Afforestation will hardly dent warming problem: study

Converting croplands or marginal lands to forests will make almost no inroads against global warming, a study says
Schemes to convert croplands or marginal lands to forests will make almost no inroads against global warming this century, a scientific study published on Sunday said.

Schemes to convert croplands or marginal lands to forests will make almost no inroads against global warming this century, a scientific study published on Sunday said.

Afforestation is being encouraged under the UN's under the theory that forests are "sinks" that soak up carbon dioxide (CO2) from the air through .

But environmental researchers, in a new probe, said that even massive conversion of land to forestry would have only a slender benefit against the greenhouse-gas problem.

This is partly because forests take decades to mature and CO2 is a long-lasting molecule, able to lurk for centuries in the atmosphere.

But another reason is that forests, even as they absorb greenhouse gas, are darker than and thus absorb more -- and in high latitudes, this may even result in net warming.

Vivek Arora of the University of Victoria in British Columbia and Alvaro Montenegro of St. Francis Xavier University in Nova Scotia modelled five scenarios in which afforestation was carried out over 50 years, from 2011 to 2060.

They used a Canadian programme called CanESM1 that simulated the impacts on land, sea and air if Earth's surface temperature rose by some 3.0 degrees Celsius (5.4 degrees Fahrenheit) by 2100 compared to 1850.

Even if all the cropland in the world were afforested, this would reduce the warming by only 0.45 C (0.81 F) by a timescale of 2081-2100, according to the study, which appears in the journal Nature Geoscience.

Fifty-percent afforestation would brake it by an even tinier 0.25 C (0.45 F).

Both scenarios are, of course, wildly unrealistic because of the need to grow food.

Fifty-percent afforestation would require at least a doubling in crop yield to feed the because half of the crop area would be taken out of use.

The other three scenarios found that afforestation in the tropics was three times more efficient at "avoided warming" than in northerly latitudes and temperate regions.

The study said that afforestation does have other benefits, for the economy and the ecoystem.

"There's nothing wrong with afforestation, it is positive, but our findings say that it's not a response to temperature control if we are going to be emitting (greenhouse gases) this way," Montenegro told AFP.

The study said bluntly, "Afforestation is not a substitute for reduced greenhouse-gas emissions."

In forest programmes, policymakers would be advised to focus afforestation efforts in the tropics but also push hard against deforestation, which accounts for 10 to 20 percent of emissions globally.

Avoiding deforestation is under discussion for post-2012 climate action under the UN flag.

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(c) 2011 AFP

Citation: Afforestation will hardly dent warming problem: study (2011, June 19) retrieved 21 October 2019 from
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Jun 19, 2011
I think this is a useful piece of research but it doesn't look at the full picture by not including rangelands in their scenarios.

Jun 19, 2011
What's happened to 90% of the old growth here in America? Timbered for three centuries, with as much forethought as with bison hunting. Why not grow food vertically, the way cities house large populations? Chicago is already creating green roofs to reduce overheating. Some creative engineering could bring our forests back.

Jun 19, 2011
Okay, perhaps it won't have an immediate effect, but it is still surely worthwhile in the long term to have these forests.

Jun 19, 2011
I doubt that the model fully accounted for the carbon sequestered in the soil, which usually builds up in forest land and diminishes in cropland. This amounts to a significant difference over decades and is a huge amount of carbon build-up over centuries and milennia.

Jun 19, 2011
not to mention the Immediate benefit it would have for fauna.

One point in the article about forests generally being darker than crops, wouldn't that create a heat sink, and this would transfer heat to the ground from the air? which would mean warmer nights, but cooler days, IMO that would reduce the occurrence of extreme weather events as it would regulate temperatures?

Jun 20, 2011
AGW is an utter fraud - study. Let's all worship at the shrine of Gaia and bow to her high priest "Global Warming". There is exactly ZERO evidence supporting AGW, outside of a very small band of discredited crackpots and so called "scientists" that make up statistics as they please. Oh, and and politicians pushing "green energy" and, incidentally, making incredible fortunes keeping the fable of AGW alive.

I call this entire thing BS...

Jun 20, 2011
There is exactly ZERO evidence supporting AGW, outside of a very small band of discredited crackpots and so called "scientists"

Ha, ha, ha. You know you're talking to a crank when you hear phrases like:

* The arrogance of 'these scientists', presuming to know it all.
* (Macro)Evolution is just a theory, not fact.
* The neutron repulsion...
* In AWT theory...
* Black holes are no more real than the Big Bang, dark matter or dark energy.
* The evidence for god is in the irreducible complexity of...(insert body part).
* You cannot prove that god doesn't exist, therefore, he does.
* Those 'scientists' are in it just for the grant money - they don't care about us.
* The climate is not warming, it's cooling. See ClimateGate conspiracy.
* The Bible says...
* The progressive, socialist liberals just want to redistrubute our wealth.
* Government should pack its bags and let Corporations and Free Market rule - death to the EPA!

Jun 20, 2011
Ha, ha, ha. You know you're talking to a moron when you hear phrases like:

Fixed that for you ;-)

Jun 20, 2011
Here's a solution to this tedious argument: We hire people like Galen Slade to live and monitor the most polluted regions on the globe, a human "canary in a coal mine" so to speak. We take blood samples, lung capacity tests, etc., and we'll pay them very well,
which is fine, because it won't be for very long.

Jun 20, 2011
@deesky - Thank you that was a great laugh and pretty much spot on.


Jun 21, 2011

I call this entire thing BS...

Well you would know all about BS as you certainly produce a lot of it youself judging by your post.

Jun 27, 2011
What a joke. Discussing reforestation and concluding that our minimum efforts wouldn't do much. Meanwhile we allow Brazil to destroy their gigantic rainforest. That rainforest belongs to the world and they are harming all of us by destroying it. That's where military intervention would actually do some long term good.

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