Caldeira Lab Research:Climate Intervention ('Geoengineering')

Geoengineering Earth's radiation balance to mitigate CO2-induced climate change

Govindasamy Bala & Ken Caldeira

Large scale intentional modification of the Earth's climate ("geoengineering") has previously been predicted to reverse the global annual mean temperature rise caused by global warming. However, the seasonal and region specific effects of geoengineering have not been modeled. This paper involves the effect that geoengineering would have on the amplitude of the seasonal cycle and changes in temperature that it would induce at specific latitudes.

G. Bala, and K. Caldeira, Geoengineering Earth’s radiation balance to mitigate CO2-induced climate change, Geophysical Research Letters 27, 2141-2144, 2000.

Surface temperature changes in doubled CO2 and geoengineered models: Induced climate changes across the globe in the model with doubled CO2 (top panels) and geoengineering (bottom panels). The left panels show temperature changes for various locations. The right panels show areas where these changes are statistically significant.

Temperature changes in the atmosphere caused by CO2 increases and geoengineering: Temperature changes at various atmospheric heights modeled in the doubled CO2 case (top) and the geoengineered case (bottom). Geoengineering reverses the effects of CO2 in the troposphere, but amplifies CO2 induced cooling in the stratosphere, which could have adverse environmental effects.


To counteract anthropogenic climate change, several schemes have been proposed to diminish solar radiation incident on Earth's surface. These geoengineering schemes could reverse global annual mean warming; however, it is unclear to what extent they would mitigate regional and seasonal climate change, because radiative forcing from greenhouse gases such as CO2 differs from that of sunlight. No previous study has directly addressed this issue. In the NCAR CCM3 atmospheric general circulation model, we reduced the solar luminosity to balance the increased radiative forcing from doubling atmospheric CO2. Our results indicate that geoengineering schemes could markedly diminish regional and seasonal climate change from increased atmospheric CO2, despite difference in radiative forcing patterns. Nevertheless, geoengineering schemes could prove environmentally risky.