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Aerosols, Chemistry and Climate

Filed under: — gavin @ 12 July 2008

Everyone can probably agree that the climate system is complex. Not only do the vagaries of weather patterns and ocean currents make it hard to see climate changes, but the variability in what are often termed the Earth System components complicates the picture enormously. These components – specifically aerosols (particulates in the air – dust, soot, sulphates, nitrates, pollen etc.) and atmospheric chemistry (ozone, methane) – are both affected by climate and affect climate, since aerosols and ozone can interact, absorb, reflect or scatter solar and thermal radiation. This makes for a rich research environment, but can befuddle the unwary.

I occasionally marvel at the amount of nonsense that is written about climate change in the more excitable parts of the web, and most of the time, I don’t bother to comment. But in relation to the issue of aerosols, chemistry and climate, I read yesterday (h/t Atmoz) probably the most boneheaded article that I have seen in ages (and that’s saying a lot).

The hook for this piece of foolishness were two interesting articles published this week by Ruckstuhl and colleagues and a draft EPA report on the impacts of climate on air quality. First, Ruckstuhl et al found that as aerosols have decreased in Europe over the last few decades (as a result of environmental standards legislation), the amount of solar radiation at the ground has increased while the amount reflected to space has decreased. They hypothesize that this may have helped Europe warm faster in the last few decades than it would have otherwise done. Or equivalently, since the aerosols are anthropogenic, that European temperatures had been subdued due to the cooling effects of the aerosols – and since they are now decreasing, the full effects of the greenhouse gases are starting to be felt. This is just an update to the ‘global brightening‘ story we have touched on before. The EPA report is concerned with the impacts that climate change can have on atmospheric chemistry, and in particular the summertime peaks in urban ground-level ozone which are a well-known and serious health hazard. These are affected by local temperatures, cloudiness, temperature sensitive biogenic emissions and patterns of weather variability. Again, it is a story we have discussed before.

But the NewsBusters article succeeded in getting almost every aspect of these stories wrong. How do I correct thee? Let me count the ways.

  1. Aerosols are not smog:

    First they confuse aerosols with photochemical smog. Both are pollutants, but the first is dominated by sulphate emissions from coal burning power plants, the second from ozone precursors such as NOx, volatile organic compounds, and carbon monoxide mainly emitted from vehicles. (Note that ozone is not directly emitted, but is created by chemical reactions from the precursors with the addition of a bit of photolysis – i.e. sunlight-driven chemistry). The effects on climate are very different: ozone is a greenhouse gas, so increases cause a warming, while sulphate aerosols are reflective, and so increases cause a cooling. The air quality issues in the EPA are almost all focused on ozone.

  2. Europe is not the Globe:

    The next error is to equate changes in temperatures in Europe to the globe. While it would be true that if global aerosol levels declined it would lead to increased global warming, aerosol trends in Asia are increasing strongly, even while those in the US and Europe are dropping. The net effect is possibly a slight drop, but the impact on global temperature is as yet unclear. This regionality matters in both the sulphates case and for ozone. The relevant chemistry is sensitive to water vapour and temperature in varying ways as a function of the pollution level. In remote ocean areas, surface ozone will likely decrease as the globe warms for instance (due to increasing water vapour). In polluted environments increased temperatures and larger temperature-sensitive emissions of isoprene cause enhanced ozone levels.

  3. Surface ozone is not in the stratosphere:

    Next, NewsBusters asserts that the ozone story is confusing because of the

    .. treaty called the Montreal Protocol. This was designed to reduce and eventually eliminate the production and release of a number of substances thought at the time to be depleting ozone.

    Ummm…. those substances (chiefly chlorofluorocarbons – CFCs) are still thought to be depleting the ozone layer – which is in the stratosphere, some 30km above the ground-level ozone that people shouldn’t be breathing. CFCs have no impact on ground-level ozone at all (since their reactive chlorine is only released in the stratosphere).

  4. The final inanity:

    Wouldn’t it be fascinating if such efforts [such as the Montreal Protocol] lead to cleaner air around the world which ended up warming the planet, and that additional warmth is now breaking down the very ozone we thought we could save?

