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ACRIM vs PMOD

Filed under: — rasmus @ 6 May 2009 - (Italian)

Two recent papers (Lockwood & Fröhlich, 2008 – ‘LF08′; Scafetta & Willson, 2009 – ‘SW09′) compare the analysis of total solar irradiance (TSI) and the way the TSI measurements are combined to form a long series consisting of data from several satellite missions. The two papers come to completely opposite conclusions regarding the long term trend. So which one (if either) is right, then? And does it really matter?

This issue is a very familiar one when it comes to long-time series from satellite data. Each individual satellite only lasts a few years, and so a 30 year time series needs to be stitched together from a series of satellites. Each of those instruments might have a different calibration, and may have non-climatic drifts associated with instrument degradation, or orbital effects. Thus it can often be the case that there is a degree of ambiguity in putting together the series. This issue is at least part of the difference between the RSS and UAH tropospheric temperature trends, and in the CERES/ERBE analyses discussed recently.

The differences between PMOD and ACRIM have already been discussed by the SkepticalScientist and Tamino, so here is just an update in the light of the two recent papers. The important issue here is the so-called ‘ACRIM-gap’, the time between the ACRIM-I instrument ceased and when the ACRIM-II observations started (mid-1989 to late 1991), and how the data from these two instruments are combined using other overlapping observations. Note that the ‘ACRIM’ name for the Willson et al time-series simply implies that it was put together by some people on the ACRIM science team, not that they use different satellite data.

The focus on these papers is what the ‘ACRIM gap’ implies for TSI levels during the solar minimum at solar cycles 21 and 22. Whereas PMOD suggests that the TSI levels during these minima are similar, ACRIM suggests that the TSI level is higher during the minimum of cycle 22. SW08 even claim that there has been a positive ‘minima trend‘.

LF08 conclude that the PMOD is more realistic, since the change in the TSI levels during the solar minima, suggested by ACRIM, is inconsistent with the known relationship between TSI and galactic cosmic rays (GCR). It is well-known that the GCR flux is generally low when the level of solar activity is high, because the solar magnetic fields are more extensive and these shield the solar system against GCR (charged particles). However the two effects don’t always go in lockstep, so this is suggestive rather than conclusive.

It is also clear from the instrumental data that the TSI tends to increase with the solar activity level – at least over the solar cycle. LF08 argue that if the ACRIM ‘minimum trend’ is correct, this will mean that past reconstruction of TSI based on e.g. sunspots are incorrect, and a lot of studies on the past climate variations would be wrong. This does not mean that the ACRIM data are useless, but that there are uncertainties regarding the relationship TSI-levels, solar activity for different time scales.

I found insufficient detailed description in SW09 of the methodology used in their analysis to be able to judge the real merit of their work. The paper provides a link to auxiliary material that does not work. However, the figures in the paper don’t really convince when I don’t know how they were made.

Furthermore, I found the SW09 a bit confusing, as it gives the impression that the PMOD composite relies on ERBS/ERBE data during the ACRIM-gap (“The PMOD team uses the sparse ERBS/ERBE data base to ‘bridge’ the ACRIM gap, conforming the higher cadence Nimbus 7/ERB to it by making adjustments due to …”). However the information in LF08 says PMOD used HF from Nimbus 7 (ERB).

The PMOD analysis involves an adjustment to correct for a glitch in the ERB data (orientation changes and/or switching off), but SW09 claims – without providing convincing arguments – that this correction cannot be justified.

The ACRIM composite does not account for a jump in the ‘ACRIM-gap’ due to instrumental changes. SW09 show a comparison between different analyses and Krivova et al. (2007) modeled TSI, but later acknowledge that the latter modeled TSI disagrees with measurements on decadal time scales. Furthermore, when the TSI is not adjusted over the ‘ACRIM-gap’, there is the apparent inconsistency between TSI and GCR.

Update: My conclusion is that the LF08 paper is far more convincing than the SW09 in terms of whether the TSI data should be adjusted over the ‘ACRIM-gap’. But the this is probably not the final word on the matter.


96 Responses to “ACRIM vs PMOD”

  1. 51
    Benjamin G says:

    I think it’s very useful to note the coincidence of the solar minimum with the current dip in global temperatures. The IPCC says we can expect a such a dip, and we’re seeing it.

