New Study Uses Satellite Data to Revise Estimates of Tropical Deforestation


Home / New Study Uses Satellite Data to Revise Estimates of Tropical Deforestation

New research calculates the extent of the Earth’s tropical forests: photo by Michael Cory

Think of carbon emissions, and you probably think of fossil fuels – but you might also think of deforestation.

Tropical forests are a significant store (or sink) of atmospheric carbon dioxide, and their loss is regarded as a main contributor to increasing atmospheric carbon dioxide levels.

Estimating the extent of this loss has, however, been problematic.

Now, new research, published today in Science, provides a more accurate estimate of the extent of deforestation – and some of the results are surprising.

The Carbon Cycle: Why Forests Are Important

Any ecologist will tell you that forests are important in terms of controlling climate change. Here’s why: forests form a natural ‘sink’ for atmospheric carbon dioxide. Plants grow through the process of photosynthesis, in which they use sunlight to convert carbon dioxide into energy for growth. Not only does this process release oxygen into the atmosphere – sustaining life – but it also removes atmospheric CO2.

We can’t say for certain how much carbon is stored in the earth’s plants, but estimates published by the Open University suggest that it’s around two thirds of that in the atmosphere – and if other organic matter (such as soil and dead leaves) is included, the proportion is much, much higher.

Estimating The Emissions From Tropical Rainforest: Study Results

Research from the environmental organization Winrock International has used satellite observations to estimate the present extent of deforestation and of existing forest stocks – and at first sight, it isn’t bad news. “Our estimates of carbon emissions from tropical deforestation are about one-third of previous estimates,” study leader Dr. Nancy Harris told Decoded Science.

Deforestation in southern Mexico:  image by Jami Dwyer

So, does this mean we are beginning to succeed in tackling the problems of deforestation and their contribution to atmospheric CO2? Unfortunately, probably not. The differences, according to Dr. Harris, are “primarily due to the availability of more accurate satellite data and a more consistent methodological approach.” And better data don’t mean there’s no longer a problem:  “Emissions from deforestation are still occurring, and this is still problematic with respect to global climate change,” she said.

Applying the Study Findings

The Winrock International study was undertaken with the purpose of establishing an accurate baseline against which a compensation program can be undertaken, so that developing countries are rewarded for reducing their levels of deforestation. But, there are wider potential applications within the field of climate change.

Satellite data has allowed us to sharpen the overall picture of tropical deforestation and pinpoint locations where carbon emissions are highest,” said Dr. Harris, making this research “useful for a better understanding of where deforestation is happening and what the impact of that deforestation is in terms of carbon emissions to the atmosphere.” That makes this information a potential contributor to reducing both deforestation and atmospheric carbon dioxide.


Harris, N. et al. Baseline Map of Carbon Emissions from Deforestation in Tropical Regions. (2012). Science. Accessed June 21, 2012.

Colling, A., Dise, N., Francis, P., Harris, N. and Wilson, C. The Dynamic Earth. (1997). Milton Keynes. The Open University.

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