So much of Climate Change is just accounting and just about every thing NOT physics that it is frustrating for many. I started this blog because I found an accounting problem with the Earth Energy Budget. There are also problems with the Carbon Budget so large they make the surface temperature squabble irrelevant. I hit on one potential biological situation that could pretty much erase fossil fuel emissions, termites and wood destroying organisms. This one is more in line with Dyson's carbon eating trees.
Trees and forests in general are a favorite because it is obvious they have huge amounts of mass above ground. Most trees though aren't that great at building below ground carbon. Since trees rule the roost so to speak, they are first in line for water and nutrients so tropical forests have extremely poor soil. The trees in the tropics may have only 10% of their total mass underground and since insects thrive in the tropics, leaf litter is pretty quickly consumed. A tropical forest can reason a carbon neutral state just because of a weak drought or shift in wind patterns that reduce wind blown nutrients, like Saharan dust fertilizing the Amazon.
Plants that are extremely drought tolerant tend to have huge root systems that allow them to survive drought and heavy grazing. On the US great plains, original homesteaders build crude houses with sod that was extremely stable because of drought tolerant grass root systems. The Sahel is greening because native shrubs and trees had extensive root systems which only required a little rain or a little less grazing to string back to life. For whatever reason, soil carbon estimates do not include deeper rooted (> 1 meter) plants that where likely native prior to industrialization. Because of that, soil carbon estimates are between 10% to 50% low (lateral carbon runoff is particularly difficult to estimate).
Botanists, didn't miss that error. "Breeding crop plants with deep roots: their role in sustainable carbon, nutrient and water sequestration" specifically addresses the issue of breeding or genetically engineering deeper rooted drought tolerant plants. The advantages of more drought tolerant plants is obvious but the carbon sequestration isn't discussed often. In fact, if you mention how conservation farming stores soil carbon, even most of the experts underestimate the potential impact. For example, replanting tropical deforestation is consider to be worth 100 tons of carbon per hectare at a maximum. Starting the reforestation with drought tolerant plants could increase that by 40% and more likely recreate the original start of the tropical forests.
A number of grand tropical plantation plans died because the soil just wasn't ready for the trees, especially in monoculture. Bananas may be on the way to extinction because of monoculture planting and a mutating fungus. The fungus remains in the soil so once infected that acreage will never produce bananas again without expensive soil fumigation. So rebuilding soils without causing some future damage isn't easy. Some of the better results came from giving up and just letting "nature" take over. Helping nature along with a variety of deep rooting native species seems to be worth a shot.
Biofuel advocates and land owners that consider productive land in the normal sense to be carbon "neutral" might need to consider carbon optimal from a more realistic perspective. Coal use for power plants accounts for about 25% of emissions with the average coal power plant still only 36% efficient. Adding secondary processes to coal power production like local heating or desalination/purification can increase efficiency to over 80% in ideal cases. At the same time, using resources generated by the thermal power plants to restore depleted and abused soils would make the coal/soil interaction a net carbon sink.
While nuclear or renewables could be used to help restore soils, coal's carbon content and trace elements Coal flyash for example may not be recommended for food crops supplement, but in reforestation efforts the flora could make use of the trace elements and help filter out unwanted heavy metals. Instead of attempting to sequester CO2, fertilizer production as a secondary process could be used to increase the growth rate of reforestation projects, which would also sequester carbon.
There is a lot of interesting research in land reclamation being marginalized by advocates of urgent actions "they" approve of.