    Every part of this sentence is wrong. The Montreal Protocol had no impact on cleaning the air, it stopped the growth of CFCs which are powerful greenhouse gases (in addition to their role in depleting stratospheric ozone), therefore it slowed global warming, rather than increasing it, and we aren’t trying to save ground-level ozone. Had any of this been true it would indeed have been fascinating.

What should we make of this? Unfortunately one must conclude that no mistake is too dumb for someone, somewhere to make if they think they can spin it into supporting their anti-science agenda. For them complexity is something to be abused rather than a challenge to be understood, underlining quite clearly (again) the difference between science and propaganda.

356 Responses to “Aerosols, Chemistry and Climate”

  1. 1

    Especially like the cartoon commentary

  2. 2
    Joseph O'Sullivan says:

    The last paragraph of this post describes the Newsbusters article exactly.

    Newsbusters has in the past tried to smear Dr James Hanson.

    Newsbusters from sourcewatch

    In particular editor Noel Sheppard, “Sheppard has used his NewsBusters posts in particular to attack the idea that global warming is caused by humans”

  3. 3
    S. Molnar says:

    My wife has always claimed that my temperature-sensitive biogenic emissions are a serious health hazard, but I guess I’ll have to start listening to her now that gavin has confirmed it.

  4. 4
    Arch Stanton says:

    Thanks Gavin.

    The saddest part is the comments to Noel’s post. So many people only accept what they want to. So many people think they know more than everyone else.

    Patience is difficult when sarcasm is so much more satisfying in the short term.

  5. 5

    Thanks Gavin,

    I have seen a few of their garbage pieces. The upside of freedom of speech and the press is you get to hear a lot of opinions. The downside of freedom of speech is you get to hear a lot of opinions.

    Separating the wheat form the chaff is the challenge we all face.

    Here are some of the articles I have done on the issue, for those that care to examine what might be called a more reasoned perspective (and of course everything on RC :)

    “We are under attack!” – A Primer on Political Spin

    Does hot air from politicians contribute to global warming?

    Hot Air in the Media Contributes to Global Warming!

    Oh, and lest we forget the wonderful work by GISS, NASA, NOAA, NCDC, NSIDC, et cetera, et cetera, et cetera

  6. 6
    Martin Vermeer says:

    Re #2: re-read the (old) Hansen piece on the purported 720k from Soros, and it still gets my blood pressure up that a scientist in his position would have to shop around for pro bono legal advice for situations related to his proper activities as a civil servant.

    $720k would not be too much for a legal fund to take on some of the more prominent libelers. Those tobacco lawyers are good but pricey in their mercedeses ;-)

    [Response: In case someone reading is confused; Hansen got no 720K, or any Soros funding, and the sum total of the connection was a letter offering legal help which was not accepted. – gavin]

  7. 7
    jhm says:

    If you’d seen the segment of C-SPAN’s Washington Journal the other day with a UCS member, you might say that it is not so much incorrect articles such as this which is the major problem, but the people who called in to accuse the UCS member of “lying;” parroting Sen. Al Gore Jr. (who is as wrong now as when he claimed to invent the internet;, et cetera.

    It’s similar to the women who didn’t believe Hon. Sen. Obama when he claimed not to be a muslim. What can one say to someone who insists on being ignorant? No amount of evidence will suffice, or even credited.

  8. 8
    webby says:

    I used to go to the Newbusters website but got banned, but that is a whole diferent story. The people at the website are very narrow minded.

    It is no surprise that Noel Sheepard wrote this post. HE usually only blogs about global warming or some liberal Hollywood actor in the news. I stopped responding to his post because of one interaction I had with him.

    HE had a post how someone was trying to blame McCain’s economic adviser for problems with the economy. I posed that he was responsible for slipping into a bill the Enron Rule, which deregulated speculation in regards to energy commodities and companies. HE said there he wanted me to provide proof from a government website. I sent him a link from written by David Corn that spelled it all out. He simply wrote back saying it was a opinion piece and brushed me off.

    I would send you the link, but like I said, I got blocked from the website, which is shocking because they always are crying about how the democrats want to intact the fairness Doctrine. Actually, it’s not surprising.

