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Comments 131601 to 131650:

131601. chris at 02:59 AM on 19 June 2008
        Arctic sea ice melt - natural or man-made?
        Refocussing on the subject of this thread (the attenuation of Arctic sea ice) and the specific question of solar "dimming"/"brightening" in the Arctic and its potential contribution to sea ice recession, there are several relevant studies [e.g. *; **; ***] and these seem to yield a generally consistent conclusion. The Arctic sea ice has steadily receded since the 1960's although the trend has quickened (faster attenuation of summer sea ice) since around 2001. http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seasonal.extent.1900-2007.jpg During this period the solar irradiance measured at the surface has decreased at least through the mid 1980's (measured in high latitude Northern European stations [*]) and through the mid 1990's measured in Arctic stations [**], [***] (i.e. "solar dimming"). During the last decade or perhaps a bit longer it has recovered somewhat (less "solar dimming" or "solar brightening"!). However the solar irradiance at the surface is still a good bit lower now than it was in the 1960's (in other words the recovery from "solar dimming" has been smallish) [*]. What does this mean? (i) It's unlikely that variations in solar surface irradiation measured at the surface can have made a contribution to Arctic sea ice attenuation during the period since the 1960's since the variation has been in the wrong direction ("dimming"). More likely the "solar dimming" has mitigated somewhat the contributions (enhanced sea and surface temperatures; albedo effect including black carbon!) at least up 'til the mid-1990's. (ii) It's possible that the quicker pace of sea ice recession since around 2000, has a contribution from the small reduction in "solar dimming" since the mid-1990's. In other words the aerosol effects that were likely countering sea ice recession in the 1960's-1980's, are now doing so less effectively. [*] C. W. Stjern et al (2008) Global dimming and global brightening - an analysis of surface radiation and cloud cover data in northern Europe; submitted to Int. J. Climatol. http://folk.uio.no/jegill/papers/Stjern_etal_2008_IJClim.pdf [**]S. T. Weston et al (2007) Interannual solar and net radiation trends in the Canadian Arctic Journal Of Geophysical Research 112, D10105 [***] Stanhill G (1995) Solar Irradiance, Air-Pollution And Temperature-Changes In The Arctic, Philosophical Transactions Of The Royal Society Of London Series A- 352 247-258 ------------------------------------------ abstracts/extracts: [**] Although the trends are not explicitly linear, both data from Alert and Resolute Bay show an overall decrease in K↓ over the past half-century. Data from Alert shows a decrease of 2.25% of the daily mean CI, and Resolute Bay shows a decrease of 2.50% of the daily mean CI per decade. Although further data are needed to tell conclusively, it also appears that both sites show a recent recovery over the past decade. As is speculated by other authors [e.g., Stanhill, 1995; Lohmann et al., 2004; Che et al., 2005], it is most likely that changes in atmospheric constituents (aerosols and/or greenhouse gases) are the major cause. Further study in this area is definitely warranted. (K↓ is solar radiation; CI is daily "clearness index") [***] A highly significant decrease in the annual sums of global irradiance reaching the surface of the Arctic, averaging 0.36 W m(-2) per year, was derived from an analysis of 389 complete years of measurement, beginning in 1950, at 22 pyranometer stations within the Arctic Circle. The smaller data base of radiation balance measurements available showed a much smaller and statistically non-significant change. Reductions in global irradiance were most frequent in the early spring months and in the western sectors of the Arctic, coinciding with the seasonal and spatial distribution of the incursions of polluted air which give rise to the Arctic Haze.
131602. chris at 01:38 AM on 19 June 2008
        Arctic sea ice melt - natural or man-made?
        Re #74 Quietman Why not explain as clearly as you can, how you interpret Tung and Camp’s manuscript, with respect to their analysis of climate sensitivity. I did so in post #71. However you’re pursuing this argument by innuendo and allusion, and it’s not easy to know what you are trying to convey (at least in a scientific sense). When I have time I’ll post a more detailed explanation of my interpretation (it seems a very straightforward manuscript to me). Then we can see where the problem of interpretation lies.
131603. chris at 01:33 AM on 19 June 2008
        Arctic sea ice melt - natural or man-made?
        re #75: That's a tad dishonest Quietman. Here's what chris said! (see post #12): referring the steady attenuation of arctic sea ice since the 1960's: ["ii) "solar brightening from lack of aerosols". Nope. The atmospheric aerosol load has increased rather significantly since the 1960's. Thus enhanced Arctic sea ice melt has increased despite the overall decreased solar irradiation reaching the surface. Rather than "solar brightening" we've actually had a bit of "solar dimming"."] This is consistent with the paper that you cited (Stjern et al (2008); urled below[***], in which solar irradiation reaching the surface is averaged over 11 high Northern latitude stations as an indication of "dimming"/"brightening". The relevant data is summarized in their Figure 3 which shows that from the 1960's (the period from which Arctic sea ice retreat began) the total surface irradiation in the high Northern latitudes has decreased very significantly (i.e. nett "dimming"), and therefore this is unlikely to be a causal factor in the long term decrease of Arctic sea ice since the middle of the last century. More specifically, the "surface solar irradiation" averages around 115 W/m2 in 1960 (note that fewer stations were monitored during this period) and decreases progressively to reach a low near 103 W/m2 around 1987 from which it recovers a bit to reach a level near 106/107 W/m2 now, still well below the levels of the early 1960's. http://folk.uio.no/jegill/papers/Stjern_etal_2008_IJClim.pdf
131604. Quietman at 00:53 AM on 19 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe My remark about reading comprehension earlier refers to little oversights like the one below: "During the last 20 years or so, there has been a reversal from dimming to brightening at stations worldwide (Power, 2003; Wild et al., 2005)." C. W. Stjern, J. E. Kristjánsson, and A. W. Hansen, 2008 (link given in #17 above) Which says the exact opposite of what chris said.
131605. Quietman at 20:38 PM on 18 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe Solar-Cycle Warming at the Earth's Surface and an Observational Determination of Climate Sensitivity. By Ka-Kit Tung and Charles D. Camp From the Abstract: This model-independent, observationally-obtained climate sensitivity is equivalent to a global double-CO2 warming of 2.3 -4.1 °K at equilibrium, at 95% confidence level. The problem of solar-cycle response is interesting in its own right, for it is one of the rare natural global phenomena that have not yet been successfully explained. From the introduction: On the other hand there is a recurrent warming of the earth by the solar cycle. The periodic nature of the phenomenon allows the use of more sophisticated signal processing methods to establish the reality of the signal. Since the forcing is known, contrasting solar-max and solar-min years over multiple periods yields a pattern of earth’s forced response, which is better than previous attempts of using “warm-year analogs in recent century”--- some of which may be due to unforced variability --- to infer information relevant to future CO2 forcing. Our procedure for the solar-cycle signal yields an interesting pattern of warming over the globe. It may be suggestive of some common fast feedback mechanisms that amplify the initial radiative forcing. Currently no GCM has succeeded in simulating a solar-cycle response of the observed amplitude near the surface. Clearly a correct simulation of a global-scale warming on decadal time scale is needed before predictions into the future on multi-decadal scale can be accepted with confidence.
131606. Quietman at 20:20 PM on 18 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe Acknowledged. I am skeptical about any hypothesis until it has been proven. But it does have some merit. I lean towards the Fairbridge idea because it is the most logical. Green activists don't like it because it's not about AGW, but it does explain why there is more vulcanism and tectonic activity in recent years and is not incompatible with Tung and Camp's paper. PS The friends remark was not aimed at you so please do not be offended. It was aimed at closed minds that will not even look at a paper if they don't like the author.
131607. Philippe Chantreau at 11:23 AM on 18 June 2008
        Arctic sea ice melt - natural or man-made?
        Quietman, you also mentioned Spencer and his "internal radiative forcing." This is, by Spencer's own admission, a speculative mechanism. Put in your words, it would be a "root cause" in which one must have "faith." That's only part of the problem with it. As all other scientific works, it is open to scrutiny, some of which can be found here: http://www.realclimate.org/index.php/archives/2008/05/how-to-cook-a-graph-in-three-easy-lessons/langswitch_lang/sp#more-567 That same thread mentions how Spencer and Christy also have a history of allowing for years the use of data that had been shown to be invalid. I'm highly skeptical about Spencer's work, with much better reason than him saying stuff different from my "friends." In any case, that paper is very much incompatible with Tung and Camp, and it would invalidate their work if proved correct.
