AGU Day 2

A few notes before I lose track of today’s event.

Stephen Schwartz’ presentation was essentially a re-statement of recent publicized JGR paper with some interesting additional commentary. Schwartz’ recent paper attempted to unpack the almost definitional equation:
\Delta T = F/S

He then showed the IPCC diagram summarizing forcings, observing the change from IPCC TAR in forcing estimates in which aerosols were estimated at -1.2 (range -2.4 to -0.6) wm-2, resulting in total forcings having a range of 0.6 to 2.4 wm-2, observing that the range was a factor of 4. He then showed the IPCC ensemble which had a very narrow range, wondering how the range in model output could be less than the range of forcings.

HE then discussed Kiehl 2007 (recently discussed here at CA) which observed an anticorrelation between climate sensitivity and aerosol forcing history, observing that the forcings and sensitivities should cover the full range.

HE then discussed the estimate of forcing sensitivity based on his article, noting that the sensitivity depended on the heat capaciy of the ocean and the response time.

One of the puzzles for climate models has been that temperature increases in the 20th century have been less than GHG models indicate – the discrepancy is usually blamed on aerosols or said to be “in the pipeline”. The “pipeline” in this case is ocean heat capacity which SChwartz estimated in ballpark terms at 1& +- 7 W yr m-2 K-1, equal to about 100 m of water.

He estimated response time using autocorrelation functions, citing “Einstein’s fluctuation theorem”. This gave a response time of about 5 years, which combined with the ocean heat capacity estimate, gave a much lower sensitivity than conventionally thought. He said that the response time estimate was the most sensitive and that a response time of 15 years or so yielded 1.5 deg K. He acknowledged that his calculations had been criticized. IT’s not clear/unlikely that the data set meets the stationarity assumptions necessary for his methodology.

He noted that the aerosol forcing from his method worked out to about – 0.3 wm-2 in the 20th C.


Ramanathan spoke on atmospheric brown clouds. Ramanathan is not as famous as Hansen, but, as far as I can tell, he is the originator of the 4 wm-2 forcing for doubled CO2. I always ask critics to provide an exposition of how doubled CO2 leads to 2.5 deg K; nobody seems to be able to answer: Ramanathan’s papers from the 1970s are where I’d start and I’ve been unable to locate any better expositions.

More recently Ramanathan raised the issue of “anomalous atmospheric absorption”, something that he believes to be resolved by aerosols and soot, which have been his recent interest. He’s been involve in some major and sophisticated measurement programs.

Determining the impact of aerosols is complicated by the fact that there are several types of aerosols with different properties. Some absorb in the atmosphere, some scatter, some reflect. HE stated categorically that aerosols had redistributed energy from the surface to the atmosphere and that:
1) they accounted for dimming of 5-10% in Asia
2) masked about 50% of surface warming in S Asia;
3) forcing was asymmetric;
4) brown cloud and soot forcing may have as large a role as GHGs in warming in Himalayas
5) brown clouds were also an (lesser) effect in the US

plus other points.

While critics have observed that aerosols seem to have been a deus ex machina solution for the failure of the climate to warm as much as the models predict and while the handling of aerosols in the GCMs seems opportinistic according to Kiehl’s results, the opportunism doesn’t mean that the effect doesn’t issue. Although it seems a formidable problem at present to develop an objective 20th century aerosol forcing history.

A discussion of aerosol optical depth in the US over the past 10 years, observing that the highest aerosol depth was in the SE; that aerosol decreased in the East, increased in the west; however he observed that the western increase was related to upward spikes in some years, which was associated with wildfires.

Presented an interesting and original theory of why N and S hemispheres moved in parallel in Milankowitch scale. He pointed out (and I’d not seen this before) that NH summer intensity follows exactly the same pattern as SH summer duration and thus attribution to one rather than the other cannot be done on statistical grounds. He suggested that SH Milankowitch warming could be accounted for by SH summer duration better than NH export.

He made an interesting distinction between NH and SH glaciers: that Antarctica was so cold that glaciers ablated in the sea by calving and the response was arguably to summer duration; while NH glaciers ablated on land (Greenland) and thus more sensitive to summer intensity. So a symmetric response could be achieved by an asymmetric response.

A discussion of methane time series. Methane sources are from wetlands, predominantly in the NH but also S America. GISP2 dO18 levels are very level through the Holocene, while methane levels decline in the early Holocene and have increased in the late Holocene ( the latter increase attributed by Ruddiman famously to early anthropogenic effects.) GISP2 and Siple Dome series were compared.

