Clark geographer awarded NASA grants to study carbon release, uptake in U.S. forests

October 23, 2014
Christopher Williams

Christopher A.
Williams

Christopher A. Williams, associate professor of geography in the Graduate School of Geography at Clark University, was recently awarded two grants from the National Atmospheric and Space Administration (NASA) for a set of projects aiming to determine the balance of carbon uptake and release across forests in the United States using the latest satellite remote-sensing data products in combination with computer modeling, field inventories, and atmospheric observations. Williams will serve as principal investigator for a project titled "Translating forest change to carbon emissions/removals linking disturbance products, biomass maps, and carbon cycle modeling in a comprehensive carbon monitoring framework," which has received a grant for $858,000 from NASA’s Carbon Monitoring System (CMS). The research team includes Dr. G. James Collatz and Dr. Jeffrey Masek of NASA's Goddard Space Flight Center, along with Dr. Gretchen Moisen of the USDA Forest Service. Clark's portion of the grant is $468,125.

Wildfires consume millions of hectares of US forest each year releasing a large amount of carbon to the atmosphere. Courtesy of Kari Greer/U.S. Forest Service

Wildfires consume
millions of hectares
of US forest each
year releasing a
large amount of
carbon to the
atmosphere.
Courtesy of Kari
Greer/U.S. Forest
Service)

The CMS project, which aims to quantify how much carbon is being released and taken up by forests across the entire United States, provides a new method for U.S. reporting to the United Nations Framework Convention on Climate Change. The team will assemble new remote-sensing products describing forest disturbances and biomass stocks with a carbon accounting framework to document regional and country-scale changes. They will apply the framework for national reporting, and in a forecasting mode to test carbon balance implications of likely management and natural disturbance scenarios. "This new funding will allow the team to continue our past work on the subject, and to deliver new tools and findings with even greater practical relevance for national and international climate change considerations," explains Williams. The funding will also benefit students interested in the topic. "Many of our geography, geographic information science, and environmental science graduate students come to Clark to learn how to monitor land change and quantify its impacts on ecosystem services such as carbon storage," notes Williams. "This research will provide yet another great opportunity for students to gain exposure to cutting-edge research and applications with the latest remote sensing and modeling technologies being applied to these important problems." Carbon is both stored in and released from forest vegetation. Williams explains that while forests are a globally significant store of carbon, this store is vulnerable to forest disturbance processes such as harvesting or fires that oxidize forest carbon and release it to the atmosphere as CO2, contributing to global warming.

Timber harvesting removes more carbon from US forests each year than any other process.

Timber harvesting
removes more carbon
from US forests each
year than any other
process. Courtesy of
USDA Forest Service.

At the same time, intact forests serve as a major offset to rising CO2 concentrations as forest growth is stimulated by rising CO2 levels, enabling forests to absorb about one third of annual carbon emissions from fossil fuels and land use change. The balance of these processes is constantly changing and it varies widely from region to region. Historical forest clearing is responsible for about one third of all human-caused carbon emissions to date with the rest coming from the combustion of fossil fuels. Avoiding further forest carbon losses and protecting forest carbon uptake are both critical components of mitigating climate change. National and international policies aimed at protecting forest carbon storage rely heavily on high quality, accurate reporting (called "Tier 3") that earns the greatest financial value of carbon credits and hence incentivizes forest conservation and protection. But methods for Tier 3 Measuring, Reporting, and Verification (MRV) are still in development.

This image shows rapid re-establishment of a young forest with vigorous regrowth after being recently cleared by a commercial harvest.

This image shows rapid
re-establishment of a
young forest with
vigorous regrowth
after being recently
cleared by a commercial
harvest. Courtesy
Christopher A. Williams.

"Our approach," Williams reports, "involves a combination of direct remote sensing, ground-based inventorying, and computer modeling methods to track forest carbon emissions and removals at a 1 km scale across the US. Few existing approaches seek to combine all of these sources of information. By doing so we will be able to deliver a new tool for Tier 3 monitoring and reporting, and because it is specific about the underlying processes driving carbon flows, our framework can be used as a decision-support tool to help test the relative benefits of various land management strategies and how today's carbon sources and sinks will trend over time." Williams will also be taking part in a project titled "Quantification of the regional impact of terrestrial processes on the carbon cycle using atmospheric inversions," being led by Ken Davis of Penn State University. That study, focusing specifically on the southeastern U.S, has been awarded $1,305,964 from NASA's Carbon Cycle Science (CCS), of which $73,973 will go to Clark. Williams will provide information on forest dynamics to complement other data from the agricultural, transportation, and energy sectors.

Maturing forest stands

Maturing forest stands.
Courtesy of Christopher
A. Williams.

Trained as a land surface hydrologist and terrestrial ecosystem ecologist, Williams investigates how earth's biosphere responds to natural and human perturbations such as severe drought events, bark beetle outbreaks, fires, harvesting, and land cover changes. His approach combines field, lab, and remote sensing data with process-based modeling aimed at understanding how terrestrial biophysical and biogeochemical processes are influenced by hydro climatic variability and disturbance. His research spans leaf to global scales, with regional foci on Africa and North America. He is also affiliated with the George Perkins Marsh Institute at Clark, and serves as adjunct in the Department of Biology.