How effective is tree-planting for carbon offsetting?
Some of our readers aren't very fond of carbon offsetting programs and I do share quite a dose of skepticism about this matter, here's some research that affirms that planting trees, although some species more than others, can effectively capture CO2 from the atmosphere and convert it into organic tissue.
Manuel Enrique Figueroa, from the University of Sevilla, directed the a project that calculated how useful certain tree species were to able to absorb CO2 during their growth process. Growing trees, according to him, is a simple yet effective (up to a certain point, of course) way to achieve this.
The species they studied were from Western Europe, but they affirmed that they could be extended to other species around the world. Do you want to see the rank and how many tons of CO2 they can absorb per year? Follow us after the jump (the picture is from the winner).
Related:
[Source: Universidad de Sevilla via Econoticias]
The winners are two varieties of pine trees: the Aleppo Pine (pinus halepensis), able to capture an average of 48,000 CO2 kg per year and the Stone Pine (pinus pinea): 27,000 kg CO2 per year. Remarkably, a popular Mediterranean tree such as the Cork Oak (quercus suber) can "only" capture 4,500 kg.
Species planted in cities have lower ratings, in general, because they tend to be smaller trees. A type of ash tree (Melia azedarach) is the best performer: ten trees on a street are able to offset CO2 from 10,373 vehicles per year. The worst performers were Acacias (offsetting just 1,619 cars), Jacarandas (1,405 cars) and Elm Trees (1,320). Take these numbers prudently, they didn't mention the car models and you can presume they didn't use V8s for calculation purposes.
Reader Comments (Page 1 of 1)
Louis 1:00PM (4/07/2009)
I'm no expert, but it is important to understand a few things. Trees absorb carbon (as CO2) and builds itself using the carbon in the gas. Trees are mainly made of cellulose (C6H10O5). Trees release oxygen and water vapour. If you leave the trees long enough they die and become coal or oil, trapping carbon in an inert from below the ground. This process has been going on for billions of years. We then take the coal and oil and, within a matter of centuries (only two) we put all this back into the atmosphere when we burn it. There is not system that can handle such a quick change in conditions without the system itself changing rapidly a well. our climate is such a system that is under strain. Utlimately we need to reduce energy use OR get a way to put carbon back under ground. Just planting trees will not make the difference; it will help, though.
When the tree uses CO2, it is not for energy, unless you refer to storing energy, and Carbon is never converted to energy. never, ever. The food we eat and the fossil fuels we use get burned and releases CO2 as a byproduct. Trees (and plants) take the carbon and puts it back as fossil fuels or food we eat (think wheat, potatoes, carrots). We then burn it up an release the CO2. Trees are generally cool the touch; they do not burn fuel like animals and heat up.
Some speculation: some people believe that Johannesburg's climate has been changed by the numerous trees that have been planted in and around the city. Aparently it is regarded as the largest man made forest in the world. Even if the trees absorb more sunlight, they aborb more CO2 at the same time, release more water vapour and making the climate more tropical with a higher rainfall.
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bioburner 5:25PM (8/10/2007)
Hay this is all well and fine but do the "educated reachers" know that one day these trees will die and when they rot the CO2 will be released back in to the atmosphere, thus there is no perminate reduction in CO2 levels?
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psgjalg318 10:40PM (10/30/2009)
Of course it's not a permanent solution. They don't just release the CO2 when they die, they release it in the winter too, when they loose all of their leaves. But it's something that everyone can do, and is easiest for those who can't afford carbon offesets or to buy a more fuel efficient car.
derek.hofmann 5:51PM (8/10/2007)
The trouble is, fossil fuel usage takes carbon from an essentially inert source and puts it into the atmosphere. Planting trees for the most part doesn't make your carbon inert again. What I'm wondering is, how much of carbon can a single tree turn back into subterranean oil?
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Nathan 9:07PM (8/10/2007)
Good insight ... but I think we will run out of oil to burn long before we run out of space to plant another tree.
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Rando 11:47AM (8/12/2007)
#1: Didn't you study photosynthesis in school? A dead tree doesn't release CO2 into the air.
The process of photosynthesis converts CO2 and H2O into Glucose (C6H12O6), Oxygen (O2) and Water. In essense, the tree is converting our gaseous waste back into sugar, clean air and water.