    This approach completely disarms those skeptics who are busy promoting various short term temperature (or ocean heat) plots as being destructive to the IPCC’s claims.

    The claim that we should be seeing monotonic heating of the upper 700m of ocean, as Pielke and Watts have been pushing, is completely thwarted when you simply note the solar minimum and say, no, we actually expect a cooling trend of the globe (including upper ocean) during this time frame, because the drop in solar input has briefly become a larger forcing than the steady accumulation of GHGs.

    Bam, you’ve taken away at least two skeptic talking points in one blow: 1) the claim that we ‘should’ be seeing monotonic heating, 2) the claim that ‘climate scientists say it’s all about human GHGs, but what about natural variation seen before man’.

  2. 52
    lgl says:

    37# Tamino,

    “so the *climate forcing* is actually a mere 0.7 * 1.3 / 4 = 0.2275 W/m^2″

    So suddenly the GH-effect is gone?
    Why isn’t this additional solar input amplified by GHGs by around 2.5 like the rest of it? Guessing *climate forcing* is energy to the surface, or?

  3. 53
    Mark says:

    Igl, #52. IIRC, the CO2 forcing is pre-feedback too. So leaving it out is appropriate.

  4. 54
    lgl says:

    53# Mark,

    And? 0.5 W/m2 radiative imbalance was mentioned up there, which must be to the surface after the immediate feedbacks (CO2 and H20) to make sense. So all you need to get this 0.5 W to the surface is 0.1% increase in solar, right?

  5. 55

    Jim Cross writes:

    I am NOT a believer in “it’s all the sun” theory, but I do believe that solar influence has been underestimated.

    I regressed temperature anomaly on ln CO2, dust veil index, and four different measures of solar activity (the latter one at at time to avoid multicolinearity): TSI, sunspot number, years since minimum, and years since maximum. The sample size was 1880-2008 (N = 129). None of the solar measures contributed significantly. The closest was sunspot number at t = 1.4. Ln CO2, however, accounted for 76% of the variance, and DVI for 2%.

  6. 56
    Mark says:

    re 54. If you recall that feedbacks were left out in the CO2 calculation too, then leaving it out with solar changes too is appropriate.

    If you do not, then no.

    Why ask anything else?

  7. 57
    Shirley says:

    On the topic of the ocean surface not warming… I don’t know if there have been any studies on this, but knowing what little about physics that I do… it seems to me that if polar ice is melting and disbursing into the sea, a drop in ocean surface temps is logical, regardless of other atmospheric factors. Melt water is fresh, not saline, therefore more buoyant, and large bodies of water take much longer to catch up to ambie nt levels than many other earthy objects (think black body radiation, what gets hotter faster when placed near a fire: a metal rod or a glass of water?). This is one of the especially complicated areas of climate science, in that oceans can be a driver and a symptom of numerous climate factors. That said, I think science on the whole is making great steps in understanding and combining the myriad factors in understanding climate. We’re likely in for a few more surprises, but it really doesn’t look like TSI is one of them.

  8. 58
    Mark says:

    Shirley, you can’t be serious.

    (Apologies to both you and Police Squad! (in color)).

  9. 59
    lgl says:

    Mark,
    I haven’t said anything about CO2 calculations. Judging by ocean heat papers 0.5 W/m2 is a significant amount of energy when over several years, for instance Lyman et al 2006, so solar seems underestimated. But of course +10 W down and +9.5 up is still 0.5 imbalance and there are lags so it’s probably to complicated for me…

  10. 60
    Mark says:

    re 59, you didn’t gainsay it either.

    Do you think you’d better check up on your figures a little better to see where they are derived from?

  11. 61
    lgl says:

    Mark,
    My figures are fine. 2.5 * 0.7 * 1.3 / 4 = 0.57 W/m^2 for 0,1% TSI increase at equilibrium. (the 10 and 9.5 was just an example)
    Your CO2 figures are 3.7 W pre-feedback and around 3*3.7=11 after I assume, for a CO2 doubling, which should be at least 3 W with the current concentration minus the negative forcings and the outgoing emission maybe ending up at 0.5 W imbalance, I don’t know.
    And when there is balance, like the last 5 years, you simply adjust the negative forcing a little and doomsday is still right around the corner, unbeatable.