131608. chris at 08:19 AM on 18 June 2008
        Arctic sea ice melt - natural or man-made?
        Re #70: You need to explain clearly what you are trying to convey there Quietman. Otherwise your comment is an unsubstantiated and cryptic one! Here's what Tung and Camp conclude and how this compares with other independent analyses as compiled, for example, in the IPCC reports. Tell us where you disagree with this interpretation and why: (i) Tung and Camp calculate a measure of the Earth's climate sensitivity to radiative forcing equivalent to an equilibrium temperature rise of 2.3 - 4.1 oC per doubling of atmospheric CO2 at 95% confidence levels. (ii) The IPCC climate sensitivity determined from an analysis of many studies, is an equilibrium temperature rise of 1.5 - 4.5 oC per doubling of atmospheric CO2 at 95% confidence levels. (iii) In other words Tung and Camp are in accord with the results of a whole slew of independent analyses compiled by the IPCC that indicates that the Earth's surface temperture responds to a forcing eqiivalent to a doubling of atmospheric CO2 somewhere near 3 oC (+/- a bit at 95% confidence levels.
131609. Quietman at 07:51 AM on 18 June 2008
        It's the sun
        Tom in Texas I know that this may sound a bit strange but parts of the U.S. actually get colder than central Canada (about as far north as civilization extends except for the coasts). For example in January 1996 northern Minnesota hit about -54 F during the Plains Blizzard, for that week it did not go higher than about -48 F (rounded to whole numbers). The same week, the urban town of North Bay and the mining town of Timmins (both Canada) never went below -45 F. and averaged about -40 F. It's because of the Jet Stream which as you know can dip as far south as Texas on occasion. It's one of the reasons that much of the cold tests conducted by car manufacturers are done in various towns in northern Minnesota. They also get more January snow than those canadian towns.
131610. Quietman at 07:34 AM on 18 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe In that last sentence please note "equivalent to a global warming of 2.3 °K at doubled CO2." You and chris have not been paying very close attention to the wording. The paper does not support chris' view, which is why Mackey used it to support his view in the Climate Science blog that I linked above in #63.
131611. chris at 02:55 AM on 18 June 2008
        Arctic sea ice melt - natural or man-made?
        shawnet, Yes, fair enough. I think the overall conclusion might be that the Antarctic sea ice is overall stable right now, whereas that in the Arctic is receding rather rapidly. If one considers the rate of change of Antarctic sea ice in the period late 1987 to now, this is a very small trend of around +12,000 km2 per year. During the same period, the Arctic sea ice trend is around -85,000 km2 per year (the trend from the start of 2001 is of the order of -131,000 km2 per year in the Arctic). One can see that the Antarctic sea ice isn't really doing a huge amount: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.south.jpg (cf the arctic sea ice: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.area.jpg ) and although direct satellite measures of sea ice are only available since the mid-70's, the less direct data indicate that Antarctic sea ice extent was larger in the period 1900-1960 than now[***], so perhaps the Antarctic sea ice is just undergoing a bit of a small fluctuation/recovery. As expected, global surface warming just isn't penetrating wholesale into the Southern polar regions as it is in the Arctic. The Antarctic is a very big place 'though, and as we know some parts are undergoing some significant warming, especially the Antarctic peninsula and the Pine Island Bay region of West Antarctica, and this seems actually to be resulting in overall mass loss of the Antarctic ice sheet [*****]. But no-one considers significant loss of the Antarctic polar ice to be very likely, whereas the loss of Arctic sea ice and attenuation of some of the Greenland ice sheet is a real concern for the future... [***] N. A. Rayner et al. (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century; Journal Of Geophysical Research, 108, NO. D14, 4407. [*****] H. D. Pritchard & D. G. Vaughan (2007) Widespread acceleration of tidewater glaciers on the Antarctic peninsula, Journal Of Geophysical Research, Vol. 112, F03S29 E. Rignot et al. (2008) Recent Antarctic ice mass loss from radar interferometry and regional climate modelling, Nature Geoscience 1, 106 – 110.
131612. shawnhet at 01:15 AM on 18 June 2008
        Arctic sea ice melt - natural or man-made?
        Just a brief point here, chris. "But these discrepancies have been addressed at length, and this is a rather well understood phenomenon relating to the heat capacity of the oceans (more ocean in the S. hemisphere and thus greater heat capacity there) and ocean circulation properties (much more efficient transfer of surface heat in the deep Southern oceans compared to the Arctic oceans). The possibility that black carbon might play a role is possible. However remember that man-made atmospheric aerosols have a cooling effect overall (see Ramanathan’s work discussed at length on this thread), and since these are produced and concentrated largely in the Northern hemisphere, that seems a less than likely interpretation, unless, of course one is dealing only with the effects of ice-deposited black carbon." The efficiency of heat transfer would be a good explanation for why the changes SH ice are of different magnitude than those of the NH IMO, but is not a particularily good explanation of why the sign of those changes is different. If the difference in ice buildup was primarily governed by the efficiency of heat transfer at the poles, one would expect the sign of the changes to be the same(one would just be slower than the other). Quietman, thanks for the link to the Rhodes Fairbridge article. Interesting stuff. Cheers, :)
131613. Quietman at 23:38 PM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe The portion I point out in the conclusion is what is overlooked most often. I left out the obvious because long posts, like long reports, are normally not read. I have written many papers in my field and know that the summary and conclusion are what most people read, and not intently. In the blog Climate Science linked to in 63, Richard Mackey and Leif Svalgaard discuss this same paper. The conclusion is the opinion the authors have arrived at from their study. The body of the paper gives the facts used to arrive at that conclusion. But it is better to read the entire paper to determine the facts.
131614. chris at 21:23 PM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        leebert/shawnet (#58/#59): You both mention the difference in effects in the Northern and Southern hemisphere in general (leebert) and specifically in relation to sea ice extent (Shawnet). You suggest that this is a problem for climate science, leebert: e.g. post #58 you say: [“One of the big hangups the honest skeptics have about dangerous CO2-driven warming is that the temperature anomalies are lower in the southern hemisphere where BC is far less common (as are all aerosol levels). This, as opposed to the Arctic's 25 perc. of sesquicentennial AGW, largely due to sootfall (around 80-90%). I think a great many misgivings about climate science would be relieved if these apparent NH vs. SH discrepancies could be addressed. Is it b/c of the relative lack of BC coupled with a function of the Antarctic or ENSO? “] But these discrepancies have been addressed at length, and this is a rather well understood phenomenon relating to the heat capacity of the oceans (more ocean in the S. hemisphere and thus greater heat capacity there) and ocean circulation properties (much more efficient transfer of surface heat in the deep Southern oceans compared to the Arctic oceans). The possibility that black carbon might play a role is possible. However remember that man-made atmospheric aerosols have a cooling effect overall (see Ramanathan’s work discussed at length on this thread), and since these are produced and concentrated largely in the Northern hemisphere, that seems a less than likely interpretation, unless, of course one is dealing only with the effects of ice-deposited black carbon. Here’s some excerpts from a recent review of ocean circulation modelling in which the mechanisms for hemispheric warming asymmetry are described, and illustrating that highly delayed Antarctic Circumpolar ocean warming has been predicted since the early 1980’s. One of the problems of this, of course, is that while the high latitude Southern oceans are apparently taking up much of the surface heat by transfer to the deeper layers, at some point this will become inefficient, and thus one might expect the Southern hemisphere warming to kick in… Here’s a bit of a summary from (direct excerpts are in [“bracketed quotation”] marks): S. Manabe and R. J. Stouffer (2007) Role of Ocean in Global Warming; J. Meterolog. Soc. Jpn. 85B 385-403. General point about ocean modulation of surface warming: [“In response to the increase in greenhouse gas in the atmosphere, the positive temperature anomaly initially appears in the well-mixed surface layer of the ocean called the “mixed layer”. Gradually, the anomaly spreads from the mixed-layer to the deeper layers of the ocean, thereby increasing the effective heat capacity of the oceans. The increase of effective heat capacity, in turn, results in the reduction of the rate of increase in surface temperature, reducing and delaying the warming as shown by Hoffert et al (1980) and Hansen et al. (1984).”] Discussing the early models of Schneider and Thompson (1981) to evaluate the delay in the response of the sea surface temperature to gradual increase in CO2, Manabe and Stouffer say: [“Their study shows that the time-dependent response of zonal mean surface temperature differs significantly from its equilibrium response particularly in those latitude belts, where the fraction of ocean-covered area is relatively large. Based upon the study, they conjectured that the response in the Southern Hemisphere should be delayed as compared to that in the Northern Hemisphere because of the inter-hemisphere difference in the fraction of the area covered by the oceans.”] In a later model Bryan et al (1988) made the same sort of analysis, investigating the role of the oceans in modulating the response of surface warming to enhanced greenhouse gases. [“They found that the increase in surface temperature is very small in the Circumpolar Ocean of the Southern Hemisphere in contrast to high latitudes of the Northern Hemisphere where the increase is relatively large.”] It’s not just the oceans per so of course. It’s also ocean and air currents, and particularly the mechanisms governing the efficiency of surface heat transfer into the deeper oceans. If this is efficient, the deep oceans will absorb heat and there might be little measured surface warming, at least for a while. So (speaking of Bryan et al (1988)) again: [“However, the detailed analysis of the numerical experiment reveals that the absence of substantial surface warming in the Circumpolar Ocean is attributable not only to the large fraction of the area covered by the oceans but also to the deep penetration of positive temperature anomaly into the oceans.”] Later models predict the same hemispherical Asymmetry that is seen in the real world. e.g. discussing the simulations of Manabe et al (1992): [“Figure 3 also reveals that there is a large asymmetry in surface warming between the two hemispheres. In the Northern Hemisphere, the surface warming increases with increasing latitude, and is particularly large in the Arctic Ocean. This is in sharp contrast to the Southern Hemisphere, where warming is relatively large in low latitudes and decreases with increasing latitudes. It becomes small in the Circumpolar Ocean of the Southern Hemisphere, particularly in the immediate vicinity of Antarctic Continent.”] Why is this, one might ask?! Here’s what Manabe and Stouffer say: [“One can ask: why the polar amplification of warming does not occur in the Southern Hemisphere, despite the existence of extensive sea ice which has a positive albedo feedback? As discussed in the following section, the absence of significant warming in the Circumpolar Ocean of the Southern hemisphere is attributable mainly to the large thermal inertia of the ocean, which results from very effective mixing between the surface layer and the deeper layers of ocean in this region. This is in sharp contrast to the Arctic Ocean, where very stable layer of halocline prevents mixing between the surface layer and the deeper layer of the ocean.”] [“In view of the absence of significant surface warming, it is not surprising that the area coverage of sea ice hardly changes in the Circumpolar Ocean despite the CO2-doubling.”] (n.b. remember this is a prediction from a model; we’re nowhere near CO2 doubling yet!). However that's what we're seeing in the real world. and so on….
