Not geoengineering, please, but geotherapy instead.
The book
Geotherapy: Innovative Methods of Soil Fertilly Restoration and Carbon Sequestration
(
https://www.crcpress.com/Geotherapy-Innovative-Methods-of-Soil-Fertility-Restoration-Carbon-Sequestration/Goreau-Larson-Campe/p/book/9781466595392)
describes the wide variety of known methods that can sequester carbon from the sky while improving soil quality (and plant growth). If these methods and techniques were brought to scale, used globally consistently, we could remove the extra carbon we put in the atmosphere over the last century or two within the next century or two. Conceivably by 2100, we could plan for a 270-280 ppm of CO2 atmosphere, the equivalent of the preindustrial level. After all, we are as Gaia so we might as well get good at it.
In Healing Earth: An Ecologist’s Journey of Innovation and Environmental Stewardship (Berkeley, CA: North Atlantic Books, 2019 ISBN 9781623172985) (
https://www.northatlanticbooks.com/shop/healing-earth/), John Todd describes his ecologically engineered water purification systems, "they are designed with the attributes of natural ecosystems like marshes, ponds, and streams,” borrowing their designs, life forms, and progressions from natural ecosystems. For John Todd "natural history is not an old-fashioned form of knowing; it comprises the narratives of living entities that provide the alphabet of the design vocabulary.” In this book, he provides a pattern language, the human grammar for that design vocabulary, a baker’s dozen of design principles for constructing living technologies and eco-machines.
Biodiversity for a Livable Planet (
http://bio4climate.org) has organized 12 conferences and symposia, so far, on the many varieties of geotherapeutic practices. Covering not only soil carbon sequestration but also freshwater and ocean systems, biodiversity, a case study for the greater Boston metropolitan area, and much more. The videos of all those conferences are available on their website:
https://bio4climate.org/conferences/
Soil 4 Climate (
http://soil4climate.org) advocates for soil restoration as a climate solution, promoting regenerative land management practices to capture atmospheric carbon, acting on the idea that “uniting ‘drawdown' strategies with emissions reduction, divestment from fossil fuels, a price on carbon, and climate justice advocacy, together creates a powerful alliance."
Drawdown (
http://http://drawdown.org) is both a compendium of 100 carbon drawdown strategies and an ongoing effort to put the best into practice. Drawdown 2.0, I understand, is in the works. Among the top 10 of those carbon drawdown methods are wind and solar power but also educating girls and reducing food waste. Four out of the top 10 relate to food and land. The number 1 carbon drawdown method they identified is the management of the refrigerants we use, even after making efforts to eliminate CFCs. It turns out that our substitute, HCFCs, are a powerful greenhouse gas.
This fact alone makes it essential that anybody proposing geoengineering should know the history of the world’s first great geoengineer, Thomas Midgeley Jr., who invented CFCs and was instrumental in putting tetra-ethyl lead in gasoline