Aerosols and "cloud lifetime effect" cited as "enormous uncertainty" in global radiation balance

From a Press Release from the Max Planck Institute for Meteorology

Every cloud is different from the next. It is therefore important to study the types of cloud systems in which aerosols have the greatest influence. Image: Max Planck Institute for Meteorology / Stevens

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

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October 6, 2009 5:42 pm

Interesting. Does this not also lead to the factor of decreased rainfall, if rain does not reach the ground? What do the experts say?

October 6, 2009 6:01 pm

And we also now have Prof. Henrik Svensmark’s new report as noted on
“Cosmic Ray Decreases Affect Atmospheric Aerosols And Clouds
ScienceDaily (Oct. 6, 2009) — Billions of tonnes of water droplets vanish from the atmosphere in events that reveal in detail how the Sun and the stars control our everyday clouds. Researchers of the National Space Institute in the Technical University of Denmark (DTU) have traced the consequences of eruptions on the Sun that screen the Earth from some of the cosmic rays — the energetic particles raining down on our planet from exploded stars.”
The piece concludes with this quote:
“The evidence has piled up, first for the link between cosmic rays and low-level clouds and then, by experiment and observation, for the mechanism involving aerosols. All these consistent scientific results illustrate that the current climate models used to predict future climate are lacking important parts of the physics”.

October 6, 2009 6:03 pm

‘To date, however, it has not been possible to quantify the influence of the cloud lifetime effect on climate.’ Nice bold highlight. In contrast to ‘NOAA understands and predicts changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.’
The science is settled! We are just not sure if clouds are a significant influence but we are sure that CO2 is ……. trace gas verses water vapor ….. but we need money to study.

Robert Wood
October 6, 2009 6:03 pm

Hmm, nice job in the tropics for a lucky few German “climate scientists”.
Sorry if I appear cynical; but hey, at least they are making empirical studies. Maybe inadequate, but a start.

October 6, 2009 6:24 pm

Ever was it so…These very same issues have confounded nearly every climate analysis in the last twenty years.

October 6, 2009 6:27 pm

Waiting for Kim’s ‘message in a cloud’…..

October 6, 2009 6:38 pm

I’m interested to see the result of that new study. Here in the Philippines, we hardly see the Sun the past few weeks and months. With or without a typhoon, clouds are everywhere. Sometimes the Sun would show up in the morning, only to disappear in the afternoon. 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.

October 6, 2009 6:38 pm

We should get Dylan Ratigan to moderate the current state of the global warming debate. He shows real promise in getting to the truth about the issue.
Here is how he dealbt with a specific health reform issue.
I know, it’s a link to Huffington Post. Please forgive me.

David Segesta
October 6, 2009 6:44 pm

Our climate is incredibly complex. To say that CO2 controls everything is a huge oversimplification.

October 6, 2009 6:46 pm

SNIP – we don’t allow discussions of chemtrails on WUWT

October 6, 2009 6:55 pm

If I recall correctly, a large cooling effect of aeresols is presumed by the global circulation models when calibrated/validated against present and past climate. If the actual cooling effect is minimal, as argued above, then a reasonable conclusion is that the warming effect from CO2 is quantitatively overestimated by the models.

October 6, 2009 6:56 pm

I take it these aerosols also compensate for the greenhouse effect of the water they create?
Sounds like perpetual motion.

Ron de Haan
October 6, 2009 6:57 pm

Help, I need a budget, I want to go to Barbados!
I ask a simple question:
We all have seen the sat images from ship tracks.
If they measure the emission output of an individual ships engine and measure the moisture levels and temperature of the surrounding air mass and the residence time of the chimney plume, they can use that data for models.
Here you have an example:
Ship Tracks in a Stratiform Cloud Layer
Just thinking scientific experiments on a poor man’s budget
I tell you in advance, the entire study won’t bring us a rats ass further because the human effects are dwarfed by natural events.
Just an example.
In all the European cities fine dust measurement are made.
One of the recent reports I read about the subject concluded that over 60% of the fine dust collected came from the Sahara desert and other natural sources.

