By Nigel Sizer, Rachael Petersen, James Anderson, Matt Hansen, Peter Potapov, and David Thau
2 April 2015
(WRI) – New, high-resolution satellite-based maps released today by the University of Maryland and Google on Global Forest Watch, a partnership of over 60 organizations convened by the World Resources Institute, reveal a significant recent surge in tree cover loss largely in Russia and Canada during 2013. There is also some good news, with a slowing of tree cover loss in Indonesia, though rates of loss continue a troubling rise across the tropics as a whole. These 2013 data are the first annual update to the influential “High-Resolution Global Maps of 21st-Century Forest Cover Change” published in Science, and are the latest globally consistent estimates of tree cover loss available.
So what do the data say? Much analysis remains to be done, but here are five immediate highlights:
Global tree cover loss in 2013 continued to be high at over 18 million hectares (69,500 square miles)—about twice the size of Portugal—slightly lower than 2012, but a troubling 5.2 percent increase over the 2000-2012 average. In 2011-2013, Russia and Canada topped the list (mostly due to forest fires), jointly accounting for 34 percent of total loss.
Tree cover loss is a measure of the total loss of all trees within a specific area regardless of the cause. It includes human-driven deforestation, forest fires both natural and manmade, clearing trees for agriculture, logging, plantation harvesting, and tree mortality due to disease and other natural causes. Tree cover gain also happened during 2013, but is not included in the 2013 update or this analysis as it is more difficult to monitor than loss. Much of the tree cover loss is only temporary, as forests regenerate after disturbances such as fire, though in the boreal region this is a very slow process.
The new maps show a recent increase in tree cover loss in parts of the world’s boreal forests in Russia, Canada and Alaska. Although the tropics had more tree cover loss overall, the boreal region showed the steepest increase of loss of any region. Russia (which at 882 million hectares has the biggest area of tree cover in the world) lost an average of 4.3 million hectares (16,600 square miles) of tree cover per year between 2011 and 2013, an area larger than Switzerland. Fires in the boreal are partly natural (natural fire dynamics play an important role in boreal forests) and partly man-made, with climate change and infrastructure increasingly having an impact. The forest will grow back, but this process takes centuries. [more]