Model shows cooling planet will boost GDP

Solar geoengineering could play a key role in reducing income inequality between countries, according to research undertaken at the University of California San Diego (UC San Diego).

Solar geoengineering — also known as solar radiation management — is a process that intentionally reflects sunlight away from the Earth’s surface to mitigate global warming.

A team of researchers from UC San Diego have examined the impacts of solar geoengineering on global and country-level economic outcomes, publishing their paper in Nature Communications. The analysis follows the response of gross domestic product (GDP) to the specific pattern of cooling that solar geoengineering produces.

The methodology estimates the historical relationship between climate, represented as mean annual temperature and precipitation, and country-level growth in economic production, measured as GDP per capita. This estimated climate–economy relationship is then applied to project and compare economic outcomes across four different climate scenarios for the next century: if global temperatures stabilise naturally; if temperatures continue to rise; if temperatures were stabilised as a result of geoengineering; and if temperatures were over-cooled from geoengineering efforts.

“While precipitation has little to no effect on GDP growth in our results, there is a relationship for temperatures,” said lead author Anthony Harding, a visiting graduate student with UC San Diego’s School of Global Policy and Strategy from the Georgia Institute of Technology.

“Applying these historical relationships for different models, we find that if temperatures cooled there would be gains in GDP per capita. For some models, these gains are up to 1000% over the course of the century and are largest for countries in the tropics, which historically tend to be poorer.”

In an economic model projecting a solar-geoengineered decrease in the average global temperature of around 3.5°C, the cooler climate would increase average incomes in developing tropical countries, such as Niger, Chad and Mali, by well over 100% over the course of the century, compared with a model where warming continues to occur.

For the US and countries in southern Europe, the same model showed a more moderate increase of about 20%. While the effects for each individual country can vary across models, the changes in temperature associated with solar geoengineering consistently translate into a 50% reduction of global income inequality.

“We find hotter, more populous countries are more sensitive to changes in temperature — whether it is an increase or a decrease,” Harding said.

“Those hotter countries are typically also poorer countries. With solar geoengineering, we find that poorer countries benefit more than richer countries from reductions in temperature, reducing inequalities. Together, the overall global economy grows.”

Understanding the risks and rewards of solar geoengineering

Harding and co-author Assistant Professor Kate Ricke from UC San Diego’s School of Global Policy and Strategy and Scripps Institution of Oceanography highlighted that there are many unknowns about the impacts solar geoengineering intervention efforts would have on the Earth’s atmosphere, a cause of concern for scientists and policymakers.

However, predicting the economic impacts of solar geoengineering is a fundamental step towards understanding the risk trade-off associated with the new field of study, which is advancing rapidly. Many emerging technologies have recently been developed to manipulate the environment and partially offset some of the impacts of climate change.

“There is a problem with solar geoengineering science in that there has been a lot of work on the physical aspects of it; however, there is a gap in research understanding policy-relevant impacts,” Ricke said.

“Our finding of consistent reduction in inter-country inequality can inform discussions of the global distribution of impacts of solar geoengineering, a topic of concern in geoengineering ethics and governance debates.”

The authors explained that their findings underscore the necessity of a robust system of global governance to ensure that any future decisions regarding solar geoengineering deployment are made for collective benefit.

Image credit: ©stock.adobe.com/au/Darren Baker