Claude Harvey
October 6, 2009 7:08 pm

Well golly-gee! Maybe clouds have something to do with global temperature? While these guys are working on aerosol effects the Swiss are onto cloud seeding via cosmic radiation (now at its highest levels since cosmic ray recording began; it’s sunspot related).
These breathless “scientists” are merely rediscovering what ancient climate prognosticators knew all along. Nature’s primary, near-term temperature control mechanism is low-level cloud cover (not the kind that makes rain). I expect they will eventually “discover” that global temperature is fundamentally “self-correcting” by way of “negative feedbacks” to any forcing function that tries to change temperature (greenhouse gasses, for example). History plainly records that the climate system is inherently stable over the short term (and long-term cyclic over a macro range of 12 deg C.) and that it is not subject to “runaway” situations and “tipping points” such as those programmed into the CO2 global warming computer models.
I find it interesting that so many big-time scientific institutions are suddenly easing themselves back off that “runaway global warming limb” (without actually saying so). We can now add the Planck Institute and the Woods Hole Oceanographic Institute to the list of scientific heavy-hitters who seem to realize they’re about to look really foolish if they don’t somehow get out ahead of what is rapidly becoming self-evident.
Global temperature peaked in 1998 (GISS data manipulations be-damned) and has since declined; that’s a FACT!

Jack Wedel
October 6, 2009 7:12 pm

In the 1970’s, my group was engaged in hydrologic study of runoff regimes of the Canadian Arctic Islands, especially for the snowmelt period. We wished to relate net solar energy inputs for the melt to the melt water runoff. To measure net solar radiation, we mounted two solid-state solarimeters, one pointing up, and one down to the smowpack. We thus obtained data for direct sunshine and the albedo. Our main concern was the substantial loss of snow water content via sublimation during the melt season. So, my question: Why could not weather satellites, properly instrumented, measure the same two parameters? That would, at the very least, provide some information for the short-wave energy components which could, in turn be linked to cloud cover beneath the satellite.

Bill Illis
October 6, 2009 7:18 pm

Hansen recently said that the Aerosols estimates were more-or-less just pulled out of a hat (and he was not kidding).
You can multiply these numbers by 0.32 to approximate the temperature impact used.

October 6, 2009 7:29 pm

I think I’ve never heard so loud
The quiet message in a cloud.
REPLY: You’re late. People were beginning to talk. – A

October 6, 2009 7:39 pm

Heh, DR, I saw the headline and jumped to my couplet.
Claude, sometimes I think that quiet message in a cloud is the magic self-centeringness of the whole system. Doubtless the real mechanism is even more complicated than just the convection, radiation and phase changes within a cloud, but it’s entertaining to imagine that there is just a simple process deep in the occult heart of a cloud.

October 6, 2009 7:48 pm

Ding, ding, ding – we have a winner! What separates ho-hum warming due to CO2 from alarming warming due to CO2 is the role of aerosols in the climate models. If you want to post at RC for the purpose of getting NO response, ask about aerosols and climate modeling. Crickets chirping.

October 6, 2009 7:59 pm

Chris, the real irony is that by manipulating the once and future record of albedo the warmistas could explain any model output they’d care to push. I think the dissonance and demoralization in that community has caused them to miss the opportunity, and now, it may be too late. We are cooling, folks; for how long even kim doesn’t know.

October 6, 2009 8:08 pm

Isn’t this just a waste of time and money since the science is settled?

October 6, 2009 8:15 pm

Do you suppose a hamster ever sees its own wheel?

October 6, 2009 8:16 pm

‘Follow the Latent Heat’.
Signed, Deep Cloud

Claude Harvey
October 6, 2009 8:46 pm

Re: Ken Roberts (20:15:39) :
“Do you suppose a hamster ever sees its own wheel?”
I never before heard or saw that profound observation and I hope you dreamed it up, because it far surpasses my “dogs chasing their own tails” description of most of this bunch of scientists. These people have no inertia. It’s not so much that they can change direction instantaneously that I find so bizarre, but that they can do so with an enthusiasm that does not wane despite repeated failures to gain any headway whatever.

