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| Cosmo |
 Posted: Fri May 30, 2008 5:44 am Post subject: Trees |
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Forum Masters Degree
Joined: 22 Nov 2007
Posts: 509
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Trees are our 'natural' air conditioners.
They absorb tremendous amounts of CO2 and recycle it to oxygen. This refreshes the air.
And they also 'cool' the planet because of all the light (photons) they absorb and use this energy for growth.
So this energy is not reradiated into the atmosphere as the deserts do.
During the last century, I estimate that 50% of the forests have been harvested for building the houses and clearings made for farming.
We do not need to use wood for building the houses and furniture.
They can be built from steel, aluminum,plaster, concrete, plant wastes (through technology) and any other means that can be developed.
At the same time, encourage tree plantings to contribute to the purification of our air quality.
Needless to say, improving the air quality would contribute to better health for the people.
Cosmo |
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| Bunbury |
| Posted: Fri May 30, 2008 7:27 am Post subject: |
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Forum Ph.D.
Joined: 26 Sep 2007
Posts: 731
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Trees are good, but don’t be fooled into thinking that by planting some trees, even millions of them, we are solving the climate change problem. Planting trees is nibbling at the edges of the problem. There might be many new technologies coming down the ‘pike, all of which will help, but the basic thing that must change is that we must burn less carbon. The way to do this is to make carbon cost more, put a realistic price on it based on the probable cost of climate change to future generations.
Freeman Dyson writes about genetically engineered trees that will absorb carbon and not re-release it the way deciduous trees do (by dropping leaves which decompose and put the carbon back into the atmosphere). He writes:
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| Carbon-eating trees could convert most of the carbon that they absorb from the atmosphere into some chemically stable form and bury it underground. Or they could convert the carbon into liquid fuels and other useful chemicals. Biotechnology is enormously powerful, capable of burying or transforming any molecule of carbon dioxide that comes into its grasp. |
Wonderful stuff, but it’s science fiction today, and I’m not willing to gamble our grandchildren’s futures on this, or other imagined technologies.
http://www.nybooks.com/articles/21494 |
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| Pong |
| Posted: Fri May 30, 2008 12:30 pm Post subject: Re: Trees |
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Forum Professor
Joined: 08 Apr 2008
Posts: 1124
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| Cosmo wrote: |
Trees are our 'natural' air conditioners.
They absorb tremendous amounts of CO2 and recycle it to oxygen. This refreshes the air.
And they also 'cool' the planet because of all the light (photons) they absorb and use this energy for growth.
So this energy is not reradiated into the atmosphere as the deserts do.
During the last century, I estimate that 50% of the forests have been harvested for building the houses and clearings made for farming.
We do not need to use wood for building the houses and furniture.
They can be built from steel, aluminum,plaster, concrete, plant wastes (through technology) and any other means that can be developed.
At the same time, encourage tree plantings to contribute to the purification of our air quality.
Needless to say, improving the air quality would contribute to better health for the people.
Cosmo |
Don't forget that other plants, marine and terrestrial, are doing their bit, especially phytoplankton - those little plants produce more oxygen than all others combined. So trees are not so great as they appear.
Now, the question of oxygen vs. carbon dioxide is hugely complicated by the fact that decomposing plants feed carbon dioxide production. So while potted saplings in a greenhouse do indeed add oxygen to the sealed atmosphere, an old growth forest including the meters of punky rotten soil beneath it pretty nearly cancels out. Trees, good; forests, inconsequential?  Maybe we should do more clearcutting and treeplanting? 
Or look to the oceans, and wonder how the heck do we make any difference there?
Do trees (more accurately: forests) cool the planet by absorbing light? Since when is absorbing light a good means of cooling? I would think a bald patch of subalpine snow (e.g. where pine beetle stripped a forest of leaves) reflects a good deal of light.
Is leaf perspiration (evaporation) significant in this picture? Anyone?
Old growth decomposition plus canopy creates a special blanket environment, where seasonal temperature does not vary much (e.g. no frost), and the air does not dry even when a nearby clearing experiences drought. Certainly these moldery forests are generating significant heat through winter, and pumping much moisture into the regional climate during otherwise dry seasons. They moderate grandly. I'm thinking mainly of Pacific Northwest rainforest, but I imagine other old growth forests do likewise.