  9. 9
    Hank Roberts says:

    jhm writes, repeatedly (+gore +invent +internet +jhm — about 66 hits)

    > What can one say to someone who insists on being ignorant?

    One can say “look it up” but jhm posts the same nonsense repeatedly (Google finds about 66 hits for (+gore +invent +internet +jhm )
    making him/herself an example:

    > No amount of evidence will suffice, or even credited.

  10. 10
    Nigel Williams says:

    Yes; Aerosols of Deceit created by a Chemistry of Greed suspended in a Climate of Fear.

    So to quote from this gentle voice from the wilderness:

    Global Warming Twenty Years Later: Tipping Points Near
    James Hansen1

    My presentation today is exactly 20 years after my 23 June 1988 testimony to Congress, which alerted the public that global warming was underway. There are striking similarities between then and now, but one big difference.

    Again a wide gap has developed between what is understood about global warming by the relevant scientific community and what is known by policymakers and the public. Now, as then, frank assessment of scientific data yields conclusions that are shocking to the body politic. Now, as then, I can assert that these conclusions have a certainty exceeding 99 percent.

    The difference is that now we have used up all slack in the schedule for actions needed to defuse the global warming time bomb…


    …. In my opinion, if emissions follow a business-as-usual scenario, sea level rise of at least two meters is likely this century. Hundreds of millions of people would become refugees. No stable shoreline would be reestablished in any time frame that humanity can conceive.


    …The disturbing conclusion, documented in a paper I have written with several of the world’s leading climate experts, is that the safe level of atmospheric carbon dioxide is no more than 350 ppm (parts per million) and it may be less. Carbon dioxide amount is already 385 ppm and rising about 2 ppm per year. Stunning corollary: the oft-stated goal to keep global warming less than two degrees Celsius (3.6 degrees Fahrenheit) is a recipe for global disaster, not salvation.

    Keep up the good work sir!

  11. 11
    Tim McDermott says:

    I know this is OT, but

    jhm embarassed himself by saying

    … Sen. Al Gore Jr. (who is as wrong now as when he claimed to invent the internet

    This is another one of those things that everybody knows that just isn’t so. Vice President Gore did not claim to have invented the internet. He claimed to have been important in its development. And I have heard Vint Cerf, one of the folks who did invent the internet, defend Gore as a vital supporter of the technology involved. See

  12. 12

    Re: #7

    Sen. Al Gore Jr. (who is as wrong now as when he claimed to invent the internet)

    Speaking of “parroting”, you should really stop repeating this piece of dittohead gibberish. Vince Cerf seems to think that Gore was instrumental in creating the internet: and he was actually there. Where were you?

  13. 13

    Sorry, my cite was removed for some reason.

  14. 14
    Al Crawford says:

    In an interesting bit of information the AP is reporting that a Rutgers University yellow submarine named “Scarlet Knight” is collecting raw data on the temperature and salinity of the seawater.

    A comment on Al Gore. In the late 1980’s and early 1990’s Al Gore was promoting the internet heavily. This was a time when I was using the predecessor of the internet. At that time I thought he was a person of vision and influence concerning the potential of the internet. It was unfortunate that he misspoke about inventing the internet. But he did see its potential before many others. His vision about the internet then and his vision about the climate now are to be commended.

  15. 15
    Hank Roberts says:

    Al Crawford writes, ignoring all the help checking the story:

    > It was unfortunate that he misspoke about inventing

    You misspeak, since that’s not what the man said. Check your sources.
    If you believe what you write is true, where are you getting it, why do you consider your source reliable on this? Who’s your authority?

  16. 16
    Chuck Booth says:

    Re: Al Gore and the invention of the Internet

    Perhaps we can put this to rest once and for all and get back on topic:

    In March 1999, Gore told CNN’s Wolf Blitzer that he “took the initiative in creating the Internet.”

    According to Stephen Wolff of Cisco Systems, who oversaw the National Science Foundation’s NSFnet (the Internet’s immediate precursor), in 1986 then-senator Gore pushed through legislation requiring a White House study on whether telephone companies could create a national network. “It’s what the Internet is now,” said Wolff.

