Forests losing the ability to absorb man-made carbon

A A A

The sprawling forests of the northern hemisphere which extend from China and Siberia to Canada and Alaska are in danger of becoming a gigantic source of carbon dioxide rather than being a major "sink" that helps to offset man-made emissions of the greenhouse gas.

Studies show the risk of fires in the boreal forests of the north has increased in recent years because of climate change. It shows that the world's temperate woodlands are beginning to lose their ability to be an overall absorber of carbon dioxide.

Scientists fear there may soon come a point when the amount of carbon dioxide released from the northern forests as a result of forest fires and the drying out of the soil will exceed the amount that is absorbed during the annual growth of the trees. Such a prospect would make it more difficult to control global warming because northern forests are seen as a key element in the overall equations to mitigate the effect of man-made CO2 emissions.

Two studies published today show that the increase in forest fires in the boreal forests – the second largest forests after tropical rainforests – have weakened one of the earth's greatest terrestrial sinks of carbon dioxide.

One of the studies showed that in some years, forest fires in the US result in more carbon dioxide being pumped into the atmosphere over the space of a couple of months than the entire annual emissions coming from cars and energy production of a typical US state.

A second study found that, over a 60-year period, the risk of forest fires in 1 million sq kms of Canadian wilderness had increased significantly, largely as a result of drier conditions caused by global warming and climate change. Tom Gower, professor of forest ecology at the University of Wisconsin-Madison, said his study showed that fires had a greater impact on overall carbon emissions from boreal forests during the 60-year period than other factors such as rainfall, yet climate was at the heart of the issue.

The intensity and frequency of forest fires are influenced by climate change because heatwaves and drier undergrowth trigger the fires. "Climate change is what's causing the fire changes. They're very tightly coupled systems," Professor Gower said.

"All it takes is a low snowpack year and a dry summer. With a few lightning strikes, it's a tinderbox," he said.

Historically, the boreal forests have been a powerful carbon sink, with more carbon dioxide being absorbed by the forests than being released. However, the latest study, published in the journal Nature, suggests the sink has become smaller in recent decades, and it may actually be shifting towards becoming a carbon source, Professor Gower said.

"The soil is the major source, the plants are the major sink, and how those two interplay over the life of a stand [of trees] really determines whether the boreal forest is a sink or a source of carbon," he said.

"Based on our current understanding, fire was a more important driver of the carbon balance than climate was in the past 50 years. But if carbon dioxide concentration really doubles in the next 50 years and the temperature increases 4C to 8C, all bets may be off."

The second study, published in Carbon Balance and Management, found carbon dioxide emissions from some forest fires exceeded the annual car and energy emissions from individual US states.

Christine Wiedinmyer of the US National Centre for Atmospheric Research in Boulder, Colorado, used satellite imaging datato estimate CO2 output based on the degree of forest cover in a particular area.

In some years, the amount of CO2 released from forest fires was equivalent to about 5 per cent of the man-made total. But in other years, more widespread and intense forest fires resulted in massively increased emissions.

"There is a significant potential for additional net release of carbon from forests of the United States due to changing fire dynamics in the coming decades," Dr Wiedinmyer said.

Sport
Laura Trott with her gold
Commonwealth GamesJust 48 hours earlier cyclist was under the care of a doctor
Life and Style
Upright, everything’s all right (to a point): remaining on one’s feet has its health benefits – though in moderation
HealthIf sitting is bad for your health, what happens when you stay on your feet for a whole month?
Arts and Entertainment
Peter Griffin holds forth in The Simpsons Family Guy crossover episode
arts + ents
News
Orville and Keith Harris. He covered up his condition by getting people to read out scripts to him
People
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
Sport
France striker Loic Remy
sportThe QPR striker flew to Boston earlier in the week to complete deal
Arts and Entertainment
Gal Gadot as Wonder Woman
arts + entsFilmmaker posted a picture of Israeli actress Gal Gadot on Twitter
Sport
Vincenzo Nibali rides into Paris on the final stage of the 2014 Tour de France
Tour de FranceVincenzo Nibali is first Italian winner since Marco Pantani in 1998
News
Bryan had a bracelet given to him by his late father stolen during the raid
people
Arts and Entertainment
Chris Pratt stars in Guardians of the Galaxy
arts + ents
Arts and Entertainment
Pedro Pascal gives a weird look at the camera in the blooper reel
arts + entsPrince Oberyn nearly sets himself on fire with a flaming torch
News
Danny Nickerson, 6, has received 15,000 cards and presents from well-wishers around the world
newsDanny loves to see his name on paper, so his mother put out a request for cards - it went viral
Arts and Entertainment
Zoe Saldana stars in this summer's big hope Guardians of the Galaxy
filmHollywood's summer blockbusters are no longer money-spinners
Sport
Red Bull Racing's Australian driver Daniel Ricciardo (C) celebrates with Scuderia Ferrari's Spanish driver Fernando Alonso (L) and Mercedes' British driver Lewis Hamilton
sport
Arts and Entertainment
comedy
Arts and Entertainment
Public vote: Art Everywhere poster in a bus shelter featuring John Hoyland
art
Arts and Entertainment
Judd Apatow’s make-it-up-as-you-go-along approach is ideal for comedies about stoners and slackers slouching towards adulthood
filmComedy was dominated by the romcom at its most insufferable
Sport
Tour de France competitor Bartosz Huzarski’s legs have highlighted the gruelling nature of the race, after he posted a picture on Facebook showing extremely prominent veins stretching from his feet and all the way up his legs
Commonwealth Games
Life and Style
Elle Kaye demonstrates the art of taxidermy
food + drinkFood revolution taken a step further in new ‘edible taxidermy’ class
News
A rub on the tummy sprang Casey back to life
video
Sport
Halsall broke her personal best in the 50m butterfly
Commonwealth GamesEnglish swimmer is reborn after disastrous time at London 2012
Arts and Entertainment
O'Shaughnessy pictured at the Unicorn Theatre in London
tvFiona O'Shaughnessy explains where she ends and her strange and wonderful character begins
Life and Style
Workers in Seattle are paid 100 times as much as workers in Bangladesh
fashionSeattle company lets customers create their own clothes, then click 'buy' and wait for delivery
Arts and Entertainment
Red Bastard: Where self-realisation is delivered through monstrous clowning and audience interaction
comedy
Arts and Entertainment
booksForget the Man Booker longlist, Literary Editor Katy Guest offers her alternative picks
Voices
The Express offices in the 1930s when writers (such as Orwell) were paid around £2 weekly
voicesWebsites offering your ebooks for nothing is only the latest disrespect the modern writer is subjected to, says DJ Taylor
Life and Style
A cut above: Katy Guest at The Ginger Pig
food + drinkThe Ginger Pig's hands-on approach to primary cuts
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Data Analyst