  12. 62
    Alf Jones says:

    #42 Barton,
    Reading between the lines … Whitehouse says the there is a 0.1% variation in the solar irradiance between minima and maxima over the 11 year cycle. So 0.1% of 1360Wm-2 = 1.3Wm-2.
    I think the variation over a solar cycle is nearer 0.08% so even his 1.3Wm-2 is probably too big.

    Alf

  13. 63
    Mark says:

    Igl, #61, so why are you complaining about feedbacks when you’re only using examples? If you’re not using the real values, any feedback will make the false ones you’re using even more wrong.

  14. 64
    Hank Roberts says:

    lgl writes:

    > the outgoing emission maybe ending up at 0.5 W imbalance, I
    > don’t know. And when there is balance, like the last 5 years ….

    What? It seems you’re assuming what you claim you’re proving.
    You claim to know the radiation budget for the planet from what source?
    Did you get Triana launched, and keep the data to yourself?

    Please publish.

  15. 65
    lgl says:

    All I’m saying is that papers indicate you would need 0.5 W/m2 to explain the rise in OHC, and that is not more than the surface gains from a 0.1% increase in solar.

  16. 66
    Mark says:

    And I think what Hank is saying Igl(#65) is that your reading is incorrect and wishes you to publish how you attained that value.

  17. 67
    lgl says:

    Well I know how to read but do not understand all of it. From Lyman et al 2006 and other places 0.5 W/m2*1year=1E22 J for the upper 700 meters, and the GHE is a positive feedback loop with gain 0.6 giving an amplification of 2.5. What I’m missing is the time constant. How long will it take to reach say 75% of equilibrium SST after a forcing step up?

  18. 68
    sn says:

    The sun spot activity determines the number of cosmic rays striking the Earth’s atmosphere and as a result how many particles are ionized. This may have a large effect on the formation of clouds and as a result the climate. Read the papers by Svensmark to learn more about this interesting model. If it is correct, CO2 is irrelevant, at least as the main driver of the climate.

    [Response: “If” is the operative word. See here, here and most recently, here and here. – gavin]

  19. 69
    Ray Ladbury says:

    sn, why not learn some real physics before veering off into the speculative. I’d be very interested to learn how your cosmic rays cool the stratosphere for instance. Good Lord!

  20. 70
    Hank Roberts says:

    lgl, “where there is balance” — where are you finding a balance between incoming and outgoing radiation? Or are you just saying you believe there must be one because you have a five year trend that proves … anything?

  21. 71
    Chris Colose says:

    It is not even correct to say that *if* cosmic rays have a significant climate influence, it follows that CO2 is close to irrelevant. Why we must always settle for those “either-or” games is beyond me. Given the uncertainty surrounding climate sensitivity and the total forcing provided by anthropogenic aerosol input, there’s still some reasonable wiggle room for forcings which have not yet been quantified or may have been overlooked, it just doesn’t look like they can be very important.

    Because there has been no secular trend in cosmic rays for many decades, it does not appear they can be be very important in the global warming signal. Certainly no reasonable policy decisions should abandon radiative physics and stuff which has been around for over a century and can be confirmed in the lab or by models quite well, just for this hypothesis which hasn’t evolved into anything convincing. The actual physical mechanisms (even if there was a trend in cosmic rays) is IMO quite unsatisfactory as a scientific theory. I’ve still yet to hear a feasible explanation as to why cosmic rays shouldn’t impact high clouds as much as low clouds.

  22. 72
    Mark says:

    re: Chris.

    Yup. Weird.

    Denialists say “The IPCC must be wrong because they only consider the CO2 to be effective in climate change. Well what about…?”

    And then when they’re saying why it isn’t CO2, they say that it must be “something else” without saying why CO2 isn’t having an effect any more.

  23. 73

    Chris (71),

    You’re absolutely right pointing out that even *if* cosmic rays have a significant effect on climate, it doesn’t negate the radiative effects of CO2 and everything we know about the climate system, something that some folks tend to forget in their desire to jump to certain conclusions.

    There is however a feasible explanation as to why cosmic rays shouldn’t impact high clouds as much as low clouds, put forward by Yu (http://www.albany.edu/~yfq/papers/Yu_CR_CN_Cloud_Climate_JGR02.pdf). It may not be the final word on it, since his modelled nucleation rates tend to be more sensitive to ion concentration than other models, but it may be feasible nevertheless.

