Geoengineering or Mitigations – A Primer

The most recent scientific assessment by the Intergovernmental Panel on Climate Change (IPCC 2007) concludes that it is very likely average global temperature will be 1.4 to 4.8ºC warmer by 2100 than it was in 1850. Further, the main cause of warming is increased greenhouse gas (GHG) concentrations due to the burning of fossil fuels and land-use change. The United Nations Framework Convention on Climate Change (UNFCCC) commits Canada and over 153 other countries, as signatories of the UNFCCC on June 12, 1992, to work towards "stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system". While there is no definition of "dangerous anthropogenic interference", there is consensus that GHG concentrations in excess of 500 - 550 ppmv carbon dioxide (CO2) equivalents would be dangerous, and many climate scientists think lower concentrations are dangerous. The August concentration of CO2 was 385 ppmv and the annual rate of increase is between 2.5 and 3.0 ppmv/yr. However, to stabilize GHG concentration at 400 ppmv CO2 eq. (i.e. the lower limit for dangerous climate change), the emissions of GHGs would have to be reduced between 70 and 90% relative to the present day and this would have to take place now!

Since the signing of the UNFCC, countries have, either as part of international agreements such as the Kyoto Protocol or individually, proposed many strategies for reducing GHG emissions, but the reality is that very few countries have made any significant progress in emission reductions - rather, most countries have had a substantial increase in emissions. For example, Canada's emissions are 25% higher than the target set by the Kyoto Protocol. The Parties to the UNFCCC are meeting in their 15th conference in Copenhagen in December of this year, but the preliminary meetings and general commentary suggest it is highly unlikely that the necessary reductions can be obtained in the near future.

The combination of steadily increasing GHG concentrations and the inability to develop effective strategies for reducing GHGs emissions have led some scientists to propose that we intervene directly in the global carbon cycle and/or the climate system. These proposals are collectively called "geoengineering" and they involve two different approaches: the capture and burial of CO2 or management of incoming solar radiation (sunlight). The proposal of geo-engineering, even as a stop-gap measure until effective emission mitigation strategies can be developed, has raised many scientific, social, and ethical concerns. Do we understand the Earth system well enough to know how to manage the planetary system? How do we assess the effectiveness of the proposed schemes? What are the risks associated with geoengineering? What are the possible side-effects? Is geoengineering scientifically, economically, and socially feasible? What are the geopolitical and ethical implications of geo-engineering? Many of the scientific questions related to geoengineering are discussed in a report released in 2008 - J. J. Blackstock et al., "Climate Engineering Responses to Climate Emergencies" (Novim, 2009) - and the scientific and broader issues are the focus of the recently released report of The Royal Society, UK: "Geoengineering the Climate: Science, Governance and Uncertainty" (September 1, 2009).


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