Didier Rousseau

A discussion of loess records. Showed a high-resolution record from Nussloch, Germany with grain size index. Argued that this series was characteristic to less deposits. Showed a section from a quarry with nicely distinctive sediments in Holocene and Eemian.

Discussed some high-res records: Lake Huguang Maar, China; Cariaco, Meerfeld Maar, Germany, observing similarities.

Argued that central American rainfall was linked to Greenland moisture source. PRoxies discussed: Hulu Cave, Mora Cave MI-2 Burns 2003, GRIP 2001, Cariaco Ti, Costa Rica stalgmite CT-6, ocean MD95-2042, MD95-2040, GeoB 3910-2, LEa et al Gapapagos, Leduc et al, Hodell Peen Itza, SChmidt et al CAribbean.

Argued tha GRIP dD excess and Costa Rica rainfall linked. Also that SST differences between Atlantic and Pacific proxies (SChmidt minus Lea) was important to rainfall in Costa Rica.

discussed the role of tropical SST to medieval drought in the US. Suggested that droughts in 1130-70, 1240-65, 1856-65 and 1932-5 had common cause. Model-based results.


discussed Chinese speleothems: Shanbao, Hulu Dongge. Compared Hulu cave to Vostok methane; that 65N insolatin had beautiful match to speleothem series.

presentation of Peten Itza sediments, a new sediment series, especially PI-6, 71 m. Mag susceptibility is key series. LGM pollen (in thick clay units) showed cool and moist, oak and pine forest. Discussed proxies OCE 326, SU8118, CAriaco, PI-6.

Discussed African proxies: Lake Malawi drilling, a hole at 592 m. A 383 m hole covered 150 kyr. The last 70000 years were a deep lake and anoxic; the previous 70000 years were quite different, had a shallow lake. The sequence was different than at NH latitudes.

Observed the very srong coherence between Makassar Mg-Ca series and Antarctic dO18 – r2 of 0.84 without fiddling. Indeed this relationship between unrelated proxies is something that is very impressive. He observed that his indicated a coherence between Antarctic and tropical proxies, arguing against primacy of NH high latitude forcing at Milankowitch scake. He argued that forcing originated in the Southern Ocean and was transmitted globally through CO2.

These notes are spotty, enough for now.


  1. John A
    Posted Dec 12, 2007 at 4:32 AM | Permalink

    And so with \Delta T = \frac{F}{S} climate science has finally discovered its own version of the Drake Equation – a single equation with two complete unknowns.

  2. Geoff Sherrington
    Posted Dec 12, 2007 at 5:44 AM | Permalink

    Re # 1 John A

    Wish I could write a critical summary as pithy as yours.

    Re Steve, We had one of the top magnetic interpretation teams in the geologic world, starting in the i950s and developing interpretative maths. One of the principals would, I’m confident, be willing to comment on Hodell’s paper because the physics has a few twists that made some cases a bit like John A’s comment above.

  3. tpguydk
    Posted Dec 12, 2007 at 5:48 AM | Permalink

    will an abstract CD be for sale at some point?

  4. yorick
    Posted Dec 12, 2007 at 6:40 AM | Permalink

    Peter Huyber’s home page is an interesting source of information on orbital forcings and insolation.

    Bergmen hints again at what I suspect is true. The thirties were warmer than today globally, as was the MWP. Of course, not he as given me the 1856-65 puzzle.

  5. Anthony Watts
    Posted Dec 12, 2007 at 9:34 AM | Permalink

    Steve, your head must hurt after absorbing all that in a day.

  6. Harry Eagar
    Posted Dec 12, 2007 at 10:06 AM | Permalink

    I’ll say. When I sit through a day of testimony about evidence a lot less detailed and recondite than what Steve absorbed, I can hardly remember my own name by the end of the day.

    Some people are just smarter than me, I guess.

  7. Will C.
    Posted Dec 12, 2007 at 10:23 AM | Permalink

    Will Steve be presenting at the AGU? Or is this just reconnaissance?

  8. Posted Dec 12, 2007 at 10:28 AM | Permalink


    Go here:

  9. Clayton B.
    Posted Dec 12, 2007 at 10:31 AM | Permalink

    Im having teleconnection overload.

