Caldeira Lab Research:Climate Intervention ('Geoengineering')

Crop yields in a geoengineered climate

Julia Pongratz, D.B. Lobell, L. Cao & K. Caldeira

Geoengineering proposals to intentionally deflect sunlight from the earth to reduce the rising global temperature have been met with concerns about the stability of food and water supplies worldwide. In this modeling study, we found that solar radiation geoengineering in a high-CO2 climate generally caused crop yields to increase. However, the most important step to protect global food security is to reduce greenhouse gas emissions.

Pongratz, J., D. B. Lobell, L. Cao, , and K. Caldeira (2012), Crop yields in a geoengineered climate, Nature Climate Change, doi: 10.1038/NCLIMATE1373


Dr. Julia Pongratz - click here to read the video transcript

Ken Caldeira - click here to read the video transcript


Figure: Yield changes for 2 CO2 and SRM simulations. Relative changes in yields for maize, wheat and rice, compared with the control climate, of the 2 CO2 simulation (top panels) and the SRM simulation (bottom panels); for changes in temperature, precipitation and combined changes in both of these factors plus CO2 fertilization (all), for the CAM3.5 climate model. Vertical lines are latitudinal mean values for all of the land area, shown for latitudes with more than 5,000 km2 of respective crop area. The grey horizontal line indicates one standard deviation across longitudes of each latitude. The beige histogram indicates the latitudinal sum of the crop area.


Crop models predict that recent and future climate change may have adverse effects on crop yields. Intentional deflection of sunlight away from the Earth could diminish the amount of climate change in a high-CO2 world. However, it has been suggested that this diminution would come at the cost of threatening the food and water supply for billions of people. Here, we carry out high-CO2, geoengineering and control simulations using two climate models to predict the effects on global crop yields. We find that in our models solar radiation geoengineering in a high-CO2 climate generally causes crop yields to increase, largely because temperature stresses are diminished while the benefits of CO2 fertilization are retained. Nevertheless, the most certain way to reduce climate risks to global food security is to reduce emissions of greenhouse gases.


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