With it  becoming increasingly apparent that temperatures during this century will increase above the 2C “guardrail” that most climatologists now agree will visit extremely serious impacts upon human institutions and ecosystems, and indeed may rise 3-4C above pre-industrial levels or beyond, the drumbeat for “geoengineering” solutions to address climate change becomes louder and louder. The term “geoengineering” encompasses a wide range of potential responses, including seeding the oceans with iron filings to stimulate algae growth (theoretically resulting in increased sequestration of carbon dioxide), various terrestrial and ocean sequestration schemes, and mechanisms to reduce solar luminosity or radiative forcing, e.g. by seeding the atmosphere with aerosols or satellite-based reflectors.

In my mind, it’s an important issue to discuss with students for several reasons: 1. Such proposals are receiving increasing credence, both in the scientific and policy community; 2. it provides another good opportunity to engage social science and law students in climate science issues in a way that many find interesting; 3. it helps to reinforce the important point that there’s no free lunch in confronting climate change, at least at this point of the game; 4. it can stimulate some interesting discussions about whether there are substantial opportunity costs to pursuing geoengineering schemes that might detract from mitigation efforts, and if there is, how we make policy decisions, especially given the massive uncertainties about the effectiveness of both geoengineering and mitigation approaches.

In the past week, a number of excellent pieces have been published that would make good readings:

1. A good “point-counterpoint” set of editorials by Skeptical Environmentalist author Bjorn Lomborg, Climate Engineering: It’s Cheap and Effective,  published in the UK’s Globe and Mail, and a response by James Fleming on The New Security Blog, Climate Engineering is Untested and Dangerous;

2. A 66-page report by a number of group of climate scientists, Climate Engineering Responses to Climate Emergencies (2009). The study is a technical review of proposed geoengineering schemes, with a focus on shortwave radiation engineering, especially stratospheric aerosol injection. The study emphasizes a number of important points, including 1. the complexity of geoengineering solutions and spatial delays and feedbacks necessitates long-term research and monitoring; 2. the fact that some issues associated with rising levels of greenhouse gases including ocean acidification, would not be addressed by such schemes; and 3. potential ecosystem impacts of such schemes make them “extraordinarily risky.”  Nonetheless, the authors argue that possibility of “climate emergencies,” defined as severe climatic consequences that might occur to rapidly to be averted by even dramatic mitigation efforts (e.g. rapidly disintegrating ice sheets that could potentially raise sea levels tens of meters), necessitates the need for an active research agenda in this context;

3. Finally, Gabriel C. Hegerl & Susan Solomon in an article in this week’s edition of Science (Risks of Climate Engineering)  (subscription required) assesses the potential negative impacts of schemes to reduce inc0ming shortwave radiation. Hegerl & Solomon conclude that such schemes could result in substantial reductions in precipitation (through reductions in evaporation) that “could rival those of major droughts,” potentially leading to conflicts over water resources and potential large migrations and political instability.

Related posts:

1. Asilomar Conference on Climate Geoengineering
2. Another Good Piece on Geoengineering: Ocean Upwelling
3. Publication: Implementation of Geoengineering Options
4. The Politics of Geoengineering
5. Ethics of Geoengineering Video Interviews