    Ref: Science, Vol. 283 (March 1999), page 1975.

  17. 17
    Al Crawford says:

    “If you believe what you write is true, where are you getting it, why do you consider your source reliable on this? Who’s your authority?”

    My source is my memory. I remember when he said it and it gained wide coverage in the press and on TV. So I do consider my source reliable. Now, he did not really mean to say he invented the internet but rather that he played a part in its development — which he did from a political standpoint. And he quickly put out corrections. But what he actually said certainly came out that he was claiming the invention of the internet. He misspoke.

    If you can find a source that contradicts my memory then so be it. But that is what I remember.

  18. 18
    Timothy Chase says:

    Al Crawford wrote in 17:

    But what he actually said certainly came out that he was claiming the invention of the internet. He misspoke.

    If you can find a source that contradicts my memory then so be it. But that is what I remember.

    Here is a recording — with sound effects added by someone who clearly doesn’t like Gore — where Gore says “I took the initiative in creating the internet.”

    You can listen to it yourself:

    “During my service in the United States congress, I took the initiative in creating the internet.”

    Here is the context that it is ripped from:

    But it will emerge from my dialogue with the American people. I’ve traveled to every part of this country during the last six years. During my service in the United States Congress, I took the initiative in creating the Internet. I took the initiative in moving forward a whole range of initiatives that have proven to be important to our country’s economic growth and environmental protection, improvements in our educational system.

    Al Gore “invented the Internet” – resources
    by Seth Finkelstein

    He is clearly claiming credit not for “inventing” the internet, but for leading the legislative action necessary to make it a reality.

    The word “invent” first appeared in a mailing-list message headline by a reporter for a Republican press release. There is a link to the message in the analysis by Seth Finkelstein which I linked to above.

    Incidentally, I didn’t have to rely upon memory — which is a good thing as my memory isn’t that great. Instead I just looked it up on the internet. First at YouTube (using “Gore internet” as the search terms to get the recording) then in Google (using the words in the recording) to get the context. Took maybe thirty seconds total.

  19. 19
    Rod B says:

    I, too, was involved with what became the internet in the mid-80s, and (truth in lending) I am not an Al Gore supporter or admirer. He did state that he invented the internet. As I recall it was an inadvertent overstatement and a misspeak (No, Hank, I’m not going to round up all the peer reviewed papers on it.), I think in the run up to the 2000 campaign. However, as Senator (if memory serves) Gore he was tremendously influential with the White House’s Office of Telecommunication Policy (OTP) and NSF (and Congress) to get funding and support for transforming the “internet” from the then network — a very small, restricted to a few Universities, National Labs, and the like, and to be used only for academic research (and funded mostly by NSF) — into the precursor of what it is today with ubiquitous and widespread (including commercial (“.com”) access and use.
    Invent it? No. Damn important to its growing up? Yes.

    Is this deja vu??

  20. 20
    Al Crawford says:

    There is a full moon out tonight — no, I do not have a reference — and it is cloudy where I am at so I can’t really see — but I know there is a full moon out tonight.

    Why do I know — because of all of the silly stuff in this thread since I made my comment about Al Gore (#14).

    I made a post about a cute yellow sub that is zipping along in the Atlantic using only the power of the currents. And it is collecting a bunch of raw data about the ocean.

    Then, as a side note, I made what I thought was a complement to Al. But I didn’t give a reference. And all hades broke loose.

    And I am completely confused about how all of this is related to the climate. I think I will go to bed and sleep on it. Maybe when I wake in the morning all the werewolves will be gone!

    Check out “We Can Solve It” and join Al’s effort at saving the world.

    And you might also like to go to also in honor of Al.

  21. 21
    Jim Peden says:

    Al Gore’s exact words were, “… I took the initiative in creating the internet.” I’ll leave it to the semantics experts to decide whether “creating” and “inventing” are the same thing.

    Actually, ARPANET had been in operation before Gore joined the Senate, so the “internet” as we know it today was more of a release for public and corporate consumption of an entity which had previously been the exclusive domain of a few universities and their government funding agencies. Actually, Big Business pushed harder for public participation than private individuals, who generally didn’t have a clue.

