Solomon Hsiang on the economic impacts of global climate change

In a centuries-old library at the University of Oxford, millions of aerial photographs taken in the final decades of the British Empire may help predict a potential 21st century calamity: an exodus of people driven by climate change to places that are more livable — but politically inhospitable.

"How global society handles this desire for people to move — whether by helping them or by, literally building walls to keep them out — is a very important and open question," says Solomon Hsiang, one of two academics spending the year at Stanford as part of the inaugural Noosheen Hashemi Visiting Scholars program at the Center on Global Poverty and Development. The program's goal is to encourage collaborations among prominent scholars from universities around the global and the Stanford community on key issues of global development.

While at the center, Hsiang is studying how climate change might set off mass migrations around the world. The British Royal Air Force photos are key to this analysis because they could reveal how populations responded to natural disasters in the 20th century — specifically, a series of extreme droughts that plagued Africa. Until the images were discovered, scholars didn’t have reliable data to study previous human movement on the continent.

"This has been an open question for a long time," says Hsiang, who is also an associate professor of public policy at the University of California Berkeley. His team is building the algorithm that will scan the digitized photos for signs of forests that were converted to farmland and new villages. Based on what he and his colleagues at Sweden’s Stockholm University find, Hsiang hopes to project what might happen in the future.

"If people are going to move around and start, for example, crowding cities, a lot of issues show up that policymakers need to be thinking about,” says Hsiang.

It's just one example of Hsiang's groundbreaking work combining data with mathematical models to understand the economic effects of climate change, particularly on poverty. He was the lead author, for example, on a seminal 2011 study linking global climate change directly to the threat of increased civil unrest worldwide. He’s co-authored studies establishing an empirical connection between violence and climate change across 12,000 years of human history, showing that higher temperatures can increase suicide rates, and documenting the extent to which climate change could impact regional economies in the United States.

More recently, Hsiang has waded into the debate over solar geo-engineering — the idea that humans could reflect sunlight and moderate global temperatures by releasing special gases into the stratosphere. In a paper published in August in the journal Nature, Hsiang and his co-authors maintain that geo-engineering would do little to offset damage from climate change to crop yields worldwide.

Hsiang’s research has made its way into a number of major policymaking discussions. For example, the late 2018 National Climate Assessment on the impact of changing weather patterns on the United States cited his data.

In 2014, Hsiang was named to Forbes magazine's annual list of "30 Under 30" global visionaries and industry leaders.

Fostering collaboration to address global poverty

Hsiang discovered his passion for Earth’s changing environment early. He was just 10 years old when he learned from a teacher how many humans were expected to populate the planet in 2100. “The numbers blew my mind,” recalls Hsiang. “From that point on, I couldn’t stop thinking ‘What are we going to do when there are all these people?’”

In 2006, Hsiang earned a BS in earth, atmosphere and planetary science and a BS in urban studies and planning with a minor in economics from the Massachusetts Institute of Technology (his thesis papers for both majors won awards). He then earned a PhD in sustainable development from Columbia and, after completing post-docs at the National Bureau of Economic Research and at Princeton, he joined Berkeley’s Goldman School of Public Policy. Among his many affiliations, Hsiang is co-principal investigator of the Climate Impact Lab.

Now on sabbatical from Berkeley, Hsiang has been spending time this year meeting with Stanford scholars he’s worked closely with and getting to know potential collaborators. He’s turned, for example, to Stanford agricultural ecologist David Lobell and economist Marshall Burke, who have pioneered the use of machine learning in remote sensing and have collaborated with Hsiang in the past. Their input is helping him design the algorithm for the African migration study.

“I’ve been learning a lot from the Stanford community and working with Lobell and Burke is like learning at the feet of masters,” says Hsiang. The benefits of Hsiang’s on-campus presence go both ways: He recently spent time helping a PhD candidate think through her thesis on California wildfires and the complex spatial analyses it requires.

Looking ahead, Hsiang has an ambitious research agenda. Among other things, he plans to look deeper into the economic costs of hurricanes and other extreme storms, an area he calls “profoundly understudied.” His previous research has shown that countries hit by extreme storms experience slower growth for about a decade. As severe weather patterns become more frequent and inflict more damage, the fallout for many countries could be devastating.

“Parts of the world are really struggling to cope with these enormous storms,” says Hsiang, who likens recovery efforts to climbing an escalator that’s moving in the opposite direction. “As these storms keep happening, they’re persistently creating disadvantages for low-income groups and their ability to work their way out of poverty.”

But when it comes to solving climate change’s economic harms, Hsiang is quick to urge scientists and policymakers to examine carefully the long-term implications of technological fixes. As an example, he cites his recent study suggesting that solar geo-engineering could have the unintended effect of harming agricultural production.

“It points to the significance,” says Hsiang, “of having some caution and respect for the scale of systems we're thinking about messing with.”

Please note that prior to May 2019, the Stanford King Center on Global Development was known as the Stanford Center on Global Poverty and Development.