Sorry for the rambling. |
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| free radical |
| Posted: Sat May 31, 2008 6:45 am Post subject: |
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Forum Masters Degree
Joined: 24 Sep 2007
Posts: 501
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The rise of trees seems to have cooled the planet in part through increased weathering. See "The rise of plants and their effects on weathering and atmospheric CO2" by Robert Berner, Science, 1997.
As to whether trees today would act as a sink or have no net effect, or even reduce albedo and increase warming, some sources suggest that latitude plays a role. In general, trees are considered a sink because their decomposition is not rapid - Soil carbon is higher in forested areas than non-forested areas, if I am not mistaken. |
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| Bunbury |
| Posted: Sat May 31, 2008 1:51 pm Post subject: |
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Forum Ph.D.
Joined: 26 Sep 2007
Posts: 731
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| Quote: |
| Trees are our 'natural' air conditioners. |
I'm wondering if it's more useful to plant trees in cities than trying to reforest deforested areas. Perhaps the effect of trees is greater in cities because of the shading effect on concrete, asphalt and buildings. |
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| Cosmo |
| Posted: Sun Jun 01, 2008 5:22 am Post subject: Re: Trees |
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Forum Masters Degree
Joined: 22 Nov 2007
Posts: 509
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| Pong wrote: |
| Cosmo wrote: |
Trees are our 'natural' air conditioners.
They absorb tremendous amounts of CO2 and recycle it to oxygen. This refreshes the air.
And they also 'cool' the planet because of all the light (photons) they absorb and use this energy for growth.
So this energy is not reradiated into the atmosphere as the deserts do.
During the last century, I estimate that 50% of the forests have been harvested for building the houses and clearings made for farming.
We do not need to use wood for building the houses and furniture.
They can be built from steel, aluminum,plaster, concrete, plant wastes (through technology) and any other means that can be developed.
At the same time, encourage tree plantings to contribute to the purification of our air quality.
Needless to say, improving the air quality would contribute to better health for the people.
Cosmo |
Don't forget that other plants, marine and terrestrial, are doing their bit, especially phytoplankton - those little plants produce more oxygen than all others combined. So trees are not so great as they appear.
Now, the question of oxygen vs. carbon dioxide is hugely complicated by the fact that decomposing plants feed carbon dioxide production. So while potted saplings in a greenhouse do indeed add oxygen to the sealed atmosphere, an old growth forest including the meters of punky rotten soil beneath it pretty nearly cancels out. Trees, good; forests, inconsequential? Maybe we should do more clearcutting and treeplanting?
Or look to the oceans, and wonder how the heck do we make any difference there?
Do trees (more accurately: forests) cool the planet by absorbing light? Since when is absorbing light a good means of cooling? I would think a bald patch of subalpine snow (e.g. where pine beetle stripped a forest of leaves) reflects a good deal of light.
Is leaf perspiration (evaporation) significant in this picture? Anyone?
Old growth decomposition plus canopy creates a special blanket environment, where seasonal temperature does not vary much (e.g. no frost), and the air does not dry even when a nearby clearing experiences drought. Certainly these moldery forests are generating significant heat through winter, and pumping much moisture into the regional climate during otherwise dry seasons. They moderate grandly. I'm thinking mainly of Pacific Northwest rainforest, but I imagine other old growth forests do likewise.
Sorry for the rambling. |
Cultivated areas of agricultural plants do not compare favorably with the forests and trees. Their areas have large soil exposure whereas the forests are completely shaded.
The rotting leaves below the trees are fertilizing the trees.
Also, the plants on land are the only ones that release 'free' oxygen in the air IMO.
For a cooler planet, trees are the best bet.
Cosmo |
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| Pong |
| Posted: Sun Jun 01, 2008 12:19 pm Post subject: |
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Forum Professor
Joined: 08 Apr 2008
Posts: 1124
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| Bunbury wrote: |
| the shading effect on concrete, asphalt and buildings. |
| Cosmo wrote: |
| Cultivated areas... have large soil exposure whereas the forests are completely shaded. |
Certainly true. Open an umbrella, there is less rain under it. Does this reduce global rainfall though, as in reduced solar heating "For a cooler planet"?