    I don’t like Al Gore for many reasons, but if he took a leadership role in prying it away from the Ivory Tower crowd and their funding sources, then I’m forced to tip my hat to him as a man with an exceptionally accurate long range vision for it’s possibilities.

  22. 22
    John Mashey says:

    Rod B & Al Crawford:

    You want to believe something that simply DID NOT happen. Gore chose his words rather carefully, and the Finkelstein reference in #18 is useful in understanding the real sequence.

    I got a copy of the Vint Cerf/Bob Kahn letter when it came out. [One of Dave Farber’s friends forwarded it to me.] It was accurate then, and that hasn’t changed.

  23. 23
    Jim Eaton says:

    For those of you who trust to sniff out urban legends, you can check out:

    Snopes agrees with Richard, Hank, Chuck, and Timothy that “invent” is pure fiction.

  24. 24
    dhogaza says:

    He did state that he invented the internet.

    No one has EVER come up with a source that shows he actually said that. The quote’s well-known, and is as has been given above, he claimed credit for taking the INITIATIVE in creating it, through funding.

    As I recall it was an inadvertent overstatement and a misspeak (No, Hank, I’m not going to round up all the peer reviewed papers on it.),

    Because, of course, he never actually said it. You want to BELIEVE he said it, nothing more.

  25. 25
    Timo Hämeranta says:

    Well, always please consider what we don’t know, e.g.:

    Fuzzi, S., M.O. Andreae, B.J. Huebert, M. Kulmala, T.C. Bond, M. Boy, S.J. Doherty, A. Guenther, M. Kanakidou, K. Kawamura, V.-M. Kerminen, U. Lohmann, L.M. Russell and U. Pöschl, 2006. Critical assessment of the current state of scientific knowledge, terminology, and research needs concerning the role of organic aerosols in the atmosphere, climate, and global change. Atmospheric Chemistry and Physics Vol. 6, pp. 2017-2038, June 9, 2006, online

    “In spite of impressive advances in recent years, our present understanding of organic aerosol (OA) composition, physical and chemical properties, sources and transformation characteristics is still rather limited, and their environmental effects remain highly uncertain….”

  26. 26
    Martin Vermeer says:

    > misspeak

    is a misnomer… no, Gore’s “error” was to provide a single, easy soundbite, ready to be ripped out of context. As everybody knows the proper thing to do is place parts of the sound bite far apart on the audio track (as he did in the NPR interview recently) so the swiftboaters have to get competent in audio editing :-)

  27. 27
    Martin Vermeer says:

    Al Gore’s exact words were, “During my service in the United States Congress, I took the initiative in creating the Internet.”

    Factually true, correct English and not even ambiguous.

    Take the Red Pill folks. Figure this one out for yourselves, and reality will never be the same again.

  28. 28
    Lawrence Brown says:

    One doesn’t have to remain ignorant. Read one or more of the books recommended listed in the post “All Paper Salutes To The Environment” or a book of your choosing that explains the science behind global warming. Don’t shoot the messenger. Al Gore is a well informed non-scientist, not the one who uncovered this phenomena. Attend lectures and conferences where available. One doesn’t have to remain ignorant except by their own choosing.

  29. 29
    Boris says:

    Newsbusters is not just a denialist site, they actively promote the idea that AGW is a fraud:

    “Results 1 – 10 of about 5,730 from for “global warming” fraud. (0.36 seconds)”

    Simply put, they are conspiracy theorists of the most irrational stripe.

  30. 30
    Hank Roberts says:

    Rod, don’t trust your memory about things you wish were true.
    If you can’t grok this you can’t do or read science.

    Yes, perhaps there’s a huge conspiracy out there altering all the records — people on all spokes of the political wheel do have this suspicion about what they think they remember seeing that they deeply believe but have never been able to document.

    But go with the odds. If you can’t find it, you probably were fooled the first time and have been fooling yourself ever since — recalling that Republican press release cited above. Read Doonesbury instead, you’ll get a clearer picture of how the world works.