  10. Posted Dec 12, 2007 at 11:21 AM | Permalink

    @John A:

    And so with \Delta T = \frac{F}{S} climate science has finally discovered its own version of the Drake Equation – a single equation with two complete unknowns.

    Sorry to be stupid, but which of the three is known? F, S or \Delta T ?

  11. MarkW
    Posted Dec 12, 2007 at 11:47 AM | Permalink

    Delta T is known with great accuracy. The models have spoken.

  12. Bernie
    Posted Dec 12, 2007 at 12:17 PM | Permalink

    You are a card!!
    Well spotted.

  13. Yancey Ward
    Posted Dec 12, 2007 at 1:20 PM | Permalink

    Well, Lucia beat me to it. Damn!

  14. Scott-in-WA
    Posted Dec 12, 2007 at 1:22 PM | Permalink

    SteveM: Ramanathan spoke on atmospheric brown clouds. Ramanathan is not as famous as Hansen, but, as far as I can tell, he is the originator of the 4 wm-2 forcing for doubled CO2. I always ask critics to provide an exposition of how doubled CO2 leads to 2.5 deg K; nobody seems to be able to answer: Ramanathan’s papers from the 1970s are where I’d start and I’ve been unable to locate any better expositions.

    We should inquire of SteveM if he has asked Ramanathan — politely, of course — if he might be willing to produce an update to his original papers which meets Steve’s criteria for a better explanation of 2xC02 yields 2.5C.

    Or, at least, to point out where useful updates done by others to Ramanathan’s original work might be found.

    And, if SteveM has already made such an inquiry, what was the response?

  15. SteveSadlov
    Posted Dec 12, 2007 at 2:59 PM | Permalink

    Good to see attention being paid to Asian pollution. I think that the combination of anthropogenic pollution and dust from Asia are a major risk, perhaps even a greater risk than GHGs. What makes them so risky is the fact that the plume mainly goes out over the North Pacific and interacts with PDO and ENSO.

  16. John A
    Posted Dec 12, 2007 at 3:42 PM | Permalink

    Lucia: \Delta T is the answer arrived at by assuming that all or nearly all of the warming observed is due to greenhouse enhancement. So F and S are chosen to produce the correct \Delta T . But F and S could have any value.

  17. Bernie
    Posted Dec 12, 2007 at 4:26 PM | Permalink

    You are right, but Lucia’s was a neat rhetorical trick.

  18. yorick
    Posted Dec 12, 2007 at 4:44 PM | Permalink

    So delta T is the compass that is used to make the circular arguments. Thanks for clearing that up.

  19. Follow the Money
    Posted Dec 12, 2007 at 6:35 PM | Permalink


    If Ramanathan, or anyone else, had said “2.5C”, it would have been reported in 1AR.

    I talked about the ARs in this thread:

    The provenance of CO2 Doubling/2.5C+ comes from Ch. 5 of 1AR, p.139, “Scientific Assessment”

    The evidence from modeling studies, from observations and from sensitivity analyses indicate that the sensitivity of global mean surface temperature to doubling CO2 is unlikely to lie outside the range 1.5 to 4.5C. There is no compelling evidence to suggest in what part of this range the correct value is most likely to lie. There is no particular virtue in choosing the middle of the range, and both the sensitivity analysis and the observational evidence neglecting factors other than the greenhouse effect, indicate that a value in the lower part of the range may be more likely. Most scientists declined to give a single number, but for the purpose of illustraing the IPCC Scenarios, a value of 2.5C is considered the “best guess” in the light of current knowledge. [orig. bold]

    The reading is complicated. Had the writers said, “We are going to take a middling number for the sake of having a standard figure to evaluate the different models” that would be acceptable–for judging the models between themselves. Which is what the “real” gravamen of the paragraph is. They have a range of 1.5 to 4.5C, 3.0C would be the middle, but the text avers “a value in the lower part of the range may be more likely,” so they found 2.5C.

    However the language about the “best guess” can be taken as a scientific finding about by t1AR about doubling and not as a convenient small fiction for testing models against each other. Indeed, if you go to Google Books, use terms like “2.5 doubling carbon” you will find many books, esp. those published in the 1990’s, that repeat doubling=2.5C+ as a scientific finding by 1AR about climate.

    1AR’s confusing language about a “best guess” morphed into a “best estimate” and I know this explanation doesn’t satisfy some who expect there must be some primary cource somewhere that opined 2.5C, but alas it does not exist.

