Earth greening despite deforestation

WHILE the news coming out of forests is often dominated by deforestation and habitat loss, research published in Nature Climate Change shows that the world has actually got greener over the past decade.

Despite ongoing deforestation in South America and South East Asia, we found that the decline in these regions has been offset by recovering forests outside the tropics, and new growth in the drier savannas and shrublands of Africa and Australia.

Plants absorb around a quarter of the carbon dioxide that people release into the atmosphere by burning fossil fuels. With a greening globe, more plants may mean more absorption of carbon dioxide. If so, this will slow but not stop climate change.

However, questions remain over how long plants can keep pace with our increasing emissions in a warmer climate.

We studied how plants and vegetation are faring by determining the amount of carbon stored in living plant mass (or 'biomass') above the ground.

We developed a new technique to map changes in vegetation biomass using satellite measurements of changes in the radio-frequency radiation emitted from the Earths surface, a technique called passive microwave remote sensing. The radiation varies with temperature, soil moisture and the shielding of water in vegetation biomass above the ground.

We extracted this vegetation information from several satellites and merged them into one time series covering the past two decades. This allowed us to track global changes in biomass from month to month, something that was not possible before.

For the period 2003-12, we found that the total amount of vegetation above the ground has increased by about four billion tonnes of carbon.

Our global analysis shows losses of vegetation in many regions, particularly at the frontiers of deforestation in the tropics of South America and South East Asia.

As expected, the greatest declines have been in the so-called 'Arc of Deforestation' on the southeastern edge of the vast Amazon forests. In South East Asia we found the most widespread declines in the Indonesian provinces of Sumatra and Kalimantan - the Indonesian part of Borneo.

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Earth greening despite deforestation