  31. 31
    Rod B says:

    All of you “took the initiative” proponents [edited] [that’s enough! No more comments from anyone on this please. -moderator]

  32. 32
    David B. Benson says:

    Please. Al Gore and the internet, however thrilling to some (yawn), has nothing to do with climatology.

    Drop it, ok?

  33. 33

    To get back to the subject: If part of the recent European warming (past 25 years or so) is due to the decrease in aerosol loading, then the rate of warming may decrease when the aerosol loading starts to stabilize. That was the bottom line of an interesting presentation at the EGU this year (not published yet). It’s bound to raise a lot of questions, and the results are prone to be abused, but the analysis seems sound (if somewhat speculative and with large error bars).

  34. 34
    Ryan Sullivan says:

    I think in your attempt to clarify the issues you have confused things a bit by over-simplifying.

    Your statement that “aerosols are not smog” is not correct. Aerosols are an important component of photochemical smog, forming through similar reactions involving hydroxyl radicals, nitric oxides, ozone, VOCs, and sunlight that also produce the gaseous component of smog. These secondary aerosols have important impacts on visibility, health, and regional climate.

    Also, stating that aerosols are “dominated by sulphate emissions from coal burning power plants” is overly simplistic and inaccurate. Yes, coal power plants are major sources of primary combustion aerosols (i.e. soot, coal fly ash) and also sulphur dioxide which can produce secondary sulphate aerosols. But sulphate aerosols are not the major aerosol component by particle mass or number. The lagest sources of aerosol mass are from sea salt and mineral dust. By number, it is typically a mix of sulphate, nitrate, ammonium, and a wide spectrum of carbonaceous (elemental and organic carbon) compounds. Most tropospheric aerosols are internal mixtures of these components, as opposed to pure single-component aerosols, which is how climate models frequently inaccurately represent them. This mis-representation and can have significant ramifications for estimating the direct and indirect effects of aerosols on climate.

    Sorry to be nit-picky but I was surprised to see such inaccurate and simplistic statements made on this blog which typically goes to great lengths to be both detailed and accurate. These misconceptions regarding aerosols are commonly stated not just in the media but also in the atmospheric sciences community and are very troubling.

    [Response: Always happy to have nitpicks – to be clear, I was talking about anthropogenic aerosols – for which sulphates are the biggest contribution. The EPA report was focused on ozone and that was the contrast I was highlighting. – gavin]

  35. 35

    European mean ground ozone levels are declining, not rising as could be expected from a possible warming trend. See here for my measurements in a semi-urban region (Diekirch, Luxembourg), and here for the US 8 hour air quality. BTW, I am not sure if the ozone health issue is not overstated. I spoke to several medicals (also lung experts) who never had a patient unwell of too high ozone levels. Usually the discomfort was a result of excessive heat and “bad air”, where O3 is only one of many factors.

  36. 36
    Rod B says:

    Hank, I was half-way with you — philosophically at least — until you wrapped your arms around Doonesbury!!! :-P

  37. 37
    Hank Roberts says:

    Rod, Doonesbury Sunday: 600? 600,000?
    Beware the press, look to the original source in the science journals

  38. 38
    Ryan Sullivan says:

    Thanks for your reply Gavin, I understand what you wanted to contrast with.

    Sulphate is not typically the dominant anthropogenic aerosol component however, though many climate models treat it as such. The carbonaceous aerosol component typically dominants PM1 aerosol mass, see for example:

    Zhang, Q. et al., Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically-influenced Northern Hemisphere midlatitudes, Geophysical Research Letters, 34 (13), doi:10.1029/2007GL029979, 2007.

    This is a nice summary of many measurements of PM1 aerosol chemical composition. Though note that the instrument used cannot measure non-volatile aerosol components that don’t evaporate > 600 C or so. Thus they cannot measure soot, mineral dust, or some refractory organic carbon compounds.

  39. 39
    Rod B says:

    Hank, Yeah, but is it peer reviewed??

  40. 40
    Jim Eaton says:

    Rod B Says:
    Hank, Yeah, but is it peer reviewed??

    Doonesbury is peer reviewed by the millions of readers who follow the strip. Can millions of readers possibly be wrong?

  41. 41
    pete best says:

    Re #10, a very sobering account given by Dr James Hansen there, one which is undoubtably true and yet very people know it to be so. Ask any normal mortal about global warming and you get a whole host of opinions from its a left wing scam perpetrated by the left wing media and politicians who do not like capatalism to its a tax revenue raiser to its real but we can’t do a lot about it as we are heading for a recession.

    It just seems to me that politicians and other vested interests want their cake and eat it to. I see no impact on fossil fuel production and use even if we do take up renewables and even go on a energy efficiency drive. The east id here and hungry for energy, if we reduce they will consume.

  42. 42
    Ike Solem says:

    Ryan, the Zhang et. al paper is at It is about developing better methods of analyzing the organic aerosol fraction (hydrocarbons, etc.) which doesn’t say anything about the sulphate fraction. Their main point is that a large (dominant) fraction of the organic aerosols are partially oxidized. They didn’t measure anything but the organic species.

    What is known is that many aerosol components have a highly variable spatial and temporal distribution, due to their low residence time in the atmosphere. For a very interesting look using airborne mass spec sampling, see here

    Figure 2 there shows how variable aerosols can be, but sulphate is always a major component. The two graphs on the right show a city region in the morning and in the afternoon – there is quite a difference. In the morning, sulphate aerosols dominate; in the afternoon it is nitrate (probably from NOx production by automobiles).

    This high variability means that the effects of aerosols on climate are not easy to work out. The general notion is that reflective aerosols at high levels tend to cool the atmosphere, while other light-absorbing aerosols at low tropospheric levels tend to warm the atmosphere. Sorting out the net effect is thus complex, and will vary from region to region. Take the infamous “Asian Brown Cloud”, for example (2007), which appears to have a net warming effect:

    The strategy used is pretty remarkable:

    “Here we use three lightweight unmanned aerial vehicles that were vertically stacked between 0.5 and 3 km over the polluted Indian Ocean. These unmanned aerial vehicles deployed miniaturized instruments measuring aerosol concentrations, soot amount and solar fluxes. During 18 flight missions the three unmanned aerial vehicles were flown with a horizontal separation of tens of metres or less and a temporal separation of less than ten seconds, which made it possible to measure the atmospheric solar heating rates directly.

    We found that atmospheric brown clouds enhanced lower atmospheric solar heating by about 50 per cent. Our general circulation model simulations, which take into account the recently observed widespread occurrence of vertically extended atmospheric brown clouds over the Indian Ocean and Asia3, suggest that atmospheric brown clouds contribute as much as the recent increase in anthropogenic greenhouse gases to regional lower atmospheric warming trends. We propose that the combined warming trend of 0.25 K per decade may be sufficient to account for the observed retreat of the Himalayan glaciers”

    ( and also )

    This just goes to show the complex nature of this area of climate science. What has been clearly shown is that when volcanoes inject aerosols into the upper troposphere, it cools the climate for a few years. The net effect of human-generated aerosols is more complicated and regionally variable – for example, in contrast to the local warming effect of the Asian Brown Cloud, global shipping produces large amounts of cooling reflective sulphate aerosols:

    The study also shows that the effect of ship emissions is most evident in the Northern Hemisphere oceans, where greater than 60 percent of sulfur dioxide concentration in the atmosphere and 30 percent of all sulfates can be attributed to ships. Except for the area encompassing Australia, the Southern Hemisphere oceans are almost unaffected. This is because of the heavier shipping that occurs in the north.

    Thus, sulfur emissions from ship boiler fuel and and coal are why sulphates are thought to be the main anthropogenic aerosol.

  43. 43
    tamino says:

    The east id [sic] here and hungry for energy, if we reduce they will consume.

    Here’s what governor Schwarzeneger had to say about that last Sunday:

    … they did not believe that they should do anything about it since China is not doing anything about it and since India is not willing to do the same thing, so why should we do the same thing.

    But that’s not how we put a man on the moon. We did not say let everyone else do the same thing, then we will do it. We said we want to be the pioneers, we want to be out there in front. … I think we have a good opportunity to do the same thing, also, with fighting global warming.

