The loss of pristine tropical forests has a far greater impact on climate change than previously thought, scientists have warned.
Analysis led by the University of Queensland in Australia suggests that once all the emissions associated with clearing intact tropical forests are taken into account, the impact on the climate is more than six times worse than thought.
The researchers looked at the loss of intact tropical forests – tracts of woods which are free of significant human activity – between 2000 and 2013.
They examined not only the immediate carbon emissions of clearing and burning woods usually used as a measure, but also estimated other impacts.
These include selective logging within the forests, the impacts of fragmentation and damage to the edge of wooded areas and even the decline of trees as a result of a reduction in the wildlife who spread their seeds.
The study, published in the journal Science Advances, also took into account the carbon that would have been stored by the forests that were lost between 2000 and 2013 if they had remained intact up to 2050.
University of Queensland conservation scientist Dr Sean Maxwell said: “Usually only ‘pulse’ emissions are considered – these are emissions released the instant intact forest is destroyed.
“Our analysis considers all impacts such as the effects of selective logging, forgone carbon sequestration, expanding effects on the edges of forests, and species extinction.
“We were shocked to see that when considering all of the available factors, the net carbon impact was more than six times worse for the climate.”
And he said: “Our results revealed that continued destruction of intact tropical forests is a ticking time bomb for carbon emissions.
“There is an urgent need to safeguard these landscapes because they play an indispensable role in stabilising the climate.”
The researchers said the difference equated to two years of emissions from changes to land use across the world.
In 2013, there were 549 million hectares of intact tropical forest remaining globally, but the researchers warn they are being lost at an increasing rate and the opportunity to use them to curb climate change was dwindling.
Most of the focus for conserving forests to reduce emissions is on curbing clearance in areas with high historical rates of deforestation, or on restoration.
But the University of Queensland and Wildlife Conservation Society’s Professor James Watson said the study’s approach better captured the true carbon impact of the loss of intact forests.
“Humanity needs to better fund the conservation of intact forests, especially now we’ve shown their larger-than-realised role in stabilising the climate.
“Our study will hopefully mobilise more funding from the climate finance sector, improving and expanding efforts to retain intact forests across the tropics,” he said.
The study’s authors included experts from the University of Queensland, Wildlife Conservation Society, University of Oxford, Zoological Society of London, World Resources Institute, University of Maryland and University of Northern British Columbia.