As co-chair of Working Group III of the Intergovernmental Panel on Climate Change (IPCC), I would like to clarify your misleading implication that I recommend geoengineering as an option for attaining ambitious climate targets (Nature 468, 13–14; 2010).
The IPCC does not have a mandate to recommend or dismiss specific policies or technologies. It aims to assess all relevant climate-change mitigation options on the basis of peer-reviewed scientific literature. This assessment must be unbiased, factual and policy-relevant, without being prescriptive.
There is ongoing public and scientific debate about using geoengineering as one of several options to mitigate climate change. Some decision-makers consider it a last resort in case technologies that are more conventional prove insufficient (for example, usage of renewable energy, carbon dioxide capture and storage, or nuclear power). Others are against a geoengineering option because of gaps in our knowledge, unwanted side effects and unmanageable risks. Notably, delegates at the United Nations Convention on Biological Diversity summit last month in Nagoya, Japan, agreed to call for a moratorium on geoengineering schemes (see http://go.nature.com/kc1b9c). Also, the governance structure of this option needs further consideration. Several fundamental questions must be answered before the deliberate alteration of Earth's radiation balance can be considered as a reliable option.
The IPCC will therefore assess the risks, feasibility, mitigation potential, costs and governance requirements of geoengineering for the first time in its Fifth Assessment Report, due to be released in 2013–14.
Meanwhile, the three IPCC working groups are coordinating a meeting of expert scientists from different disciplines as a platform for exchange and discussion. The aim is to encourage research into the implications of different geoengineering technologies, as well as to study their potential impact on biodiversity, human society and the climate system.
Readers are welcome to comment online on anything published in Nature: http://www.nature.com/nature . Submissions to Correspondence may be sent to firstname.lastname@example.org
About this article
Mitigation and Adaptation Strategies for Global Change (2013)