We used a new, 100-year, 1 ¿ 1¿ global fire map and a carbon cycle model (CASA) to provide a yearly gridded estimate of the temporal trend in carbon emissions due to wildfires through the 20th century. 2700--3325 Tg C y-1 burn at the end of the 20th century, compared to 1500--2700 Tg C y-1 at the beginning, with increasing uncertainty moving backward in time. There have been major changes in the regional distribution of emissions from fires, as a consequence of i) increased burning in tropical savannas and ii) a switch of emissions from temperate and boreal forests towards the tropics. The frequently-used assumption that pre-industrial emissions were 10% of present biomass burning is clearly inadequate, in terms of both the total amount and the spatial distribution of combustion.