortcuts to get the water out. It has to go out the old fashioned way by diffusion.
The thinker the dry layer the more "insulating" it is from a water diffusion standpoint. It's kind of like lake ice. The thicker it gets the slower it gets thicker.
Well, the granary of the roman empire was gradually ruined by man. animal and climate drift. Some say goats inexorably stripped all green plants and shifted the ecology. Other say the climate drift? Was one caused by the other?
https://en.wikipedia.org/wiki/Sahara
Basically there are some concepts around atmospheric river 'heart pumps' associated with forests, evapotranspiration and it's role in the 'small water cycle', how moisture can 'hop' from coast further inland (or not), and how urbanization & modern agriculture has impacted water (urban heat dome effect, water drainage, etc.). There's probably some interesting opportunities/research in seeing this better.