From a Press Release from the Max Planck Institute for Meteorology
Do dust particles curb climate change?
A knowledge gap exists in the area of climate research: for decades, scientists have been asking themselves whether, and to what extent man-made aerosols, that is, dust particles suspended in the atmosphere, enlarge the cloud cover and thus curb climate warming. Research has made little or no progress on this issue. Two scientists from the Max Planck Institute for Meteorology in Hamburg (MPI-M) and the American National Oceanic and Atmospheric Administration (NOAA) report in the journal Nature that the interaction between aerosols, clouds and precipitation is strongly dependent on factors that have not been adequately researched up to now. They urge the adoption of a research concept that will close this gap in the knowledge. (Nature, October 1st, 2009)
Greenhouse gases that heat up the earth’s atmosphere have their adversaries: dust particles suspended in the atmosphere which are known as aerosols. They arise naturally, for example when wind blows up desert dust, and through human activities. A large proportion of the man-made aerosols arise from sulfur dioxides that are generated, in turn, by the combustion of fossil fuels.
The aerosols are viewed as climate coolers, which compensate in part for the heating up of the earth by greenhouse gases. Climate researchers imagine the workings of this cooling mechanism in very simple terms: when aerosols penetrate clouds, they attract water molecules and therefore act as condensation seeds for drops of water. The more aerosol particles suspended in the cloud, the more drops of water are formed. When man-made dust particles join the natural ones, the number of drops increases. As a result, the average size of the drops decreases. Because smaller drops do not fall to the ground, the aerosols prevent the cloud from raining out and extend its lifetime. Consequently, the cloud cover over the earth’s surface increases. Because clouds reflect the solar radiation and throw it back into space, less heat collects in the atmosphere than when the sky is clear. Climate researchers refer to this mechanism as the “cloud lifetime effect”.
To date, however, it has not been possible to quantify the influence of the cloud lifetime effect on climate. The estimates vary hugely and range from no influence whatsoever to a cooling effect that is sufficient to more than compensate for the heating effect of carbon dioxide.
According to Bjorn Stevens from the MPI-M and Graham Feingold from the Earth System Research Laboratory at NOAA in Washington D.C the enormous uncertainty surrounding this phenomenon is indicative of the fact that the explanation of the cooling mechanism generated by aerosols is oversimplified. The two cloud researchers have analyzed the specialist literature published on this topic since the 1970s. In their survey of the literature they encountered observations that disagree with the cloud lifetime effect: for example, a field study carried out a few years ago found that clouds in the Trade Wind region rain out more quickly rather than more slowly in the presence of virtually opaque aerosols.
On the completion of their analysis of the literature, Stevens and Feingold came to the following conclusion: “Clouds react to aerosols in a very complex way and the reaction is strongly dependent on the type and state of the cloud,” says Stevens. Therefore the aerosol problem is a cloud problem. “We climate researchers must focus more on cloud systems and understand them better,” he stresses.
As the researchers write, processes in the clouds that counteract or even negate the influence of the aerosol particles have not been taken into account up to now. One example: when a cumulus cloud comes into contact with aerosols, it does not rain out. However, this has certain consequences: the fluid rises and evaporates above the cloud. The air that lies above the cloud cools down and becomes susceptible to the upward extension of the cumulus cloud. Higher cumulus clouds rain out more easily than lower ones. This is what causes precipitation. Therefore, in such situations the aerosol does not prevent the cloud from raining out.
Stevens and Feingold believe that due to such buffer mechanisms the cooling effect of the aerosols is likely to be minimal. They admit, however, that the cloud lifetime effect is not unsuitable per se as a way of explaining the processes triggered by aerosols in the clouds. “All cloud types and states cannot, however, be lumped together,” says Stevens. He calls for rethinking aerosol research and makes a comparison with cancer research: “People used to think that cancer was based on a single mechanism. Today, it is known that each type of cancer must be researched individually,” says the scientist.
According to Stevens and Feingold, research must first identify the cloud systems on which aerosols have the greatest influence. They suggest starting with particularly common types of cloud, for example flat cumulus clouds over the oceans (Trade Wind cumuli), which cover 40 percent of the global seas.
A research project to be undertaken jointly by the Max Planck Institute for Meteorology and the Caribbean Institute for Meteorology and Hydrology in Miami will make a start on this. The two-year empirical field study will commence on the Caribbean island of Barbados, which is located in the Trade Wind region, in 2010. The researchers will install remote sensing instruments on the island’s windward side that will focus on the clouds coming from the open ocean. The land measurements will be complemented by measurements taken in the clouds themselves by HALO, the German research aircraft. The data from this measurement campaign should help the scientists to reach a better understanding of the relationships between cloud cover, precipitation, local meteorological conditions and aerosols.
