Syracuse University Magazine

SU Team Looks to Rangeland Soils to Combat Climate Change

Wildebeests migrate across the Serengeti landscape with a grass fire burning in the background. The SU interdisciplinary team of professors Mark Ritchie, Jane Read, David Driesen, and Peter Wilcoxen is working on ways in which managing fire and grazing by wildlife or livestock can generate soil carbon credits in East Africa and other rangelands across the globe.

Biology professor Mark Ritchie has spent many a day digging into the soils of rangelands in the American West and Africa, studying the biodiversity of ecosystems and the impact of interactions between wildlife and plants. A productive rangeland ecosystem features flourishing vegetation that pulls carbon dioxide out of the atmosphere during photosynthesis and sequesters the carbon in plant roots and soil—a valuable asset that naturally reduces carbon dioxide emitted by burning fossil fuels, the main culprit in global warming. At the Serengeti National Park in Tanzania, where he has conducted research since 2004 in continuing a long-term study originally begun by SU professor emeritus Sam McNaughton, Ritchie notes a parallel between wildlife grazing intensity and carbon levels in the soil. Heavily grazed areas—where, for instance, migrating wildebeests regularly feed—contain greater accumulations of carbon than areas with scarce wildlife populations. "In areas depleted of wildlife, there's not much grazing going on, so they accumulate dead grass and burn too often, and there's basically not as much carbon accumulation as there could be, or they are actually suffering ongoing losses of carbon," Ritchie says. "So, my thought was that if you could build back up the wildlife numbers in these depleted areas, you could create a lot of carbon storage."

For Ritchie, the idea presents a monumental opportunity. As governments and industries around the globe wrestle with ways to cut greenhouse-gas emissions and curb climate change, Ritchie envisions a vital role for rangelands as vast carbon sinks. After all, rangelands—uncultivated, non-forested land, from the plains and prairies of North America to the grasslands of Africa—account for about one quarter of the Earth's land surface. Focusing on the savannas of East Africa, Ritchie believes a widespread combination of improved wildlife conservation and land-management practices, including wildfire controls, could remove more than a billion tons of atmospheric carbon dioxide each year and create a viable source of income for impoverished rural and farming communities in East Africa—such as the traditionally nomadic Maasai tribes—through the sale of carbon credits on emerging emissions-trading markets. "By far the biggest capacity for storing carbon in soil is in the rangelands," he says. "Most people aren't thinking about what's going on in the soil."

As a way of putting his theory to the test, Ritchie assembled an interdisciplinary team of SU faculty members: University Professor David Driesen, a climate-change law expert; economics professor Peter Wilcoxen, director of the Center for Environmental Policy and Administration at SU; and geography professor Jane Read, who specializes in remote-sensing and satellite imagery analysis. Supported by a two-year, $125,000 Chancellor's Leadership Project grant, the team is developing a unique methodology for quantifying rangeland carbon storage and investigating the possibility of selling the sequestered carbon as a commodity. Ritchie has met with nongovernmental organization administrators and government officials in East Africa to apprise them of the idea, and has established Soils for the Future, a start-up company that will develop carbon storage projects there. "Mitigating rural poverty in Africa is a significant challenge," Ritchie says. "There aren't many feasible options, given the lack of investment capital."

The project's most daunting task is creating a method to accurately quantify sequestered carbon and validate and monitor it as a credit for sale on the market. "From the standpoint of the climate-change law regime, the main legal and policy issues revolve around what constitutes a bona-fide credit," Driesen says. The principal concern, he notes, is that if a greenhouse-gas producer, such as a coal-fired electric utility, is allowed to increase its emissions by purchasing "credits" for carbon sequestered elsewhere, those credits must be legitimate. They also must satisfy criteria for "additionality," meaning that credits must be generated by a change in practice and also benefit the environment beyond what a business may do as part of its normal operations. "With carbon credits you run into controversy because people want to know that the quantity and permanence they're getting are equivalent to what they're giving up when carbon credits are used to justify increased emissions somewhere else," Driesen says. "With any kind of carbon sequestration project, developing methodologies to satisfy the legal regime has been difficult because of the variability in biological processes." 

The impact of such factors as seasonal changes, weather, fires, vegetation, and grazing must be considered in soil carbon sequestration, as well as how to measure it over vast areas and periods of time. As a way to quantify and validate carbon storage, Ritchie and Read are exploring a methodology that incorporates field data with spatial and spectral information gathered from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite system. Each pixel of an image captured by MODIS represents a defined area of about 250 square meters, while the light an object absorbs or reflects from different bands of the electromagnetic spectrum helps define it. Healthy vegetation, for instance, can be distinguished by analyzing differences between the red and near-infrared bands and the heat emitted by the landscape. "Our goal is to gain insight into vegetation density, fire frequency, soil temperatures/moisture, etc.," Read says. "Linking the remotely sensed-derived products with field data, we hope to compare differences between grazed and non-grazed areas and assess performances of different remote-sensing algorithms." While Read and Ritchie believe their work, which involves computer modeling to scale up field measurements to large tracts of land, may allow them to measure and monitor carbon sequestration with some degree of reliability, they both admit it's a challenge. But if they succeed, they may provide the scientific community with a groundbreaking methodology. "There is currently much ongoing research with remotely sensed data for carbon monitoring for forests," Read says. "However, less has been done for savanna systems." 

If their methodology offers reliable measurements and verification, it can clear the way for trading sequestered rangeland carbon as an economic venture. Right now, protocols are being developed for different kinds of sequestration projects to trade credits on contract. For example, the European Union emissions-trading program only allows credits for afforestation and reforestation projects as carbon catchers. As Wilcoxen points out, soil carbon sequestration is one piece of a very large puzzle dealing with climate change, but if it proves a viable option, there's great economic potential. "Looking at the precision of the sensing technology and how accurately we can quantify what's in the soil will determine the riskiness of the assets," he says. "If it turns out the precision is relatively good and the uncertainty is not so bad, that it can be applied to certain soil types and certain land conditions, then the potential goes from being just academic to practical." 

With so many fluctuating factors, Ritchie says the group will continually analyze data and make adjustments. "You're always learning as you go," he says. "You're not following a Julia Child recipe—that's what makes people nervous about it." It's this challenge that makes the project intriguing—and the potential rewards all the greater. "If you can go into East Africa and convert tens of millions of acres to doing these kinds of carbon projects, the cash infusion to the people and local economies will be transformative," Ritchie says. "I see it as a way to change the world." —Jay Cox

Biology professor Mark Ritchie and geography professor Jane Read make a preliminary estimate of grazing intensity across the Serengeti landscape based on calculations from MODIS satellite imagery. Black lines show major roads and the borders of Serengeti National Park and surrounding game reserves. Green and yellow areas signify less grazing; blue and lavender areas represent heavier grazing. 

A Maasai warrior proudly stands in front of his cattle. Income from soil carbon credit projects could help rural people like the Maasai maintain their cultural identity as pastoralists and use the land in a more sustainable way.

Photos and satellite image by Mark Ritchie