Promise or peril?

AuthorNicholson, Simon
PositionEYE ON ECOLOGY - Geoengineering

GEOENGINEERING, by definition, is any deliberate large-scale manipulation of the planetary environment to counteract human-caused climate change. As the planet continues to warm, the potential solutions offered by geoengineering are tempting, and several serious projects actively are being pursued. In a State of the World report, "Is Sustainability Still Possible?," we examine the pros and cons of such an approach to responding to climate change.

The technological prospects for geoengineering are vast, and fall into two main camps:

Solar radiation management (SRM) is a tactic that aims to reflect solar radiation back into space so that it is not absorbed by the atmosphere. The intent is to counteract heat-trapping gases by scattering or deflecting some percentage of incoming solar radiation by, for instance, streaming sulfate particles into the stratosphere or launching sunshades into space.

Carbon dioxide removal (CDR) is an approach that involves drawing large amounts of carbon out of the atmosphere, and storing it where it should not cause future harm. Land-based ideas have included carbon dioxide scrubbers that would pull large quantities of CO2 straight from the air, or growing forms of biomass and then reducing it to charcoal, which can be buried. Ocean-based ideas mostly involve the cultivation of plankton, which take in carbon from the atmosphere and bring it to the bottom of the ocean with them when they die.

SRM strategies are receiving the bulk of the attention. It is hard to see a CDR scheme coming online quickly enough or being deployed at a large enough scale to make a real dent in the atmospheric carbon load. However, solar radiation management is not any kind of real answer to climate change. At best, SRM can reduce the planet's fever for a period. Talk of geoengineering is gaining traction because it has the appearance of an easy, sacrifice-free approach to tackling climate change. It is critically important to recognize that there are sacrifices, some obvious and some harder to spot, associated with the bulk of geoengineering schemes.

Here is an outline of the promises and perils of geoengineering:

Climate catastrophes. The most obvious concern is the potential for causing catastrophic and...

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