    Here’s what I wrote about it in the aerosol nucleation & climate post (http://www.realclimate.org/index.php/archives/2009/04/aerosol-effects-and-climate-part-ii-the-role-of-nucleation-and-cosmic-rays):

    Based on his model for ion induced nucleation, Yu found that at low altitude, the number of particles produced is most sensitive to changes in cosmic ray intensity. At first sight, this may be a surprising result in light of the increasing cosmic ray intensity with increasing altitude. The reason is that high aloft, the limiting factor for particle formation is the availability of sulfuric acid rather than ions. Above a certain GCR intensity, increasing ionization further could even lead to a decrease in ion induced nucleation, because the lifetime of ion clusters is reduced (due to increased recombination of positive and negative ions). In contrast, at low altitude particle formation may be limited by the ionization rate (under certain circumstances), and an increase in ionization leads to an increase in nucleation.

  24. 74
  25. 75
    chris colose says:

    Thanks Bart.

    There are a couple other papers I wanted to point out, if they haven’t been already throughout the comments. One is a recent paper in GRL by Pierce and Adams on cosmic rays (http://www.agu.org/pubs/crossref/2009/2009GL037946.shtml). They conclude that hypothesized changes in Cloud Condensation Nuclei from cosmic ray fluctuations over the solar cycle are far too small to explain changes in cloud-cover extent, and so changes in the cosmic ray flux during the 20th century have likely had little impact on the present-day climate shift. They suggest further research into other mechanisms aside from the popular “ion-aerosol clear-air” hypothesis.

    The other paper is http://www.agu.org/journals/pip/gl/2009GL037519-pip.pdf (PDF file, no abstract available yet since it is still in press) where the authors assume that the solar irradiance changes are entirely caused by the evolution of the solar surface magnetic fields and use solar surface magnetic field distributions and compare with the populat TSI composites, PMOD, ACRIM, and IRMB. The best agreement is achieved with the PMOD composite, and any long-term trend in solar irradiance cannot be due to the surface magnetic field

    [Response: My reading of the Wenzler et al paper is that if solar irradiance changes are caused by (or correlated to) magnetic variability, then PMOD is the best fit. If irradiance changes are not not solely driven by magnetic changes, or if there are additional factors that perhaps do not impact the magnetics, then it is still unclear, though your last line still holds. This is important for longer term reconstructions too because both 10Be and 14C rely on the magnetic field-to-irradiance connection to work. – gavin]

  26. 76
    Hank Roberts says:

    LGL, you’re claiming a “balance” of incoming and outgoing heat.
    You point to a PDF as your source for claiming this.
    That’s a comparison of sea levels, not of radiation balance.
    What’s your real source?

  27. 77
    Hank Roberts says:

    By the way, lgl, the first page of that PDF says their study raises the question:
    “… could the recent rate of sea level rise (since 2003) be explained by fresh water input to the ocean …”?

    Here’s an answer: http://www.agu.org/pubs/crossref/2009/2009GL037525.shtml
    McPhee, M. G., A. Proshutinsky, J. H. Morison, M. Steele, and M. B. Alkire (2009), Rapid change in freshwater content of the Arctic Ocean, Geophys. Res. Lett., 36, L10602, doi:10.1029/2009GL037525.

  28. 78

    Re #68 where sn says:

    “The sun spot activity determines the number of cosmic rays striking the Earth’s atmosphere and as a result how many particles are ionized. … If it is correct, CO2 is irrelevant, at least as the main driver of the climate.”

    CO2 is not the main driver of the climate. It is well known that water vapour has more effect as a greenhouse gas, and that changes in cloud cover have an even greater effect on weather and climate. The main driver is solar radiation.

    It may well be that changes in cosmic radiation can influence cloud cover, but that does not alter the fact that if we increase the carbon dioxide content of the atmosphere too much we will cause a catastrophe. We do not know if cosmic rays affect the clouds, nor do we know how much CO2 is too much!

  29. 79

    I don’t know but this might be of interest for some:
    http://www.ltu.se/tkg/avd/Geovetenskap/d24226

    Nordic Palaeomagnetic Workshop

  30. 80

    Chris (75), I discussed the paper by Pierce and Adams in the same post as mentioned above.

  31. 81

    Alastair, when sn wrote in 68:

    The sun spot activity determines the number of cosmic rays striking the Earth’s atmosphere and as a result how many particles are ionized. … If it is correct, CO2 is irrelevant, at least as the main driver of the climate.