131615. dave287 at 12:51 PM on 17 June 2008
        Empirical evidence for positive feedback
        you have already decided on the ANSWER,,,then you have a ,6 grade mentality pretend to discuss it all as suposedly free discussions,,but you leave the intelligent posters out
131616. dave287 at 12:44 PM on 17 June 2008
        Empirical evidence for positive feedback
        what a joke this site is --why bother to read it
131617. Philippe Chantreau at 10:23 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        Quietman:"conclusion" is the heading to the section for the quote (cut and paste, nothing added)." Nothing added, but some omitted, see the complete conclusion given by Chris in post 54. Do you dispute that Tung and Camp come up in that paper with a sensitivity of 2.3 K at CO2 doubling? You talk about twisting good work. Tung and Camp reach a value for climate sensitivity to CO2 doubling that is almost identical to what the IPCC says, yet you suggest that their paper demonstrates that the climate sensitivity to CO2 has been overestimated by mainstream climate science (of which we'll assume IPCC's reports to be representative). I don't understand.
131618. Quietman at 08:27 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        chris Sorry - in my last post I meant to link Mackey's email address, epitrochoid@hotmail.com, but linked his office by mistake.
131619. Quietman at 08:20 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        chris On "Rhodes Fairbridge and the idea that the solar system regulates the Earth's climate." August 24th, 2007 by Warwick Hughes. "Rhodes is one of the few scientists to research the sun/climate relationship in terms of the totality of the sun’s impact on the earth (i.e. gravity, the electromagnetic force and output and their interaction)." ... "Rhodes also researched the idea that the planets might have a role in producing the sun’s variable activity. If they do and if the sun’s variable activity regulates climate, then ultimately the planets may regulate it." As for Dr. Mackey, the scientist you tore apart, his views are contained in his replies in a blog: Richard Mackey says: December 28th, 2007 at 5:03 am I suggest if you disagree with him that you contact him yourself. Richard Mackey. The article published by Dr. Fairbridge can be found here.. I am sorry but I do not have access the the published paper that the article is based on, nor his later papers. But the article is quite clear and in plain english. Dr. Fairbridge and his hypothesis is also referenced in this recent paper: Fingerprints of a Local Supernova by Oliver Manuel and Hilton Ratcliffe, which explains implications of the hypothesis.
131620. Quietman at 06:34 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        phillipe I only have one point to make - nature has much greater effect on climate than AGW. All of the papers that I use for reference support this stance if you read them carefully without presupposition. I am an environmentalist but moreover I am a naturalist in the traditional sense of the word. I live in accord with nature. I study it for what it is and do not believe in tampering with it in any way for any reason. But I can read, have been for a very long time, first course in how climate works was those science books for children back in the 50s. I do not appreciate good work being twisted to meet someones agenda. I have read your comments in all of these posts and while I don't always agree with your views I do respect them.
131621. Quietman at 06:18 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe Chantreau "conclusion" is the heading to the section for the quote (cut and paste, nothing added). I stopped arguing my point when I realized the problem was a predetermined view of any paper referenced and an accusation of my not reading them. I take the authors for what they say, no inference. In once case the author actually states three possibilities, that is what words like "IF" usually mean. This I consider a credible argument, the author says "IF" rather than making an assumption that a hypothesis he did not propose is a fact. The other paper clearly states that AGW needs a rethink, not that the hypothesis is bad but that it isn't good either. Again, given the evidence, this is credible. To blandly argue that a hypothesis is true because your friends say so is totally without merit.
131622. Quietman at 06:06 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        chris Re: "I just don't see the point." I agree.
