NCAR Imperative 5 Support Decision Making | Population & Fires

A new study by a team of scientists, including experts from CGD, found that the future pattern of population growth, not climate change, is likely to be the dominant factor in determining whether the amount of land burned by fires increases or decreases this century.  NCAR experts in collaboration with colleagues from Lund University in Sweden and the Karlsruhe Institute of Technology in Germany —found that the anticipated increase in total burned area due to a warmer climate will likely be offset by the carbon dioxide itself, which can act as a fertilizer, affecting plant growth and driving down fire risk globally.

When climate change, carbon dioxide concentration, and population are all considered, the total area burned across the globe could very well decrease over the rest of this century, according to the study, published in the journal Nature Climate Change.

 Climate change generally increases global fire risk by drying the fuel — trees, grasses, and other vegetation — that feeds the flames.  At the same time, the additional carbon dioxide in the atmosphere tends to decrease global fire risk, largely by encouraging the growth of shrubs in areas that are now grasslands. On average, more than 70 percent of the total area burned each year across the world is on grassland savannah, where fire can spread very quickly. As shrubs encroach, they fragment the grassland and create natural firebreaks.  People, on the other hand, have a complex effect on fire risk. In general, humans suppress fires more than they ignite them, leading to an overall downward trend in acres burned when population increase is considered on its own, the study found. This helps explain why global burned area has actually decreased over the last century, despite a warming climate, Jiang said.

Grassland fire
A grass fire burns through an open area. September 1983. Photo credit: CSIRO, Malcolm Paterson