Douglas DC
October 6, 2009 8:56 pm

As the Warmists sink into the west, the evidence is rising in the east,for them a cold,bad Moon on the rise.
Apologies to Creedence Clearwater…

October 6, 2009 9:02 pm

Happy days are here again. What a relief. I was led to believe the planet was going to go up in a fiery ball of flames, and it was all my fault.
Antarctic Ice Melt at Lowest Levels in Satellite Era

October 6, 2009 9:05 pm

I must confess I made it up; excuse me while I catch my breath.

October 6, 2009 9:23 pm

I suppose I should be happy that some scientists are finally admitting climate is more complex then they thought. However I am saddened at the slant of “to see how much this is masking global warming”. I mean from as far as we know except for the minuscule warming that SHOULD occur with CO2 there has been no real warming at all.
I suppose that is where the media, and maybe even most other ‘science’ blogs get skeptics wrong. It is not that we do not believe that CO2 will warm the atmosphere. It is the preposterous levels that are claimed that leave us slack-jawed from shock ( I am using the royal we here – I suppose it is really simply myself that feels this way but I feel so much better saying we )
It is not that an increase in CO2 does not ‘warm’ the atmosphere, but rather a question of the silly feedback mechanisms that have been used to ‘predict’ large amounts of warming, rather then looking for other possible climactic causes. Just the fact that the almost linear progression of CO2 has not even come close to matching up to the temperature increase to data ( CO2 steady climb, temperature not so much I mean if we were in the 70’s we would be asking if CO2 had a negative impact on temperature somehow lol )
That is again not to say that CO2 could not be a catalyst for runaway warming, but… it is pretty theoretical at this point since it hasn’t happened. I am tired of reading stories like “unless something is done about CO2 the temperature COULD increase as much as 2 degrees Celsius by 2050. Does not Could imply that it may do nothing of the sort? Could it not also not change?
Sorry if this is a rant, this article managed to make me feel tired of saying the same thing over and over again. I am tired of science being something you advocate rather then study. I am thankful to everyone out there who rather then be silenced by the majority ( the consensus ) is still researching and asking questions other then, how much higher can we say the temperature will go? If in the end the ‘consensus’ is right we will know not because they told us, but because we proved it… but at this time the truth is still out there buried in a million different places.

October 6, 2009 9:32 pm

Innocentious (21:23:00) :”I am tired of science being something you advocate rather than
study. “

“If in the end the ‘consensus’ is right we will know not because they told us, but because we proved it… but at this time the truth is still out there buried in a million different places.”
Hear hear!
Norfolk, VA, USA

October 6, 2009 9:36 pm

I sat on a hillside
and gazed up at the clouds
while others were acting
like they were not around
they made a few models
showing temperatures up
and blaming emissions
for the increase of heat
then it grew stormy
I am sorry to say
and all of that heat
simply went away
clouds it would seem
play a pretty big role
in temperature regulation
don’t you know

October 6, 2009 9:39 pm

Sometimes human beings just don’t like being told everything under the Sun is their fault. Human beings with a spine may rebel at that notion. It only took 12% of the original colonists with a backbone to form the greatest nation on Earth.

October 6, 2009 9:50 pm

It is reaaally amazing to see so many issues popping up one after another in the sacrosanct “Debate is Over” Science.

October 6, 2009 9:57 pm

I feel past volcanic events have provided evidence that aerosol particulates can cause cooling, whether through global dimming or cloud nucleation. While anthropogenic additions to aerosol particulates may be small compared to natural sources, they are more of a concern than CO2. The last thing we need in the next decades is more cooling.
Improvements in air quality in developed nations over the past few decades shows that we can do a lot to decrease anthropogenic aerosol particulates. More could be achieved with regard to surface transport such as ships, trains and trucks. The problem may be getting people to care.
So many people have been crying Wolf on CO2 so loud and for so long… Based on studies of twelve hairs we found the size of the wolf is unprecedented…The planet could be sheep free in less than a decade…It’s more bitey than we thought…and the rest. Will anyone be interested in aerosol particulates?
I feel there may be good reason to study the impact of aerosol particulates. Creating an excuse that CO2 warming has been “masked” but is still a huge threat would not be among them.

