Carbon capture and geoengineering

In a previous post, I made the point that even if all anthropogenic greenhouse gas emissions ceased tomorrow, the half-lives of greenhouse gases already in the atmosphere, together with climate change-driven gas emissions from melting permafrost and methane clathrates doom us to decades more of warming. The only ways to avert this are (1) carbon capture to actively remove gases from the air and/or (2) geoengineering on a planetary scale.

It has been suggested that we plant more trees, since trees can sequester carbon from the atmosphere. The problems with that idea are:

• the consequences of global warming are coastal flooding, desertification and loss of fresh water; where would all those trees go?

• the world’s remaining forests are already being lost to agriculture, and that will only accelerate as arable land is lost to coastal flooding and desertification.

Ocean phytoplankton are responsible for ca. 70% of Earth's oxygen production by exchanging carbon dioxide for oxygen. Thus, like trees, phytoplankton are a form of carbon capture, and when the plankton die (or the animals the feed on them die), much of that carbon sinks to the bottom of the oceans.

In the pelagic ocean, nutrients limit phytoplankton growth. One of these nutrients is iron. It has been proposed to fertilize the world’s oceans with iron to promote phytoplankton growth leading to global natural carbon capture. The experiments to date are at best equivocal as to how effective this would be, and there are concerns that phytoplankton blooms would aversely affect coastal underwater plant life by blocking sunlight, water acidification and oxygen balance.

Is phytoplankton an important key to reversing atmospheric carbon and abating global warming? More research is desperately needed, and soon, to determine if this relatively low-tech measure can avert disaster for humanity. Are there risks? Sure, but there are great risks in doing nothing. https://sgp.fas.org/crs/misc/R47172.pdf