World’s forests cover 9% more space than previously assessed

Two workers wearing safty helmets cleaning solar panels on a rooftop

Primary forest in the Amazon basin from the air. Photo: Oliver Hölcke/IKI

The current estimates of the size of the forest cover worldwide are to be increased by at least 9%, which may lead to new calculations of the global carbon budget. A study coordinated by the Food and Agriculture Organization of the United Nations (FAO), carried out in cooperation with Google Inc. and 16 leading organisations and supported substantially by the German Federal Environment Ministry (BMUB) through its International Climate Initiative (IKI) has produced new results.

The new data were obtained thanks to precise measurement techniques based on satellite data and special photo interpretation methods. Measurements of forests in arid zones, which make up 41.5% of Earth’s land mass and host some of its most sensitive and endangered ecosystems, have not been sufficiently accurate up to now.  With advancing global warming, the arid zones could expand by another 11-23% by the end of the 21st century and would then cover over half of the world’s land.

Thanks to the high-resolution photo measurement techniques, which utilise access to Google’s large up-to-date photo databases and computing capacities through the Collect Earth tool the company developed with FAO, experts were able to show that in 2015, 1.327 million hectares of arid regions had 10% tree cover and accounted for 1.079 million hectares of forest. In total, 239 specially trained local experts around the world have interpreted and evaluated 213,795 sample parcels of land with the software.

The results exceed previous estimates by around 40 to 47 per cent. Overall this corresponds to 467 million hectares of additional forest globally that has never been recorded. It is around the size of the Amazon rainforest and is located in regions that were partially not regarded as forests up to now. This could result in future opportunities to expand forest protection measures to other new regions, better define them geographically and track them, and address drivers of deforestation more effectively.

The projects Global Forest Survey and National Forest Monitoring Systems are being financed by the IKI of the BMUB and are currently carrying out data collection on forests and land-use trends in arid regions and for all ecosystems on land masses worldwide.

The most significant results of this study were featured today, 12 May, in the renowned scientific journal Science. Its publisher is the largest scientific association in the world, the Association for the Advancement of Science.