« November 2008 »
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
Entries by Topic
All topics  «
about editor
aust govt
big media
contact us
donations to SAM
election nsw 2007
election Oz 2007
free SAM content
human rights
independent media
local news
nsw govt
nuke threats
publish a story
zero waste
Blog Tools
Edit your Blog
Build a Blog
RSS Feed
View Profile
official indymedia
ecology action Australia
ecology action
Advertise on SAM
details for advertisers
You are not logged in. Log in

sydney alternative media - non-profit community independent trustworthy
Saturday, 8 November 2008
Forest terpenes help make rain and natural global dimming: science report
Mood:  cool
Topic: 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.


Scientists discover cloud-thickening chemicals in trees that could ... 31 Oct 2008
Scientists discover cloud-thickening chemicals in trees that could offer a new weapon in the fight against global warming

    * 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.


Sent: Sunday, November 02, 2008 6:23 PM
Subject: Re: [chipstop] Chemical released by trees can help cool planet, scientists find

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.  


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.


Sent: Monday, November 03, 2008 8:01 AM
Subject: [chipstop] complexity of unnatural global dimming Re: [chipstop] Chemical released by trees can help cool planet, scientists find

Just a little brief on the incredible complexity in this area. If you google 4 Corners and global dimming you will get their show in about 2005 about how since 1950 or so about 10% less sunlight is reaching the earth. That's big.
How so - well it looks like its industrial particulate pollution over that time. Similar effect of cloud formation too.
But the clouds formed this way are slight different sized droplets which cause a change in rainfall pattern they say. Resulted in famine in Africa from failed monsoonals due to European particulates etc.
Soooo ....what's that got to do with terpens - well there has been a measurable plateaux in temperature rise in the last 2 years apparently.
My firm belief is that this correlates with Chinese and Indian huge economic expansion .... namely particulate pollution. Which in turn has carried it's component of global dimming over the world.
I know the particulate pollution from China is huge and impacts neighbour Korea etc. Then there are the Indonesian peat forest fires every summer.
In short global warming forcings have the foot on the accelerator of temperature increase. Pollution has the foot on the brake as well. Terpens sound like a natural enhancement of the braking effect.
Notice too the increase in pollution derived dimming has major implications for lung diseases and changed landscape scale rainfall patterns.
Yours truly, Tom
Sent: Tuesday, November 04, 2008 12:22 PM
Subject: [chipstop] Chemical released by trees can help cool planet, scientists find

From a scientist on the topic ...

Yes, it is correct but only part of a much more complex story (ref NSF Newsl. 2006-2007).

Similar to the di-methyl sulphide produced by marine algae, many forests release significant quantities (100s of mt/an) of volatile terpenes and pinenes that oxidise and coagulate in the air to produce aerosol micro-nuclei responsible for forming persistent humid hazes. We can see them as the natural blue haze of our 'Blue Mountains' or the smokey haze of the Smokey Mts in the US.

In addition to these natural haze micro-nuclei, humans have also been releasing vast equivalent quantities of smog, smoke and particulate micro-nuclei into the air adding to these humid haze levels over lagre areas eg the Asian brown haze over India to China.

These haze water micro-droplets absorb incoming solar radiation and thus result in the well documented global dimming (of up to 15%) and cooler surface temperatures. However because they increase humidities these persistent hazes also decrease pan evaporation levels (by some 10%). This plus the inability of the small haze micro-droplets to coalesce into the larger drops needed to form rain has resulted in part of the systemic decline in rainfall over affected areas such as southern Australia or Asia where the brown haze is associated with a 30% decrease in monsoonal rainfall.

While dimming the solar intensity at the earth's surface, the absorption of heat by the increased levels of persistent haze micro-droplets is also responsible for much of the warming of the lower atmosphere. In fact the hazes have a double warming effect absorbing short wave solar radiation while in the liquid phase and absorbing long wave re-radiated infra red heat from the earth's surface while in the water vapour phase, the earth's dominant natural greenhouse effect. Hence managing these hazes is critical if we are to cool regions and the planet in time to avoid the otherwise dangerous climate meltdown.


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):

Posted by editor at 7:56 AM EADT
Updated: Saturday, 8 November 2008 8:43 AM EADT

View Latest Entries