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Ocean Cooling. Not.

Filed under: — gavin @ 18 April 2007 - (Português) (Français)

A lot has been made of a paper (Lyman et al, 2006) that appeared last year that claimed that the oceans had, contrary to expectation, cooled over the period 2003-2005. At the time, we (correctly) pointed out that this result was going to be hard to reconcile with continued increases in sea level rise (driven in large part by thermal expansion effects), and that there may still be issues with way that the new ARGO floats were being incorporated into the ocean measurement network. Now it seems as if there is a problem in the data and in the latest analysis, the cooling has disappeared.

Ocean heat content changes are potentially a great way to evaluate climate model results that suggest that the planet is currently significantly out of equilibrium (i.e. it is absorbing more energy than it is emitting). However, the ocean is a very big place and the historical measurement networks are plagued with sampling issues in space and time. Large scale, long term compilations globally (such as by Levitus et al, 2001; Willis et al, 2004) and regionally (i.e. North Atlantic) have indicated that the oceans have warmed in recent decades at pretty much the rate the models expected.

Since 2000, though, ARGO – which is a network of floats that move up and down in the ocean and follow the currents – has offered the potential to dramatically increase the sampling density in the ocean and provide, pretty much for the first time, continuous, well spaced data from the least visited, but important parts of the world (such as the Southern Oceans). Data on ocean heat content from these floats had been therefore eagerly anticipated.

Initial ARGO measurements were incorporated into the Willis et al, 2004 analysis, but as the ARGO data started to dominate the data sources from around 2003, Lyman et al reported that the ocean seemed to be cooling. These were only short term changes, and while few would confuse one or two anomalous years with a long term trend, they were a little surprising, even if they didn’t change the long term picture very much.

The news this week though is that all of that ‘cooling’ was actually due to combination of a faulty pressure reading on a subset of the floats and a switch between differently-biased observing systems (Update: slight change in wording to better reflect the paper). The pressure error meant that the temperatures were being associated with a point higher in the ocean column than they should have been, and this (given that the ocean cools with depth) introduced a spurious cooling trend when compared to earlier data. This error may be fixable in some cases, but for the time being the suspect data has simply been removed from the analysis. The new results don’t show any cooling at all.

Are we done then? Unfortunately no. Because of the paucity of measurements, assessments of ocean heat content need to use a wide variety of sensors, each with their own quirks and problems. Combined with switches in data sources over the years, there is a significant potential for non-climatic trends to creep in. In particular, the eXpendable BathyThermographs (XBTs – sensors that are essentially just thrown off the side of the ship) have a known problem in that they didn’t fall as quickly as they were originally assumed to. This gives a warm bias (see this summary from Ingleby and Palmer or the paper by Gouretski and Koltermann) , particularly in data from the 1970s before corrections were fully implemented. We are still going to have to wait for the ‘definitive’ ocean heat content numbers, however, it is important to note that all analyses give long term increases in ocean heat content – particularly in the 1990s – whether they include the good ARGO data or exclude the XBTs or not).

There are a number of wider lessons here:

  • New papers need to stand the test of time before they are uncritically accepted.
  • The ARGO float data are available in near real-time, and while that is very useful, any such data stream is always preliminary.
  • The actual problem with these data was completely unknowable when Lyman et al wrote their paper. This is in fact very common given the number of steps required to create global data sets. Whether it’s an adjustment of the orbit of a satellite, a mis-calibration of a sensor, an unrecorded shift in station location, a corruption of the data logger or a human error, these problems often only get fixed after a lot of work.
  • Anomalous results are often the driver of fundamental shifts in scientific thinking. However, most anomalous results end up being resolved much more straightforwardly (as in the case, or the MSU satellite issue a couple of years back).

Scientists working in a field build up a certain intuition about how things ‘work’. This intuition can come from a gut instinct, deep theoretical understanding, robust model results, long experience with observations etc. New results that fall outside of that framework often have a tough time getting accepted, but if they are solid and get subsequent support they will generally be incorporated. But that intuition is also very good at detecting results that just don’t fit. When that happens, scientists spend a lot of time thinking about what might be wrong – with the data, the analysis, the model or the interpretation. It generally pays to withhold judgment until that process is finished.