  20. Francois Ouellette
    Posted Dec 12, 2007 at 6:43 PM | Permalink

    About aerosols, one should also not forget “black carbon”. Look at the recent work by Mark Flanner et al., that estimates the forcing from black carbon to be more important than CO2 in the Arctic:

    “Present-day climate forcing and response from black carbon in snow”,
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, D11202, doi:10.1029/2006JD008003, 2007

    Mark G. Flanner, Department of Earth System Science, University of California, Irvine, California, USA
    Charles S. Zender, Department of Earth System Science, University of California, Irvine, California, USA
    James T. Randerson, Department of Earth System Science, University of California, Irvine, California, USA
    Philip J. Rasch, National Center for Atmospheric Research, Boulder, Colorado, USA

    We apply our Snow, Ice, and Aerosol Radiative (SNICAR) model, coupled to a general circulation model with prognostic carbon aerosol transport, to improve understanding of climate forcing and response from black carbon (BC) in snow. Building on two previous studies, we account for interannually varying biomass burning BC emissions, snow aging, and aerosol scavenging by snow meltwater. We assess uncertainty in forcing estimates from these factors, as well as BC optical properties and snow cover fraction. BC emissions are the largest source of uncertainty, followed by snow aging. The rate of snow aging determines snowpack effective radius (r e), which directly controls snow reflectance and the magnitude of albedo change caused by BC. For a reasonable r e range, reflectance reduction from BC varies threefold. Inefficient meltwater scavenging keeps hydrophobic impurities near the surface during melt and enhances forcing. Applying biomass burning BC emission inventories for a strong (1998) and weak (2001) boreal fire year, we estimate global annual mean BC/snow surface radiative forcing from all sources (fossil fuel, biofuel, and biomass burning) of +0.054 (0.007-0.13) and +0.049 (0.007-0.12) W m-2, respectively. Snow forcing from only fossil fuel + biofuel sources is +0.043 W m-2 (forcing from only fossil fuels is +0.033 W m-2), suggesting that the anthropogenic contribution to total forcing is at least 80%. The 1998 global land and sea-ice snowpack absorbed 0.60 and 0.23 W m-2, respectively, because of direct BC/snow forcing. The forcing is maximum coincidentally with snowmelt onset, triggering strong snow-albedo feedback in local springtime. Consequently, the “efficacy” of BC/snow forcing is more than three times greater than forcing by CO2. The 1998 and 2001 land snowmelt rates north of 50°N are 28% and 19% greater in the month preceding maximum melt of control simulations without BC in snow. With climate feedbacks, global annual mean 2-meter air temperature warms 0.15 and 0.10°C, when BC is included in snow, whereas annual arctic warming is 1.61 and 0.50°C. Stronger high-latitude climate response in 1998 than 2001 is at least partially caused by boreal fires, which account for nearly all of the 35% biomass burning contribution to 1998 arctic forcing. Efficacy was anomalously large in this experiment, however, and more research is required to elucidate the role of boreal fires, which we suggest have maximum arctic BC/snow forcing potential during April-June. Model BC concentrations in snow agree reasonably well (r = 0.78) with a set of 23 observations from various locations, spanning nearly 4 orders of magnitude. We predict concentrations in excess of 1000 ng g-1 for snow in northeast China, enough to lower snow albedo by more than 0.13. The greatest instantaneous forcing is over the Tibetan Plateau, exceeding 20 W m-2 in some places during spring. These results indicate that snow darkening is an important component of carbon aerosol climate forcing.

  21. buck smith
    Posted Dec 12, 2007 at 6:47 PM | Permalink

    Isn’t the response to volcanic aerosols much less than 1 year? Why anothropogenic aerosols be different?

  22. Francois Ouellette
    Posted Dec 12, 2007 at 6:51 PM | Permalink

    #21 The same authors are presenting this paper in San Francisco:

    AN: A44B-01
    TI: Concentrations and Sources of Soot in Greenland Precipitation from 1788 to 2002: Implications for Radiative Forcing
    AU: * McConnell, J R et al.