I think that forest canopy does a great job capturing sunlight.
I love trees, but though trees shade me and smell good to me I won't conclude forests have the same effect on our climate. |
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| Bunbury |
| Posted: Sun Jun 01, 2008 6:38 pm Post subject: |
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Forum Ph.D.
Joined: 26 Sep 2007
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| Quote: |
| Open an umbrella, there is less rain under it. Does this reduce global rainfall though, as in reduced solar heating "For a cooler planet"? |
Photons roll off the leaves and drip to the ground?
Buildings shaded by trees use less air conditioning. I live under an elm tree. It's cool. |
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| free radical |
| Posted: Sun Jun 01, 2008 8:09 pm Post subject: |
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Forum Masters Degree
Joined: 24 Sep 2007
Posts: 501
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I also enjoy trees.
In order to provide a few points of reference:
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Offset of the Potential Carbon Sink From Boreal Reforestation by Decreases in Surface Albedo
Betts, R A
The Kyoto Protocol includes afforestation and reforestation as means of reducing net carbon emissions. The motivation is a desire to reduce the radiative forcing of climate change. However, since a forest generally has a lower albedo than open land, particularly when snow is lying, forestation may provide a positive radiative forcing by albedo change which opposes the negative forcing by carbon sequestration. A spatially-explicit comparison of these forcings was made$^{1}$, using general circulation model results and estimates of the carbon sequestration potential of global vegetation and soils. It was found that in many high-latitude areas, the positive albedo forcing is greater than the negative sequestration forcing. Forestation in those areas |
See also:
http://www.springerlink.com/content/k5k0x5p854737498/
And oh dear this next one can't be good for trees:
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Using the integrated
assessment model IMAGE 2.2, we found that the large-scale implementation in the
extra-tropics of either carbon-sequestration, or modern-biomass plantations decreases
the CO2 concentration with 70-80 ppmv by the year 2100 compared to a non
mitigation baseline. In a coupled land/atmosphere/ocean/sea-ice model this moderates
global warming over the 21st century by 10%. However, the carbon-sequestration
option raises the absorption of solar radiation due to a lower albedo compared to the
scenario involving modern-biomass plantations (for biofuels production). The albedo12
induced difference in global-mean temperature is as large as the mitigation by CO2
changes in the two scenarios compared to the baseline. Further, an atmospheric
circulation change in the carbon-plantation scenario weakens the supply of moisture
from the oceans to North Africa and central Eurasia. In our model this decreases
annual-mean precipitation over North Africa by up to 10% and further increases
summer temperatures over Eurasia. These findings lead us to conclude that other
climate impacts than just CO2 changes have to be taken into account when discussing
climate-change mitigation options that involve land-use changes. |
The entire PDF for that is available and it is the most recent of the bunch:
http://www.phys.uu.nl/~opsteegh/publications/CO2paperMichiel.pdf |
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| Pong |
| Posted: Sun Jun 01, 2008 11:52 pm Post subject: |
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Forum Professor
Joined: 08 Apr 2008
Posts: 1124
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| Bunbury wrote: |
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| Open an umbrella, there is less rain under it. Does this reduce global rainfall though, as in reduced solar heating "For a cooler planet"? |
Photons roll off the leaves and drip to the ground?
Buildings shaded by trees use less air conditioning. I live under an elm tree. It's cool. |
Alright, my analogy sucked. So... open an umbrella, there is less sunlight under it. Does this reduce global warming? Suppose we fill the landscape with black umbrellas...?
I totally favour trees as shade for people and houses etc. Many even take down the awning every winter - one just rakes it into bags.
Thanks Free Radical for good info. |
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| Bunbury |
| Posted: Mon Jun 02, 2008 7:12 am Post subject: |
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Forum Ph.D.
