Refining atmospheric climate models

Feb 01, 2011
The fresh scent of pine may end the search for missing sources of organic molecules in the air—which, it could well turn out, aren't missing after all. In work appearing in this week's Proceedings of the National Academy of Sciences Early Edition Online, researchers found that particles containing compounds such as those given off by pine trees evaporate more than 100 times slower than expected by current air-quality models

(PhysOrg.com) -- A long, frustrating search for the source of "extra" aerosols seen in field experiments but not in models might have come to an end when scientists at Pacific Northwest National Laboratory and Imre Consulting discovered the particles aren't what people thought. The particles are not liquids. Instead, the aerosols, known as secondary organic aerosols (SOA), are solid and evaporate more than 100 times slower than expected. What researchers previously thought takes seconds actually takes days.

"This work could resolve the discrepancy between and models," said principal investigator Dr. Alla Zelenyuk, a chemist at PNNL. "The results will affect how we represent organics in climate and air quality models, and could have profound implications for the science and policy governing control of submicron levels in the atmosphere."

In predicting the impact of different scenarios on the planet's climate, atmospheric scientists want to use the most accurate models possible. This study gives scientists the information they need to properly represent secondary organic aerosols in the models, more accurately reflecting what is measured in the environment.

For a couple of decades, researchers have interpreted lab and field measurements under the assumption that secondary organic aerosols are liquid droplets that evaporate quickly, to establish equilibrium with their surroundings, which is central to the way these particles are modeled. Secondary organic aerosols are of chemically modified organic compounds floating in the air. They absorb, scatter or reflect sunlight, and serve as cloud nuclei, making them an important component of the atmosphere. However, researchers have failed to explain the high amounts observed in real-world measurements.

So, researchers at PNNL and Imre Consulting used equipment that could study the particles under realistic conditions. Zelenyuk developed a sensitive and high-precision instrument called SPLAT II that can determine the composition, count, size, and measure the evaporation characteristics of these particles at room temperature. The instrument is located in EMSL.

To establish their methodology the researchers made particles from other, well-understood organic molecules that are known to form solids or liquid droplets, such as one called DOP and demonstrated that they behaved precisely as expected.

They then created secondary organic particles in the lab by oxidizing alpha-pinene, the molecule that makes pine trees smell like pine. Oxidation of this and similar volatile organic compounds is what happens in the atmosphere and results in formation of secondary organic aerosols.

Monitoring the various particles with SPLAT II for up to 24 hours, the research team found that while DOP particles behaved as expected, the pinene-based particles did not. About 50 percent of their volume evaporated away within the first 100 minutes. Then it slowed. Only another 25 percent of their volume dissipated in the next 23 hours. In addition, this fast-slow evaporation occurred similarly whether the particle was big or small, indicating the particles were not behaving like a liquid.

In the world, the secondary organic aerosols from pinene are formed in the presence of many other organic molecules, and some of these molecules slam into the particle and get incorporated, forming coatings. Experiments with the co-mingled secondary organic aerosol precursors and other showed the researchers that these coated particles evaporate even slower than single-source secondary organic aerosols.

This lack of evaporation could put to the rest an intense effort by many scientists focused on finding other sources of atmospheric organics. "Our findings indicate that there may, in fact, be no missing SOA," said Zelenyuk.

The team then tested how close to reality their lab-based secondary organic aerosols were. By sampling the ambient air in Sacramento, Calif., they found the behavior of atmospheric secondary organic aerosols (whether from trees and shrubs or anthropogenic pollution) paralleled that of the co-mingled pinene-derived aerosols in the lab and did not behave like liquids.

The results suggest that in the real atmosphere, secondary organic aerosols evaporation is so slow that scientists do not need to include the evaporation in models. The researchers believe that incorporating this information into atmospheric models will improve the understanding of aerosols' role in the climate.

The scientists are continuing their research into measuring the properties of secondary and working with modelers on properly representing the aerosols' properties and their impact on the environment and atmospheric models.