£30000 per annum: Ashdown Group: A highly reputable software house is looking ...

Application Support Analyst / Junior SQL Server DBA

£40000 - £45000 per annum: Ashdown Group: An established professional services...

Commercial Litigation

Highly Attractive Salary: Austen Lloyd: CITY - SENIOR COMMERCIAL LITIGATION SO...

BI Developer - Sheffield - £35,000 ~ £40,000 DOE

£35000 - £40000 per annum + competitive: Progressive Recruitment: My client is...

Day In a Page

A new Russian revolution: Cracks start to appear in Putin’s Kremlin power bloc

A new Russian revolution

Cracks start to appear in Putin’s Kremlin power bloc
Eugene de Kock: Apartheid’s sadistic killer that his country cannot forgive

Apartheid’s sadistic killer that his country cannot forgive

The debate rages in South Africa over whether Eugene de Kock should ever be released from jail
Standing my ground: If sitting is bad for your health, what happens when you stay on your feet for a whole month?

Standing my ground

If sitting is bad for your health, what happens when you stay on your feet for a whole month?
Commonwealth Games 2014: Dai Greene prays for chance to rebuild after injury agony

Greene prays for chance to rebuild after injury agony

Welsh hurdler was World, European and Commonwealth champion, but then the injuries crept in
Israel-Gaza conflict: Secret report helps Israelis to hide facts

Patrick Cockburn: Secret report helps Israel to hide facts

The slickness of Israel's spokesmen is rooted in directions set down by pollster Frank Luntz
The man who dared to go on holiday

The man who dared to go on holiday

New York's mayor has taken a vacation - in a nation that has still to enforce paid leave, it caused quite a stir, reports Rupert Cornwell
Best comedians: How the professionals go about their funny business, from Sarah Millican to Marcus Brigstocke

Best comedians: How the professionals go about their funny business

For all those wanting to know how stand-ups keep standing, here are some of the best moments
The Guest List 2014: Forget the Man Booker longlist, Literary Editor Katy Guest offers her alternative picks

The Guest List 2014

Forget the Man Booker longlist, Literary Editor Katy Guest offers her alternative picks
Jokes on Hollywood: 'With comedy film audiences shrinking, it’s time to move on'

Jokes on Hollywood

With comedy film audiences shrinking, it’s time to move on
It's the best of British art... but not all is on display

It's the best of British art... but not all is on display

Voted for by the British public, the artworks on Art Everywhere posters may be the only place where they can be seen
Critic claims 'I was the inspiration for Blanche DuBois'

Critic claims 'I was the inspiration for Blanche DuBois'

Blanche Marvin reveals how Tennessee Williams used her name and an off-the-cuff remark to create an iconic character
Sometimes it's hard to be a literary novelist

Sometimes it's hard to be a literary novelist

Websites offering your ebooks for nothing is only the latest disrespect the modern writer is subjected to, says DJ Taylor
Edinburgh Fringe 2014: The comedy highlights, from Bridget Christie to Jack Dee

Edinburgh Fringe 2014

The comedy highlights, from Bridget Christie to Jack Dee
Dame Jenny Abramsky: 'We have to rethink. If not, museums and parks will close'

Dame Jenny Abramsky: 'We have to rethink. If not, museums and parks will close'

The woman stepping down as chair of the Heritage Lottery Fund is worried