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buddy 11:33AM (8/13/2007)
Yeah, bioburner, Rando's got you on that one - a pine tree cannot 'absorb' 48,000 kg of carbon per year and store it till death any more than I can 'absorb' the pounds and pounds of french fries I've eaten over my life time and store them til death. Trees aren't carbon sponges, but carbon filters. Just as those fries were converted to energy that carbon is converted as well.
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virgil 9:32AM (8/13/2007)
@ #4 - yes I'm sure #1 did read photosynthesis in school, but in addition probably learned about decomposition processes too (i.e. composting). When the bacteria & fungi chew up a dead tree, they release the CO2 back from metabolism of the sugars.
One thing the article doesn't mention, which is a major factor, is that trees need water to grow, and global warming will significantly reduce the amount of available water and suitable land for arborculture (and agriculture). Thus, planting trees only works if you do it EARLY in the global warming cycle - if you wait until its too late, the trees won't grow and then you're really screwed.
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Donovan Woollard 4:00PM (8/14/2007)
Hi all,
It's worth pointing out that reforestation is not the only form of carbon offset project. Assuming that reforestation does work - and it's a big assumption - then this approach still does nothing to help us shift our energy systems and practices away from those that cause carbon emissions in the first place.
Offsetters Climate Neutral Society (www.offsetters.ca) puts its carbon offset money into renewable energy and energy efficiency projects that ensure that carbon stays in the ground and that help to shift the adoption curve toward next generation energy systems to help us out of the climate problem we're in. Check them out.
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Scott 2:56PM (8/13/2007)
Plus, all trees shed large amounts of leaves/needles over the course of their lifetime which biodegrade and thus release CO2. There's no free lunch, people. We're essentially re-releasing millions upon millions of tons of hydrocarbons/CO2 that had been in "permanent" storage underground in an extremely short period of time. That's going to cause some issues. Will the planet "die"? By no means, but there will be some very interesting changes up ahead. We'll definitely survive as a species given our far superior ability to adapt, but I'm not as hopeful for most of our fellow planet inhabitants.
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David Stein 7:42AM (11/23/2007)
It seems to me that some tree species do store significant carbon as wood while alive-- which would be a century or two with some types, giving us some breathing space to reorganize our industries and energy patterns towards greater sustainability. Then, if instead of allowing them to rot, we harvest them, turn them into houses, furniture, etc. significant carbon would continue to be stored.
On the other hand, I ran across an article a few months ago claiming that any CO2 reduction by planting trees would be offset by their greater absorbtion of the sun's heat (trees are generally darker and less reflective of sunlight than cropland or dry range). Can anyone point me towards further information on this?
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farmer 5:47PM (8/16/2008)
It's a-lot harder to put carbon back than to pull it from the ground!!!
I'm trying what I know will help and what I can do.
take a look www.acresofgreen.com
I don't know any system that would ever be 100%.Whats ur opinion?
Ru Hartwell 2:03PM (10/10/2007)
Lots of interesting points here.
A couple more...
1. Trees have evolved over millions of years to become incredibly efficient and powerful at withdrawing carbon from the atmosphere. This is precisely the job that we need doing right now so it is a tragedy that we are not taking advantage of what could be potentially our most powerful ally in the fight against climate change. We need to be planting them by the billion.
2. Trees are an effective carbon sink whilst they remain alive. After all any carbon that is held in the living tissue of a tree is carbon that is not contributing to the problem. People say that the store of carbon provided by the tree is only 'temporary'. Well there are trees alive today that where doing their carbon absorption work when they built the pyramids, over 4,500 years ago. If you think that is a temporary store you need to think things through a bit more. The important question is what happens to the tree when it dies? If it is harvested for timber and kept dry it may retain its absorbed carbon for thousands of years. Don't believe me? Go and have a look at the roof timbers of Ely Cathedral in England. They are made from trees that were 300 years old when the Cathedral was built in the 10th century. that means they have held onto their absorbed C for 1300 years. How temporary is that?
3. The research that suggests that trees in temperate zones have a warming effect that counteracts their cooling value is simplistic and incomplete. Lots more info, if you want to go deeper on this here: http://www.treeflights.com/faqs.html#section16
Ultimately we are all totally dependent on trees and other plants to mediate the suns energy for us, to cool our planet and to maintain healthy ecosystems. Some of the contributors to this debate may have forgotten this.
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fastgrowingtree 8:47AM (1/14/2008)
hether planting trees for carbon-offsetting makes sense or doesn’t is secondary. The bigger picture out here is planting trees to preserve the ecology, or rather what’s remaining of it!
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