anna v
October 6, 2009 10:48 pm

Well, have a look at this flash back
WND has obtained a copy of a college textbook Holdren co-edited with Malthusian population alarmist Paul R. Ehrlich in 1971, entitled “Global Ecology,” now a rare out-of-print book that cost WND over $100 to buy on Amazon.
Warning the world was headed for a new ice age unless the government mandated urgent measures to control population, including the possibility of involuntary birth control measures such as forced sterilizations, Holdren predicted “ecocide” or the “destruction of all life on this planet” were a possible consequence of inaction.
In an essay contained in the textbook entitled “Overpopulation and the Potential for Ecocide,” Holden and Ehrlich predicted on pages 76-77 a “world cooling trend” they estimated at measuring “about 2 degrees Celsius in the world mean surface temperature over the past century.”
Holdren and Ehrlich attributed the cause of global cooling to “a reduced transparency of the atmosphere to incoming light as a result of urban air pollutions (smoke, aerosols), agriculture air pollution (dust), and volcanic oil.” (Parenthesis in original text.)
The authors worried “a mere 1 percent increase in low cloud cover would decrease the surface temperature by .8C” and that “a decrease of 4C would probably be sufficient to cause another ice age.”
Holdren and Ehrlich warned, “The effects of a new ice age on agriculture and the supportability of large populations scarcely need elaboration here.”
They continued: “Even more dramatic results are possible, however; for instance, a sudden outward slumping in the Antarctic ice cap, induced by added weight, could generate a tidal wave of proportions unprecedented in recorded history.”

Even a stopped clock is accurate twice a day, coming and going.

John F. Hultquist
October 6, 2009 11:08 pm

FYI: A photo (high resolution) of a dust storm in Easthern Washington State (Sun., Oct. 4th) is here:
State boundaries appear as light gray lines. Dust is the light brown under the white cloud.
A simple news story and a photo with a locator town is here:

October 6, 2009 11:17 pm

Re Anna V on Holdren & Ehrlic
Some of us are old enough to remember reading that; and Nigel Calder’s “Weather Machine”. I still have my copy of the latter. That’s one of the reasons so many of us sceptics (and lukewarmers) are so much older than the warmers. We don’t swallow the BS. We’ve heard it all before.
Personally, when I read some alarmist drivel I run around in a circle flapping my hands and chanting: “wibble, wibble, wibble”. Then I have a nice cold glass of Marlborough district sauvignon blanc and feel much better 🙂

Phillip Bratby
October 6, 2009 11:19 pm

“Greenhouse gases that heat up the earth’s atmosphere”. I thought it was the energy from the sun that was responsible. If I put a greenhouse gas into my house, will it heat up the house’s atmosphere and will I be able to turn down my heating system and save energy and money?

October 6, 2009 11:33 pm


Julian Flood
October 7, 2009 12:31 am

Well, if kim’s allowed to repeat himself:
The oceans produce salt particles which become CCNs.
Man makes dust/smoke which becomes CCNs. shows us a mechanism whereby Man can reduce the amount of oceanic CCNs. (Briefly: 363 million gallons of oil spills down the drain each year; 5ml of oil will smooth a hectare of ocean surface; smoothed ocean reacts less with the wind and fewer breakers form — the loss of engagement is equivalent, I believe on the evidence of one set of wind data from WWII, to a reduction of windspeed of 7 m/s, but that’s very flakey; fewer salt particles, less cloud in the boundary layer, warmer ocean surface.) thus there is a conflict between sea surface pollution and atmospheric pollution. From 1946 to 1970 we made more sulphur etc CCNs than we suppressed salt CCNs. It cooled. Before and after those dates our oil spills predominated in their climate effects. Spill less oil and the world will cool.
For the hypothesis: global warming starts in 1850, well before CO2 can have been the cause, and the warming rate from 1910 to 1940 (CO2 forcing .25w/m^2) is the same as from 1970 to 2000 (CO2 forcing 2 w/m^2); there is an enormous hump in temp from 1940 to 46 — raw data — which is hidden when the Folland and Parker bucket correction is phased in; polar ice melting is concentrated in areas where oil spills are to be expected. Large oil spills clear cloud downwind.
Against: the big Mexican oil spill doesn’t show any effect.
:Lindzen doesn’t think the effect is big enough.
: no-one’s done the research.
Google for “the last polar bear” image and look at the sea surface behind the poor little bear on his tiny square floe. All the surface is smoothed, but long lines of extra pollution show as lighter areas.
I leave the effect of smoothed surfaces on the rate of uptake of heat during the day (hint, albedo goes down) and the rate of heat loss at night (hint, emissivity goes down) to the keen student.
kim, there was a line from a poem that the chap who did the last page in Flight used to quote, but it’s not on the web. ‘And suddenly a cloud took all away’. If science begins to look at clouds, finds that the science is far from being settled and is all tosh, it could be a very apt line.