    … the first thing I would remind him of is that we understand the physics behind warming due to CO2 as result of its increasing the opacity of the atmosphere to infrared radiation. If he doubts that carbon dioxide has this effect upon infrared radiation, he might want to check out the following:

    Aqua/AIRS Global Carbon Dioxide
    http://svs.gsfc.nasa.gov/vis/a000000/a003400/a003440/index.html

    The dark orange off the east and west coasts of the United States? That is carbon dioxide at roughly 8 km altitude — infrared at 15 μm in wavelength has been absorbed and emitted at lower levels of the atmosphere, but this is where it gets emitted for the last time before escaping to space — and as such the brightness temperature at that wavelength reflects the cooler temperature at that altitude – and signifies the trapping of thermal energy in the layers below it.

    Thus if he is trying to come up with an alternative explanation for the era of modern global warming (from 1975 to present), he can’t simply give an alternative explanation, but now must provide an explanation as to why a mechanism that is well-understood didn’t give rise to this warming, e.g., suggest some cooling mechanism that cancelled out the warming due to carbon dioxide trapping thermal radiation.
    *
    Alastair McDonald wrote in 78:

    It may well be that changes in cosmic radiation can influence cloud cover, but that does not alter the fact that if we increase the carbon dioxide content of the atmosphere too much we will cause a catastrophe. We do not know if cosmic rays affect the clouds, …

    Well, we do know that there isn’t much of any correlation between cosmic rays (which show quasi-periodic behavior but not trend) and global warming.

    Please see for example:

    Uncooperative cosmic rays
    http://cce.890m.com/solar-cosmic-rays/#_ednref27

    However, I notice that Gavin has provided him with some additional reading material. (See the inline response to 68 above.)
    *
    Alastair McDonald wrote in 78:

    … nor do we know how much CO2 is too much!

    Here is something that might interest you, Alastair:

    Tropical ‘Runaway Greenhouse’ Provides Insight into Venus
    http://www.nasa.gov/centers/ames/news/releases/2002/02_60AR.html

  32. 82
    David B. Benson says:

    Alastair McDonald (78) — My somehwat informed opinion is that anything above 290 ppm CO2e is too much in the long run.

    [reCAPTCHA appears to agree, entoning "devilry way".]

  33. 83
    Hank Roberts says:

    Thanks Timothy for the pointer to that NASA Release: 02-60AR “TROPICAL ‘RUNAWAY GREENHOUSE’ …” — I knew I’d seen that somewhere.

    Alastair, photographing the upper atmosphere in the bands where CO2 emits would seem convincing, wouldn’t it? I recall this coming up as a possible test of your idead a few years ago, before that satellite went up.

  34. 84
    lgl says:

    Hank, 76#

    It shows thermosteric level is almost unchanged which means OHC has not changed which means radiative balance.

  35. 85

    Hank Roberts wrote in 83:

    Thanks Timothy for the pointer to that NASA Release: 02-60AR “Tropical ‘Runaway Greenhouse’ …” — I knew I’d seen that somewhere.

    No problem.

    Incidentally, here is a paper by the same individuals dated 2004:

    The Runaway Greenhouse Effect on Earth and Other Planets Maura Rabbette, Peter Pilewskie, Christopher McKay, and Richard Young
    http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040171753_2004168321.pdf

    Actually I believe what they are referring to is the same phenomena known as the “Super Greenhouse Effect”:

    Satellite studies (8–10) have found that for clear skies and SSTs above 298 K, the spatial variation of Ga with SST, dGa/d(SST), exceeds the rate of increase of sea surface emission, ds(SST)4/d(SST) = 4σ(SST)3. For a tropical SST of 300 K, 4σ(SST)3 ~ 6.1 W m-2 K-1. This effect, termed the “super greenhouse effect” (11), occurs in both hemispheres during all seasons. It is also observed for interannual variations of Ga with SST during the El Nino in the tropical Pacific (12). Observations in the tropical Atlantic ocean (11) show that the clear sky downwelling infrared flux incident on the surface (Fa-) also increases faster than the surface emission with increasing SST. The net result is further warming of the surface, which in turn induces additional heating of the atmosphere column above.