282 Responses to “Ocean Cooling. Not.”

  1. 201
    Ray Ladbury says:

    William, the problem with a GCR driven mechanism is that it has to be operative at the time of the effect it tries to explain–and GCR fluxes simply are not changing–based on either satellite observations or neutron monitoring. Moreover, I would characterize the latter half of the 19th century to be a time of exceptionally high solar activity, rather than the present being low. The 1854 Carrington flare was the biggest on record–generating auroral displays as far south as Havana. The proton fluxes for the solar cycles of that era were significantly higher than the present–but also higher than past solar cycles.
    I really don’t trust estimates of GCR fluxes prior to our ability to measure neutron fluxes and especially GCRs themselves. And I especially don’t trust such estimates for energys lower than 1 GeV. Hell, solar protons have energies up to about 300 MeV, and at fluences higher than GCR over a solar cycle. I’m afraid the whole GCR theory is a house of cards–just one last straw for skeptics to grasp. I just don’t understand why people believe in such a mish-mash when there is a perfectly credible theory based on well known physics with mountains of evidence in favor.

  2. 202
    Ray Ladbury says:

    Ellis (#200)–they can and do look at trapped gasses in ice as soon as forms (about 10 years, I think). They also correlate well with other measures. Ice physics is pretty well understood. Also, what would you expect to be the effect if the gas content did correlate with time? Would you expect the warming to line up with CO2 content as we see it, or would you expect no correlation? Systematic errors generally do not give rise to order.

  3. 203
    tamino says:

    Re: #201 (Ray Ladbury)

    Do you have a link to GCR data, both space-based and ground-based measurements?

  4. 204
    Steve Reynolds says:

    Re196: Steve Bloom> Per Gavin the ISCCP team think these papers are correct (that the long-term cloud trends are more or less flat).

    That is not what I see at your link. The conclusion seems to be that there is currently no reliable data on long term cloud trends.

    From Evan et al.:
    “Our results suggest that in its current form, the ISCCP data may not be appropriate for certain long-term global studies, especially those focused on trends.”

  5. 205
    Darrel says:

    The issue of cosmic rays affecting climate really comes down to whether there is a trend in cosmic rays or not, and people don’t seem to agree on that. Nir Shaviv shows cosmic ray data from ion chambers (ie high energy GCR) on his website http://www.sciencebits.com/CO2orSolar (Fig 6. note that the graph has an inverted y-scale), claiming that these high energy rays are more relevant for atmospheric ionization than low energy GCR’s as measured by neutron counters. The trend is different for different energies, for which he doesn’t have an explanation. Which measurements should we trust more, and why?

    [Response: There is a perfectly sensible explanation. The figure Shaviv uses to demonstrate a trend is a splice between two individual stations with different means (Cheltenham/Fredricksburg and Yakutsk) - neither of which have a trend - but as you go from one to the other (C/F in the early years, Y later on), you get an apparent shift. No single detector of any GCR related quantity shows a trend over this period. - gavin]

  6. 206
    Ray Ladbury says:

    Hi Tamino,
    I looked at the space based data (GOES and other satellites) myself as part of a study we were doing. It fluctuates of course, but I didn’t see any trend in the mean.
    The terrestrial stuff is here:

    http://ulysses.sr.unh.edu/NeutronMonitor/Misc/neutron2.html

    More recently, Clive Dyer et al. have been doing research using neutron monitors on airliners.
    All of this data says to me that there is no clear trend–certainly not one sufficient to see the level of warming we are seeing.

    A caveat about the GOES data–it just looks at particle fluxes–so you have to confine yourself to times of solar quiet–either solar min or between events during solar max.

  7. 207
    tamino says:

    Re: #206

    Thanks for the link and the info! I don’t doubt the absence of a trend (although I’m sure to run the numbers anyway), I just have a blog reader who keeps asking.