October 7, 2009 12:51 am

Sorry to comment to an OT, but I couldn’t help myself. In response to:
Happy days are here again. What a relief. I was led to believe the planet was going to go up in a fiery ball of flames, and it was all my fault.
Antarctic Ice Melt at Lowest Levels in Satellite Era
It still will not stop the media recycling that picture of a dirty great crack along the ice shelf and telling us that when it breaks off (again) that it is a unique and dangerous proof of evil selfish motorists killing those cute and fluffy white polar bears.
They cannot allow the truth to get in the way of good propaganda.

October 7, 2009 12:55 am

The two-year empirical field study will commence on the Caribbean island of Barbados, which is located in the Trade Wind region, in 2010.
Nice work if you can get it.

October 7, 2009 1:02 am

Thanks for the link M. Simon. We sailplane pilots spend much of our time looking up at cumulus clouds but every now and again after a climb to cloudbase, if conditions are just right and you push out into wind, things suddenly go smooth and you get a magic carpet ride up the side of a cumulus and maybe well above its top. *Then* we look at clouds from both sides.

p.g.sharrow "PG"
October 7, 2009 1:11 am

These guys want to know about forests so they study one verity of trees. Maybe they are near sighted.

Hoi Polloi
October 7, 2009 1:16 am

And so the begging for new funds for more climate research continues. Them scientist know how to keep on pouring in more tax payers money…

Robert Wood
October 7, 2009 3:35 am

Innocentious (21:23:00) :
You state my position pretty well, but That is again not to say that CO2 could not be a catalyst for runaway warming, is an unnecessary caution. CO2 has been much higher in times past and temperatures have not run away.