    AB: Black carbon (BC) in the atmosphere results from biomass and fossil fuel combustion. It alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about BC emission or deposition histories. Monthly resolved measurements of BC in an ice core indicate that concentrations in central Greenland precipitation varied greatly during the period of record from 1788 to 2002. Parallel measurements of vanillic acid and non-sea-salt sulfur in the same ice core suggest that BC in Greenland came from wildfires and industrial activities. Prior to 1850, BC concentrations were highest in late summer to autumn and resulted primarily from boreal forest fires. Beginning about 1850, industrial emissions resulted in a seven-fold increase in ice core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower, probably as a result of wildfire suppression policies and the shift from coal burning to oil and gas in North America. Late 20th century increases in BC, however, may be linked to coal combustion in the rapidly expanding economies of Asia. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 W per square meter, more than eight times typical pre-industrial forcing.

  23. Francois Ouellette
    Posted Dec 12, 2007 at 7:02 PM | Permalink

    #22 hate to be a serial poster, but I also found this summary of their work here.

    And yes, anthropogenic aerosols also have a short lifetime in the atmosphere, but we keep pumping more. Reconstructing the aerosol history is, IMHO, mission impossible. They’ve come and gone. Aerosols have always been “the” ad-hoc hypothesis supporting most of the AGW hypothesis, thanks to Jim Hansen.

    Funny that in the “black carbon” work, they find that there was less black carbon after 1951, which could explain the cooling of the 50’s to the 70’s. The surge of economic activity in China and other parts of the world would then result in more black carbon in the 80’s, hence more warming. This is the exact opposite of the “aerosol” hypothesis, which blames the cooling on more aerosols, and the 80’s warming on anti-pollution laws kicking in.

  24. Posted Dec 12, 2007 at 7:25 PM | Permalink

    SteveSadlov says:
    December 12th, 2007 at 2:59 pm
    Good to see attention being paid to Asian pollution. I think that the combination of anthropogenic pollution and dust from Asia are a major risk, perhaps even a greater risk than GHGs. What makes them so risky is the fact that the plume mainly goes out over the North Pacific and interacts with PDO and ENSO.

    Risk of what, exactly? Please clarify.

  25. Sam Urbinto
    Posted Dec 12, 2007 at 7:54 PM | Permalink

    I will try to make this both short and simple.

    Soot? Look at the receding (and/or mass losing) glaciers, and take a look at where they are having issues and what’s on top in those locations. Draw your own conclusions.

    As far as the 2.5 C thing; mere guesses about a random process. Ignoring significance and order, pick a decade and draw conclusions:

    +.00C anomaly trend, +10 ppmv CO2
    +.22C anomaly trend, +20 ppmv CO2
    -.16C anomaly trend, +02 ppmv CO2
    +.09C anomaly trend, +14 ppmv CO2
    +.12C anomaly trend, +14 ppmv CO2
    +.00C anomaly trend, +06 ppmv CO2

  26. Steve Beery
    Posted Dec 12, 2007 at 9:02 PM | Permalink

    “One of the puzzles for climate models has been that temperature increases in the 20th century have been less than GHG models indicate – the discrepancy is usually blamed on aerosols or said to be “in the pipeline”. The “pipeline” in this case is ocean heat capacity which SChwartz estimated in ballpark terms at 1& +- 7 W yr m-2 K-1, equal to about 100 m of water.”
    I can see it coming.
    New policy
    From GHG modeling
    To all weather reporting stations
    “Temperture reading” will be stated as observe and pipeline combined.
    If the computer says it’s 100 degrees F, that means 90% observed and 10% pipline. (This way we can reconcile actual readings with GHG models.)
    So, please report the GHG models “temperature readings” to your listeners and viewers.
    And people wonder why I question GHG models.

  27. Philip_B
    Posted Dec 12, 2007 at 9:40 PM | Permalink

    Also, look at where glaciers are advancing like New Zealand. They all seem to be west coast. Clean air relatively free of particulates coming off the ocean. BTW, advancing glaciers are normally ascribed to increased precipitation, but I haven’t seen a study supporting this cause,

  28. Bruce
    Posted Dec 12, 2007 at 9:41 PM | Permalink

    NASA thinks clear skies are part of the problem:

    In one study, a team led by Jennifer Kay at the National Center for Atmospheric Research, Boulder, Colo., examined the influence of polar clouds on 2007’s record low extent of Arctic sea ice. Using data from CloudSat and NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite, they found the total cloud cover over the western Arctic, where most of the ice loss occurred, was 16 percent less over the 2007 melt season than in 2006. The resulting clearer skies in 2007 heated the Arctic surface enough to warm ocean waters by 2.4 degrees Celsius (four degrees Fahrenheit) or enough to melt 0.3 meters (one foot) of sea ice.

