Earth’s landscape has been subjected to both natural and anthropogenic fires for millions of years.
Natural, lightning-caused fires are known to have occurred in geological time continuously at least since the late Silurian epoch, 400 million years ago, and have shaped the evolution of plant communities.
Hominids have used controlled fire as a tool to transform the landscape since about 700,000 years ago. These hominids were Homo erectus, ancestors of modern humans. Paleofire scientists, biogeographers and anthropologists all agree that hominid use of fire for various purposes has extensively transformed the vegetation of Earth over this period.
The nature of Earth’s modern-day biomes would be substantially different if there had been no fires at all. William Bond and colleagues (2005) used a Dynamic Global Vegetation Model to simulate the area under closed forest with and without fire. They estimated that in the absence of fire, the area of closed forest would double from the present 27% to 56% of present vegetated area, with corresponding increase in biomass and carbon stocks. This would be at the expense of C4 grasslands and certain types of shrub-land in cooler climates.