October 7, 2009 3:42 am

It seems that we get all tied up and sometimes fixated on each new hypothesis that comes along and purports to solve the questions on what and how the global climate is changed and “controlled” by some proposed feedback mechanism.
The CO2 hypothesis as the proposed global climate changing mechanism is a classic case of this fixation where unfortunately, for some totally inflexible proponents of this hypothesis, no alternative explanations will tolerated or considered at all.
Clouds and global cloud cover are currently getting a run amongst those who do not necessarily accept the CO2 hypothesis and on the face of it, the available evidence suggests that clouds seem to be the single most important feedback mechanism for the control of the global temperatures.
If the above is accepted, then by implication clouds and their associated feedback mechanisms control the global climate within very tight constraints and within a remarkably stable range of only a few percentage point changes in absolute temperature.
Lots and lots of questions remain about cloud cover effects which range all the way from low level cloud cover effects to Lindzen’s iris effect where high altitude equatorial clouds seem to cycle in their abilities to both trap and reflect infrared solar radiation.
Now the debate as above, is starting to switch to the way in which global and regional cloud cover is generated and the influences and factors involved in the changes in cloud cover.
The front runner for the mechanism involved in global cloud cover generation and control is Svensmark’s theory where a measured decline in solar magnetic fields is now allowing a greater influx of galactic cosmic rays to penetrate deep into the inner solar system and into the Earth’s upper atmosphere where collisions with upper atmospheric particles create a shower of cloud droplet nucleating particles which lead to greater cloud cover.
Lief’s comments from the latest WUWT posting above seems to question Svensmark’s theory as he points out the 10Be cosmic ray radionuclide counts don’t seem to be backing Svensmark’s theory.
Now we have this current posting on WUWT suggesting that aerosols may be very big contributors to the formation of cloud droplets.
This particular line of thought has been around for a long time and research in the past has shown that aerosols are indeed nucleating agents for cloud droplet formation and therefore play a big role in cloud formation.
However, that seems to leave out any known or guessed at feedback mechanism that would control the aerosol levels which in turn would control cloud formation and have a controlling effect on global climate.
Aerosols can be made up of inert particles such as silica and other mineral dust particles such as iron and etc.
Aerosols can also include chemical origin particles and biological particles such as bacteria, viruses and spores.
These latter two agents, in addition to the inert dust particles, are of biological origin and with the inert dust, are overlapping and interdependent.
The chemically based aerosols are isoprene and dimethyl sulphide, both of which are emitted by phytoplankton and are known to be involved in the process as a part of the cloud droplet nucleating agents.
There may be other chemicals, the research for which so far has not appeared for publication or has just been ignored as clouds don’t count with the climate modelers.
The inert mineral dust in the overall aerosol group above quite likely plays a role in dramatically increasing the nutrients available to the phytoplankton and to other ocean life that also emits droplet nucleating chemicals.
The third factor in the known cloud droplet nucleating agents are bacteria, viruses and spores.
One of the ice nucleating bacteria which is also used to help snow making in the snow fields, causes a good deal of grief to a range of agricultural industries as the bacteria create ice on the leaves of plants at temperatures still just above freezing thus damaging the plant.
This species of bacteria, amongst many bacterial species, is often found in quite high concentrations in cloud droplets during high altitude air sampling flights and even in fog droplets over the hills of Scotland.
The Indians were shocked when they recently found 3 new species of very UV tolerant bacteria at some 10 to 50 kilometres up in a couple of upper atmosphere balloon sampling flights.
My suggested feedback mechanism here is that the lower atmosphere origin bacteria / viruses / spores are all highly susceptible to the upper part of the UVC band which ranges from about 100nm to 280nm.
This UVC band is commonly used for germicidal control; ie; to help control bacterial infections.
It also penetrates deep into the lower atmospheric levels.
The UV bands are where the Sun has shown one of it’s largest decreases in activity with a 6% drop in UV levels during this solar minimum.
I think this is a satellite measurements but whether the measured solar UV levels are even lower at the lower atmospheric cloud levels during this solar minimum does not seem to have been checked.
The long term variations in the solar UV levels do not appear to be known with any real accuracy.
I would suggest that another additional mechanism for explaining the variations in global cloudiness could possibly be the changing solar UV levels and their impact on the biological cloud droplet nucleating agents and even on the ocean’s phytoplankton and thus on the phytoplankton’s
output of the cloud droplet nucleating isoprene and dimethyl sulphide chemicals.
Lower levels of solar UV output during this solar minimum, therefore higher survival levels of cloud droplet nucleating bacteria / viruses / spores and therefore increased cloud droplet formation and the consequent greater cloudiness and lower global temperatures.
And the reverse of course.
The whole question of cloud generation factors is a very complicated and interwoven and interdependent group of factors, some of which are probably not known or even guessed at for the moment.
It will take many years to disentangle the cloud effects whether large or minor on the global climate.
It will take even longer to disentangle which cloud forming factors are the most important and I suspect that these factors will be an ever changing morass in the way they shift and change according to the local conditions and influences on the cloud droplet nucleating agents.
I simply don’t believe the simplistic view that changes in global cloud formation can be explained by just one simple factor.
Nature is far more subtle, tricky and perverse than that!
I suggested the above bacterial cloud droplet nucleating agents scenario about a year ago in my first post on WUWT.
Not that I have done more than a handful of posts.
That first post was done with great trepidation as to a not very well educated, retired old farmer, the levels of knowledge displayed here by nearly all the regular posters is just simply beyond daunting in it’s range and quality.
Nothing has changed except the knowledge base and quality have become even more formidable to the average Joe and that makes it even more daunting to post on WUWT.

John Moore
October 7, 2009 3:59 am

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.

October 7, 2009 4:19 am

Anthony –
Are keeping abreast of the CERN Cloud 9 experiment?
Powerpoint of Cloud 9
IPCC concedes that clouds are poorly understood, then continues with their conclusions – remarkable to say the least.