    Direct radiometric observations of the water vapor greenhouse effect over the equatorial Pacific Ocean
    F.P.J. Valero, W.D. Collins, P. Pilewskie, A. Bucholtz, and P.J. Flatau
    Science, 274(5307), 1773-1776, 21 March 1997

    I would have to look it up, but also believe that this was another one of those phenomena predicted by climatologists prior to its actual observation.

  36. 86
    Hank Roberts says:

    lgl, and you believe the first claim based on that short time span how?
    And the “which means” steps in your logical sequence — how?
    Are you getting whata you’re posting from somewhere?

    Start with the first “it shows” claim you make — how long a time span is needed for that particular data set to detect a significant likelihood that there is really a trend?

    Or are you just looking at the picture and ignoring what the researchers say in the text of the article it’s from?

  37. 87
    Ray Ladbury says:

    To say there is radiative balance based on 5 years of data is a rather bold conclusion, I would say. Remember that the oceans are a huge heat reservoir.

  38. 88

    lgl wrote in 84:

    Hank, 76#

    It shows thermosteric level is almost unchanged which means OHC has not changed which means radiative balance.

    Actually another thought comes to mind.

    When in 74 you refer us to:

    http://etienne.berthier.free.fr/download/Cazenave_et_al_GPC_2009.pdf

    … it shows the sea level continuing to rise – in fact it even appears to be rising more quickly than only a few years ago, although I myself can’t say whether this is statistically significant. However, according to the text, the rising sea level mostly as the result of melt water from land — which is increasing the mass of the ocean. This afterall is what the Grace satellite measurements are all about that are mentioned in the article.

    This being the case, you have ice cold melt water from Greenland and Antarctica (for example) entering the ocean raising the sea level. But what else will ice cold melt water do? Cool things off — I believe, essentially bringing the temperature of the ocean down from what it would otherwise be, in all likelihood cancelling out what would be a warming trend.

    However, here is something else to keep in mind. When you point to the fact that the increase in volume is not due to heat content but additional mass, ice cold water will itself have a smaller volume than the surrounding water, and thus will decrease the volume to mass ratio, or alternatively increase the mass to volume ratio — otherwise known as the “density.” Likewise, when it cools the surrounding water it will increase the density of that water and decrease the volume that it takes up. And you are basing your argument off of the fact that while the volume is expanding, this expansion is not due to thermal expansion.

    Ice water lowering the temperature of sea water from what it would otherwise be and slowing the rate at which the ocean warms is not what I would consider to be evidence of “radiative balance.”

    Thank you for the link to the article.

  39. 89
    Hank Roberts says:

    > ice cold fresh water

    Yep. See the article on that, linked in the post
    at 24 May 2009 at 4:09 PM

  40. 90

    Hank Roberts wrote in 89:

    Yep. See the article on that, linked in the post at 24 May 2009 at 4:09 PM

    77. Understood.

    Actually I think that my whole response was a bit more wordy than it needed to be — but I was in a hurry. I believe that pretty much all that needed to be said is that if sea level is rising and therefore volume is increasing (and it would appear to be increasing more rapidly than before) but this is due to increased mass rather than thermal expansion, then that additional water has to be coming from somewhere. About the only place that large volumes of water can come from (particularly when absolute humidity is rising) is from melting ice.

    Sea ice. Greenland’s ice. Antarctica’s ice. Glaciers. And each of these, it would appear, will tend to lower the temperature of the ocean, or alternatively, reduce the rate at which the ocean warms, thereby diminishing thermal expansion. So if the volume is increasing but the rate of expansion due to temperature has flattened, then obviously there is still a radiation imbalance in the ocean itself, but it is being masked by the ice-cold melt water.

    With that said I must admit that fresh water will typically be less dense than salt water — and consequently my bringing in water density was inessential to the argument and flawed. I left an opening — but having corrected myself that opening is now closed.

  41. 91
    Nigel Williams says:

    Timothy! All god stuff!

    You are correct in my view with the observation that the melting ice and the warming oceans are all acting as global heat-sinks which are masking the forcing of GHG on surface temperatures. This has the potential to become a major up-tick in the global surface temperature trend because the more the ice sheets fracture and expose their surface area the faster they will melt and the more they suppress air temperature rise as they do so. But as they approach end of melt then we loose that heat sink and the forcing returns full on.

