Fires are ravaging the forests of Russia and Canada, burning at a higher rate in some cases than at any time in the past 10,000 years.
High-resolution satellite maps from Global Forest Watch showed the two nations lost a combined average of nearly 6.8 million hectares (26,000 square miles) per year between 2011 and 2013. That equates to an area equivalent to the size of Ireland.
"This new data shows in detail how Russia and Canada have faced a massive spike in tree cover loss," said Nigel Sizer, the global director of forest programs for the World Resources Institute, which is the lead organization in Global Forest Watch.
The new data comes from the University of Maryland and Google, and represent the largest and most up-to-date global data set for tree cover loss available to researchers.
"These forests and soils contain vast carbon stocks so losses represents a significant contribution to the greenhouse gas emissions that are driving climate change," he said. "As we head toward the pivotal 2015 climate summit in Paris, more attention is needed (to manage) and monitor boreal forests."
The researchers said about 70 percent of the tree cover loss was blamed on fires - some driven by the warmer temperatures brought by climate change - as well as pests like pine beetles that have laid waste to huge chunks of evergreen forests.
Bigger than the Amazon, these so-called boreal forests, located in the far north latitudes, are the largest terrestrial ecosystem in the world. The fires not only destroy forests but also torch the peatlands that anchor parts of these forests. That, in turn, releases huge amounts of carbon into the atmosphere, which further contributes to global warming.
"This should be a clear call to action to look closely at forest management in Russia and Canada in the face of climate change," said Olga Gershenzon, board chair of the Russian NGO Transparent World and founder of ScanEx, a Russian commercial satellite imagery company that is part of the project. "The massive tree cover loss shows there is much to be improved in terms of monitoring and understanding the causes and types of forest fires, as well as making information about fires available to the public in real time along with maps of land allocation and responsibility."
Alain Cacchione, a spokesman for Natural Resources Canada, the country's environment ministry, said the findings confirm what Canadian authorities had reported in the past - that areas of Canada burned by wildfires in 2013 was double the 10-year average.
But Cacchione took pains to make clear the forest loss in Canada shouldn't be lumped in with deforestation - which is rampant in places like Brazil and Indonesia.
"Wildland fires are part of the natural forest cycle - particularly in the boreal forest - and play an important role in maintaining forest health and biodiversity," he said in a statement. "The vast majority of forest cover loss in Canada is the result of wildfires and insect disturbances, not harvesting. In 2012, for example, fire and insect outbreaks alone affected about 17 times more forest than harvesting."
The forest loss in these two countries - 4.3 million hectares and 2.5 million hectares respectively - accounted for more than a third of the tree cover loss globally.
The remainder of the more than 18 million hectares (69,500 square miles) lost included the deforestation in Brazil and Indonesia - which have the world's highest rates - as well as commercial tree harvesting in the United States.
Deforestation across the globe has intensified 62 percent in the past two decades.