Joined: 26 Sep 2007
Posts: 731
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| Quote: |
| Alright, my analogy sucked. So... open an umbrella, there is less sunlight under it. Does this reduce global warming? Suppose we fill the landscape with black umbrellas...? |
Trees do something umbrellas don’t do - they convert solar energy into chemical energy by converting atmospheric carbon into cellulose.
Here’s the slightly puzzling part about the Schaeffer et. al. paper quoted by free radical: they report that trees planted as carbon sinks have a lower albedo than non-woody plantations for biofuels, and this lower albedo is enough to offset the difference in global warming potential between growing and burning biofuels, versus growing and not burning trees (is this a reasonably accurate summary?).
This seems intuitively wrong to me. That lower albedo means less light is reflected, so where does that energy go? If it goes into making cellulose, then it doesn’t go into warming the atmosphere. The only way it can warm the atmosphere is by first warming the leaves (converting visible light into thermal energy) and then reradiating it as IR. Does this happen, I mean are leaves warmer than the surrounding atmosphere? I guess they are, although I’d never thought about it.
The paper has lots of assumptions that went into the models (and I’ve only skimmed it). It’s the number of assumptions the authors had to make that makes me wonder a little how valid their conclusion might be. |
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| Cat1981(England) |
| Posted: Wed Jun 04, 2008 11:00 am Post subject: |
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Joined: 09 Sep 2006
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I may have this wrong, but i thought that young growing trees absorb much higher amounts of co2 than mature trees? If so the best thing for us to do would be to increase the use of wood as a building material through tree farms. Although much of the timber we use in the building trade is bent like a banana (because of the quick growth of the trees), furniture, i presume, would require much higher quality timber and therefor may not be economically viable.
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| KALSTER |
| Posted: Wed Jun 04, 2008 12:29 pm Post subject: |
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In Swaziland where i used to work they have Gum tree plantations. They grow quick and straight and you can make some good furniture from them as well 
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| Pong |
| Posted: Wed Jun 04, 2008 1:08 pm Post subject: |
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| Cat1981(England) wrote: |
| increase the use of wood as a building material through tree farms. Although much of the timber we use in the building trade is bent like a banana (because of the quick growth of the trees), furniture, i presume, would require much higher quality timber and therefor may not be economically viable. |
Monoculture planted after clearcut does grow quite straight. A gardener would call this "leggy" - every tree is going for the dwindling light, which is uniformly above. When the canopy locks up though growth abruptly stops, and there are other problems with monoculture.
As for bent lumber, as material. This is superior to straight wood when engineers and carpenters use their brains. The carpenter actually prefers to set a beam, joist, rafter, etc. bowed slightly up, to compensate for deflection under load. Your traditional English shipwrights did select severely bent wood ("knees") grown from deliberately isolated and therefore wildly twisted oaks called "standards". Now, today, I think economies of scale could easily sort lumber by such "defect" and I think industries like those prefabricating engineered trusses in a factory setting could make smart use of curved lengths - obviously a house roof truss built of curved segments is going to be stronger and lighter than one built of straight only. But there must be greater coordination between mills and manufacturers.
Currently, a mill will divert boards that come out warped to be chopped into short lengths and then finger-jointed (with glue) end-to-end as long straight boards, which are used where strength is unimportant. Also these reject boards may be chipped and pressed (with glue) into rather poor sheet goods.
When I've got my architect & engineer hats on, I have to design with straight wood because this is all the mills produce, or strive to produce.
In furniture, bent wood kicks ass so hard we even steam-bend straight pieces. There are thousands of furniture factories right now buying straight boards only to bend them to a stronger form. |
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| Cat1981(England) |
| Posted: Wed Jun 04, 2008 11:18 pm Post subject: |
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Thats true, but i need straight timber. Its not just the speed at which they are grown, they are also not given time to season. At the moment, we put the twisted and bent timber to one side and use them for noggins and in the rafters. Usually with the weight of the slates, the timber will be pushed down onto the struts. At the moment most of the internal walls in a new build (over here anyway) are made with timber and plaster board/dry wall with picture frame steel work through the centre of the house. My thinking was to replace the cavity wall with stud-work increasing the amount of timber we use. Anyway off to work.
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