Related links:
[1] Aerosols, Clouds, Precipitation and Climate: Barbados Field Study
[2] HALO Website (The High Altitude and LOng Range Research Aircraft)
Original work:
Bjorn Stevens, Graham Feingold
Untangling aerosol effects on clouds and precipitation in a buffered system
Nature, October 1st 2009, Volume 461, pages 607 – 613
Michael (21:02:51) :
The law of unintended consequences: All that burning of fossil fuels released all that C02, which in this planet’s ecosystem is the ultimate battery. To charge that battery, it’s busy taking heat energy back out of the system.
The energy that was stored in the fossil fuels, we used that up.
Net result is a planet much cooler than when the fossil fuels were made with a a new appetite for heat energy.
Oops…the warmists had it backwards. Rod Serling strikes again.
Enjoy your global warming while it lasts.
Plants colonized the Earth’s land surface about 475 million years ago. The Earth’s surface would have just been sand dunes, wet sand, mud and rock before that.
Just think of the dust storms/aerosols that were in the atmosphere during those times. The climate model simulations put the aerosols impact at -487 watts/metre^2, just enough to put surface temperatures below absolute zero.
Burnt ground is hydrophobic and refuses to wet. Presumably dust made of burnt materials is hydrophobic too? Not just any aerosols will do.
The fact that the ice core data shows CO2 increases follow warming should in itself be enough to know that our climate models are wrong.
GIGO.
Forgive me for being vague, but wasn’t there a study that claimed the late 20th century warming in Europe was at least partially due to less cooling because of reduction in particles from air pollution?
Barbados, huh? Trade winds, huh? The great boundary between the tropical oven and the Northern Hemisphere radiator.
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RBateman 5:13:08 Was shaking the bottle before popping the cork OK?
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“The aerosols are viewed as climate coolers, which compensate in part for the heating up of the earth by greenhouse gases.”
Even in their skepticism they have to genuflect to the AGW gods.
Re: John Moore (03:59:45) :
“Clouds are described as having a cooling effect by reflecting the sunlight. However at night they have a very noticable insulating effect; the difference in temperature after a sunny day followed by a clear night is large.”
The effect you note has always plagued engineers who thought “cooling ponds” would be a nifty substitute for “evaporative cooling towers” to handle power plant waste heat rejection. The performance of the ponds was all over the map, depending on cloud cover. Radiant heat transfer from the ponds to black space is tremendous on clear nights and pitiful on cloudy ones.
Anthony
As a physicist, I’d like a answer to the following question: why is the IR absorption of aerosols/dust always ignored for the Earth’s atmosphere? In astronomy we observed IR absorption by carbon-rich interstellar dust
Nonoy Oplas (18:38:16) :
Most clouds are low-lying, but sometimes they are thinly dispersed from the higher atmosphere to low level, perhaps hust half kilometer up from the surface. And yet we are near the equator.
The same is happening now over Lima, Peru, S.A. (12° south). No springtime really due to cloud cover. Pacific anticyclone is on, also.
Only a true believer would try to create a deterministic model of a chaotic system.
If somewhere in the code of a Global Circulation Model there is the equivalent of:
Output = Output * Randomize(EstimatedCloudPercent);
Then the output of the model is useless.
If the effect of clouds is assumed to be understood and constant:
Then the output of the model is useless.
I am always curious if the authors had to at some point pay homage to the AGW Gatekeepers so to insure that RealClimate has something to post on its website when asked to rebut. As someone who doesn’t have access to all the journals It is always hard to tell from abstracts and commentaries where there is cherry picking and bias.
ROM (03:42:00)
That’s a very well written post for someone ‘not very well educated’.
I don’t see the bacterial influence as a primary driver but the biosphere including bacteria could well be a significant modulating factor.
Please clarify my understanding of the quote below.
“Greenhouse gases that heat up the earth’s atmosphere have their adversaries: dust particles suspended in the atmosphere which are known as aerosols. They arise naturally, for example when wind blows up desert dust, and through human activities. A large proportion of the man-made aerosols arise from sulfur dioxides that are generated, in turn, by the combustion of fossil fuels.”
1. I understand that that pollution control devices such as scrubbers and catalytic converters capture most SO2 particulates produced from fossil fuel combustion in North America. Am I wrong?
2. The primary source of SO2 emissions are volcanoes. That dwarf the contribution from anthropogenic sources. Is this correct?
Please explain your answers. Thanks, Paddy.
“”” Do dust particles curb climate change?
A knowledge gap exists in the area of climate research: for decades, scientists have been asking themselves whether, and to what extent man-made aerosols, that is, dust particles suspended in the atmosphere, enlarge the cloud cover and thus curb climate warming. “””
Now how’s that again about man made dust particles ? Do they have some good figures for how much of those recent Australian dust particles came out of somebody’s carpet.
Yes I know that poor human land use practices, can have an effect.
Under current California environmental laws; the air as far as dust particles goes is actually cleaner than what it was before man came to California.
Then how about those little words:- “enlarge the cloud cover and thus curb climate warming.” Is there some agenda here ? Are they saying the natural variation in cloud cover, is not just nature’s built in feedback regulator of earth’s temperature.
