Carbon Dioxide Removal: Assessing potentials - and risks

06/24/2013 - With global greenhouse-gas emissions continuing to rise and a possibility that international cooperation in climate policy will continue to be delayed, a number of large-scale technical approaches have been suggested to counter strong climate change. Direct carbon dioxide removal (CDR) from the atmosphere is a measure that two groups of scientists at the Potsdam Institute for Climate Impacts Research (PIK) are now looking into. Theoretically, it could make ambitious mitigation economically more feasible, increase the likelihood of achieving the 2-degrees warming threshold agreed by the international community, or lower atmospheric carbon dioxide concentrations in the future to partially compensate for lack of mitigation today. The PIK projects are part of a programme financed by Deutsche Forschungs-Gemeinschaft on climate engineering that is starting this month.
Carbon Dioxide Removal: Assessing potentials - and risks
Biomass plantation with sugarcane: Using food crops for energy production has obvious tradeoffs. Photo: thinkstock

“Any form of climate engineering bears substantial risks, if not dangers. They should not be considered as more than a theoretical consideration unless the consequences are completely clear,” says Wolfgang Lucht, co-chair of PIK’s research domain on Earth System Analysis. “The environmental costs, political pitfalls and ethical justification of these techniques are not well understood, which is why scientists are now investigating whether the proposed approaches are effective at all, and what their implications for the rest of the Earth system are.” Carbon dioxide removal should by no means be a substitute for cutting emissions, he points out. “This is about potential emergency action if humankind fails to act responsibly now,” Lucht says.

His project, which he leads together with PIK scientists Dieter Gerten and Tim Beringer, analyses in detail the consequences of large-scale biomass plantations for absorbing CO2 on the global environment, particularly on climate, nature conservation, freshwater resources and agricultural production. The consequences of large-scale afforestation and industrial biomass monocultures will be quantified. The carbon gained could be left standing, used for energy production, stored underground, or in the soil as biochar. In this project, PIK is cooperating with the Max-Planck-Institute for Meteorology in Hamburg.

Another team led by Ottmar Edenhofer and Elmar Kriegler of PIK’s research domain Sustainable Solutions focuses on the role CDR could play for future mitigation strategies. “In principle, CDR can compensate for emissions in the past and in sectors that are most costly to decarbonize. Whether this is desirable will depend on a careful analysis of the risks and trade-offs of CDR deployment. It is our initial hypothesis that society will assess the desirability in the context of available alternatives and targets. Our project aims to inform such an assessment,” says Kriegler. In addition to afforestation, two other ways of taking CO2 out of the atmosphere are being examined: direct air capture with chemical solvents and enhanced weathering of rocks. This is in cooperation with the University of Hamburg and the Institute of Advanced Sustainability Studies in Potsdam.

Weblink to study on CO2 removal reducing costs of climate protection:

Weblink to opinion piece in PNAS on geo-engineering:

Weblink to tradeoffs in global biomass plantations for bioenergy:

Weblink of the DFG programme: