In 1999, emissions from land clearing are estimated at 89.7 Mt with just under half coming from soil emissions. This was offset by a 18.0 Mt sink from vegetation regrowth. Though the estimates of annual emissions and the extent of reductions over time should be treated with caution, the information does indicate a decline in emissions from land clearing from 1990 to 1999. Presently available data indicate a considerable decline in land clearing from the 1970s to the 1980s and again from the 1980s to the early 1990s. Remote sensing and other analyses are being undertaken to gain a better picture of past clearing activity.
Land clearing is the most uncertain part of the Inventory.
In recent years, measurement of land use change has moved from relying on surveys and judgements of the actual uptake of clearing permits, to assessing the variations between sets of satellite images recorded at different times. The methodology is continually evolving. Data on historical and current rates of land clearing are being improved through ongoing research and better data acquisition and analysis. As more images are analysed and the process refined, confidence will increase in estimates of clearing rates. Work is also continuing on matching the location of clearing activities with vegetation and soil types to improve estimates of the amount of carbon that was stored.