Groundbreaking New Report on Geoengineering Tackles Carbon Dioxide Removal Experiments

February 10, 2015
Brenda Ekwurzel
Senior Climate Scientist, Director of Climate Science

The scientific body established by a law signed by President Lincoln released two groundbreaking reports today on geoengineering. The National Research Council of the U.S. National Academy of Sciences (NAS) emphasized in each report that reducing heat-trapping emissions and adapting to a changing climate are the two main options for reducing the risks of climate change.

The NAS committee, chaired by Marcia McNutt, recommended avoiding the terms “geoengineering” or “climate engineering,” which imply an engineering precision that is not warranted. Plus “geological engineering” has a different meaning in the context of mining. The committee preferred to define the term “climate intervention” as “purposeful actions intended to produce a targeted change in some aspect of the climate.”

Carbon overload

The core problem is overloading the atmosphere with heat-trapping carbon dioxide.

The first report assesses ways to strike at the core of the problem by intentional carbon dioxide removal and reliable sequestration. These have the potential to reduce the risks of most consequences that stem from overloading the atmosphere with carbon dioxide, including ocean acidification. The second report, assesses ways of reflecting sunlight to cool Earth. (To learn more about this report check out the blog by my colleague Peter Frumhoff.)

Climate intervention raises questions of governance

Both reports also point out that intentional experiments such as these raise profound issues regarding governance that are at present not well developed in most countries or international organizations.

Appropriately, given the role of the NAS to advise the federal government on matters of science or of a technical nature, the reports recognize that other disciplines need to weigh in on improving governance before deployment should be considered in many cases. For example, the Bipartisan Policy Center and the Oxford Principles in the UK represent early explorations of governance.

One of the issues raised is that those who may experience the consequences of intentional experiments would ideally be brought into the review of proposals, and prior approval would be sought before conducting experiments in the field. Another idea is to have an independent team of experts study potential consequences of any experiment proposed.

Carbon removal and sequestration more costly than reducing emissions

Among the key findings from the report on carbon dioxide removal and reliable sequestration is that the costs of many current proposals are likely to exceed that of reducing heat-trapping emissions through wide deployment of renewable energy sources and significant reductions in fossil fuel combustion.

For example, current cost estimates for scrubbing the parts per million carbon dioxide concentrations from the atmosphere are exceedingly high. Though less costly then direct air capture, costs are still high for capturing carbon dioxide directly at a concentrated point source such as a bioenergy source. As far as the reliable sequestration portion of the entire enterprise, saline aquifers seem the most promising of the geologic reservoirs examined in the United States.

Reducing emissions is most economical and least risky choice

Most proposals for carbon dioxide removal and reliable sequestration are far costlier than widespread deployment of renewable energy sources and other ways to reduce fossil fuel combustion.

The report noted that some carbon dioxide removal and reliable sequestration projects have already been explored with unequal results. For example, reforestation can sequester carbon for at least the lifetime of the trees. Far riskier is intentional acceleration of carbon dioxide removal by enhancing the biological uptake in the ocean through iron fertilization. According to the report, “deploying ocean iron fertilization at climatically relevant levels poses risks that outweigh potential benefits.”

Decades to achieve – not a quick fix

Most proposals would likely take a decade or longer to achieve modest climate effects. What if the funding stopped for a carbon dioxide removal experiment? The report assesses this as well. The committee determined that any sudden stoppage of a carbon dioxide removal and sequestration experiment is considered a low-risk action. Given the time delay of most proposals, this gives time to conduct thorough research into potential consequences (e.g. earthquakes associated with injecting carbon deep into geologic reservoirs).  Most of the carbon removal and sequestration research experiments examined were considered in the report to be relatively regional with regard to governance aspects.

The bottom line is that this report is a call for further research into safe ways for carbon dioxide removal and reliable sequestration. In particular, ramping up research into land use and reforestation approaches seem the least risky of those covered in the report. The National Science Foundation and U.S. federal agencies could spur innovation with investments in transparent research programs on carbon dioxide removal and reliable sequestration.