131623. shawnhet at 04:14 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        Just a brief piece of info to inform this discussion, "As we approach the time of year of the peak of areal coverage of Arctic sea ice and the minimum areal coverage in Antarctic sea ice, Climate Science is presenting a status report based on the excellent data analysis provided at the University of Illinois website The Cryosphere Today. The coverage for January 31 2008 is about 900,000 square kilometers below average for the Arctic [Northern Hemisphere] (see) and about 500,000 square kilometers above average for the Antarctic [Southern Hemisphere] (see). The Illinois website has also introduced an effective display of past Arctic sea ice coverage at the same time of the year (see Compare Daily Sea Ice)." http://climatesci.org/2008/01/31/current-status-of-arctic-and-antarctic-sea-ice-coverage/ Now, I really don't know what's causing the difference btw Arctic and Antarctic sea ice, but there certainly seems to be a large non-C02 component to sea ice variation. Cheers, :)
131624. leebert at 04:08 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe, Chris, Thanks for the info. I too am short on time these days so I can't cover all the bases. Perhaps the crux of the misunderstanding is this: The brown clouds may provide a net masking but the BC detracts from the total possible masking. Is that a better synopsis? (FWIW I never intended to conflate BC with all global aerosol clouds). And when Ramanathan states that 40% of the Pacific's temp. anomalies are being caused by BC, I find that a very clear statement. Yes, it's a one-time fix, but it's also a 20-year window. Philippe: I'm glad to see GreenPeace along with Grist have come along but big environmental newspaper writers like Andy Revkin (dot Earth) have actively pooh-poohed the entire question of soot deposition in the Arctic. Good grief, I practically handed it on a plate to Revkin. He blew it off, discounting it as marginal against other dynamics affecting ice. John Tierney took interest, however. And if the activists *KNOW* about the airborne soot issue, then why aren't they announcing it as part of their campaign? Is their message getting diluted by the media? For the politicos to raise heck about polar bears & the Arctic w/out talking about soot mitigation seems disingenuous. There's something wrong with the game plan, and having been involved in a couple of activist organizations, I come into this with some pretty strong suspicions about their politics (having endured rants by 9/11 Truthers and anti-capitalists, etc.). Science fat vs. activist fancy? Well.... The climate moderates who suspect CO2's global impact tending toward the lower bounds are happy to pursue soot & ozone mitigation first and as objective efforts they seem far more feasible and certain. I think a gradual, stepped conversion to a low-carbon society is entirely feasible, but getting per capita CO2 output down to preindustrial levels by 2050? Not bloody likely! There's more to be learned, however, about aerosols in general. One of the big hangups the honest skeptics have about dangerous CO2-driven warming is that the temperature anomalies are lower in the southern hemisphere where BC is far less common (as are all aerosol levels). This, as opposed to the Arctic's 25 perc. of sesquicentennial AGW, largely due to sootfall (around 80-90%). I think a great many misgivings about climate science would be relieved if these apparent NH vs. SH discrepancies could be addressed. Is it b/c of the relative lack of BC coupled with a function of the Antarctic or ENSO? NCAR's Ken Ternberth's recent apostasy re: the Argo floats has kept the discussion very much alive, as have the recent studies showing lower relative humidity in the middle troposphere and less water vapor in the Antarctic as well. How those all shake out will take some time, as will Keenlyside. The calls against complacency don't seem to address the temperature plateau, since even were more warming due, the relative plateau (relative to the 1990's) doesn't seem to portend a worst-case outcome. Without the anticipated pipeline of heat in the seas, and with every year of slowed warming relative to accelerated CO2 levels, nature would have to exhibit an exponential rate of warming relative to CO2 levels alone. That seems truly unlikely to me. The climate stance of Pielke, Carter, Spencer, Lindzen, etc., is seeming more reasonable, that other mitigating factors are at play (cloud dynamics). If the honest skeptics are mistaken, what could be misleading them? Net aerosol effects? Help me then: The sun has dimmed -0.1 degrC worth since the early 1990's, that's about a -0.07/decade offset (and it's due to dim more) while the low end of aerosol masking -0.09 degr/decade, sea temperatures are currently stable (last I checked). If temperatures rise despite those negative forcings, there's a big problem. If temperatures remain stable with those negative forcings intact, will be fair to surmise those would represent the CO2 signal? That'd be a 0.18 degr/decade signal. Not ideal, but is it dangerous? People like good hard numbers, but not sound bites that scream "panic." Those breed suspicion b/c it smells like demagoguery. Smart people can read a balance sheet that accounts for the sun's dimming, the real net aerosol maskings, the Arctic warming (and what of it can be reversed), etc. Those IPCC bar graph & summaries are inadequate to the task. W/out some clearer figures as to what society is really dealing with the majority of people are going to be understandably reluctant to embark on a big program. What I constantly read looks like some very incomplete science and lots of politics. If you wonder why people resist the theory of dangerous AGW, this is why. What the CO2 mitigation program looks like is a self-administered austerity program (barring a sudden expansion of low-carbon technologies). Austerity programs hurt, and hurt big, and can even impair the ability to pay for a conversion to a low-carbon society. W/out a lot of extra heat in the pipeline, do we really need to pursue something so drastic, then? Already Britain is verging on an anti-green rebellion, the invasive burden of gov't interference would cause a real revolution here in the 'states. Japan says they can't afford Kyoto-level targets. The EU is looking at losing their steel industry to Asian steel makers. And with increasing trade deficits it's hard to bear yet more economic burdens. Bjorn Lomborg is correct in pointing out that we can't afford everything (even w/out big SUVs), so we can only do what's feasible. Which... brings us back to soot.
131625. Philippe Chantreau at 02:32 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        The Grist article and Leebert's post: http://www.grist.org/news/2008/03/24/soot/index.html That post does look interesting a first glance. A Greenpeace account of "field work" or whatever you'd want to call it: http://www.projectthinice.org/blog/view/13057/ Snippet: "We are also seeing a lot of dark material (soot) covering some of the flatter ice as well. Anywhere there is soot, the snow is melting away faster than the surrounding areas." Would the Greenpeace people (green activists if there ever were some) really publish that kind of stuff if they wanted to sweep it under the rug?
131626. Philippe Chantreau at 02:16 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        Quietman:"I do read the papers, but I do not read into them, just the facts, not conclusions based upon some faith in a root cause." It seems that you don't read them that well, since you missed the entire conclusion of the T&C paper. Or when you say conclusions, do you mean the conclusions of the authors themselves? Furthermore, you put together papers whose conclusions are totally incompatible, and you do so only because they appear to support your opinion on one point, while in fact they don't really do that, which you would know if you actually read the papers. Leebert, you accuse activists of sweeping the issue of soot under the rug. Yet a relatively recent Gristmill article does a fairly accurate rendition of what Ramanathan found out, and it seems to agree with your position on the necessity of targeting BC. I did not read your (very)extensive post there - not as much disposable time as you or Chris - but I noticed that it was there for all to read, i.e. nobody tried to sweep it anywhere. Grist is as greenly active as it gets. A quick glance at what Greenpeace has on its site indicated that they would be highly favorable to any kind of reduction in BC soot emissions (surprise). I found little evidence on these "activist" sites that the issue was being avoided out of fear to detract from the CO2 problem. There may be a case to be made that it does not attract as much attention. Since the total particulate forcing is still negative (per Ramanathan), that lack of attention might not be as terrible a thing as you argue. According to yourself, it is rather governments that are trying to sweep the soot (highly inefficient way to dispose of it). You cited China and India but ironically, a little reading on the "activist" pages shows that the Bush EPA too has been trying its darndest to not enforce the CAA against industries violating particulate matter rules. Of course, they have been heavily criticized for that by, hmm, the activists. So you say that activists are trying to sweep the soot while they actually are actively fighting it. You also say that polluting countries governments are trying to sweep the soot, and in the case of the US they are doing so against opposition from the activists. Confusion indeed. As for the Ramanathan paper, there is anything but confusion in Chris's mind. His review is outstanding and does a much better job of carrying the author's findings than the press release you cited. FYI, I am not an "activist" and I'm interested in all the science about these issues that is accessible to me. Big thanks to Chris, who just made a bunch of science more accessible and also summarized it and nicely emphasized some important points (gee, you should get paid for that!). And finally, Leebert, I totally agree with you that BC emissions should be selectively reduced by all possible means.
131627. chris at 00:40 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        Re #51 and #52 It's unfortunate, Quietman, that you feel the need to hijack this thread by dumping inappropriate stuff. I just don't see the point. We've already seen that Tung and Camp is pretty much a mainstream paper, the conclusions of which are in accordance with solar/climate science in general (their max-min solar cycle contribution is a bit larger than others get, but their climate sensitivity measure is smack in the IPCC range). Let's very briefly (since this isn't the thread to address this stuff) look at the others. Spencer's paper. It seems odd that you've dumped both Spencer's paper and Tung and Camp's paper at the same time. They're totally incompatible. Spencer is pretending that some unsupported phenomenon ("internal radiative forcing") means that the Earth doesn't respond to enhanced greenhouse gas forcing as pukka science indicates. However Tung and Camp's analysis indicates that the Earth warms at equilibrium by 2.3 - 4.1 oC per doubling of atmospheric CO2. That's exactly what the rest of informed mainstream science says too. So which is it Quietman? You need to come to some conclusion yourself before just dumping inappropriate papers here. Scaffeta and West's paper is a mathematical exercise that addresses the issue entirely phenomenologically according to a set of "what if..." assumptions. They are neither climate nor solar scientists and their paper is a hypothetical exercise. Scientists that do solar science have established that the sun hasn't made any significant contribution to the warming of the last 30-odd years. Here's the Director for the Sun-Heliosphere Department of the Max Planck Institute for Solar System Research, Sami Solanki, writing in a paper several months ago [***]: ["The observed correlations between the Sun's behaviour and the Earth's climate have completely failed since the 1970s. In the past 30 or 40 years the Earth's temperature has gone up much more rapidly than you would expect from the Sun – indeed there is strong evidence that since 1985 all the changes in the Sun have been in the opposite direction to that required to warm the Earth."] and: ["But, in our view, there is no doubt at all that the ongoing global warming is not being caused by the Sun but mainly by the greenhouse gases such as CO2 that we are emitting."] [red]***[/red][i][b]Priest, Lockwood, Solanki and Wolfendale (2007)[/i] Astronomy & Geophysics Volume 48 Issue 3 Page 3.07-3.07.[/b]
131628. chris at 00:24 AM on 17 June 2008
        Arctic sea ice melt - natural or man-made?
