Mood:
coolTopic: globalWarming
Terpenes! The role of terpenes adds to our knowledge of how forests cycle water naturally. The role of forests up until now has been summarised here in this diagram (terpenes not indicated)
Now we need to add into the diagram that forests naturally produce a natural haze of tiny particles called terpenes, which seed rainfall of correct droplet size. Correct in the sense that they create normal clouds and drive the natural monsoonal and rainfall patterns in predictable fashion for agriculture and human society.
Till now we have mainly been concerned with the impact of logging on this water cycle as follows;
Now we can say logging also removes terpenes from the rainfall cycle.
This compares with industrial particulates which is known to also form droplets and changed landscape scale rainfall patterns including failed monsoonal rains in North Africa: Four Corners - 21/03/2005: Global Dimming
These particles are also blamed for global dimming of some 10% of sunlight from reaching the earth's surface. That's incredible.
Notice this string of email in several parts about the role of terpens and the complexity of the inter relationship with global dimming, natural and unnatural.
#1
* David Adam, environment correspondent
* guardian.co.uk,
* Friday October 31 2008 16.46 GMT
* Article history
Trees could be more important to the Earth's climate than previously thought, according to a new study that reveals forests help to block out the sun.
Scientists in the UK and Germany have discovered that trees release a chemical that thicke ns clouds above them, which reflects more sunlight and so cools the Earth. The research suggests that chopping down forests could accelerate global warming more than was thought, and that protecting existing trees could be one of the best ways to tackle the problem.
Dominick Spracklen, of the Institute for Climate and Atmospheric Science at Leeds University, said: "We think this could have quite a significant effect. You can think of forests as climate air conditioners."
The scientists looked at chemicals called terpenes that are released from boreal forests across northern regions such as Canada, Scandinavia and Russia. The chemicals give pine forests their distinctive smell, but their function has puzzled experts for years. Some believe the trees release them to communicate, while others say they could offer protection from air pollution.
The team found the terpenes react in the air to f orm tiny particles called aerosols. The particles help turn water vapour in the atmosphere into clouds.
Spracklen said the team's computer models showed that the pine particles doubled the thickness of clouds some 1,000m above the forests, and would reflect an extra 5% sunlight back into space.
He said: "It might not sound a lot, but that is quite a strong cooling effect. The climate is such a finely balanced system that we think this effect is large enough to reduce temperatures over quite large areas. It gives us another reason to preserve forests."
The research, which will be published in a special edition of the Royal Society journal Philosophical Transactions A, is the first to quantify the cooling effect of the released chemicals. The scientists say the findings "must be included in climate models in order to make realistic predictions".
Because trees release more t erpenes in warmer weather, the discovery suggests that forests could act as a negative feedback on climate, to dampen future temperature rise. The team looked at forests of mainly pine and spruce trees, but Spracklen said other trees also produce terpenes so the cooling effect should be found in other regions, including tropical rainforests.
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#2
At 05:40 PM 2/11/2008, you wrote:
I know that weensy particles called nuclei are needed for moisture to form around and make clouds and rain. Basic weather dynamics. Those can come from dust or from the minuscule particles forests send up when they do their evapotranspiration thing. Not sure how different this is to the chemicals they are talking about below. But it's great to see it reinforcing of the role forests play in rain making. An old farmers saying was something like ' The rain follows the trees '. Australia's euc forests also give off such a haze, especially in warm weather.
#3
I did a quick search and found that terpenes are definitely present in eucalypt leaves, too. Although most of the scientific discussion seems to be related to the digestibility of leaves by marsupials and to the eucalypt's characteristic of retarding growth of young plants close to them, I don't see why we shouldn't extend the European conclusion to our forests too.
#3
Yes, it is correct but only part of a much more complex story (ref NSF Newsl. 2006-2007). ............................... Meanwhile we in SE Australia at Eden NSW allow 1 million tonnes of trees to be woodchipped per year including this one recorded a few weeks ago (via Goongerah East Gippsland over the border in Victoria): |
