A fifth of the Amazon rainforest now emits more carbon dioxide than it absorbs thanks to deforestation and forest fires, researchers have discovered.
The team has been monitoring greenhouse gas emissions over the Amazon for the past ten years, with millions of trees lost.
While tree growth absorbs carbon dioxide from the atmosphere – traditionally turning the forest into a carbon storage facility or ‘sinking’ – dead trees release it instead.
The team is concerned that the Amazon will turn into a net carbon source sooner than expected and will soon reach a tipping point from where it will not recover.
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A fifth of the Amazon rainforest now emits more carbon dioxide than it absorbs thanks to deforestation and forest fires, researchers have discovered
Climate researcher Luciana Gatti of the Brazilian National Institute for Space Research and colleagues have been studying greenhouse gases in the Amazon for 10 years.
Every two weeks the researchers fly sensor-laden aircraft through the rainforest and map their findings.
Although the team discovered that much of the rainforest is still capable of absorbing large amounts of carbon dioxide – and even more so in wetter years – they identified a large area that has been aggressively deforested and has lost this ability.
In fact, this southeastern part of the forest – which makes up one fifth of the total area – has become a source of carbon emissions, rather than a so-called ‘sink’, thanks to the trees dying off and releasing carbon into the atmosphere.
“Every year is worse,” Professor Gatti told BBCs Newsnight.
“We have established that this area in the southeast is an important carbon source. And it doesn’t matter if it is a wet year or a dry year. 2017-18 was a wet year, but it made no difference. “
The team has been monitoring greenhouse gas emissions over the Amazon for the past ten years, during which time millions of trees have been lost
“[The Amazon] was a very strong carbon well in the eighties and nineties, which removes maybe two billion tons of carbon dioxide from the atmosphere every year, “co-author Carlos Nobre of the University of Sao Paulo told the BBC.
“Nowadays, that power might be reduced to 1-2 billion tons of carbon dioxide a year,” he added – a figure that corresponds to three times the UK emissions in 2018.
However, this does not explain the opposite release of carbon dioxide caused by both deforestation and forest fires.
Deforestation rates have risen considerably in recent years, following the reductions observed in the last decade.
Last year in particular was particularly bad for the rainforest, which lost more than 1,000 square kilometers every month between July and September.
Brazilian President Jair Bolsonaro has made development in the Amazon a priority at the expense of rainforest conservation efforts.
The team is concerned that the Amazon will turn into a net carbon source sooner than expected and will soon reach a tipping point from where it will not recover
Experts are concerned that the rainforest eventually loses the ability to renew itself and starts emitting more carbon dioxide than it takes up – a threshold called the “Amazon’s tipping point.”
For Professor Nobre, the findings of his team are “very worrying” because he fears that the situation they are now observing might represent the turning point approach.
Over the next 30 years, he said, more than half of the Amazon rainforest could be turned into savannah instead.
“In our calculations, if we exceed deforestation by 20-25 percent and global warming continues unabated with high emission scenarios, the tipping point would be reached,” Professor Nobre told the BBC.
“Today we are around 17 percent,” he added.
There is some disagreement among experts as to when the tipping point can be reached, Simon Lewis, geographer from University College London, told the BBC.
“Some people think it’s only heating up three degrees – so by the end of the century,” he said.
“While other people think we can get [it with] deforestation above 20 percent or so and that can happen in the next decade or two. “
“So it’s really, really uncertain.”
Professor Lewis, however, noted that the results of the latest study were “shocking,” especially given that they are based on practical observations rather than models.
“It tells me that this may be more short-lived than I initially thought,” he added.
MAP DISCLOSES THE IMMEDIATE PERFORMANCE REPORTING AROUND THE BOL
Using Landsat images and cloud computing, researchers mapped forest cover worldwide, as well as forest loss and growth. For 12 years, 888,000 square miles (2.3 million square kilometers) of forest were lost and 309,000 square miles (800,000 square kilometers) re-grown
The destruction caused by deforestation, forest fires and storms on our planet has been revealed in unprecedented details.
High-resolution maps published by Google show how worldwide forests experienced a total loss of 1.5 million km² during 2000-2012.
In comparison, that is a loss of forested land that is the same size as the entire state of Alaska.
The maps, made by a team from NASA, Google and the researchers from the University of Maryland, used images from the Landsat satellite.
Each pixel in a Landsat image shows an area the size of a baseball diamond and provides enough data to zoom in on a local region.
Previously, country-to-country comparisons of forestry data were not possible at this accuracy level.
“When you compile datasets that use different methods and definitions, it’s hard to synthesize,” said Matthew Hansen at the University of Maryland.