        re #50 - You're still not getting it Quietman. Tung and Camp's analysis relates to the damped variation of the Earth's surface temperature response to the solar cycle. Their analysis suggests that they can pull out a solar cycle variation of nearly 0.2 oC. That means for example that at the solar cycle maximum near 1991 to the solar cycle minumum near 1997, the solar contribution was a cooling one by around 0.18 oC (according to Tung and Camp....from 1997 minimum to the maximum near 2001 the solar contribution was to add back that warmth....from 2001 to 2007/8 the solar cycle contribution subtracted that 0.18 warmth again...and so on... in other words the Earth has a slow damped cyclic response to the solar cycle. No one expects otherwise. Tung and Camp's value (0.18 oC solar cycle max-min) is a bit larger than others find. But it makes no nett warming/cooling contribution (unless the strength of the solar cycle varies very significantly). So as the Earth's surface warms under the influence of enhanced greenhouse gas forcing, so the sun provides a small cyclic warming---cooling---warming----cooling----warming etc. (it's the solar cycle!). Right now the solar cycle is making a slight cooling contribution, but during the next few years its contribution is going to be adding to the anthropogenic greenhouse gas contribution..... You truncated the Conclusion section from Tung and camp's preprint. I've reproduced it below the dotted line at the bottom of the post. Notice that the second thing that Tung and Camp determine is a measure of the Earth's climate sensitivity to doubling of atmospheric CO2 (or CO2 equivalents). They determine a value of 2.3 - 4.1 K (oC) per doubling of atmospheric CO2 equivalents. This is pretty much exactly what the rest of the scientific measurements of the Earth's climate sensitivity to CO2. Tung and Camp are pretty much in accordance with the rest of the science on solar and greenhouse gas contributions to the Earth's temperature. ---------------------- Full conclusions from Tung and Camp's paper that Quietman partially reproduced in post #50 " Using NCEP reanalysis data that span four and a half solar cycles, we have obtained the spatial pattern over the globe which best separates the solar-max years from the solar-min years, and established that this coherent global pattern is statistically significant using a Monte-Carlo test. The pattern shows a global warming of the Earth’s surface of about 0.2 °K, with larger warming over the polar regions than over the tropics, and larger over continents than over the oceans. It is also established that the global warming of the surface is related to the 11-year solar cycle, in particular to its TSI, at over 95% confidence level. Since the solar-forcing variability has been measured by satellites, we therefore now know both the forcing and the response (assuming cause and effect). This information is then used to deduce the climate sensitivity. Since the equilibrium response should be larger than the periodic response measured, the periodic solar-cycle response measurements yields a lower bound on the equilibrium climate sensitivity that is equivalent to a global warming of 2.3 °K at doubled CO2. A 95% confidence interval is estimated to be 2.3-4.1 °K. This range is established independent of models."
131629. chris at 23:52 PM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        leebert, I don't disagree that your quotes by Ramanathan are probably accurate. However they are soundbites that tell only part of the story. Statements from press releases and press releases in general are not very good primary sources for the science. However we have the very recent review by Ramanathan and Carmichael at hand (see citation in my posts above), and you have given us the url to Ramanathan's prepared testamonial for the Wegman hearing. These give a very straightforward account of the science according to Ramanathan, and I recommend you read Ramanathan's Wegman hearing testimonial again carefully. i.e.: http://oversight.house.gov/documents/20071018110734.pdf Rather than soundbites, it (and the Ramanathan & Carmichael review) gives a considered scientific account. It's then straightforward to come away with unambiguous conclusions concerning Ramanathan's interpretation of his (and other's) data: These are: (i) If one is interested in the Earth's average surface temperature anomaly, which we all take to be the parameter by which global warming is assessed, atmospheric aerosols en masse (including black carbon, atmospheric brown clouds and sulphurous/nitrous aerosols and so on) result in nett cooling of the Earth's surface. (ii) This results from the fact that aerosols (especially black carbon) have the dual effect of both cooling the surface by reflecting or scattering incident solar irradiation, preventing some of it from reaching the Earth's surface - global "dimming", and the atmospheric warming effect of trapping or scattering incident solar irradiation or (especially black carbon), absorbing solar irradiation reflected from the Earth's surface. (iii) We can't talk about the atmospheric warming contributions of aerosols without also considering the cooling contributions, particularly since the latter dominate the total effect of aerosols. As Ramanathan says in the Wegman testimonial you urled (url copied above - see page 5), after describing that the nett anthropological aerosol effect is a cooling one of -1.5 Wm-2 (+/- a bit) while the net anthropogenic greenhouse forcing is equivalent to +3 Wm-2: "..it leads to the conclusion that, globally, ABCs may have masked as much as 50% (+/- 25%) of the warming due to greenhouse gases." (iv) and of course it logically follows that if one were to eliminate anthropogenic aerosols the world would warm. Ramanthan states this very clearly (page 5 again): "The logical deduction from this estimate is that, if and when air pollution regulation succeeds in eliminating emission of these particles, the surface warming can intensify by about 0.7 to 1.5 K, where the range is due to a range in assummed climate sensitivity of 2 to 4 K per doubling of CO2." I don't think I or Ramanathan could say this more clearly! The nett anthropogenic aerosol effect is to cool the Earth. (v) Now if we could remove black carbon selectively (not easy since BC emissions occur with other emissions, and much of the BC warming effect is due to its interactions with other aerosols), then we could get a nett "once and for all" cooling, and this could help mitigate the effects of continued anthropogenic release of greenhouse gases. This is because black carbon's atmospheric warming effect is larger (by around 0.9 Wm-2 averaged globally) than it's surface cooling effect. I won't address your points about politics/activism, since I think one needs to get the science right before addressing the latter...
131630. Quietman at 23:36 PM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        chris "low frequency, internal radiative forcing amounting to little more than 1 W m-2, assumed to be proportional to a weighted average of the Southern Oscillation and Pacific Decadal Oscillation indices since 1900, produces ocean temperature behavior similar to that observed: warming from 1900 to 1940, then slight cooling through the 1970s, then resumed warming up to the present, as well as 70% of the observed centennial temperature trend. While the proposed mechanism is admittedly speculative, it is also speculative to alternatively assume that low frequency changes in the general circulation associated with ENSO and the PDO do not cause non-feedback TOA radiative budget changes on the order 1 W m-2 - an amount that is less than 1% of the mean radiant energy flows of 235 W m-2 in and out of the Earth’s climate system. Based upon the evidence, it seems likely that the neglect of sources of internal radiative forcing has resulted in diagnosed feedbacks which give the illusion of a climate system that is more sensitive than it really is. This has then led to the development of climate models which produce too much global warming in response to the external radiative forcing caused by anthropogenic greenhouse gas emissions." From Summary and Discussion: Internal Radiative Forcing And The Illusion Of A Sensitive Climate System Roy Spencer University of Alabama at Huntsville April 22, 2008
131631. Quietman at 23:28 PM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        chris "On the other hand, if a secular temperature showing large preindustrial variability is adopted, such as MOBERG05, the climate is found to be very sensitive to solar changes and a significant fraction of the global warming that occurred during last century should be solar induced. If ACRIM satellite composite is adopted the Sun might have further contributed to the recent global warming. From the Conclusion: Phenomenological reconstructions of the solar signature in the Northern Hemisphere surface temperature records since 1600 N. Scafetta1 and B. J. West2
131632. Quietman at 23:24 PM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        chris "Using NCEP reanalysis data that span four and a half solar cycles, we have obtained the spatial pattern over the globe which best separates the solar-max years from the solar-min years, and established that this coherent global pattern is statistically significant using a Monte-Carlo test. The pattern shows a global warming of the Earth’s surface of about 0.2 °K, with larger warming over the polar regions than over the tropics, and larger over continents than over the oceans. It is also established that the global warming of the surface is related to the 11-year solar cycle, in particular to its TSI, at over 95% confidence level." From the Conclusion: Solar-Cycle Warming at the Earth’s Surface and an Observational Determination of Climate Sensitivity. By Ka-Kit Tung and Charles D. Camp
131633. leebert at 10:11 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        Chris, Well, this is a reflection the state of confusion about aerosols in general. The above quotes are from Ramanathan himself. So can we first assume he knows what he's saying? I think the confusion is this: 1. Brown aerosol clouds 2. Aerosol clouds in general (not brown) There's a difference. IOW, a global, generic aerosol negative forcing is correct, and a global, specific brown cloud positive forcing is also correct. Both statements are correct and not mutually exclusive. Ramanathan explains that only WRT to brown clouds that the mid-tropospheric exceeds the surface shading. Check out his testimony before Rep. Henry Waxman's subcommittee last fall. Summary: http://oversight.house.gov/story.asp?ID=1550 The video: http://oversight.house.gov/story.asp?ID=1639 Transcript: http://oversight.house.gov/documents/20071127165326.pdf Prepared statements: http://oversight.house.gov/documents/20071018110734.pdf As for aerosols in general, it's again a question of mix. If the aerosol clouds are white, then they are cooling from albedo & surface shading. If the aerosol clouds are dark they create a net heating (I think this is assuming they rise to the mid-troposphere). So yes you are correct that specifically targeting soot is key, before abating the whitish sulfates. As for the question of activists, the problem is that they are trying to galvanize a constituency into driving policy, notably Al Gore and others. The rhetoric and spin on CO2 overshadows any other discussion, it's been latched onto well beyond measure. There are many reasons for this, not least of which is Kyoto's cap & trade system and the implications (painfully demonstrated in Europe) for a vast expansion of dirigist power. I could go into excruciating detail, but I'll illustrate what's wrong with Kyoto by posing a simple question: Would you go for a cap & trade system where the high emitters pay low emitters to emit more of what the high emitters are already emitting? I wouldn't, I'd think that system was utterly daft. But that is, in fact, what Kyoto not only allows, but is currently implementing via UNFCCC CDM clean coal projects. Although not bad in of itself, since clean coal projects avert increased soot emissions for new power generation, the emission credits are for CO2, not soot. And so firms in developed countries will be penalized and made to pay firms in developing countries to emit yet more! For starters that's a market distorting artifice that'll increase CO2 emissions. And as you may have noted, clean coal also means reduced whitish sulfates output relative to the CO2 emitted. This is just one part of why I say what I do about activists, politicos and policy makers. The entire scheme looks terribly broken and yet we're supposed to subsume all other considerations to CO2 mitigation. This also yet another reason that the chances for a Kyoto-II are becoming increasingly poor. This doesn't bode well, then, for real CO2 reductions against any climate change that poses any real risk, does it? Which brings us to soot.