  8. 208
    Paul M says:

    Scientists have a love for discovering, and sometimes will go to great lengths to keep on doing what they love, which is scientific inquiry and discovery. They need funding, so they develop a relationship with the government similar to a trophy wife who marries for money. This relationship works out well, at least it used to. Unfortunately scientists are at the whims of the funding source, and this is the paradigm that has to change. That is why science and politics mix. The new science has to discover for the cause without the money having a say.

  9. 209
    Ray Ladbury says:

    Paul M. (#207) Like most scientists, I really hate writing grant proposals. However, I view it as a necessary evil because I have questions that I need to answer if I’m to be able to do my job (making satellites fly in a radiation environment). I make my living as a physicist–that means somebody has to pay my salary–in my case about 330 million somebodies (thanks, y’all, by the way). Ultimately, I am answerable to them for the quality of my work, and they or their representatives have to decide whether the work I do is worth the investment. I am, however, hardly a trophy wife–not nearly ornamental enough for one thing. My salary does not buy my complicity in producing bad science that supports policy. As a scientist, part of my job description is: “Tell the truth.” That is true no matter who signs my paycheck, and if my employer does not understand that, then they might want to think again about employing a scientist. Despite the tendency of the current administration to try to control the flow of information, scientists have insisted on speaking out–not because they necessarily oppose the administration, but because it is their job.
    In the past, I have worked for industry, and the tendency of scientists to bluntly state the truth was alarming to customers. The solution in business was to create layers of management between the scientist and the customer to sugar coat the bad news. Now that I am a customer of these same businesses, I insist on talking to the scientists.

  10. 210
    Steve Bloom says:

    Re #294: Possibly I was imprecise. The papers throw into question what had been thought by some to be a long-term trend, while the ISCCP team believe that there is no significant trend (i.e., there won’t be one after the correction is made).

  11. 211
    Richard Tol says:

    I was surprised by your edit of Roger Pielke’s comment. I am also surprised that I am not allowed to express my surprise. Is this RealClimate or RealCensorship?

  12. 212
    tamino says:

    Re: #209 (Ray Ladbury)

    I have worked for industry, and the tendency of scientists to bluntly state the truth was alarming to customers.

    Boy howdy, I hear that! I used to do mathematical analysis for astrophysicists, and they wanted the straight story good or bad. I’m now in industry, and although the pay is a lot better, it surprises me how often management will wince when I try to give it to ‘em straight.

    And they don’t let me near customers.

  13. 213
    William Astley says:

    Hi Ray, in reply to your comment:

    “William, the problem with a GCR driven mechanism is that it has to be operative at the time of the effect it tries to explain–and GCR fluxes simply are not changing–based on either satellite observations or neutron monitoring.”

    It is hypothesized that planetary cloud cover can be reduced without a drop in GCR. The high speed solar winds which occurred at the end of cycle 21 and 22 it is hypothesized energized the global electric circuit (see Tinsley and Yu’s paper in my comment above for a discussion of the mechanism). It is hyphothesized the increase in the global electric circuit current, through the process of electroscavenging removes cloud forming ions. The effect is greatest over the oceans. Palle’s paper references Tinsley and Yu’s electroscavenging mechanism and states he believes his data supports, that planetary cloud cover has reduced over the oceans due to that mechanism.

    Due to the sun’s hypothesized affect on the global electric circuit, the sun’s overall affect on cloud cover and climate is not a simple linear relationship of number of sunspots. I can see why other researchers who only looked at number of sunspots could not find a simple relationship between sunspot number and climate. Cycle length is also important as is the large planet’s cyclic gravitation change of solar position, which appears to affect the radiative zone to convection zone boundary. Based on this most recent solar change.

    In reply to your second comment that solar activity was high around 1854.

    Ken McCracken’s data and analysis (see attached below) compared current solar activity and GCR to that at the end of the 1900 century (not mid 19th century) At the end of 1900 century solar activity has low and the climate was coincidently cold.

