Atmospheric scientists at Harvard's School of Engineering and Applied Sciences (SEAS) and their colleagues have determined that as the climate warms in the coming decades, the frequency of wildfires will increase in many regions.
SEAS Senior Research Fellow Jennifer Logan led the study.
In their pioneering work, Logan and her collaborators investigated the consequences of climate change on future forest fires and on air quality in the western United States.
"Warmer temperatures can dry out underbrush, leading to a more serious conflagration once a fire is started by lightening or human activity," said Logan. "Because smoke and other particles from fires adversely affect air quality, an increase in wildfires could have large impacts on human health," she added.
Using a series of models, the scientists predict that the geographic area typically burned by wildfires in the western United States could increase by about 50 percent by the 2050s due mainly to rising temperatures.
The greatest increases in area burned (75-175 percent) would occur in the forests of the Pacific Northwest and the Rocky Mountains.
In addition, because of extra burning throughout the western US, one important type of smoke particle, organic carbon aerosols, would increase, on average, by about 40 percent during the roughly half-century period.
To conduct the research, the team first examined a 25-year record of observed meteorology and fire statistics to identify those meteorological factors that could best predict area burned for each ecosystem in the western US.
To see how these meteorological factors would change in the future, they then next ran a global climate model out to 2055, following the A1B scenario in greenhouse gas emissions.his scenario, one of several devised by the Intergovernmental Panel on Climate Change, describes a future world with rapid economic growth and balanced energy generation from fossil and alternative fuels.
Relative to the other scenarios, it leads to a moderate warming of the earth's average surface temperature, about 3oF (1.6 oC) by 2050.
"By hypothesizing that the same relationships between meteorology and area burned still hold in the future, we then could predict wildfire activity and emissions from 2000 to the 2050's," explained Logan.
As a last step, the researchers used an atmospheric chemistry model to understand how the change in wildfire activity would affect air quality.his model shows the emissions and fate of the smoke and other particles emitted by the future wildfires.
The resulting diminished air quality could lead to smoggier skies and adversely affect those suffering from lung and heart conditions such as asthma and chronic bronchitis.