131634. chris at 06:11 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        leebert, someone seems to be mistaking their apples for the oranges! I'm not saying it isn't me...however I'm sitting here with Ramanathan and Carmichael's review in front of me, and what you say just doesn't seem to accord with what they say... I think the problem is that in the press release quotes that you are reproducing, the speaker/author is talking only about the atmospheric warming effect. However that's only part of the story. The surface effects have to be taken into account too. It's the total effect that is relevant when one considers the contribution to the Earth's surface temperature. If total aerosols (brown clouds/black carbon included) warm the atmosphere by a total of 2.8 W/m2 and cool the surface by a total of -4.4 W/m2 (through reduced solar irradiance at the surface; that's what Ramanathan and Carmichael show in their table 2 - I've reproduced the numbers again below [*****]), then if we're interested in the effect of aerosols on global warming, we need to consider both the atmospheric and surface effect. The total effect is to cool the Earth and to offset the warming contribution of atmospheric greenhouse gasses (nett effect of all atmospheric aerosols is a cooling of -1.4 W/m2). We can quote Ramanathan and Carmichael directly (p 222, column 2): ["At the top of the atmosphere (TOA), the ABC (that is BC + non-BC) forcing of -1.4 Wm-2, which includes a -1 Wm-2 indirect forcing, may have masked as much as 50% (+/- 25%) of the global forcing due to GHGs. The estimated aerosol forcing of -1.4 Wm-2 due to ABCs is within 15% of the aerosol forcing derived in the recent IPCC report as is also consistent with other stidies."] So however one plays this, atmospheric aerosols result in a nett coolong forcing, and partially offset the warming due to enhanced greenhouse gas emissions. Even if we consider only atmospheric brown clouds, the conclusion is similar. That seems to be implicit in Ramanathan and Carmichael's statement: ["The logical deduction from Fig 2a,c,d is that elimination of present day ABCs through emission strategies would intensify surface warming by 0.4 to 2.4 oC." (ABC being atmospheric brown cloud)."] It's only if one were able selectively to remove the black carbon component from brown clouds that one would effect a net cooling. That's what Ramanathan and Carmichael are advocating. As for "activists" who cares? Policymakers and their advisors presumably get their information from the science and not from "activists". Anyway, I don't see why "activists" should or shouldn't mention soot. It would be good to reduce aerosolic pollution, but according to Ramanathan and Carmichael, that would be dangerous in general, since that would exacerbate the problem of greenhouse gas forcing. However the value of Ramanathan and Carmichael's work seems to be in highlighting the possibility for targetted intervention to reduce black carbon. This (if it were possible) would have a significant effect in giving a temporary respite against the growing temperature effects of continued enhancement of the Earth's greenhouse effect, and would have large health benefits in the developing world. So I would have thought everyone, "activists" included, should support Ramanathan's efforts. -------------------------------------- [*****] Forcings extracted from Figure 2 of V Ramanathan and G. Carmichael (2008) Nature Geosciences 1, 221-227. black carbon (BC): atmosphere +2.6 surface -1.7 total +0.9 non BC man-made aerosols: atmosphere +0.4 surface -2.7 total -2.3 all GHG’s (CO2, methane, N20, halons, ozone): atmosphere +1.4 surface +1.6 total +3.0 (W/m2 presumably) CO2: atmosphere +1.0 surface +0.6 total +1.6
131635. leebert at 03:18 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        Chris: I think you're getting hung up on one aspect of the aerosol problem. I think you might be mixing apples & oranges. The heating effect of *brown clouds* is different from all aerosols. IOW, "white cloud" aerosols (sulfates) that lend net albedo to the air are offsetting a great deal of warming that'd happen otherwise. In those regions where whitish aerosols dominate the warming trend at the surface *IS* indeed offset & masked. That's OK. The actual problem is the soot & sulfate mixed brown clouds that in fact are said to enhance warming. So the aerosol sources have to have a strong BC mix in order to lend to a net warming effect. IOW airborne soot, once at altitude, causes vast interzonal and intermeridional forcings throughout SE Asia & the vast Pacific. The problem comes down to knowing what the extent of brown clouds vs. white aerosol clouds are, and the constraints of the white aerosol-dominated clouds are poorly quanitifed at this point in time. Just as with the 1970's, the *REAL* in-cloud effect is less known than the TOA & surface data. And, FWIW, this also goes for rainclouds as well. Why would R&C's paper state: “It is important to emphasize that BC reduction can only help delay and not prevent unprecedented climate change due to CO2 emissions.” The operative word here is "delay." I can understand the reservations but Hansen is not caught up on this, AFAIK. IPPC AR5 us purported to better reflect this. This will help put this into perspective: "The conventional thinking is that brown clouds have masked as much as 50 percent of the global warming by greenhouse gases through the so-called global dimming ... This study reveals that over southern and eastern Asia, the soot particles in the brown clouds are intensifying the atmospheric warming trend caused by greenhouse gases by as much as 50 percent." http://www.scienceagogo.com/news/20070701162100data_trunc_sys.shtml http://scrippsnews.ucsd.edu/Releases/?releaseID=777 "...On a regional level, that amount of heating, or positive radiative forcing, the black carbon causes in the skies over the Pacific is about 40 percent of the forcing that has been attributed to the carbon dioxide increase of the last century.." As for the activists, they will not mention soot.
131636. chris at 03:01 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        Quietman, That makes no sense again. One can't just quote/cite stuff and assume that the paper is actually about what you hope it might be about! You need to read it. So far on this thread you've: (i) asserted that my statement about aerosols is incorrect, because (according to you) "The most recent paper on Solar Dimming / Brightening indicates exactly the opposite of what you indicate." However, on reading the paper that you cite one finds it does no such thing (see my post #19) (ii) asserted that (according to you) "RW Fairbridge's "hypothesis" "has been the best explanation to date for climate change". However, on reading Fairbridge's work one finds it has nothing whatsoever to say about the very marked warming of the last 30-odd years (see my post #28), let alone Arctic sea ice attenuation. (iii) asserted that a eulogy of Fairbridge by some statistician who has never published anything on climate-related, or solar-related science, provides a valid description of a hypothesis on solar contributions to climate. However on reading Mackey's article, one finds that it's a non-scientific and rather disgraceful effort (see my post #28 - numbered points below dotted line). (iv) asserted that a rather straightforward paper by Tung and Camp on the solar cycle and an analysis of the Earth's temperature response to enhanced [CO2] "questions the effect of AGW". However on reading the paper we find that Tung and Camp are in complete agreement with mainstream science on AGW, and calculate a climate sensitivity of 2.3-4.1 oC of warming per doubling of atmospheric [CO2], that is in complete agreement with the rest of the mainstream science (see my post #32). ....and so on... The point is that we can't just say stuff and hope that it might be a valid representation of what people actually discover and publish. One may as well read the work and find out what the data shows and what the authors are trying to say. All science is about skepticism, but skepticism only has meaning in relation to an honest and informed acquaintance with the science. Otherwise it's not skepticism...it's something else like conspiracy theorising...or denialism..or some other thing with a less than honourable connotation...
