A Global Fire History of the Past Century
Yang, J., Tian, H., Tao, B., Ren, W., Kush, J., Liu, Y. and Wang, Y. 2014. Spatial and temporal patterns of global burned area in response to anthropogenic and environmental factors: Reconstructing global fire history for the 20th and early 21st centuries. Journal of Geophysical Research: Biogeosciences 119: 249-263.
In an attempt to provide what had previously been lacking in this regard, Yang et al., as they describe it, "developed a 0.5° x 0.5° data set of global burned area from 1901 to 2007 by coupling the Global Fire Emission Database version 3 with a process-based fire model and conducted factorial simulation experiments to evaluate the impacts of human, climate and atmospheric components." In doing so the seven scientists found that (1) "the average global burned area was about 442 x 104 km2/yr during 1901-2007," with (2) "a notable declining rate of burned area globally (1.28 x 104 km2/yr)," that (3) "burned area in the tropics and extra-tropics exhibited a significant declining trend, with no significant trend detected at high latitudes," that (4) "factorial experiments indicated that human activities were the dominant factor in determining the declining trend of burned area in the tropics and extra-tropics," that (5) "climate variation was the primary factor controlling the decadal variation of burned area at high latitudes," that elevated CO2 and nitrogen deposition (6) "enhanced burned area in the tropics and southern extra-tropics," but that (7) they "suppressed fire occurrence at high latitudes." Given such findings, it is clear that mankind's various activities constitute by far the most important single factor among the many that have resulted in a net century-long history of ever-decreasing global burned area.