    This gets a bit angrier too when we consider:

    June 2008.
    Global warming twenty years later: tipping points near: James Hansen
    http://www.columbia.edu/~jeh1/2008/twentyyearslater_20080623.pdf

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

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

    and in May 2009:
    “The new projections, published this month in the american meteorological society’s journal of climate, indicate a median probability of surface warming of 5.2 degrees celsius by 2100, with a 90% probability range of 3.5 to 7.4 degrees. this can be compared to a median projected increase in the 2003 study of just 2.4 degrees. ”

    http://globalchange.mit.edu/news/news-item.php?id=76

    so: in May 2009 MIT scientists running a sophisticated and well-respected climate model tell us that there is a median probability that the earth will be 5.2 degrees celsius warmer by 2100.

    and: in 2008 Hansen stated that even 2 degrees celsius of global warming ‘…is a recipe for global disaster…’, and …if emissions follow a business-as-usual scenario, sea level rise of at least two meters is likely this century. … … no stable shoreline would be reestablished in any time frame that humanity can conceive.”

    Thus: Given our practical inability to return CO2 levels below 350 ppm, and the new predictions of global temperatures by 2100, global sea level rise is both inevitable and unstoppable by mankind.

    Bother.

  42. 92
    jh says:

    This paper concludes by offering a testable prediction with regard to climate change.

    http://adsabs.harvard.edu/abs/2003ESASP.535..317D

    jh

  43. 93
    lgl says:

    Yes of course. If you mix a bucket of water containing 10 units of energy with another containing 5 units of energy then the total will be around 10. 10+5=10 yeah that’s very close.

  44. 94

    lgl wrote in 93:

    Yes of course. If you mix a bucket of water containing 10 units of energy with another containing 5 units of energy then the total will be around 10. 10+5=10 yeah that’s very close.

    You have been arguing that since (presumably) there has been no thermal expansion of the ocean that the ocean is in radiation balance.

    You wrote in 84:

    It shows thermosteric level is almost unchanged which means OHC has not changed which means radiative balance.

    … where It referred to figure 5 of the paper:

    http://etienne.berthier.free.fr/download/Cazenave_et_al_GPC_2009.pdf

    Now you speak of units of energy and/or heat.

    However, heat per se doesn’t cause thermal expansion. If the ocean consisted of four liters of water at 5°C and you added one liter of water at 5°C there would be no thermal expansion, but only expansion due to mass. Increased temperature causes thermal expansion.
    *
    Since the expansion of the ocean from increased mass (~80% of total expansion) has been due to ice melt where the ice melt is colder than the ocean it is pouring into, we know that if the ocean were in radiation balance there should have been thermal contraction. So even if the thermal expansion of the ocean were neither positive nor negative but exactly zero we already know that the ocean is not in a state of radiation balance.

    However, not all of the expansion of the ocean can be accounted for by increased mass. Therefore some of the expansion has been due to net thermal expansion and net warming. (Roughly 20%, it would appear judging from the paper you referred us to.)
    *
    Now to get at the figure from which you argued that there has been no thermal expansion to the ocean you had to skip over the abstract, pass over three pages of main text and pass several other figures. You were looking at Figure 5 which shows little or no thermal expansion.

    However the other figures showed expansion due to increased mass and increased mass as the result of ice melt. Figure 1 shows expansion due to increasing mass. Figure 2 shows expansion due to increasing mass as the result of ice sheet contribution.

    Figure 3A shows expansion due to increasing mass as the result of Greenland’s ice sheet loss. Figure 3B shows expansion due to increasing mass as the result of Antarctica’s ice sheet loss. Figure 4 shows altimetry-based sea level rise and the smaller contribution of land-ice melt to this sea level rise.

    Even if you entirely avoided the abstract and the main text, you would have had to avoid five figures to avoid realizing that the ocean was expanding, and you would have had to avoid four figures to avoid realizing that the expansion from increased mass was due to ice melt — where ice melt would have the effect of lowering the temperature of the ocean and reducing thermal expansion.

    It would be very difficult to attribute your “mistake” to either ignorance or stupidity. At this point I can only conclude that it is pointless to argue with you.

  45. 95
    Hank Roberts says:

    jh, what testable prediction do you see in that paper?
    Could you find any subsequent research citing that paper and saying something about testing a prediction from it?

  46. 96
    lgl says:

    Timothy,
    Ok, so I’m 0.004 W/m2 wrong, the power needed to heat 2 mm of seawater from 0 to 15 C in one year. (heat capacity 4,2 kJ/kg/K)


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