Yes dust and volcanic ash, and other short lived things from time to time can greatly enhance the cloud cover and its cooling effect; but so what else is new ?
They simply won’t let go of that “vlimate warming” issue will they. Well so we know that the climate has been warming since the last ice age; are we missing something here ?
George
But I’m going to read what they have to say anyway; it’s nice to see somebody finally paying attention to Gaia’s natural temperature regulator.
“”” Re: John Moore (03:59:45) :
“Clouds are described as having a cooling effect by reflecting the sunlight. However at night they have a very noticable insulating effect; the difference in temperature after a sunny day followed by a clear night is large.” “””
Now please explain just what it is about a cloud’s intelligence that tells it to turn on its “insulating” effect at night, and turn it back off during the daytime. Well those clouds were there during that sunny day weren’t they ?
Well if not, you are just talking about last night’s weather, and not any climate phenomenon. Warm susnny days’ particularly humid ones stay warm at night, and tend to form high clouds at night. You have to have the evaporation of that warm sunny day to get any clouds; day or night.
“”” ROM (03:42:00) : “””
Don’t want to paste in your entire essay ROM; but have you considered that H2O; aka water has some very specific physical and chemical properties.
Freezing point, boiling point, specific heat, latent heat of freezing, latent heat of boiling, surface tension, dielectric constant, refractive index, electric dipole moment (that 104 dergee angle business), optical absorption spectrum (the whole spectrum), the densit versus temperature function, and so on.
Those specific properties; plus its biological effects , and the large amounts of it present on earth, establish a regime of temperatures, which encompass the phase transition, from solid to liquid to gas, and vice versa, in conjunction with the earth’s atmospheric composition, its density, and specific heat, the level of solar energy input at earth’s orbit location; blah blah blah !
And together that all defines a range of temperatures; which just happens to be a satisfactory living condition for much of the life on earth.
We are not likely to change much of any of that; well you might see if the atomic physicists can get H2O to change that 104 degree angle to something else; but without it, life on earth would not exist.
So the computer games folks can play with their statistical mathematics and regressions and R^2 numbers and so on; but unless you can change the properties of water; you aren’t going to accomplish much in climate engineering.
ROM (03:42:00)
Fascinating post. And emergence of three new species of non-terrestrial bacteria in the stratosphere bodes well for new understanding of life’s origins. With regard to dimethyl sulphide influence in cloud formation – there is a paper (cannot locate at the moment) demonstrating phytoplankton production of ds increases with a lowering of ocean pH (“acidification!”) This suggests an elegant system whereby atmospheric CO2 absorbed by seawater tickles the phytoplankton releasing ds that increases cloud formation. Which then modulates insolation, precipitation, heat balance etc. etc…
Factors that puny computer models do not now or in the future portend to include. It’s a far more interesting world than the doomers would have us believe!
Robert,
I put it in because just because something has not happened in the past does not mean it CANNOT happen in the future. However I feel the odds of CO2 being a catalyst for major feedback warming is low based on prior history to the point of being ridiculous that it is what all the warming is based on. However, I will not say that it is NOT possible, just highly improbable. I will not close my mind to a possibility that may explain what it is happening until it can be proven one way or another… As a skeptic I feel that while I may not BELIEVE until it is proven I am willing to allow people to espouse it as theory until proven correct or incorrect.
But as you say, there is no historical context for the feedback mechanism to be based on CO2. At this point it appears that CO2 is a follower of warming not the leading cause. But it will be interesting to see in the coming years what happens. I expect that in the next 4 to 5 decades this question will be at least partially answered.
Wow,
These guys have it down, don’t they. Another man caused effect on climate but this one causes cooling ( and requires research in Barbados ).
So does AGW (from CO2) offset AGC (from aerosols) so there is no problem? Something tells me that we are going to have to have our behavior(s) controlled in regards to both, that’s aways seems to be the direction.
“”” Do dust particles curb climate change? “””
NO they do not; they are one of the causes of climate change; sorry, what is your next question ?
“”” Indiana Bones (12:05:42) :
ROM (03:42:00)
Fascinating post. And emergence of three new species of non-terrestrial bacteria in the stratosphere bodes well for new understanding of life’s origins. “””
Seems like biologists keep on discovering new species all the time; hundreds of them every year; maybe thousands.
So what is so special about finding some bugs where they didn’t look for them before ? You should see some of the non terrestrial critters they find around black smoker vents at the bottom of the ocean.
George, good point. There are many extremeophiles discovered in a variety of hostile environments on earth. The India project is enthused by their results because of the precautions taken to ensure these particular bacteria had no terrestrial contact below their apparent habitat.
“The precautionary measures and controls operating in this experiment inspire confidence that these species were picked up in the stratosphere.”
Of course being bacteria they could have blown in from almost anywhere.
http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=40626&src=eorss-nh