    K.G. McCracken’s “Long Term Trends in the Intensity of GCR and Frequency of occurrence of Solar Particle Events.”

    http://hesperia.gsfc.nasa.gov/sspvse/oral/Ken_McCracken/wintergreen1.pdf

    Your comment that there was a strong solar flare in 1854 does not necessarily mean solar activity was strong during that period. (This is more an aside, I have been reviewing what papers I can find concerning the solar cycle mechanism, what causes a Maunder minimum, and Super solar flares.)

    The following is Hathaway’s comment from the attached link, which notes that super flares can and have occurred at solar minimums. (The attached link notes that the sun was at a minimum February 2006. It is again at minimum April 2007. As to what to expect for solar cycle 24, there is not agreement. Both high and low predictions. Cycle 23 was predicted to end sometime between December 2006 and October 2007.)

    “But not absolutely quiet,” adds Hathaway. “During solar minimum we can have occasional sunspots and solar flares.” Indeed there was at least one monster spot and one X-class solar flare (the most powerful kind) during each of the last three minima in 1976, 1986 and 1996.

    http://science.nasa.gov/headlines/y2006/06mar_solarminimum.htm

  14. 214
    Rod B. says:

    Ray, Tamino, et al: I was (in part) on the marketing and product management side in industry (big ticket computer systems and telecommunications). I found customers once in a while demanded direct interface with the scientists/engineers/techies; I was all in favor. Every now and then the techie would perceive a non-problem as an upcoming disaster and I’d have to patch that up, but a small price to pay for the credibility gained. If you’re trying to sell a $50 milllion system or network you can forget it if 1) you have poor credibility with the customer, or 2) you leave some strongly-felt technical questions go unanswered. And if the scientist describes a really dirty truth (hopefully before a customer meet…) you’d damn-well better know it long before the day after the system install.

  15. 215
    Ray Ladbury says:

    William, I guess we need to define what we mean by solar activity–I’m looking at solar particle event frequencies, which correlate with sunspot activity. By my definition, the solar cycles in the latter half of the 19th century were quite active compared to today. And the Carrington event was about 4x larger than any other SPE we know of. What is your definition?
    The solar cycle is actually 22 years, but we really only see a sort of absolute value reflected in solar activity. Solar max is roughly 7 years long, while solar min is roughly 4 years long. GCR oscillates on the same 11 year cycle, but is max during solar min and vice versa. What is more, if you’re saying that the fin de siecle solar activity was low, how does that square with the fact that climate has been warming since the end of the 18th century? Indeed, the basic mechanisms of greenhouse warming were developed to explain this trend.
    Finally, there is zero evidence that gcr fluxes are changing significantly. They fluctuate–hell there are only 6 particles per cm2/sec, they’re bound to fluctuate. But mean fluxes are not changing. And unlike CO2, if fluxes aren’t changing your driver is gone–there’s no persistence.

  16. 216
    Jack says:

    Re: #186. Diatoms are made out of silica; coccolithophorids and foraminifera are made out of CaCO3.

  17. 217
    William Astley says:

    Hi Ray,

    Ak is my parameter of choice, to measure the solar affect on planetary temperature. Ak is a measure of the sun’s affect on the geomagnetic field. (The are a number of solar changes that affect Ak. i.e. In addition to energy of particle such as strength of the solar large scale magnetic field) There is an interesting paper that shows there is close correlation of 20th planetary temperature changes and changes in Ak.

    Some believe there is evidence for an increase in the solar large scale magnetic field in the 20th century. (See below.) Do dispute that evidence or conclusion?

    Evolution of the Sun’s large-scale magnetic field since the Maunder minimum

    http://www.nature.com/nature/journal/v408/n6811/abs/408445a0.html

    “A part of the Sun’s magnetic field reaches out from the surface into interplanetary space, and it was recently discovered3 that the average strength of this interplanetary field has doubled in the past 100 years. There has hitherto been no clear explanation for this doubling. Here we present a model describing the long-term evolution of the Sun’s large-scale magnetic field, which reproduces the doubling of the interplanetary field. The model indicates that there is a direct connection between the length of the sunspot cycle and the secular variations.”