  29. tpguydk
    Posted Dec 12, 2007 at 9:45 PM | Permalink

    30: wouldn’t advancing glaciers on NZ’s West Coast make sense because they’re in the lee of the mountains? I read (and I’ll dig for a link to something, sorry I don’t have one now) somewhere that this is the case in parts of the Alps as well…

  30. SteveSadlov
    Posted Dec 12, 2007 at 9:47 PM | Permalink

    RE: #31 – Interesting they attribute SST anomalies in that area to local isolation and not mass movement of waters. Not saying I agree or disagree, it is just interesting. For a number of reasons.

  31. Posted Dec 12, 2007 at 9:57 PM | Permalink

    @28– Steve Berry
    But GISS II used by Hansen et al 1988 has an 8 layer ocean model with a thickness of 1000 m! So, the heat capacity is supposedly in the model.

  32. Philip_B
    Posted Dec 12, 2007 at 11:01 PM | Permalink

    tpguydk, No, west coast NZ glaciers are not in the lee of mountains. Prevailing winds blow west to east in the SH, just like the NH. It’s the winds around cyclones and anticyclones that blow in the opposite direction.

  33. Posted Dec 13, 2007 at 12:08 AM | Permalink

    Real climate has a critique of Douglas, Pearson and Singer, & Christy’s recent paper on Tropical tropospheric trends, attempting to demonstrate that the uncertaininties in their observations do not rule out the models, as they assert. Which they sum up as follows

    “What happens to Douglas’ figure if you incorporate the up-dated radiosonde estimates and a reasonable range of uncertainty for the models? This should be done properly (and could be) but assuming the slight difference in period for the RAOBCORE v1.4 data or the selection of model runs because of volcanic forcings aren’t important, then using the standard deviations in their Table IIa you’d end up with something like this:”

    To which I have posted the following comment (see how long it stays posted)

    The same kind of statement can be made about GISS surface temperature estimates and the AGW models. All you’ve succeeded in this discussion is making the case for the climate auditors (e.g., Steve McIntyre et al — shudder!), that neither observations or models are “certain enough to confirm AGW.

    So the null hypothesis (no warming trend) is just as vaild as any other 🙂

    Looking forward to seeing how long my comment stays up!

  34. Posted Dec 13, 2007 at 12:44 AM | Permalink

    Re Bruce says:
    December 12th, 2007 at 9:41 pm

    quote NASA thinks clear skies are part of the problem:unquote

    Well, there’s a surprise. Told you so and I didn’t need billions of dollars worth of satellite equipment, just OriginalThought(TM).

    Now the next stage: why is low level cloud cover decreasing?

    Do organic surface films on sea salt
    aerosols influence atmospheric
    chemistry? – A model study
    L. Smoydzin and R. von Glasow
    Institute of Environmental Physics, University of Heidelberg, Im Neuenheimer Feld 229, 69120
    Received: 21 September 2006 – Accepted: 13 October 2006 – Published: 17 October 2006
    I can’t read this –it’s behind a PPV wall — but I’m sure NASA could stump up the dollars and maybe read round the subject. Even I am not quite sufficiently immodest to suggest that my website might give them a deeper insight. Not quite….

    There was a recent study of productivity loss in the Bering Sea where they mentioned skimming the surface millimeter, looking for surfactant pollution. That should be worth looking at as well.

    Essenhigh has suggested that Arctic melting will lead to albedo increases (snow and cloud) which will be a self-correcting feedback: this is only true if there is no anthropogenic suppression of that mechanism. Sad to think of the little under-ice organisms desperately pumping out DMS and methyl iodide, trying to save their little worlds and failing to up the number of CCNs, depleted by pollution, to cloud forming levels.


  35. Derek Walton
    Posted Dec 13, 2007 at 1:01 AM | Permalink

    Re Julian Flood:
    December 13th, 2007 at 12:44 am

    The paper is available here.

  36. JohnB UK
    Posted Dec 13, 2007 at 2:29 AM | Permalink

    Julian #38

    “”Now the next stage: why is low level cloud cover decreasing?””

    Julian – wouldn’t Svensmark say this could be due to reduced cosmic rays which would also account for decreased temperatures in the Antartic?

    Do we have any figures for trends in muons over the arctic during the last 10 years?

