25 November 2010, Nature Correspondence: Assessing geoengineering doesn’t mean recommending geoengineering
This is the unedited version of the letter. For the published version, please see:
Edenhofer, O. Nature 468, 508 (2010)
Dear Sir or Madam,
The Nature News author Jeff Tollefson quoted me in his article “Geoengineering faces ban”, published online on 2 November 2010 on Nature News, saying:
“Geoengineering is one option, and it should be included in a portfolio of other options.” In addition, I have been quoted arguing that ambitious goals of limiting global warming to 1.5 or 2 degrees Celsius cannot be met without measures of geoengineering.
The article conveys the misleading impression that I, as Co-Chair of the IPCC’s Working Group III, recommend geoengineering as an option to reach very ambitious climate targets. Let me emphasize that the IPCC does not have the mandate to recommend or dismiss specific policies or technologies. The IPCC aims at assessing all relevant mitigation options based on scientific peer-reviewed literature. This assessment has to be unbiased, factual, and policy relevant without being policy prescriptive.
The IPCC has noticed that there is an on-going public and scientific debate about the role of geoengineering as a component of a portfolio of options to mitigate climate change. For some decision-makers it may appear as the last resort if more conventional technologies (e.g. renewables, CCS or nuclear power) are insufficient to halt dangerous climate change. Others might argue that this option should be banned due to the knowledge gaps, unwanted side effects and unmanageable risks. In addition, the governance structure of this option requires further considerations. A number of questions have to be answered before knowingly altering the Earth’s radiation balance can be included as a reliable component in a portfolio of mitigation options.
Therefore, the IPCC will, for the first time, assess geoengineering in view of risks, feasibility, mitigation potential, costs and governance requirements in its Fifth Assessment Report to be published in 2013/2014. In preparation for this, the three IPCC Working Groups are organizing an Expert Meeting to provide a platform for exchange and discussion among scientists from the different disciplines and to encourage more research on the implications of various geoengineering technologies as well as their potential impacts on biodiversity, human society, and the climate system.
Nature News: Geoengineering faces ban, by Jeff Tollefson