Deforestation Impact Calculator

Clearing a forest does not release all of its carbon, and how much escapes depends almost entirely on what the land becomes afterwards. Conversion to cropland or pasture typically mobilises around 90 percent of the biomass carbon because residues are burned or decay within a few seasons, while urbanisation approaches complete loss and mining removes both vegetation and soil profile. Selective logging is far lower, on the order of half, since stumps, roots, and unmerchantable material remain on site and a portion of the harvested carbon is locked into sawn timber and panels for decades. Ecosystem carbon density differs sharply by forest type: tropical rainforest holds roughly 200 tonnes of carbon per hectare in biomass over about 100 in soil, boreal forest inverts that ratio with only about 60 in biomass but 150 or more in cold, waterlogged soil, and mangroves are the extreme case, storing the majority of their 350 tonnes per hectare in deep anoxic sediments. Carbon is converted to carbon dioxide using the 44 over 12 molar ratio. Soil carbon is treated separately because it does not vent immediately. After conversion, tropical topsoils commonly lose something like a quarter to a half of their organic carbon over the first two to three decades rather than at once, so applying the full stock as an instantaneous emission overstates near-term flux. The biodiversity, erosion, runoff, and monetary figures are order-of-magnitude ecosystem service transfers, not site measurements, and species at risk means local population loss rather than global extinction.

Systematic accounting of forest loss began with inventory rather than climate concern. The Food and Agriculture Organization compiled its first world forest inventory in 1948 and has issued Global Forest Resources Assessments on a recurring cycle ever since, initially depending on national reporting of widely varying quality. The climate dimension arrived in the 1970s and 1980s, when Richard Houghton, George Woodwell, and colleagues built bookkeeping models that tracked carbon through land conversion by combining land use change statistics with per hectare carbon stocks and decay curves for biomass, products, and soil. That structure, area multiplied by density multiplied by a release fraction, is still the backbone of the calculation. Satellite observation replaced reporting as the primary evidence base. Landsat 1 launched in 1972 and its successors accumulated the multi-decadal archive that made change detection possible. Brazil began annual Amazon deforestation mapping through the PRODES programme at its National Institute for Space Research in 1988, adding the near real time DETER alert system in 2004. In 2013 Matthew Hansen and collaborators published a global 30 metre forest change dataset in Science, which became the basis of the World Resources Institute Global Forest Watch platform launched the following year. Valuation of the non-carbon losses draws on the ecosystem services literature that followed Robert Costanza and colleagues in 1997, while monetised climate damage uses social cost of carbon estimates, notably the figure of about 51 dollars per tonne adopted by the United States interagency working group in 2021.