131637. chris at 02:44 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        leebert, yes and no again! According to Ramanathan and Carmichael (R&C) the nett effect of atmospheric brown clouds (ABC) is cooling. They say: “The logical deduction from Fig 2a,c,d is that elimination of present day ABCs through emission strategies would intensify surface warming by 0.4 to 2.4 oC." (ABC being atmospheric brown cloud)." in other words if you take away the atmospheric brown clouds the Earth gets a bit warmer. So atmospheric brown clouds are partially offsetting the warming that results from anthropogenic increases in greenhouse gasses. After all global warming relates to the Earth's surface (land and ocean). That makes sense because that's where the Earth's biota (us included!) resides. I agree with you that the shading effect in the ABC seems also to cause regional droughts b/c it slows ocean surface evaporation, interrupting regional hydrological cycles. R&C say exactly that in their review (cited in my post #39). But I don't agree with you that the "masking effect" from aerosols is wrong. According to all the published energy balances, the nett effect of atmospheric aerosols, including soot and atmospheric brown clouds is a cooling one. Therefore aerosols “en masse” are rather significantly, partially "offsetting" the effects of manmade greenhouse gas emissions. That's clear from R&C's data in their Table 2 (numbers reproduced in my post #39) and in Hansen's energy balance "budget"): Hansen et. al. (2005): Earth's energy imbalance: Confirmation and implications. Science, 308, 1431-1435 http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf (see Figure 1) and: Hansen, J et al. (2007) Climate simulations for 1880-2003 with GISS modelE. Clim. Dynam., 29, 661-696. http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_3_small.pdf (see Figure 5). On a couple of other points: (i) tipping points: I was just quoting R&C there! But they didn't mention tipping points. They talked about "unprecedented climate change". Of course one should ask "unprecedented" in what sense? It would certainly be unprecedented with respect to the Holocene... (ii) Ramanathan’s funding/politics. It’s perhaps not surprising that there was a bit of a hoohaw about Ramanathan’s INDOEX findings. Political sensibilities were strained. The developing nations, especially India, Pakistan and Indonesia felt that the developing world was being singled out. But Ramanathan isn’t doing badly. He's well funded and his work is considered important and seems to be widely respected. He is director of the Center for Cloud, Chemistry and Climate. He oversaw $25 million of funds for the INDOEX study..his Center seems to be well funded by the National Science Foundation amongst others. Despite the political nonsense the United Nations environmental Programme funded his follow up Atmospheric Brown Cloud Project. He’s presently pursuing corporate sponsorship for Project Surya to do a fairly large scale pilot study in converting cooking practices in rural India to non-soot emitting methods and so on… (iii) So I think you’re wrong about the nature of the politicking. It’s not about trying to pretend that global warming is all about greenhouse gas emissions. Because global warming really IS pretty much about greenhouse gas emissions. However if some reduction of black carbon emissions is effected through the efforts of Ramanathan et al then so much the better. But I don’t think we should turn Ramanathan’s work into a “cause celebre” for “skepticism” or for conspiracy theorising. And as Ramanathan and Carmichael state in their review, we need to be careful in dealing with aerosol emission reduction, since across the board cut backs of aerosols (black carbon, aerosols, atmospheric brown clouds et al) will only exacerbate the problem. (iv) as for your question about sulphates and nitrates? I would say that emissions of sulphurous and nitrous oxides into the atmosphere result rather quickly in their conversion by hydration into sulphurous (esp sulphuric) and nitrous (esp nitric) acids that within a short period are washed out of the atmosphere into the oceans and onto the land surface. They cause acidification.
131638. Quietman at 01:39 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        chris I do read the papers, but I do not read into them, just the facts, not conclusions based upon some faith in a root cause.
131639. leebert at 00:54 AM on 16 June 2008
        A new twist on mid-century cooling
        I know two old navy engineers who pooh-pooh this claim. The induction ports were located far way from the machinery. The ships hulls did not conduct much heat fwd b/c of they didn't use the hulls to cool their systems, esp. w/ huge engine mounts.
131640. leebert at 00:51 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        And again: What do sulfates and nitrates become when they hit the ocean?
131641. leebert at 00:48 AM on 16 June 2008
        Arctic sea ice melt - natural or man-made?
        Chris, The intent of my statement is not incompatible with Ramanathan & Carmichael, however, I will clarify: I'm not objecting to the "shading" effect, like I wrote, we're talking "net," (heating minus shading); I'm objecting to "shading and masking" as in the conventional view that ABCs were masking CO2's effects. This view still gets currency amongst ardent environmentalists and its very hard to get them to even read the news releases and change their minds. The point I'm making is that b/c of inadequate instrumentation on the surface & TOA all the effects of ABC looked like shading. Instruments looking at TOA can't see that it's brown clouds instead of CO2. So the real masking effect was only from field instruments being able to see the real effect at altitude. And even though the *NET* effect from sooty brown clouds is still warming, the shading effect in the ABC also causes regional droughts b/c it slows ocean surface evaporation, interrupting regional hydrological cycles. Here, this might help: http://www.latimes.com/news/printedition/asection/la-na-carbon25mar25,1,6570023.story "...The report concludes that the atmospheric warming effect of black carbon pollution is as much as three to four times the consensus estimate [emphasis mine] released last year in a report by the U.N.-sponsored Intergovernmental Panel on Climate Change." "...The paper concludes that carbon pollution contributes to global warming at a level that is about 60% of carbon dioxide's warming effect.." "...A mass of black carbon in the atmosphere causes about 300,000 times as much instantaneous warming as the same amount of carbon dioxide." The seasonal and regional extent of ABC's is confusing. Another study from Scripps indicated that 40% of the warming over the entire Pacific was from brown cloud, the net, annual effect is still a real warming. “It is important to emphasize that BC reduction can only help delay and not prevent unprecedented climate change due to CO2 emissions.” Yes, that is correct. I don't necessary agree with the overall CO2 science that claims a precipitous tipping point (that's another discussion) but I'm fine with CO2 driving warming. My point is that brown clouds were thought to contribute a net cooling effect b/c of the reflectivity of sulfates. The problem is that the white reflective sulfates, although they do impart albedo at the cloud tops, actually DRIVE near-IR right into the soot particles. At current mix ratios of soot:sulfates the heating effect is very pronounced while also causing droughts, depositing heavy metals, reducing ice albedo, etc. This is enough for Ramanathan to stress that a 20-year window of opportunity can be opened against any real risk that CO2-driven warming might pose. If you think the risk is high then our first order of business is to mitigate soot while we sort out the economic critical path of CO2 mitigation (a crash program will be expensive, the Stern Report's glowing forecasts are quite unlikely, it fails to account for loss of competitiveness & already high gov't taxes in Europe - already the EU is grappling with this and Japan says they can't afford the Kyoto targets). If, OTOH, the risk is moderate, a midpoint from the low end of the forecasted warming, then soot abatement may provide yet more proportional relief, esp. to the boreal environment. Please understand that Ramanathan is a very conventional AGW researcher and he's gone against conventional thinking on the matter & is pushing this pretty hard. I'm afraid the issue is being ignored for political purposes on both sides, the industrial apologists for obvious reasons, the environmental activists b/c their afraid that soot will dilute the message on CO2. This angers me quite a bit & would put=s the lie to a lot of their rhetoric about the polar bears if one doubts the sincerity of the activists. If the risk is high and the polar bears matter, and the odds are poor humanity can curb CO2 against any real risk that GHG pose, then the first order of business would be to mitigate soot. And I know the activist org's know this b/c I've read their news blogs about soot & Arctic albedo (EDF, WWF...). So it's really time the environmental groups stopped playing games name soot in its own right & stop conflating "carbon emissions" as though all are GHGs. It's obvious chicanery and it's undermining their credibility, badly for anyone who is realistic and is concerned about the worst-case scenarios (3 degrC) or the climate moderates who see a moderate case of 1.7 degrC at 580 ppm. The skeptics see it as impugning the whole case against CO2, in my case I see a partial exculpation of CO2 in terms of political reality, that the oft-claimed "masking effect" from aerosols was wrong and used to demonstrate current warming as solely from GHGs. Understand there's a dark political reality behind the entire soot business. Ramanathan's INDOEX work had its funding clipped at the behest of the Indian & CHinese gov't lobbying against his work. It was restored, but not first w/out a fight. Ramanathan mused publicly over the political messiness of climatology science w/in the field. We all should take that point thoughtfully.