  18. 218
    Ray Ladbury says:

    When I see the word “correlation” in an abstract, alarm bells go off in my head. Solanki’s a good researcher, but he is sometimes off in the weeds. If heliomagnetic field has doubled, that would affect primarily the low-energy end of the GCR spectrum–and those particles probably won’t contribute to cloud formation at low altitudes in any case. What is more, there does not seem to be ANY indication that GCR fluxes are changing over the last, say 60 years, and warming has definitely accelerated during this period. That’s one of the problems with this work–if you look at a blow-up of warming and solar activity in recent years, there’s zero correlation. What is more, the reliance on correlations with zero understanding of the physics (why heliomagneitic field correlated with sunspot, how and whether GCR facilitate cloud formation, why the cloud formation should be at low rather than high altitude, and so on) makes the theory rather murky. On the other hand, there is a perfectly well worked out theory with well understood physics that does an excellent job of explaining the observed trends. The anthropogenic ghg theory works. It ain’t broke. There’s no indication that it has any difficulty explaining what we see. And we understand the physics. Pray tell, why would I swap a working theory for a not-quite-half-baked outline?

  19. 219
    Hank Roberts says:

    Jack corrects me quite properly. Diatoms use silica, and it’s the organisms with calcite and aragonite shells that are at risk. They all show up in the sediment cores, and the variation’s part of the info there.

  20. 220
    Hank Roberts says:

    Speaking of which, here’s an interesting thesis on the oceanic shelled plankton, a good general read with some interesting bits:
    http://www.nioz.nl/public/annual_report/2005/brummer.pdf

  21. 221
    William Astley says:

    Ray, the 20th century temperature increase has not be a linear change. (See the paper below.) There is a hypothesized mechanism and evidence that the forcing function for that mechanism was been active during the 20th century. There is correlation of solar changes and planetary temperature. The question is what is the appropriate weighting of the two forcing functions, GHG and solar?

    I have looked at the abrupt temperature changes in the past. I do not understand how ocean current changes could cause abrupt simultaneous wide spread planetary cooling including tropical oceans or what could cause semiperiodic stoppage of ocean currents. As to insolation changes driving the glacial cycle, besides specific periods when there is not even correlation, I support David’s comment that it is fact that the insolation forcing is balanced if both hemispheres are considered or both seasons are considered. As the planet is 70% covered with water and the thermal capacity of the ocean is 1000 times that of the atmosphere, it seems reasonable the oceans would smooth symmetrical insolation changes.

    As the solar cycle seems to be about to abruptly slow down, we will all have a change to observe what the correct bifurcation of forcing functions is. Have you had a chance to look at recent solar data?

    http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf

    CMEs, however, are not the only source of high speed solar wind. Early in the 20th century it was noticed that many geomagnetic storms occur without any visible solar disturbance. Such storms tend to recur every 27 days – the period of solar rotation, therefore they originate from long-living regions on the Sun which come back into geoeffective position rotation after rotation. Only when X-rays telescopes were flown above the atmosphere, it was found out that are large regions of open magnetic field geometry, and sources of high speed solar wind. They are now known as Coronal Holes (CHs) because, due to their lower density and temperature compared to the surrounding corona, they look darker in X-rays.

    In Figure 6 the long-term variations in global temperature are compared to the long-term variations in geomagnetic activity as expressed by the ak-index (Nevanlinna and Kataja 2003). The correlation between the two quantities is 0.85 with p<0.01 for the whole period studied. It could therefore be concluded that both the decreasing correlation between sunspot number and geomagnetic activity, and the deviation of the global temperature long-term trend from solar activity as expressed by sunspot index are due to the increased number of high-speed streams of solar wind on the declining phase and in the minimum of sunspot cycle in the last decades.

  22. 222

    [[Ak is my parameter of choice, to measure the solar affect on planetary temperature.]]

    The problem here is in your first phrase above. I don’t think you’re doing it deliberately, but it’s possible you’re looking through all the solar indices to find one that correlates well with temperature, then seeking to figure out a physical explanation for it later. That’s not good science. Look at enough time series and you can nearly always find one that seems to match another series of interest, but that’s not a theory, that’s just the fallacy of the enumeration of favorable circumstances.

