Christopher A. Williams, assistant professor at the Graduate School of Geography at Clark University presented two invited talks and participated in a NASA-sponsored media briefing on “Fire in a Changing Climate and What We Can Do About It,” at the American Geophysical Union’s 45th annual Fall Meeting, Dec. 3-7 in San Francisco. Williams and other Clark University researchers were among more than 20,000 Earth and space scientists, educators, students, and other leaders gathered to present groundbreaking research and connect with colleagues at the AGU meeting.
On Dec. 4, he joined the press briefing and teleconference, then followed with a presentation titled “Fire induced carbon emissions and regrowth uptake in western United States forests: Documenting variation across forest types, fire severity, and climate regions,” his part of a session focused on “Fire as a Biogeochemical Catalyst in the Earth System.” During the AGU media briefing, Williams and other panelists presented NASA satellite data and climate models that indicate drier conditions likely will cause increased fire activity across the United States in coming decades. Other findings about U.S. wildfires, including their amount of carbon emissions and how the length and strength of fire seasons are expected to change under future climate conditions.
As the U.S. land area burned by fire each year has increased significantly in the past 25 years, so too have the emissions. Carbon dioxide emissions from wildfires in the western U.S. have more than doubled since the 1980s, according to Williams. The satellite-based view allowed Williams and his colleagues to quantify how much carbon has been released from fires in the U.S. West.
The team used data on fire extent and severity derived from Landsat satellites to calculate how much biomass is burned and killed, and how quickly the associated carbon was released to the atmosphere.
The team found carbon emissions from fires have grown from an average of 8 teragrams (8.8 million tons) per year from 1984 to 1995 to an average of 20 teragrams (22 million tons) per year from 1996 to 2008, increasing 2.4 times in the latter period.
“With the climate change forecast for the region, this trend likely will continue as the western U.S. gets warmer and drier on average,” Williams said. “If this comes to pass, we can anticipate increased fire severity and an even greater area burned annually, causing a further rise in the release of carbon dioxide.”
On Dec. 5, Williams presented another invited talk titled “Carbon consequences of droughts, fires, bark beetles, and harvests affecting forests of the United States: comparative analysis and synthesis,” part of a session focusing on “Impacts of Extreme Climate Events and Disturbances on Carbon Dynamics” (available as video on demand).
Also at the AGU meeting, Williams co-chaired a session titled “Biosphere-Atmosphere Greenhouse Gas Fluxes in Terrestrial Ecosystems,” the largest session in the area of biogeosciences. Several Clark University scientists contributed at the AGU meeting on different topics:
Williams noted that, as expected, Clark alumni were to be found among the scientists in attendance at the AGU meeting, including Claire Griffin (ES ’10) a former undergraduate researcher in Frey’s Polar Science Research Laboratory (and Polaris Project alumna).
Griffin is in the Ph.D. program at the Marine Science Institute, University of Texas at Austin, continuing her research in Arctic river biogeochemistry and satellite remote sensing.