The impacts of climate, land use, and demography on fires during the 21st century simulated by CLM-CN 1Land in the Earth System, Max Planck Institute for Meteorology, Hamburg, Germany
26 Jan 2012
2Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
3Department of Earth System Science, University of California, Irvine, CA, USA
4National Center for Atmospheric Research, Boulder, CO, USA
Received: 15 August 2011 – Published in Biogeosciences Discuss.: 28 September 2011 Abstract. Landscape fires during the 21st century are expected to change in response to
multiple agents of global change. Important
controlling factors include climate controls on the length and intensity of
the fire season, fuel availability, and fire management, which
are already anthropogenically perturbed today and are predicted
to change further in the future. An improved understanding of future fires will
contribute to an improved ability to project future anthropogenic climate
change, as changes in fire activity will in turn impact climate.
Revised: 20 December 2011 – Accepted: 03 January 2012 – Published: 26 January 2012
In the present study we used a coupled-carbon-fire model to investigate how
changes in climate, demography, and land use may alter fire emissions. We used
climate projections following the SRES A1B scenario from two different climate
models (ECHAM5/MPI-OM and CCSM) and changes in
population. Land use and harvest rates were
prescribed according to the RCP 45 scenario. In response to the combined
effect of all these drivers, our model estimated, depending on our choice of
climate projection, an increase in future (2075–2099) fire carbon emissions by
17 and 62% compared to present day (1985–2009). The largest increase in fire
emissions was predicted for Southern Hemisphere
South America for both climate projections. For Northern Hemisphere Africa, a region that contributed
significantly to the global total fire carbon emissions, the response varied
between a decrease and an increase depending on the climate projection.
We disentangled the contribution of the single forcing factors to the overall
response by conducting an additional set of simulations in which each factor
was individually held constant at pre-industrial levels. The two different
projections of future climate change evaluated in this study led to increases
in global fire carbon emissions by 22% (CCSM) and 66% (ECHAM5/MPI-OM). The RCP 45
projection of harvest and land use led to a decrease in fire carbon emissions
by −5%. The RCP 26 and RCP 60 harvest and landuse projections caused decreases around −20%. Changes in human ignition led to an increase of 20%.
When we also included changes in fire management efforts to suppress fires in densely populated
areas, global fire carbon emission decreased by −6% in response to changes in population density.
We concluded from this study that changes in fire emissions in the future are
controlled by multiple interacting factors. Although changes in climate led to an increase
in future fire emissions this could be globally counterbalanced by coupled
changes in land use, harvest, and demography.
Citation: Kloster, S., Mahowald, N. M., Randerson, J. T., and Lawrence, P. J.: The impacts of climate, land use, and demography on fires during the 21st century simulated by CLM-CN, Biogeosciences, 9, 509-525, doi:10.5194/bg-9-509-2012, 2012.