Explore further: NASA finds heavy rainfall and wind shear in newborn Tropical Storm Bertha

More information: Vaden TD, et al. 2011. "On the Evaporation Kinetics and Phase of Laboratory and Ambient Secondary Organic Aerosol." Proceedings of the National Academy of Science USA, Early Edition. Online the week of January 24, DOI: 10.1073/pnas.1013391108

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NotParker
2.5 / 5 (11) Feb 01, 2011
"Trees cause more pollution than automobiles do." -- Ronald Reagan, 1981

The Gipper was brilliant!
NotParker
2.5 / 5 (11) Feb 01, 2011
"An unexpected and startling discovery that plants emit millions of tonnes of greenhouse gas methane every year has plunged climate change discussions into disarray.

Trees and plants emit up to 30 per cent of the world's methane, Frank Keppler at the Max Plank Institute for Nuclear Physics, Heidelberg, Germany, and his colleagues claim. After discovering that fallen leaves, or plant litter, produced methane, Keppler investigated whether living plants also produce this highly reduced gas in air - an oxygen rich environment. He calculated that plants give off between 60 and 240 million tonnes of methane per year.

The news has shocked the atmospheric science community."

ht_Delete_tp://www.rsc.org/chemistryworld/News/2006/January/12010601.asp
gvgoebel
4.3 / 5 (6) Feb 01, 2011
Notes from a 2007 article in SCIENTIFIC AMERICAN online:

"In 2006, geochemist Frank Keppler of the Max Planck Institute for Chemistry in Mainz, Germany, reported that trees emit large quantities of methane, which is over 20 times more potent a greenhouse gas than the carbon dioxide that the trees soak up. Now a study by botanist Tom Dueck and his colleagues at Plant Research International in Wageningen, the Netherlands, found that methane emissions from plants were down in the noise, that the concentrations were so low and variable that they did not significantly differ from zero.'"

In reality, Keppler had never claimed the methane emissions from trees were any real problem. The emissions were large in absolute terms, but only a small fraction of the amount of CO2 sequestered sequestered by the tree, degrading the benefit of the tree by only 4% at most."

An academic quarrel followed between Keppler and Deuck over methodology.
NameIsNotNick
not rated yet Feb 01, 2011
"An unexpected and startling discovery that plants emit millions of tonnes of greenhouse gas methane every year has plunged climate change discussions into disarray.

Trees and plants emit up to 30 per cent of the world's methane, Frank Keppler at the Max Plank Institute for Nuclear Physics, Heidelberg, Germany, and his colleagues claim. After discovering that fallen leaves, or plant litter, produced methane, Keppler investigated whether living plants also produce this highly reduced gas in air - an oxygen rich environment. He calculated that plants give off between 60 and 240 million tonnes of methane per year.

The news has shocked the atmospheric science community."


And exactly where, in the article, does the quote you were kind enough to highlight appear? I can't find it...
gvgoebel
not rated yet Feb 01, 2011
Meredith Knight, "Are Plants Really Villains In Climate Change?" 1 June 2007

https COLON SLASH SLASH //www DOT scientificamerican DOT com/article.cfm?id=are-plants-really-villains-in-climate-change

Google "Keppler Dueck trees methane" and a pile of links pop up, including this one.
gvgoebel
5 / 5 (1) Feb 01, 2011
See also a 2007 SCI-AM article by Keppler & colleagues, "Methane, Plants, & Climate Change":

http COLON SLASH SLASH www DOT pages DOT pomona DOT edu/~cjt04747/chem106ps/Scientific American Feb 2007 DOT pdf

It is actually abivalent in some ways, but it does state: " ... our calculations show that the climatic benefits gained by establishing new forests to absorb carbon dioxide would far exceed the relatively small negative effect of adding more methane to the atmosphere (which may reduce the overall carbon uptake of the trees by 4 percent at most)."
Jimee
not rated yet Feb 01, 2011
One more bit of data in support of...
NotParker
1.8 / 5 (5) Feb 02, 2011
ht_delete_tp://www.nature.com/news/2007/071128/full/news.2007.307.html

