A new high-resolution global map of forest loss and gain has been created with the help of Google Earth.
The interactive online tool is publicly available and zooms in to a remarkably high level of local detail - a resolution of 30m.
It charts the story of the world's tree canopies from 2000 to 2012, based on 650,000 satellite images by Landsat 7.
In that time, the Earth lost a combined "forest" the size of Mongolia, enough trees to cover the UK six times.
End Quote Prof Matthew Hansen University of Maryland
This is the first map of forest change that is globally consistent and locally relevant”
Brazil's progress in reducing deforestation was more than offset by losses in Indonesia, Malaysia, Paraguay and Angola, according to a study in the journal Science.
"This is the first map of forest change that is globally consistent and locally relevant," said Prof Matthew Hansen of the University of Maryland, who led the project team which developed the map.
"What would have taken a single computer 15 years to perform was completed in a matter of days using Google Earth Engine computing."
Their study reports a number of key findings on forest change from 2000-2012 - based on the satellite imagery.
The Earth lost 2.3 million square kilometres of tree cover in that period, due to logging, fire, disease or storms.
But the planet also gained 800,000 sq km of new forest, a net loss of 1.5 million sq km in total.
Brazil showed the best improvement of any country, cutting annual forest loss in half between 2003-04 and 2010-11.
Indonesia had the largest increase in deforestation, more than doubling its annual loss to nearly 20,000 sq km in 2011-12.
In the United States, the "disturbance rate" of south-eastern forests was four times that of South American rainforests - more than 31% of forest cover was either lost or regrown.
Paraguay, Malaysia and Cambodia had the highest national rates of forest loss.
Overall, tropical forest loss is increasing by about 2,100 sq km per year, the researchers said.
The map will be updated annually and could be used to assess the effectiveness of forest management programmes.
It could also help environmental groups monitor the impacts of deforestation - including biodiversity threats, carbon storage and climate change.
"This new monitoring approach can for the first time provide - on a global scale - transparent accountability for monitoring progress toward achieving real declines in deforestation," said Daniel Zarin, of the Climate and Land Use Alliance.