  23. 223
    Dan Fregeau says:

    #167 (Steve Bloom) – Eldrett paper

    I think that it is an interesting finding that should raise some eyebrows given that current models cannot duplicate the scenario unless you have much lower CO2 levels. It is hard for me to conclude that it does not raise any serious questions about current assumptions regarding expected climate during very-high CO2 periods given that the paper states:

    “Recent palaeoclimate model experiments generate substantial ice sheets in the Northern Hemisphere for the Eocene only in runs where carbon dioxide levels are lower (approaching the pre-anthropogenic level)”

    Furthermore, the degree to which this represents small or large glaciers vs. giant ice-sheets is still unknown, but the paper suggests large ice-sheets for at least a part of this period. Paraphrasing the paper’s conclusion:

    “By inference, our data strengthen the case for … more extensive ice-sheets at the glacial maximum of the Eocene â�� Oligocene transition”

    Given that much of the support for the Greenhouse Theory, including quantifying/bracketing sensitivity, comes from the long-term correlation between glaciation = low CO2 levels, and warm periods = high CO2 levels, as measured during the Phanerozoic (Royer 2004; Berner 2004), this paper seems to be of some significance to the ongoing discussion by pointing to the fact that paleoclimate is still not fully understood (unlike what appears to be the much higher certainty claimed for our modern climate).

    [Response: You were on the right track citing Royer and Berner, but you're out of date. The most recent work by this group shows that the Phanerozoic record of CO2 in fact independently supports a sensitivity to greenhouse gas forcing that is eerily close that estimated by most other methods (just under 3C for 2xCO2). The article requires subscription, but there is a news release summarizing the study here. - mike]

  24. 224
    Dan Fregeau says:

    #179 (Pat Cassen) Svensmark and Solar Wind
    Of course not, although there might be local current variations, but the density/intensity of the solar wind is greater at perihelion than at aphelion. Per Svensmark, greater solar wind would cause more GCR shielding, reducing nucleation and cloud cover, hence increasing atmospheric transparence. Therefore, the season of perihelion (more solar wind = less GCR) would have fewer clouds and therefore be warmer and converserly the season of aphelion (less wind = more GCR) would have more clouds and therefore be cooler. This should vary according to precession, with coincidence of perihelion-solstice representing a maximum seasonal effect of solar wind/cloud cover relationship. Of course, this will also be modulated by eccentricity such that when eccentricity is high, the seasonal solar wind/cloud cover will vary more, but when eccentricity is low as it is today, the seasonal solar wind/cloud cover differential will be less.

    So putting this in the modern context, because we are approaching coincidence of perihelion-solstice at low eccentricity, the solar wind would be greatest in southern hemisphere summers and northern hemisphere winters. This would maximize summer heat absorbtion in the southern oceans, as well as inhibit winter glaciation with increased melting in the northern hemisphere, and this seems to be occuring today.

  25. 225
    Dan Fregeau says:

    #166 (Ike Solem) – Timescales
    Let’s be clearer on this. I do not dispute that burning fossil fuels, large-scale deforestation, various types of agriculture, industrial cement processing, etc. are all increasing atmospheric GHG concentration. I also do not dispute that the resultant GHG increases are warming the earth and will have an impact of the biogeochemistry of the earth, and that therefore we should take appropriate steps to manage our emissions and environmental practices. I think we are all on the same page on these points, i.e. the earth is a great place to live and we should take care of it as best we can.

    But the degree to which GHGs will be warming the earth by comparison to perihelion-solstice approach in the next century or thousand years, is what I am trying to debate. While it is true that changes in annual global insolation, i.e. due to solar variation, by themselves cannot account for significant climate change, it is equally true that large-scale changes in regional insolation due to orbital geometry can cause large regional temperature differences, witness the fact that we have annual seasons, as one obvious example.