131642. chris at 21:30 PM on 15 June 2008
        Arctic sea ice melt - natural or man-made?
        oops! I've started calling Ramanathan "Ramanachan"! Apologies to Dr. Ramanathan..
131643. chris at 21:08 PM on 15 June 2008
        Arctic sea ice melt - natural or man-made?
        Having just read your post #37, according to Ramanachan and Carmichael, this statement of yours is quite incorrect: ["Sorry but the latest studies are showing that soot-ladened aerosol clouds (mid-tropospheric brown clouds) have a net positive forcing, with a Pacific-wide effect alone of 40 percent (that's be 12% of all global warming anomalies right there). And the big surprise: Sulfates are pushing NIR into the soot particles, driving the extra heating. So much for that shading and masking effect, eh?"] That's clearly incompatible with Ramanachan's and Carmichaels statement (p. 226, column 1). “The logical deduction from Fig 2a,c,d is that elimination of present day ABCs through emission strategies would intensify surface warming by 0.4 to 2.4 oC." (ABC being atmospheric brown cloud). Obviously if elimination of atmospheric brown clouds would result in an intensification of surface warming by 0.4 to 2.4 oC, then atmospheric brown clouds must be having a cooling contribution, acting to offset some of the warming due to man-made greenhouse gas enhancement.
131644. chris at 21:00 PM on 15 June 2008
        Arctic sea ice melt - natural or man-made?
        leebert, I only partially agree with your interpretation of Ramanathan and Carmichael’s work. It’s clear that the man-made aerosol burden including black carbon (BC) and atmospheric brown clouds (ABC’s) is providing a large nett negative (cooling) effect on the Earth’s surface temperature which is making quite a large contribution to partially offsetting man-made global warming. The Earth would be warmer still without man-made aerosols and ABC. This is pretty straightforward interpretation in Ramanathan and Carmichael’s (R&C) review. R&C do consider that BC alone has a nett warming contribution; however it’s not obvious that one could selectively eliminate BC in isolation, without removing some of the cooling aerosol contributions too. Here’s what I consider some of the pertinent points form R&C’s review: V. Ramanathan & G. Carmichael (2008) Global and regional climate changes due to black carbon; Nature geoscience 1, 221-227. (1) In Table 2 R&G diagram the contributions from various man-made greenhouse gas (GHG) and man-made aerosols, considering the effect on both the atmosphere or surface: all GHG’s (CO2, methane, N20, halons, ozone): atmosphere +1.4 surface +1.6 total +3.0 (W/m2 presumably) CO2: atmosphere +1.0 surface +0.6 total +1.6 black carbon (BC): atmosphere +2.6 surface -1.7 total +0.9 non BC man-made aerosols: atmosphere +0.4 surface -2.7 total -2.3 (2) Total man-made aerosols including that of BC are strongly nett cooling. One would need to eliminate BC selectively to mitigate part of global warming, and this would effectively be a “one-off” contribution. As R&C say (page 226, column 1): “It is important to emphasize that BC reduction can only help delay and not prevent unprecedented climate change due to CO2 emissions.” (3) The problem is outlined explicitly by R&C (p 226 column 1): “The logical deduction from Fig 2a,c,d is that elimination of present day ABCs through emission strategies would intensify surface warming by 0.4 to 2.4 oC. If only the non-BC aerosols were controlled, it could potentially add 2.3 W/m2 to the TOA forcing and push the system closer to the 3 oC cumulative warming (since 1850s), which is a likely threshold for unprecedented climate change.” (4) however (the good news!): “If on the other hand, the immediate target for control shifts entirely to BC (owing to its health impacts) without a reduction in non-BC aerosols, the elimination of the positive forcing by BC will decrease both the global warming and the retreat of sea and ice glaciers.” (5) So overall elimination of BC would be a good thing, as much as for anything else due to the health benefits – R&C point out that over 400,000 fatalities annually among women and children result from smoke inhalation from indoor cooking, a strong source of atmospheric aerosols including BC. (6) R&C point out that this isn’t straightforward (p 226, column 2): “However changes in BC alone do not tell the entire story as the climate response also depends on how the BC to non-BC aerosol fraction responds to future emissions. As BC is co-emitted with non-BC aerosols, it is necessary to evaluate how various mitigation strategies impact this fraction.” (7) Other points: (i) R&C highlight as do the other groups cited in my post above, that (relevant to the subject of this thread) the BC effect on ice albedo is particularly pronounced in Asia (Himalaya;Tibetan plateau;NE China). (ii) R&C’s analysis support the effect of aerosols and ABC’s in producing widescale global “dimming” (see discussion on p. 223, column 1). The dimming is particularly strong from atmospheric brown clouds. (iii) As far as I can see the overall effect of atmospheric brown clouds for global warming seems to be overall cooling. Regionally ABC cause surface cooling while warming the atmosphere in the winter and spring.
131645. Philippe Chantreau at 18:51 PM on 15 June 2008
        Arctic sea ice melt - natural or man-made?
        Agreed. I did not pretend such thing. Black carbon is nonetheless anthropogenic. If you want to nitpick words and argue that John's post was restricted to natural vs. CO2 only driven AGW, go ahead.
131646. leebert at 16:17 PM on 15 June 2008
        The Mystery of the Vanishing Ocean Heat
        Lee Grable: I've had the same question. Another contemporaneous effect was also Pinatubo's lingering aftermath that aiding in the destruction of ozone in the stratosphere, hence cooling the stratosphere by -0.6 degrC, cooling the upper troposphere but allowing a great deal more UVb into the troposphere (heating surface-level ozone even more).
131647. leebert at 16:06 PM on 15 June 2008
        Misinterpreting a retraction of rising sea level predictions
        Is everyone forgotting the famous quote of Kevin Ternberth from NCAR? http://www.npr.org/templates/story/story.php?storyId=88520025 "...But if the aquatic robots are actually telling the right story, that raises a new question: Where is the extra heat all going? Kevin Trenberth at the National Center for Atmospheric Research says it's probably going back out into space. The Earth has a number of natural thermostats, including clouds, which can either trap heat and turn up the temperature, or reflect sunlight and help cool the planet. That can't be directly measured at the moment, however. "Unfortunately, we don't have adequate tracking of clouds to determine exactly what role they've been playing during this period," Trenberth says." Hello? Can you say, "Heat exchange system?"
131648. leebert at 16:01 PM on 15 June 2008
        Arctic sea ice melt - natural or man-made?
        Chris: > The total effect of soot on global warming > seems to be about nett neutral worldwide > (‘though presumably net positive in regions > with snow). So it seems one would have to > be rather careful to eliminate just those > components of the aerosol burden that gives > rise to positive forcings. Sorry but the latest studies are showing that soot-ladened aerosol clouds (mid-tropospheric brown clouds) have a net positive forcing, with a Pacific-wide effect alone of 40 percent (that's be 12% of all global warming anomalies right there). And the big surprise: Sulfates are pushing NIR into the soot particles, driving the extra heating. So much for that shading and masking effect, eh? Ramanathan & Carmichael (2008) are seeing a global effect that's 60 percent of CO2's (a 37/53 mix). Read their paper, the effect has been masked both from surface temperatures and satellite. Ramanathan's point: We buy a 20 year window of opportunity from mitigating soot. The conventional view that brown clouds had a net masking effect are being shown to be completely wrong and it took Ramanathan's robot planes to find it, not satellites, not ground instruments, not climate models, not educated guesses. He was surprised when the data showed the effect, so he had his team at Scripps double-check the results. There's nothing like real field data taken in situ, now is there? Shall we exculpate CO2 by the same margin that aerosols were used to implicate it (via masking)? Here's a question: What do sulfates and nitrates become when they hit the ocean?
131649. leebert at 15:59 PM on 15 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe Chantreau: Soot and CO2 are not fungible and no one should pretend they are.
131650. leebert at 15:48 PM on 15 June 2008
        Arctic sea ice melt - natural or man-made?
        Philippe Chantreau: Soot and CO2 are not fungible and no one should pretend they are.

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