Geoengineering, through the eyes of the IPCC

Examples of geoengineering proposals.

Kathleen Smith, Lawrence Livermore National Laboratory

It has been well established that our emissions of greenhouse gases are changing the Earth’s climate, and that in order to avoid future warming and ocean acidification, fossil fuel use will need to be limited. There is a sort of “Plan B” however—the intentional manipulation of the climate, known as “geoengineering.” Some forms of geoengineering could be done relatively easily, while others seem more like “terraforming” schemes out of sci-fi novels.

As part of its latest report, the Intergovernmental Panel on Climate Change (IPCC) includes a review of research into the two main categories of geoengineering: the artificial removal of CO₂ from the atmosphere and the artificial reduction of sunlight reaching the Earth. There’s nothing yet about the practical feasibility of any techniques—that may appear in sections of the report that have not yet been released—but it nicely describes how various schemes actually work.

Taking off some blankets

The removal of carbon dioxide from the atmosphere could take many forms, some of which have much more potential than others. The first is biological. The regrowth of forests that have been cleared does have an effect, but it can only remove about as much carbon as the forests released when we cut them down. Soil provides another place to stuff some atmospheric carbon, though. By adopting soil-carbon-enhancing farming techniques, restoring some low-quality agricultural land, and producing and mixing in biochar, soils could make a bigger difference than reforestation over the twenty-first century.