    I couldn’t have said it better myself.

  44. 44
    Ryan Sullivan says:

    @ #42.

    You make some interesting points, though my research involves single-particle mass spectrometry of atmospheric aerosols to study their chemical composition and mixing state as a function of particle size, so I’m well aware of these issues and they are important. I am at UCSD and well aware of Ramanathan’s work with UAVs, they are definitely providing important unique insights. Here is a recent paper of mine to give you an idea of what I do:
    Sullivan, R. C., and Prather, K. A.: Investigations of the diurnal cycle and mixing state of oxalic acid in individual particles in Asian aerosol outflow, Environ. Sci. Technol., 41 (23), 8062-8069, 2007.

    And a review article from a few years back:
    Sullivan, R. C., and Prather, K. A.: Recent advances in our understanding of atmospheric chemistry and climate made possible by on-line aerosol analysis instrumentation, Anal. Chem., 77 (12), 3861-3885, 2005.

    Your interpretation of the Zhang et al. paper is incorrect. In Figure 1 they show the fraction of non-refractory PM1 aerosol mass that was organics, nitrate, sulphate, chloride, or ammonium. The organic mass fraction dominates.
    There are many other studies that show that organics are a major fraction of submicron aerosol mass, using filter measurements, the AMS, and also single-particle mass spectrometry and electron microscopy. This one was just to easiest way to show the chemical composition for a wide range of locations. While sulphate is an important aerosol component, it is typically NOT the dominant anthropogenic aerosol component. More importantly, pure (ammonium) sulphate particles are rarely found to exist in the lower troposphere via single-particle analysis. They are typically found to be internally mixed with other particles types including soot, organics, mineral dust, biomass smoke, etc.

    Yes, ships emit a lot of sulphate and its precursors, but they also produce a lot of soot and some organics as well. It depends on the type of fuel they are burning. Military ships usually burn very low-sulphur fuel so that their emissions do not produce ship tracks.

  45. 45
    Richard Ordway says:

    #41 Pete Best.

    Re. Hansen. I think it is interesting to read his strong stance about coal plants…ie. To paraphrase him, close all of them down unless they do carbon sequestering (storing CO2).

  46. 46

    Re 42 & 44
    I think it is reasonably well established that organics often dominate the aerosol composition by mass, but what is less known is what proportion of that organic aerosol is anthropogenic, and thus what is the dominant *anthropogenic* component. The anthropogenic fraction of sulfate is bound to be larger (at least over the continents) than that of organic aerosol. For climate models what matters is the anthopogenic enhancement. It is clear that any single species approximation has severe shortcomings.

  47. 47
    pete best says:

    Re #45, ah yes coal, 1000 new stations almost certain to be build globally within 5 to 10 years. The US ones will be carried through by CCS sequestration ready logos assgigned to them. G8 etc will ush it through and CTL and more tar sands etc.

  48. 48
    Dave says:

    Re: coal

    This to me seams a more real wildcard on the negative (vs. current projections) side than most other worries.

    If we don’t start really spinning up rational energy plans, then more, not less, coal will be burned.

    Conservation, renewables, nukes and even more oil drilling would all be better than falling back on coal.

    PS., a meta comment on the Gore debate. This is a simple example of how well media based progranda can win over reason. I think the OP really did believe he heard him say it.

  49. 49
    CL says:

    If the logic dictated by scientific insights, as outlined regularly here, were to be followed,then one might expect very substantial spending on research and development of alternative energy technologies. However, as many will know, forty percent of US taxes go on the military. A relatively tiny amount on science.

    which leads me to ponder why so, what’s the thinking ? I don’t know, but perhaps this piece suggests what the reasoning is, or was.

    Taken from a selection of opinions as to what the future has in store for us, here :

  50. 50
    Hank Roberts says:

    Ryan uses the word “component” and Gavin uses the word “contribution” for sulfates.

    I’m guessing:

    Does “component” refer to a total fraction of what’s in the air — weight, volume, length of hang time in the air? And does “contribution” refer to known radiative forcing effect?

    Or do the other components have unknown forcings?