News: Georgia Tech Economics Doctoral Student Co-Authors Paper on Solar Geoengineering in ‘Nature Communications’

School of Economics doctoral student Anthony Harding

Posted January 13, 2020

Solar geoengineering—the intentional reflection of sunlight away from the Earth’s surface—may reduce income inequality among countries, according to a new paper ­­co-authored by a Georgia Institute of Technology School of Economics Ph.D. student who conducted his research while a visiting student at the University of California San Diego.

In the study, published Monday, Jan. 13 in Nature Communications, Anthony Harding and his co-authors examined the impacts of solar geoengineering on global and country-level economic outcomes. Their paper, “Climate econometric models indicate solar geoengineering would reduce inter-country income inequality,” is the first to look at the economic impacts of climate projections associated with solar geoengineering.

While de-carbonizing the world’s emissions sources continues to pose a large challenge, solar geoengineering —  the process of intentionally reflecting sunlight to cool rising temperatures through methods such as adding sulfate aerosols to the stratosphere — could help avoid the worst consequences of global warming. This analysis is the first to project the response of Gross Domestic Product (GDP) to the specific pattern of cooling solar geoengineering produces.

The methodology estimates the historical relationship between climates — 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 stabilize naturally; if temperatures continue to rise; if temperatures were stabilized as a result of geoengineering; and if temperatures were over-cooled from geoengineering efforts.

“We find hotter, more populous countries are more sensitive to changes in temperature — whether it is an increase or a decrease,” said Harding, whose research at Georgia Tech focuses on the economic implications of climate change. “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.”

In an economic model projecting a solar-reengineered decrease in the average global temperature of around 3.5 degrees Celsius, 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 to a model where warming continues to occur. For the United States 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.

Similar to previous studies which have explored the relationship between hot weather and low productivity, the findings published in Nature Communications do not reveal the mechanisms for why this correlation occurs. 

A fundamental step in understanding the potential risks and rewards of solar geoengineering

Harding and corresponding-author Kate Ricke, assistant professor with UC San Diego’s School of Global Policy and Strategy and Scripps Institution of Oceanography, highlight 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 tradeoff 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.”

While the economic models used in the study do not reveal the impacts solar geoengineering has on income inequality within countries’ borders, the research results on GDP growth provide incentive for additional work on the global governance of solar geoengineering.

The authors write, “Our findings underscore that a robust system of global governance will be necessary to ensure that any future decisions about solar geoengineering deployment are made for collective benefit.”

The research was supported by UC San Diego’s Deep Decarbonization Initiative.

Georgia Tech’s School of Economics is a unit of the Ivan Allen College of Liberal Arts.

This article was written by Christine Clark of the University of California San Diego with assistance from Michael Pearson of Georgia Tech’s Ivan Allen College of Liberal Arts.

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