Yes, plants produce methane.
NotParker
1.8 / 5 (5) Feb 02, 2011
As Scientific American said:

"The emissions were large in absolute terms"

Yup. Not to be ignored.
NotParker
1.6 / 5 (7) Feb 02, 2011
Of course they also used to think there were only a few thousand undersea volcnoes emitting methane and CO2.

But it looks like there are at least 3 million.

And if the Ocean is acidifying, it is the volcanoes since no freshwater lakes are acidifying (since there aren't 3 million volcanoes in any lake)

ht_delete_tp://www.suite101.com/content/acid-oceans-due-undersea-volcanoes-not-humans-a220085
Vendicar_Decarian
2.3 / 5 (3) Feb 02, 2011
A retarded and scientific illiterate blogger by the name of John O'Sullivan is the source of NotParker's QuackTard nonsense.

NotParker's source also provides us with the following nugget of Scientifically Illiterate Quackery...

"We are forever being told that the sun is a vast gas ball of hydrogen and helium at the center of our solar system. But new evidence may help prove this isn’t the case after all..." - John O'Sullivan - Jan 03, 2011

"The four key points made by the iron core theorists are:

1. We do not “see” the Sun;

2. We see waste products emitting light when they reach the top of the Sun's atmosphere (photosphere);

3. The "smoke" we see is (H and He) from a neutron star;

4. The global eruption was triggered by the tiny, energetic, dense neutron-rich core of the Sun or by the iron-rich mantle that surrounds it." - John O'Sullivan - Jan 03, 2011

gvgoebel
5 / 5 (2) Feb 02, 2011
As Scientific American said:

"The emissions were large in absolute terms"

Yup. Not to be ignored.


But the 25 gigatonnes of human CO2 emissions per year can be ignored, right? Even though they are a fraction of natural emission processes.
NotParker
1.8 / 5 (5) Feb 02, 2011
A retarded and scientific illiterate blogger by the name of John O'Sullivan is the source of NotParker's QuackTard nonsense.


Actually, it was from a peer reviewed paper still considered valid in 2011. Look it up.

Try telling better lies. Your current crop is pathetic.
Skeptic_Heretic
5 / 5 (2) Feb 02, 2011
Actually, it was from a peer reviewed paper still considered valid in 2011. Look it up.

Try telling better lies. Your current crop is pathetic.
Your sense of scope and current understanding of science is the pathetic piece in this equation.
NotParker
2 / 5 (4) Feb 03, 2011
Your sense of scope and current understanding of science is the pathetic piece in this equation.


Being able to read and find papers on the internet is not a tough skill to learn. You should try it instead of just regurgitating Al Gore's lies.
Doom1974
not rated yet Feb 12, 2011
Have you ever heard of non-linear dynamics and bifurcations due to a "small" parameter? Ohh and forgive me what I mean "small". Compare the forest coverage before agriculture and today. Then calculate how much carbon has been put into the system. Geology is much too slow to have sequestered all that CO2 into carbonates. Still exists in the atmosphere and the sea. Do the calcs. And by the way volcanoes have always been there. There has not been an increase in volcanism over the last few thousand years compared to prior periods. Therefore CO2 emissions from volcanoes (apart from being balanced by particulates and SO2) are a random background noise to the whole system. The only thing that has been increasing has been the emission of CO2 because of the humans.
Skeptic_Heretic
not rated yet Feb 12, 2011
Your sense of scope and current understanding of science is the pathetic piece in this equation.


Being able to read and find papers on the internet is not a tough skill to learn. You should try it instead of just regurgitating Al Gore's lies.

Care to tell me which one I've parrotted or are you just listening to the media rather than the science?