The share of nitrous oxide in total AFOLU emissions is small, but accounts for as much as 75 percent of global anthropogenic emissions of the gas. Organic soils (those with a high concentration of organic matter, such as peatlands) and the burning of biomass (e.g. savanna fires) account for relatively smaller amounts of emissions. Forests also mitigate climate change by removing GHG from the atmosphere through forest growth, as seen in the negative values. However, the average contribution of forests to carbon sequestration has fallen from 2.8 Gt annually in the 1990s to 2.3 Gt in the 2000s, and is estimated at 1.8 Gt in 2014.