Caldeira Lab

Regional Responses to Solar-Radiation Management: Dr. Katharine L. Ricke



In this paper we were looking at what the regional effects of solar-radiation management or a type of climate engineering would be if you were to use SRM to stabilize global temperatures. We used fully coupled, general circulation model or a GCM to look at a range of different solar-radiation management or SRM scenarios that would stabilize mean global surface air temperatures at different levels. What we found is that, with the whole range of different SRMs scenarios, we could stabilize global temperatures and that, under the controlled global warming scenario, global temperatures would continue to rise.

Global precipitation would rise without SRM, so in the controlled global warming scenario. And all of the different SRM scenarios, precipitation went down over the length of the simulations. So that’s at the global level what was happening.

At the regional level, we found that the effects in different regions were different. An open policy question about climate engineering is, who gets to set the global thermostat? The corresponding science question here was, what are, actually physically, the kind of range of different levels of the thermostat that regions might actually want?

So we looked at the results from the model in these 22 different Giorgi regions, these macro regions that are climatically and physiographically similar. We found that if we constrained the regional preferences by some criterion, for example in that figure, we looked at what global temperature a region would want if they wanted to minimize their combined seasonal temperature and precipitation anomaly when those temperature and precipitation anomalies were measured in the standard deviations in terms of inner-annual variability in that region.

What we found is that indeed different regions prefer different amounts of SRM and that the longer that you use SRM to compensate for rising greenhouse gases in the atmosphere, the more different that regional preferences become. So you can imagine that any sort of negotiations over the amount of SRM from an international relations or global governance perspective could become more contentious the longer these types of activities were used to compensate for rising greenhouse gases in the atmosphere.

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