[chr1]

According to [1] the terrestrial biosphere contains 2000 gigatons of carbon combined oil and gas reserves contain only 370 gigatons. 28% of earth surface is taken by deserts, and if we simply restored ecosystem there it would take 560 gigatons of carbon. So we do not need to store any amount under ground, we only need enough people to make irrigating deserts profitable.

[1] https://en.m.wikipedia.org/wiki/Carbon_cycle

[datenwolf]

> irrigating deserts profitable

Irrigating deserts doesn't really work that well. The main problem is, that undistilled water always contains some ions, i.e. salts (it's got electrolytes!). If the main process for loss of water is evaporation these salts are left behind leading to salinization. You don't really want that.

If you want to fight desertification, then you must combat evaporation first, which you'd do for example with engineering the soil. Only after you've figured out how to make the soil keep the water, then you may start to thing about irrigation.

[mywittyname]

> If you want to fight desertification, then you must combat evaporation first,

This is something plants can be remarkably good at!

I don't think you can get around irrigation to bootstrap the process. We could probably begin the process by putting down some irrigated top soil, and laying a bio-degradable, transparent moisture barrier to keep the water from evaporating while the ground cover grows.

Alternatively, I'm sure we could construct a man-made river running through a desert to revitalize it. I'm not a geologist, but I suspect that the existence of an active river is a strong influence on whether a region becomes a rain forest or a desert.

[microtonal]

So we do not need to store any amount under ground, we only need enough people to make irrigating deserts profitable.

In an ideal free market, perhaps, yes. In the real world, people will just move/flee from dry areas. As the global temperature rises and more regions of Africa and America become uninhabitable, people will just slowly migrate north (or perhaps partially south America). If you thought that we had a refugee crisis, just wait a couple of decades.

[chr1]

Fair enough, it won't happen automatically, but maybe instead of wasting money on subsidising biofuels, building non-effective renewable installations, funding additional border patrol or helping refugees, the rich countries can focus on helping the poor countries to build irrigation infrastructure and to become rich.

[bluGill]

irrigation isn't something they will build without reason. Thus biofuels encourage irrigation.

[chr1]

Sadly that's not what happens in practice, currently biofuels encourage cutting down forests and repurposing the land that could be used for normal food production.

[bluGill]

Not everybody flees from dry areas though. There are always a few people who love the area enough and stay behind trying to make a living. If they have the opportunity (mostly a combination of legal rights, knowledge, but there are a bunch of other factors not all of which I will claim to know) to make their part of the desert better, the total of all those small changes is a big thing.

My personal use of coal/oil (including indirect use in the products I buy) is insignificant to global warming. However across the population of the world...

[adrianN]

Adding trees where there where once desert is not automatically good for the climate. Sand reflects sunlight fairly well, trees are dark. That is actually one of the feedback mechanisms that make climate change worse: Rising temperatures in the arctic allow forests to grow in places that were once covered in ice.

[VBprogrammer]

It seems to me that if you are changing significant enough areas of land that the reflectivity of the surface matters then you've changed several variables at the same time. Particularly the amount of water transpired into the atmosphere would presumably result in greater cloud cover.

[adrianN]

Yes of course it's not simple. But there are papers about the topic, for example https://iopscience.iop.org/article/10.1088/1748-9326/aa6b3f and https://www.pnas.org/content/104/16/6550

From these papers it looks like deforestation has overall a cooling effect, especially in the arctic.

[mikorym]

You can't just create forests out of deserts, that is not exactly nature conservation.

[BurningFrog]

Many deserts were created by man. Just long before our time, so we're used to them.

Not that I think restoring the planet to some technically natural state is particularly desirable. We need a livable and healthy planet a lot more!

[benj111]

The 2 don't have to be perfectly aligned. Wind turbines kill birds, I would expect climate change to kill orders of magnitude more.

So yes you may want to be a purist about it, I'm not sure it's a luxury we can really afford at this time though.

[chr1]

I do not want to conserve nature, i want to convert it to the form that is useful for people.

[mikorym]

When the Khoisan and their distant cousins of other names were killed by colonisers from West Africa and later Europe, the Kalahari desert turned out to be a very useful (and the last) place for them.

[s_kilk]

The exact kind of thinking that got us into this mess in the first place.

[chr1]

If by "this mess" you mean civilisation in general, then yes, civilisation and science have originated in places where people had to make large scale changes to environment to survive (mesopotamia, egypt, etc.). But then "this mess" is much better than the alternative of small tribes living as hunter gatherers, until planet would run out of CO2 in 600mln years https://en.wikipedia.org/wiki/Timeline_of_the_far_future

[panzagl]

And this is why some many people dismiss climate change as just noise- 'Climate change will kill us all'- 'then we should plant trees here'- 'we can't do that- think of the cacti and gerbils'

If climate change is really something that needs OMG now levels of response you can't then dismiss every response on philosophical reasons.

[mantap]

A desert is by definition the absence of life. There is nothing to conserve.

[goda90]

Have you ever been to a desert? Some deserts are incredibly filled with life and diversity. It's no forest or prairie, but life finds a way. Desert by definition is someplace that gets little rainfall and lacks as much vegetation as other areas.

[chr1]

I have lived near deserts/semi-deserts, they are desolate and miserable places where some life survives despite all odds. Keeping a small number of national parks as deserts is of course important, but that does not need to be more than 1% of the area that is taken by deserts today.

[0xfaded]

Reminds me of my favorite freeciv strategy, irrigate the deserts, effect global warming, attack.