http://www.guardian.co.uk/congo/story/0,,2054203,00.html
The world's remaining rainforest is the size of America and is being destroyed at the rate of one Florida a year. When that's gone - no more oxygen.

fostertom, have you seen the self supporting green roof system on roofkrete website and steveleigh posting on the asmet thread.
The answer to disappearing forest has got to be installing this self supporting roof system on the roofs of all our existing housing stock and planting trees as fast as they are felling the rain forest. - and conserving water on the roof.

Guest, would green roofs on our housing stock help that much?
There seems to be increasing evidence that tree planting in northern areas doesnt' help global warming because it helps absorb solar radiation.
Mirrors on our roofs might be a better option...

"Just don't buy it - not even with an FSC sticker - it only encourages them."

As everyone knows (wood manufacturers do): a forest that pays, STAYS.
Meaning: make it worthwhile to be FSC certified (sustained forest/plantations, meaning replanting, reforesting) and we'll all keep our forests (even in Europe!)
Wood for Good:
http://www.woodforgood.com/environment/2tonnesenv.html

Posted By: Guestinstalling this self supporting roof system on the roofs of all our existing housing stock and planting trees as fast as they are felling the rain forest

A great and necessary idea, but not a chance, as stated, unfortunately. Except in the occasional case our existing stock hasn't the structural strength to support such massive, and top-heavy loads. It's something for new-build - let's concentrate on that, for 'extensive' (deep soil, trees etc) green roofs. A better chance for some of the existing stock might be 'intensive' green roofs (thin, light layer of soil, drought-resistant alpines).
For that new-build, maybe ASMET - but even better is use of lots of heavy structural timber - de-barked pine trunks as roof beams etc - to support the weight. Provided it's replanted as soon as cut, the more timber we can incorporate into buildings, the better for the planet. The trick is to take masses of biomass out of the otherwise-inevitable carbon cycle; to sequester as much unoxidised hydrocarbon as possible in permanently warm, dry places so that it doesn't burn, rot, compost itself or otherwise return to dust, which it otherwise would, emitting heat and CO2 and consuming precious oxygen in the process.

Every tree is a huge solar collector, neatly providing inter-seasonal storage (as wood fuel) of all that it collects, making our manufactured solar panels seem puny. A temperate forest tree has 4 acres of collector (leaf area); however a rainforest giant has 14 acres. That's why the rainforests are so important; homegrown plant-a-tree schemes are no substitute.

Posted By: fostertom

Posted By: arthurevidence that tree planting in northern areas doesnt' help global warming because it helps absorb solar radiation

Absorbs solar radiation yes but much/most (what %age?) of that radiation doesn't go to warm the environment up; it's soaked up without temperature rise by powering the endothermic reaction (i.e. a reaction that doesn't happen without external energy input) of converting atmospheric CO2 and ground H2O into CH.... hydrocarbons (wood), emitting O2 as 'waste'. So the more of that kind of solar absorbtion, the better. The rest of the solar radiation that trees absorb does indeed warm up the environment, daytime, but every bit of that energy (and more) is re-emitted to the night sky. It's possibly true that more trees increases the mean equilibrium temperature at the earth's surface, at which that nett-loss energy transaction occurs.

I meant the second type of absorption you mention. Why would every bit and more be re-emitted at night? Surely the increase in greenhouse gases is preventing that?
What do you make of this type of report:
http://news.bbc.co.uk/1/hi/sci/tech/6540119.stm
There seem to have been a few of these studies now.

Leaving aside whether or not trees help, wouldn't putting mirrors on everyone's roofs help. Or painting them all white would seem to be a cost-effective measure.

Posted By: arthurgreenhouse gases work by blocking infrared radiation, not convection like a real greenhouse

No, you're right, a real greenhouse works primarily because glass (like the atmosphere) offers little resistance to (is relatively transparent to) incoming high frequency solar radiation (it's high frequency because it emanates from a high temperature source). That radiation warms the flowerpots, worms and spare wellies (and in the case of the atmosphere warms everything on the surface). All those objects then re-radiate everything they've received, but at low frequency (because they're not such a hot source). The glass (and the atmosphere) offer much more resistance to (are relatively opaque to) this would-be outgoing low frequency radiation. Yes, a real greenhouse also blocks convection cooling but that's secondary.

Posted By: arthurWhy would every bit and more be re-emitted at night? Surely the increase in greenhouse gases is preventing that?

