EVANSTON - A new Northwestern University study suggests that paying people to conserve their trees could be a highly cost-effective way to reduce deforestation and carbon emissions and should be a key part of the global strategy to fight climate change.
The study, led by Seema Jayachandran, associate professor of economics in the Weinberg College of Arts and Sciences at Northwestern, sought to evaluate how effective “Payments for Ecosystems” (PES) is at reducing deforestation. PES is a program in which people are given financial rewards for pro-environment behaviors.
In the study, people who owned forest in 60 villages in western Uganda were given cash rewards if they kept their forest intact and refrained from deforesting it. Forest owners in another 61 villages in western Uganda received no monetary incentives.
“We found that the program had very large impacts on forest cover,” said Jayachandran, also a faculty fellow with Northwestern’s Institute for Policy Research. “In the villages without the program, 9 percent of the tree cover that was in place at the start of the study was gone by the end of it, two years later. In the villages with the PES program, there was 4 to 5 percent tree loss. In other words, there was still deforestation, but much less of it.
The first of its kind, the study applies the method of field experiments, or randomized controlled trials, to the question of how effective PES is. The study design helped the researchers accurately measure the averted deforestation caused by the program.
Jayachandran said the cost effectiveness of the program compared to other approaches to reduce carbon emissions, such as subsidies for hybrid or electric vehicles in the U.S., was eye opening.
“A major contribution of the study was to compare the benefit of reduced deforestation to the cost of the program. What’s that extra forest worth to society? We do that by applying what’s called the ‘social cost of carbon,’” Jayachandran said.
The findings highlight the advantages of focusing on developing countries when working to reduce global carbon emissions. While the benefit of conserving a tree is the same regardless of the location, paying individuals to conserve forests in developing countries like Uganda is less expensive, making it cheaper to reduce overall emissions.
“Cash for carbon: A randomized trial of payments for ecosystems services to reduce deforestation” will be published in the journal Science on July 21.
In addition to Jayachandran, additional authors include Joost de Laat of Porticus, Amsterdam, Netherlands; Eric F. Lambin of Stanford University; Charlotte Y. Stanton of the Carnegie Institution for Science; Robin Audy; and Nancy E. Thomas of the University of California, Berkeley.