    If this post makes no sense please accept my apologies !! – I’m not a scientist – but I’ve just read Svensmark and Calder’s “Chilling Stars” which seems to make this suggestion.

    To follow on from Svensmark – and also Friis-Chritensen and Lassen’s work on solar cycle length and temperature – given that Cycle 23 seems to be extended and (some) forecasts for 24 and possibly 25 are weak – could we see raised muon levels, increasing cloud, and falling temperatures over the Arctic (and elsewhere) in the relatively near future?

    Wouldn’t this match with the apparent plateau of global temperature since ’98 and the longer cycle 23?

  37. PaulM
    Posted Dec 13, 2007 at 3:31 AM | Permalink

    Leon your post is not there at realclimate and is unlikely to appear since you mention Steve by name. Here is what I just posted there – I wonder if it will appear.
    ‘It seems to me that you are misquoting the paper.
    You say “Now the claim has been greatly restricted in scope and
    concerns only .. the rate of warming”, but the abstract of the paper
    says “above 8 km, modelled and observed trends have opposite signs”.’
    Steve please can we have a thread for this paper?

  38. Posted Dec 13, 2007 at 4:26 AM | Permalink

    Re 39

    Thank you. Some snippets:

    More than 20 yeas ago Gill et al. (1983) brought up the
    idea that organic surfactants which can be present on sea salt
    aerosols might be of potential importance as they might affect
    processes like droplet activation and droplet growth.

    Organic matter can be directly incorporated in marine particles
    when gas bubbles burst at the surface.

    It is very difficult to draw a clear conclusion from our
    model runs regarding the effect of an organic surface film on
    atmospheric chemistry due to the large range of uncertainties
    concerning the data from laboratory and due to the numerous
    assumptions we had to make in our model setup.

    Knowledge about the breakdown products of surfactants
    and their properties is required for a more in depth
    assessment of the problem. Current laboratory studies
    give information about secondary chemistry of the oleic
    acid-ozone system only. Even for this system the available
    information is not detailed enough. That makes the
    inclusion of these processes in atmospheric chemistry
    models difficult.

    In other words, we don’t need more models, we need research. I see no mention of synthetic surfactants or mineral oil.

    Re 40

    John, you wouldn’t expect me to agree with the GCR hypothesis, now would you? Not with my own corner, the Kriegesmarine hypothesis, to fight. Calling in GCRs seems like multiplying entities to me: I prefer the notion that yes, it’s us, yes, it’s oil (and dodecyl benzene sulfonate) but no, it’s not oil burning. We’ve reduced low level stratocu over the oceans: that is my proposal, forecast, it’s not yet measured fact as far as I know. I’d call the definitive book ‘The Warming Tide’ but I’m sure Proctor and Gamble would object…

    Is there any suggestion that in the last few years the oil sheen and surfactant load on the relevant parts of the Arctic ocean has increased? I think I’ll have a think.


  39. Pierre Gosselin
    Posted Dec 13, 2007 at 4:51 AM | Permalink

    Spot the Hockey Stick

  40. Pierre Gosselin
    Posted Dec 13, 2007 at 5:06 AM | Permalink

    The State of New hampshire (Live Free or Die) is also using the hockey stick.

  41. MarkW
    Posted Dec 13, 2007 at 5:35 AM | Permalink


    Anthropogenic aerosols should flush out of the atmosphere even faster than volcanic ones, since they never get out of the troposphere.

  42. kim
    Posted Dec 13, 2007 at 6:44 AM | Permalink

    It’s discouraging to consider that albedo, or ‘pollution’, is going to be the smokescreen that allows any rationale or scenario to see the light of day, and to wave away, as if with a wand, any temperature change. Smoke and mirrors, indeed.

  43. SteveSadlov
    Posted Dec 13, 2007 at 9:55 AM | Permalink

    RE: #49 – Nascent North Atlantic Triple Junction leading to new mid ocean rift zone in a NW – SE orientation(or similarly, a failed third arm)?

  44. Posted Dec 13, 2007 at 10:25 AM | Permalink

    Re 41

    Hi Paul, I quote (in 37) from real climate’s dismissal of the paper, not the paper.

    Real climate’s analysis of the paper concludes with the quote in #37 (as I read it) that the real climate’s estimate of the uncertainties in the observations used in the paper are too large to rule out the GCMs (with reasonable model uncertainty applied by real climate) fitting the observations.

