Determination of the deforestation rates of the world's humid tropical forests

August 13, 2002

Ispra, Italy, 9 August 2002

Reliable data on the change in forest cover for the humid tropics help reduce the uncertainty in the calculation of carbon fluxes to and from the atmosphere, which is essential for estimating the extent of global climate change.

A team of scientists from the IES Global Vegetation Monitoring and Land Management units, together with collaborators from the British company Conservation Technology Limited and the JRC Directorate of Science Strategy, now has completed a research programme (TREES) employing the global imaging capabilities of Earth-observing satellites for obtaining updated information on the status of the world's humid tropical forest cover.

A new statistical sampling strategy using satellite imagery provides a reliable measurement of forest cover in a uniform, independent, and repeatable manner.

Between 1990 and 1997, 5.8 ± 1.4 million hectares of humid tropical forest were lost each year, with a further 2.3 ± 0.7 million hectares of forest visibly degraded. These figures indicate that the global net rate of change in forest cover for the humid tropics is 23% lower than standard estimates of the Food and Agriculture Organisation (FAO) of the UN that are mainly based on expert opinions and secondary information from the countries concerned.

Using some long-term models for biomass conversion into CO2, the JRC scientists estimate a maximum of about 0.96 gigatons/year of net carbon emissions into the atmosphere from land-use change in the tropics. This value is far lower than estimates reported by the Intergovernmental Panel on Climate Change (IPCC) for the years 1989 to 1998.

A full report of this work has been published in today's Vol 297 of the magazine Science. Information on the JRC Institutional project Global Environment Information System (GEIS) can be found here


Joint Research Centre

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