October 7, 2009 4:33 am

Claude Harvey (19:08:05)
” I expect they will eventually “discover” that global temperature is fundamentally “self-correcting” by way of “negative feedbacks” to any forcing function that tries to change temperature.”
I’ve already ‘discovered’ that by suggesting that the negative feedbacks always work back towards a temperature equilibrium at the ocean/air interface and also ensure that energy leaving the Earth for space does not significantly exceed the energy reaching the Earth from the sun.
In each case components of the air circulation change as necessary in order to speed up or slow down the hydrological cycle which in turn alters the rate of energy transfer from surface to space so that those equilibria cannot be disturbed for long.
See my regular contributions to this site and my various articles here:
I’m just waiting for the ‘professionals’ to catch up.

Dave (now in Delaware)
October 7, 2009 4:52 am

Chinook Winds dust storms in Eastern Washington state and the Idaho panhandle
John F. Hultquist (23:08:22) :
FYI: A photo (high resolution) of a dust storm in Easthern Washington State (Sun., Oct. 4th)
Your photo reminded me of a study I worked on in the early 1970s to quantify the type and amount of dust brought by Chinook wind storms. I was in northern Idaho at the time. As I recall, the hills in Eastern Washington were purported to have formed from dust and dirt dropped by the winds sweeping across the state. This was said to have created hills with as much as 60 feet depth of top soil.
The study was attempting to measure dust data from a Chinook dust storm. There were several air filters set up on rooftops in the area. (my job was to make daily rounds of these filters to gather the exposed filters and replace with fresh filter media) There were micropore filters, which captured particles down to very small size, and could be used to do microscopic particle analysis. Then there were larger ‘volume’ filters, with a calibrated air pump to pull air through a filter pad about 2 ft square, mounted in a shelter with louvered side openings, much like a Stevenson Screen.
We gathered data for weeks (months?) with no dust storm. Then when a storm came through, it was all we could do to keep up changing the volume filter media. Where previously a 24 hour cycle would bring a light coating of dust on a volume filter pad, during the storm we were changing the filters multiple times during the day, EACH WITH AN INCH OR TWO OF DIRT ON THE FILTER PAD. I never did see the resultant published paper (I was a grad student making some extra money running the rooftops), but I was pleased that we were able to get them some “Solid” data.

October 7, 2009 5:13 am

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.

Bill Illis
October 7, 2009 6:08 am

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.

Kevin Kilty
October 7, 2009 6:18 am

Burnt ground is hydrophobic and refuses to wet. Presumably dust made of burnt materials is hydrophobic too? Not just any aerosols will do.

John Galt
October 7, 2009 6:30 am

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.

John Galt
October 7, 2009 6:34 am

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?

October 7, 2009 7:09 am

Barbados, huh? Trade winds, huh? The great boundary between the tropical oven and the Northern Hemisphere radiator.

October 7, 2009 7:10 am

RBateman 5:13:08 Was shaking the bottle before popping the cork OK?

October 7, 2009 7:21 am

“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.

Claude Harvey
October 7, 2009 7:26 am

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.

October 7, 2009 7:38 am

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

October 7, 2009 7:39 am

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.

October 7, 2009 8:11 am

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.

October 7, 2009 8:38 am

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.

October 7, 2009 9:36 am

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.

October 7, 2009 10:10 am

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.

George E. Smith
October 7, 2009 10:45 am

“”” 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 ?
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.

George E. Smith
October 7, 2009 10:54 am

“”” 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.

George E. Smith
October 7, 2009 11:11 am

“”” 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.

Indiana Bones
October 7, 2009 12:05 pm

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!

October 7, 2009 2:24 pm

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.

October 7, 2009 3:30 pm

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.

George E. Smith
October 7, 2009 4:19 pm

“”” 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 ?

George E. Smith
October 7, 2009 4:23 pm

“”” 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.

Indiana Bones
October 8, 2009 9:02 am

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.

October 8, 2009 5:10 pm

Limericks, of course are a low, low grade of humour. But still….
A caution for warmists who thirst
for funding, and getting in first
for what you intend
may turn out in the end
to obliterate you in one burst

October 22, 2009 3:30 am

While each state has its own rules of evidence, many states model their rules on the Federal Rules of Evidence, which themselves relate closely to the common-law mode of examination. ,

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