    That struck me as real climate applying Steve’s auditing principals that if the observations are uncertain and the models are uncertain, then the models have no prediction power.

    So Steve is having more impact than imagined on real climate, they’re adopting Steve’s approach!

    And it a further test of the predictive power of that mentioning Steve on real climate results in immediate removal of the offending comment.

  45. Posted Dec 13, 2007 at 12:37 PM | Permalink

    # 10


    Yours is a very important question that must be answered in a straight way. Which one from delta T, F and S is well known? I always wondered why the modelers took the delta T of the 1870s like the “standard” when the most plausible delta T to be a “standard” delta T is that one corresponding to the last 12000 years. The problem with that ample delta T is that it is enough wide (some 3-7 K) as to blur the current “global warming”.

  46. Posted Dec 13, 2007 at 12:45 PM | Permalink

    On the other hand, the standard temperature for the northern hemisphere is 300.15 K (27 °C or 80.6 F), than any deviation from that temperature must be considered a change of temperature. If it was true, then the change of temperature for the last month on my latitude would be 3 K… Impossible, isn’t it? However, if I consider than the median of temperature for November on my latitude along the last century was 293 K, then the change of temperature for the last month would be only 0.15 K, which is more credible.

  47. Sam Urbinto
    Posted Dec 13, 2007 at 2:35 PM | Permalink

    Thanks trevor. Perhaps I should have given which decade was which and the significance of the temp anomaly:

    1966-1975 +.00C anomaly trend (19.8%), +10 ppmv CO2
    1996-2005 +.22C anomaly trend (94.5%), +20 ppmv CO2
    1895-1904 -.16C anomaly trend (88.7%), +02 ppmv CO2
    1986-1995 +.09C anomaly trend (78.9%), +14 ppmv CO2
    1976-1985 +.12C anomaly trend (44.1%), +14 ppmv CO2
    1956-1965 +.00C anomaly trend (06.6%), +06 ppmv CO2

    What I wonder is what 2006-2015 is going to look like….

  48. Posted Dec 13, 2007 at 4:44 PM | Permalink

    About aerosols:

    The Pinatubo eruption injected some 20 million tonnes of SO2 directly into the stratosphere, where it stayed for 2-3 years (to make it convenient, let’s say 800 days). The total effect (including water vapour feedback) was a cooling of maximum 0.6 ºC. Humans emit around 80 million tonnes per year, mainly in the troposphere where it lasts for average 4 days. The direct effect of both (scattering on wetted sulphate particles) is virtually the same, which means that the direct effect of human made aerosols is around 0.025 ºC (including a 4-day accumulation). Tropospheric aerosols also have an indirect effect on clouds (more reflective, longer lasting). The IPCC gives a fourfold range increase for this forcing, compared to the direct effect. If we assume this is right, then the net effect of human made SO2 emissions would be 0.1 ºC.

    That is only for cooling aerosols, but black carbon (coal) and the Asian brown cloud (wood, browncoal, peat), are warming the lower troposphere above India (and China?) + albedo changes over snow and ice fields…

    Thus the net effect of all aerosols together may be positive, not negative…

    Further detailed comments at RC, here and here, the latter without any reaction of the guest specialists in aerosols, Ron Miller and Dorothy Koch from NASA GISS.

  49. Sam Urbinto
    Posted Dec 13, 2007 at 4:49 PM | Permalink

    As I’ve been saying! Do we really know what’s happening in how the airborne ones act in conjunction with the non-GHG, non-AGHG, AGHG and clouds in the first place, much less what they’re doing on the ground? What’s the ratio heating/cooling overall?


  50. Posted Dec 14, 2007 at 7:31 AM | Permalink

    Has Schwarts replyed to the critisism on his sensitivity analysis?

    Schwartz paper:

    and critisized e.g. here:

    I personally find large parts of the critique to be invalid (e.g. pretending that a GCM is a “system” as the climate; it should be rather embarrasing for a scientist to use a model to falsify a model…), but never the less would not want to miss his answers.

  51. Alan B
    Posted Dec 15, 2007 at 9:09 AM | Permalink

    Lunch with JEG sounds productive!

  52. Alan B
    Posted Dec 15, 2007 at 9:34 AM | Permalink

    Click here for JEG’s blog on AGU & lunch with Steve M

  53. steven mosher
    Posted Dec 15, 2007 at 11:13 AM | Permalink

    JEG quotes Tom Waits. That makes him ok to moshpit.

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