GeoengineeringGeoengineering not a substitute for reducing carbon emissions: Scientists

There is no substitute for dramatic reductions in greenhouse gas emissions to mitigate the negative consequences of climate change, a National Research Council committee concluded in a two-volume evaluation of proposed climate-intervention techniques. Strategies to remove carbon dioxide from the atmosphere are limited by cost and technological immaturity, but they could contribute to a broader portfolio of climate change responses with further research and development. Albedo-modification technologies, which aim to increase the ability of Earth or clouds to reflect incoming sunlight, pose considerable risks and should not be deployed at this time.

Carbon dioxide removal and albedo-modification techniques have been grouped up until now under the common term “geoengineering,” but they vary widely with respect to environmental risks, socio-economic impacts, cost, and research needs. Carbon dioxide removal addresses the root cause of climate change — high concentrations of the greenhouse gas in the atmosphere — and generally have well-understood benefits and risks, but current technologies would take decades to achieve moderate results and be cost-prohibitive at scales large enough to have a sizeable impact. By contrast, albedo-modification techniques would only temporarily mask the warming effect caused by high CO2 concentrations, and present serious known and possible unknown environmental, social, and political risks, including the possibility of being deployed unilaterally.

A NRC release reports that these differences led the committee to evaluate the two types of approaches separately in companion reports, a distinction it hopes carries over to future scientific and policy discussions.  In addition, the committee believes that these approaches are more accurately described as “climate intervention” strategies — purposeful actions intended to curb the negative impacts of climate change — rather than engineering strategies that imply precise control over the climate.

“That scientists are even considering technological interventions should be a wake-up call

that we need to do more now to reduce emissions, which is the most effective, least risky way to combat climate change,” said committee chair Marcia McNutt, editor-in-chief of Science and former director of the U.S. Geological Survey. “But the longer we wait, the more likely it will become that we will need to deploy some forms of carbon dioxide removal to avoid the worst impacts of climate change.”