Because if the planet was continuously absorbing solar energy but not getting rid of same back into space, it would rapidly get hotter and hotter, like to spontaneous combustion within days. It's more than that - Earth has to get rid of every bit of solar energy it receives *plus* it has to get rid of its own core heat production, otherwise again it would just get hotter and hotter. That's not to deny that we owe our relatively high surface and air temperature to the sun; without the sun the biosphere wouldn't be a biosphere - it would be far too cold for life. But as I say, earth isn't a nett energy absorber, from the sun or anywhere else - it's a nett energy emitter. Daytime it absorbs, night time it emits all of that plus a bit. The greenhouse gas doesn't prevent that; it simply resists it. If that resistance is preventing solar and/or core heat from getting away, the surface (and the air) warms up, yes. As it warms up it succeeds in emitting more heat, against the resistance. Eventually its temperature rises to the point where it suceeds in emitting exactly as much as the total it's receiving in both solar and core heat - equilibrium has been reached. If there's an increase in greenhouse gasses, they resist a bit more, so the surface (and air) temperature rises a bit more too, until a new equilibrium is established at a higher level. That's climate change for you.

PS Arthur, you have to click the html button at the bottom if you want to use the quoting facility. If you click the Edit button on your post, you can do that even now.

Hm, much more important? when there wouldn't be any convection to block, if the greenhouse effect hadn't done its thing in the first place? when vents and doors have to be opened in high summer to create enough convection to moderate the greenhouse-effect-created heat?

Wikipedia says that its possible to prove that its mainly convection blocking that's important to a real greenhouse by building one out of rock-salt which doesn't block IR like glass does.
http://en.wikipedia.org/wiki/Greenhouse_effect#Real_greenhouses

So, is there no way of reflecting incoming solar radiation back in a similar high frequencey form so it doesn't get absorbed by the greenhouse gases? Wouldn't conventional mirrors or uv mirrors on roofs help? All the wacky US plans seem to involve putting things up to block the incoming radiation in space but wouldn't it be better to do it on earth?

A global effort to mirror roofs might make some difference perhaps? More than green roofing perhaps (although i accept there are other benefits to green roofs). And perhaps cheaper than plans of launching things into space. Painting white, as they do in hot countries anyway, would be cheaper but I don't know if it would reflect at the same wavelength.

Mirrors would probably screw up global satelite communications!

Posted By: fostertomearth isn't a nett energy absorber, from the sun or anywhere else - it's a nett energy emitter. Daytime it absorbs, night time it emits all of that plus a bit

Mind you, it's not as direct and instant as that.
Heat is absorbed daytime and may then take part in all sorts of processes - climatic, chemical, biological etc. It may get turned into other forms of energy than heat. In these ways it may get stored for long periods - seasons or millenia. But eventually, at different timescales, it turns back to a form of energy, mainly heat, that can be, and is, re-radiated, plus a bit. But what's re-radiated tonight, from whatever source, process or timescale, pretty well equals what was absorbed today.
Principal fluctuations in this principle:
Seasonal - there's an absorbtion gain - maybe a total nett gain - in energy absorbed over the summer, but this is matched by an even larger emission loss - certainly a nett loss - in energy lost over the winter.
Polar - there's permanent high absorbtion gain - maybe a permanent nett gain - in energy absorbed in the tropics but this is matched by an even larger emission loss - certainly a nett loss - in energy lost from the polar regions. Energy is transferred by various means, mainly ocean currents and winds, from the tropics to the poles. That's how weather happens.

I am getting more confused. Near the begining of this thread Biff stated not to buy hardwood even FSC but I am not sure I understand why. Should I buy softwood knowing it will have rotted in 5-10 years? Should I buy metal which has high production energy implications? Should I use plastic same high energy issues? Or should I not buy anything and have a "low" quality of life?

I was thinking this summer of buying a rocking seat for the garden to spend time outside watching the world go buy rather than the TV. But now I am just starting to feel guilty.

Biff,

Thanks for the feedback. My woodwork skills, well lets just say I wouldn't want to put my weight on anything I had made! I'll stick with basic DIY, plumbing and electrics.

Seriously, where do I start to look for local wood products? How can I make sure it is English / European wood? Are European hardwoods Oak, Ash, Redwood? What about birch (seems to be loads in the Sussex and Kent area), beech and anything else I might have missed

Many thanks Biff