Saturday, 04.09.2010
Geoengineering
Until recently, geo-engineering has been shunted off to the sidelines as a highly questionable subject that was almost unethical to discuss. But the tides have turned, and geo-engineering is now being discussed more openly and commonly among scientists, politicians, and the general public.
We believe that the proximity to irreversible tipping points in the eartth's climatic system combined with the slowness of the needed changes in policy, necessitate a serious and wide discussion of geoengineering. To facilitate such discussion, we provide information on various aspects of geoengineering.
However, it is essential to point out, that the possibilities that geo-engineering might provide for stabilizing our climate must not be used as an excuse to not do our very best to avoid the use of geoengineering. geo-engineering must only be discussed as a safety break in case of a climate emergency - a state that we will hopefully never reach.
General background and opinions
Annotated bibliography
Presentations on geo-engineering
Past and upcoming conferences on geoengineering
Institutions and researchers working on geoengineering
1) History of geoengineering
Fleming, J. R. Presentation given at the AAAS meeting in San Diego, USA, 2010.
"Some climate engineers claim they are the “first generation” to propose the deliberate manipulation of the planetary environment. History says otherwise. In what seems to be a perennial quest to control nature, commercial and military interests inevitably influence what scientists might consider to be purely technical issues."
"Some climate engineers claim they are the “first generation” to propose the deliberate manipulation of the planetary environment. History says otherwise. In what seems to be a perennial quest to control nature, commercial and military interests inevitably influence what scientists might consider to be purely technical issues."
2) General aspects and opinions
Brewer, P. G. (2007). Evaluating a technological fix for climate. PNAS 104: 9915–9916
Alan Robock (2008). 20 reasons why geoengineering may be a bad idea. Bulletin of the Atomic Scientist: 64: 14-18.
"Carbon dioxide emissions are rising so fast that some scientists are seriously considering putting Earth on life support as a last resort. But is this cure worse than the disease?"
"Carbon dioxide emissions are rising so fast that some scientists are seriously considering putting Earth on life support as a last resort. But is this cure worse than the disease?"
3) Methods of geoengineering
I. Reducing solar radiation
a) Sulfate injections into the stratosphere
Robock, A., L. Oman, G. L. Stenchikov (2008). Regional climate responses to geoengineering with tropical and Arctic SO2 injections. J. Geophys. Res. 113.
"Anthropogenic stratospheric aerosol production, so as to reduce solar insolation and cool Earth, has been suggested as an emergency response to geoengineer the planet in response to global warming. ….We find that if there were a way to continuously inject SO2 into the lower stratosphere, it would produce global cooling. .... Both tropical and Arctic SO2 injection would disrupt the Asian and African summer monsoons, reducing precipitation to the food supply for billions of people. These regional climate anomalies are but one of many."
"Anthropogenic stratospheric aerosol production, so as to reduce solar insolation and cool Earth, has been suggested as an emergency response to geoengineer the planet in response to global warming. ….We find that if there were a way to continuously inject SO2 into the lower stratosphere, it would produce global cooling. .... Both tropical and Arctic SO2 injection would disrupt the Asian and African summer monsoons, reducing precipitation to the food supply for billions of people. These regional climate anomalies are but one of many."
b) Sunshades
Angel, R. (2006). Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point. PANS 103: 17184–17189.
"The concept considered here is to block 1.8% of the solar flux with a space sunshade orbited near the inner Lagrange point …The concept builds on existing technologies. It seems feasible that it could be developed and deployed in 25 years at a cost of a few trillion dollars."
"The concept considered here is to block 1.8% of the solar flux with a space sunshade orbited near the inner Lagrange point …The concept builds on existing technologies. It seems feasible that it could be developed and deployed in 25 years at a cost of a few trillion dollars."
c) Risks of methods that reduce solar radiation
Bala, G., P. B. Duffy, K. E. Taylor (2008). Impact of geoengineering schemes on the global hydrological cycle. PNAS 105: 7664–7669.
The rapidly rising CO2 level in the atmosphere has led to proposals of climate stabilization by ‘‘geoengineering'' schemes that would mitigate climate change by intentionally reducing solar radiation incident on Earth's surface. In this article we address the impact of these climate stabilization schemes on the global hydrological cycle. By using equilibrium climate simulations, we show that insolation reductions sufficient to offset global-scale temperature increases lead to a decrease in global mean precipitation. This occurs because solar forcing is more effective in driving changes in global mean evaporation than is CO2 forcing of a similar magnitude. … Hence, the hydrological cycle is more sensitive to temperature adjustment by changes in insolation than by changes in greenhouse gases. This implies that an alteration in solar forcing might offset temperature changes or hydrological changes from greenhouse warming, but could not cancel both at once.
The rapidly rising CO2 level in the atmosphere has led to proposals of climate stabilization by ‘‘geoengineering'' schemes that would mitigate climate change by intentionally reducing solar radiation incident on Earth's surface. In this article we address the impact of these climate stabilization schemes on the global hydrological cycle. By using equilibrium climate simulations, we show that insolation reductions sufficient to offset global-scale temperature increases lead to a decrease in global mean precipitation. This occurs because solar forcing is more effective in driving changes in global mean evaporation than is CO2 forcing of a similar magnitude. … Hence, the hydrological cycle is more sensitive to temperature adjustment by changes in insolation than by changes in greenhouse gases. This implies that an alteration in solar forcing might offset temperature changes or hydrological changes from greenhouse warming, but could not cancel both at once.
II. Increasing CO2 uptake
a) Ocean fertilization
Boyd, P. W. et al. (2000). A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization. Nature 407:695-702.
Changes in iron supply to oceanic plankton are thought to have a significant effect on concentrations of atmospheric carbon dioxide by altering rates of carbon sequestration, a theory known as the ‘iron hypothesis'. For this reason, it is important to understand the response of pelagic biota to increased iron supply. Here we report the results of a mesoscale iron fertilization experiment in the polar Southern Ocean, where the potential to sequester iron-elevated algal carbon is probably greatest. … Our findings demonstrate that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.
Changes in iron supply to oceanic plankton are thought to have a significant effect on concentrations of atmospheric carbon dioxide by altering rates of carbon sequestration, a theory known as the ‘iron hypothesis'. For this reason, it is important to understand the response of pelagic biota to increased iron supply. Here we report the results of a mesoscale iron fertilization experiment in the polar Southern Ocean, where the potential to sequester iron-elevated algal carbon is probably greatest. … Our findings demonstrate that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.
Jin, X., N. Gruber, H. Frenzel, S. C. Doney, J. C. McWilliams. (2007). The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump. Biogeosciences, 5, 385–406
Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical biogeochemical ecological model. … Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.
Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical biogeochemical ecological model. … Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.
4) Ethical considerations
5) Political considerations
6) Presentations
7) Conferences
Past conferences:
March 22-26, 2010. The Asilomar International Conference on Climate Intervention Technologies. Asilomar Conference Center, Pacific Grove, California
February 18-22, 2010. AAAS Annual meeting. Session on human dimensions of geoengineering.
San Diego, USA
Read the Statement from the conference's scientific organizing committee.
San Diego, USA
Read the Statement from the conference's scientific organizing committee.