Fires could turn Amazon rainforest into a desert as human activity and climate change threaten ‘lungs of the world’, says study

Drying out of the rainforest threatens to ignite the tree-filled habitat – with its rich biodiversity – and convert it almost overnight into barren desert

Science Editor

The Amazon rainforest is becoming increasingly vulnerable to catastrophic forest fires due to a combination of droughts, climate change and human activities such as deforestation, farming and habitat fragmentation, a major study has concluded.

One of the last great wildernesses on earth – known as the lungs of the world – is balancing dangerously close to a “tipping point” where forest fires will become so commonplace and extensive that they will change much of the landscape forever, scientists said.

Although fires have always occurred in Amazonia, they have been largely controlled by the natural humidity of the region. Now, however, the drying out of the rainforest threatens to ignite the tree-filled habitat – with its rich biodiversity – and convert it almost overnight into barren desert, they warned.

For the first time, scientists have shown in experiments on the ground how extreme, dry weather combined with the effects of human activities can create a tinderbox environment where intensely damaging forest fires can spread easily, killing trees that have taken hundreds of years to grow.

The study, carried out on three large experimental plots of rainforest monitored by satellite, showed that droughts abruptly increased the risk of intense forest fires compared to non-drought years, and this effect can be exacerbated significantly in areas influenced by human activities.

“These results provide, to our knowledge, the first experimental evidence of the link among extreme weather events, widespread and high-intensity fires and associated abrupt changes in forest structure, dynamics and composition,” said the scientists from the US and Brazil.

“This mechanism of rapid forest degradation could operate over a larger geographical area, such as the ‘arc of deforestation’, where droughts, forest fragmentation and forest fires are already common,” they said in a study published in the journal Proceedings of the National Academy of Sciences.

The researchers monitored the three 50-hectare plots of Amazon rainforest over an eight-year period. During this time they subjected two of the plots to controlled fires, either on an annual or a three-year basis, and left the third plot untouched as a control for comparison.

They found that while the rainforest did not burn very much in years with normal rainfall, it burned intensively and extensively in drought years, which are expected to increase in both frequency and severity due to climate change causing shorter, more intense rainy seasons and longer dry seasons.

Trees in the tropical rainforests, unlike more temperate woodlands, are not naturally immune to forest fires and are easily killed by flames. The study found that this vulnerability caused a collapse of the overhead canopy cover and an invasion of the forest by more flammable vegetation from the inhabited forest edges, causing a cascade of events that increased the chances of an irreversible “tipping point” triggered by fire.

“Agricultural development has created smaller forest fragments, which exposes forest edges to the hotter dryer conditions in the surrounding landscape and makes them vulnerable to escaped fires,” said Marcia Macedo of the Woods Hole Research Centre in Falmouth, Massachusetts.

“These fragmented forests are more likely to be invaded by flammable grasses, which further increase the likelihood and intensity of future fires,” Dr Macedo said.

The researchers emphasised that most computer models of how the Amazon will respond to climate change do not take into account the true scale of the threat posed by forest fires, which is a serious flaw in the assessment of what could happen over the coming decades of warmer global temperatures.

“This study shows that fires are already degrading large areas of forests in southern Amazonia and highlights the need to include interactions between extreme weather events and fire when attempting to predict the future of Amazonian forests under a changing climate,” said Paulo Brando of the Instituto de Pesquisa Ambiental da Amazonia in Belem, Brazil, and lead author of the study.

Over the past 10 years, the Amazon has experienced several unusual droughts. In 2005, a drought occurred over a wide area that was calculated to be a one-in-100-year event, however, an even more extensive drought occurred in 2010.

On both occasions, scientists believe the Amazon went from being a net absorber of carbon dioxide to a net producer. In 2005, for instance, researchers calculated that it turned from being a net absorber of about 2 billion tonnes of CO2 to a net producer of as much as 5bn tonnes of CO2 – almost as high as the 5.4bn tonnes emitted annually by the US.

However, in the drought of 2010 was far larger, causing the massive Rio Negro river – the biggest tributary of the Amazon – to fall to its lowest level since record began more than a century ago. On this occasion, the forest expelled some 8 billion tonnes net of CO2, scientists said.

A more regional drought in 2007, which mainly affected southeast Amazonia, caused a significant increase in forest fires in the area, which burned about 10 times more forest than in typical years – an area equivalent to a million soccer fields.

The scientists believe that the findings show that the response of the Amazon to rising global temperatures and the increased risk of severe drought years can be unpredictable and “non-linear” because of a sudden breach of an irreversible tipping point.

“None of the models used to evaluate future Amazon forest health include fire, so most predictions grossly underestimate the amount of tree death and overestimate overall forest health,” said Michael Coe, another Woods Hole researcher and member of the joint US-Brazil team.

PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
News
ebooksAn evocation of the conflict through the eyes of those who lived through it
Extras
indybest
Travel
Flocking round: Beyoncé, Madame Tussauds' latest waxwork, looking fierce in the park
travelIn a digital age when we have more access than ever to the stars, why are waxworks still pulling in crowds?
Arts and Entertainment
tv
Arts and Entertainment
Judi Dench appeared at the Hay Festival to perform excerpts from Shakespearean plays
tvJudi Dench and Hugh Bonneville join Benedict Cumberbatch in BBC Shakespeare adaptations
Sport
Is this how Mario Balotelli will cruise into Liverpool?
football
News
Ronahi Serhat, a PKK fighter, in the Qandil Mountains in Iraqi Kurdistan
i100
Arts and Entertainment
Poet’s corner: Philip Larkin at the venetian window of his home in 1958
booksOr caring, playful man who lived for others? A new book has the answer
Arts and Entertainment
Exhibition at the Centre Pompidou in Metz - 23 May 2012
art
News
Matthew McConaughey and his son Levi at the game between the Boston Red Sox and the Houston Astros at Fenway Park on August 17, 2014 in Boston, Massachusetts.
advertisingOscar-winner’s Lincoln deal is latest in a lucrative ad production line
Life and Style
Pick of the bunch: Sudi Pigott puts together roasted tomatoes with peppers, aubergines and Labneh cheese for a tomato-inspired vegetarian main dish
food + drink
Arts and Entertainment
Alfred Molina, left, and John Lithgow in a scene from 'Love Is Strange'
film
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Junior Quant Analyst - C++, Boost, Data Mining

£25000 - £35000 per annum: Harrington Starr: Junior Quant Analyst - C++, Boost...

Service Desk Analyst- (Desktop Support, Help desk)

£25000 - £35000 per annum: Harrington Starr: Service Desk Analyst- (Desktop Su...

Junior Quant Analyst (Machine Learning, SQL, Brokerage)

£30000 - £50000 per annum: Harrington Starr: Junior Quant Analyst (Machine Lea...

UNIX Application Support Analyst- Support, UNIX, London

£45000 - £55000 per annum: Harrington Starr: UNIX Application Support Analyst-...

Day In a Page

Air strikes? Talk of God? Obama is following the jihadists’ script

Air strikes? Talk of God? Obama is following the jihadists’ script

The President came the nearest he has come yet to rivalling George W Bush’s gormless reaction to 9/11 , says Robert Fisk
Ebola outbreak: Billy Graham’s son declares righteous war on the virus

Billy Graham’s son declares righteous war on Ebola

A Christian charity’s efforts to save missionaries trapped in Africa by the crisis have been justifiably praised. But doubts remain about its evangelical motives
Jeremy Clarkson 'does not see a problem' with his racist language on Top Gear, says BBC

Not even Jeremy Clarkson is bigger than the BBC, says TV boss

Corporation’s head of television confirms ‘Top Gear’ host was warned about racist language
Nick Clegg the movie: Channel 4 to air Coalition drama showing Lib Dem leader's rise

Nick Clegg the movie

Channel 4 to air Coalition drama showing Lib Dem leader's rise
Philip Larkin: Misogynist, racist, miserable? Or caring, playful man who lived for others?

Philip Larkin: What will survive of him?

Larkin's reputation has taken a knocking. But a new book by James Booth argues that the poet was affectionate, witty, entertaining and kind, as hitherto unseen letters, sketches and 'selfies' reveal
Madame Tussauds has shown off its Beyoncé waxwork in Regent's Park - but why is the tourist attraction still pulling in the crowds?

Waxing lyrical

Madame Tussauds has shown off its Beyoncé waxwork in Regent's Park - but why is the tourist attraction still pulling in the crowds?
Texas forensic astronomer finally pinpoints the exact birth of impressionism

Revealed (to the minute)

The precise time when impressionism was born
From slow-roasted to sugar-cured: how to make the most of the British tomato season

Make the most of British tomatoes

The British crop is at its tastiest and most abundant. Sudi Pigott shares her favourite recipes
10 best men's skincare products

Face it: 10 best men's skincare products

Oscar Quine cleanses, tones and moisturises to find skin-savers blokes will be proud to display on the bathroom shelf
Malky Mackay allegations: Malky Mackay, Iain Moody and another grim day for English football

Mackay, Moody and another grim day for English football

The latest shocking claims do nothing to dispel the image that some in the game on these shores exist in a time warp, laments Sam Wallace
La Liga analysis: Will Barcelona's hopes go out of the window?

Will Barcelona's hopes go out of the window?

Pete Jenson starts his preview of the Spanish season, which begins on Saturday, by explaining how Fifa’s transfer ban will affect the Catalans
Middle East crisis: We know all too much about the cruelty of Isis – but all too little about who they are

We know all too much about the cruelty of Isis – but all too little about who they are

Now Obama has seen the next US reporter to be threatened with beheading, will he blink, asks Robert Fisk
Neanderthals lived alongside humans for centuries, latest study shows

Final resting place of our Neanderthal neighbours revealed

Bones dated to 40,000 years ago show species may have died out in Belgium species co-existed
Scottish independence: The new Scots who hold fate of the UK in their hands

The new Scots who hold fate of the UK in their hands

Scotland’s immigrants are as passionate about the future of their adopted nation as anyone else
Britain's ugliest buildings: Which monstrosities should be nominated for the Dead Prize?

Blight club: Britain's ugliest buildings

Following the architect Cameron Sinclair's introduction of the Dead Prize, an award for ugly buildings, John Rentoul reflects on some of the biggest blots on the UK landscape