Forests could flip from sink to source of CO2: study

Apr 17, 2009 by Marlowe Hood
A view of a lowland rainforest on Sumatra, Indonesia. Forests that today soak up a quarter of carbon pollution spewed into the atmosphere could soon become a net source of CO2 if Earth's surface warms by another two degrees Celsius (3.6 degrees Fahrenheit), cautions a report to be presented Friday at the UN.

Forests that today soak up a quarter of carbon pollution spewed into the atmosphere could soon become a net source of CO2 if Earth's surface warms by another two degrees Celsius (3.6 degrees Fahrenheit), cautions a report to be presented Friday at the UN.

Plants both absorb and exhale , but healthy forests -- especially those in the tropics -- take up far more of the than they give off.

When they are damaged, get sick or die, that stored carbon is released.

"We normally think of forests as putting the brakes on ," said Risto Seppala, a professor at the Finnish Research Institute and head of the expert panel that produced the report.

"But in fact over the next few decades, damage induced by could cause forests to release huge quantities of carbon and create a situation in which they do more to accelerate warming than slow it down."

Authored by 35 of the world's top forestry scientists, the study provides the first global assessment of the ability of forests to adapt to climate change.

Manmade warming to date -- about 0.7 C since the mid-19th century -- has already slowed regeneration of tropical forests, and made them more vulnerable to fire, disease and insect infestations. Increasingly violent and frequent storms have added to the destruction.

If temperatures climb even further, the consequences could be devastating, according to the report by the Vienna-based International Union of Forest Research Organisations (IUFRO).

"The current carbon-regulating functions of forests are at risk of being lost entirely unless carbon emissions are reduced drastically," said Alexander Buck, IUFRO's deputy director and coordinator of the report.

"With a global warming of 2.5 C (4.5 F) compared to pre-industrial times, the would begin to turn into a net source of carbon, adding significantly to emissions from fossil fuels and deforestation," he told AFP by phone.

The UN's Intergovernmental Panel on Climate Change (IPCC) predicted in 2007 that average global temperatures would go up before 2100 by 1.1 C to 6.4 C (2.0 F to 11.5 F), depending on efforts to curb the gases that drive global warming.

Any increase of more than 2.0 C, the panel said, would unleash a maelstrom of human misery, including drought, famine, disease and forced migration.

Since the IPCC report, however, a growing number of climate scientists have said that this threshold is likely to be crossed no matter what actions are taken.

The forest assessment did contain what appears to be some good news: cold-clime boreal forests stretching across vast expanses of Russia, northern Europe, Canada and Alaska are set to expand rapidly as climate change kicks in.

But while this may be a boon for the timber industry, it is not likely to help curb global warming, it said.

"One might assume with the increasing growth in boreal forests that more carbon would be taken up by forest ecosystems and removed from the atmosphere," said Buck.

"But these positive effects will be clearly outweighed by the negative impacts on forest ecosystems."

The report urged international negotiators trying to hammer out a new global climate change treaty before the end of the year to take into account the potential impact of warming on forests.

Up to now, discussions on forests at the UN climate talks have focused almost exclusively on the impact of deforestation.

The destruction of vegetation straddling the equator -- some 130,000 square kilometers (50,000 square miles) disappear every year -- accounts for nearly 20 percent of total .

"But it is also important to keep in mind that those forests that remain will be affected by climate change to a degree that might exceed their capacity to adapt," Buck cautioned.

The IUFRO report will be submitted to the UN Forum on Forests.

(c) 2009 AFP

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User comments : 12

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Roach
4.5 / 5 (8) Apr 17, 2009
KILL ALL THE RAIN FOREST NOW BEFORE THEY ATTACK!!!! I'VE GOT THE MATCHES!!!!
Velanarris
5 / 5 (4) Apr 17, 2009
It's a good thing that almost all of the warming measured thus far has been observed at the poles while the tropical latitudes have remained virtually untouched, aside from the developing UHIE, according to the satellite data.
GrayMouser
5 / 5 (4) Apr 17, 2009
It's also good that the slight temperature rise and minor increase in CO2 will actually be good for trees.
bmcghie
5 / 5 (2) Apr 17, 2009
As a young North American male, I'm actually kind of hoping it all goes to pot. It will be very interesting to see how fast humans can innovate if the water levels start to rise, the temp goes through the roof, and the oxygen concentrations start dropping...

But that's just the biologist in me talking. :)
SteveS
5 / 5 (3) Apr 18, 2009
Anthropologically speaking, it's a win win situation. If AGW is real we will learn a lot about how societies work together to mitigate a global threat, or not as the case may be. If it's false we will learn a lot about mass hysteria, fear based politics, and weaknesses in the scientific method.

Either way we're going to learn something interesting about ourselves.
dachpyarvile
5 / 5 (1) Apr 19, 2009
All plants expirate CO2 at night. That is, in fact, why CO2 levels rise during the late night and early morning hours, and fall again during the day in many areas of the world.

Oh! The horror! Plants use O2 at night and add CO2 into the atmosphere!?! Yep... Under most circumstances they use up what they produce in optimum conditions for photosynthesis.
Velanarris
5 / 5 (1) Apr 19, 2009
Although many people think this doesn't happen, plants migrate just as much and as well as animals do.

If temps rise in their native area by a few degrees, that means local, adjacent areas that were formerly uninhabitable, will become more habitable.
dachpyarvile
5 / 5 (1) Apr 19, 2009
This also is true and has been observable even in our own lifetimes.
GrayMouser
not rated yet Apr 20, 2009
All plants expirate CO2 at night. That is, in fact, why CO2 levels rise during the late night and early morning hours, and fall again during the day in many areas of the world.

Oh! The horror! Plants use O2 at night and add CO2 into the atmosphere!?! Yep... Under most circumstances they use up what they produce in optimum conditions for photosynthesis.

You forgot that they also add hydrocarbons to the air at the same time. That is why the LA basin had smog before there was any significant population.
SteveS
not rated yet Apr 20, 2009
You forgot that they also add hydrocarbons to the air at the same time. That is why the LA basin had smog before there was any significant population.


I haven't heard of this before, can you post a link.
dachpyarvile
not rated yet Apr 24, 2009
All plants expirate CO2 at night. That is, in fact, why CO2 levels rise during the late night and early morning hours, and fall again during the day in many areas of the world.







Oh! The horror! Plants use O2 at night and add CO2 into the atmosphere!?! Yep... Under most circumstances they use up what they produce in optimum conditions for photosynthesis.




You forgot that they also add hydrocarbons to the air at the same time. That is why the LA basin had smog before there was any significant population.




That's right! I did forget. The two most notable hydrocarbons emitted by various plants are terpenes and isoprenes. These react with NO2 from both natural and artificial sources to produce ozone at the ground level.
Velanarris
not rated yet Apr 24, 2009
You forgot that they also add hydrocarbons to the air at the same time. That is why the LA basin had smog before there was any significant population.
I haven't heard of this before, can you post a link.
Photosynthesis, in some species of plants, produce hydrocarbons to store the energy, hence why things like biodiesel and ethanol are viable. At night when these hydrocarbons are broken down to produce ATP, H2O, and CO2, some hydrocarbons escape. As for whether this is the case for CA smog I don't know if you could say there was smog before population as the population viewed the valley as a desert. The landscape kept the area very dry until we started pumping water in during the 20's.