    The notion that we might also have much longer term “seasons” at the millenial time scale (to use your term) should not be haphazardly discounted, particularly given the reality of the paleoclimatic record, which suggests just that. Furthermore, the fact that we are approaching a longer-term “seasonal” zone, i.e. perihelion-solstice coincidence in the southern hemisphere during a long low-eccentricity interglacial, warrants a better understanding of the scope of natural vs. anthropogenic forcing within that zone, particularly given the fact that we have evidence that natural forcing during prior MIS-11 interglacial analogue may have been significant based on reported sea levels as well as Northern European fossils of warmer species during that period. Do you disagree?

  26. 226
    Eric (skeptic) says:

    Re #222, Barton, it’s also possible to look through anthropogenic factors to pick out a set that correlate with temperature although fitting in the physics is generally easier than with the sun’s effects. William, although there is a natural component to the current warming (and CO2) that must be combined with the human component to get a complete theory.

  27. 227
    Dan Fregeau says:

    #189 and #197 (Blair Dowden)

    Please clarify why you think that heat gain and heat loss are in balance. This seems like a critical assumption and I would like to understand your reasoning here.

    Unlike the northern landmasses, the southern oceans have greater heat capacity, and the entire system is well insulated by the atmosphere. Heat transport via oceanic currents is very slow, so it’s not clear to me how higher heat gain during southern hemisphere summers would be offset in the winter.

  28. 228
    Dan Fregeau says:

    #223 Response by Mike

    Re. Nature Royer/Berner – yes I read that report and the sensitivity is at least or greater than 1.5 as stated in the abstract (with 2.8 being the best fit currently), but that still does not explain glaciation in Greenland which is what my point was really about.

    If there was no extensive glaciation at very high CO2 ppm levels, then that would support the belief that increased CO2 is responsible for massive deglaciation via global greenhouse warming. But if there was still large glaciation with very high CO2 ppm levels, then it’s not that simple, per the Science paper I referenced. Do you disagree?

  29. 229
    Hank Roberts says:

    Dan, aren’t you forgetting albedo there? Ice builds up extensively; albedo goes up; while albedo is high, CO2 can increase and stay quite high. It’s a time series of events you have to follow, not a snapshot.

  30. 230
    Ray Ladbury says:

    Dan, do the math. The solar wind will decrease as the inverse square of the distance from the Sun–just as insolation does. Thus, both effects are <1%. The effect of the 11 year solar cycle is much larger–roughly a factor of 3x in gcr fluxes.

  31. 231
    Dan Fregeau says:

    #218 (Ray Ladbury) The theory ain’t broke

    “On the other hand, there is a perfectly well worked out theory with well understood physics that does an excellent job of explaining the observed trends. The anthropogenic ghg theory works. It ain’t broke. There’s no indication that it has any difficulty explaining what we see. And we understand the physics. Pray tell, why would I swap a working theory for a not-quite-half-baked outline?”

    I thought that the goal of science was to understand what is really happening, i.e. the reality of Real Climate. Svensmark is not advocating “swapping” anything that I am aware of, nor should his findings be exclusive of any other climate changing factor in any way. GHG is certainly a component of the truth, perhaps even the most important component of today’s climate, as most believe.

    But what if there were other critical components that also merit scientific research – astronomical cycles, cosmic ray flux variability, heliospheric currents, geophysical feedbacks, etc. Are you suggesting that it would be better science to discount researching those altogether, or to attack them by restricting their funding? Please clarify as I don’t really understand your position here.

  32. 232
    Ray Ladbury says:

    William, It doesn’t matter how good your correlation is if GCR fluxes aren’t changing, and they aren’t. BTW, for a “correlation” type study such as this, a correlation of 0.85 is not that great, mainly because the search for a correlation is not constrained by an underlying physical model that tells you what parameters to look at. Thus if p=.01 for an 85% correlation, if you look at 100 different variables, you’re sure to find such a correlation with one of them. In effect, what you are doing is epidemiology here. And while epidemiology comes up with interesting results from time to time, it has a pretty poor track record as a scientific discipline.
    And here’s the thing that I don’t understand. There is LOTS of evidence for a forcing of ~3 degrees C per doubling of CO2–tons of evidence. So it seems to me that if you find that a cosmogenic mechanism is important, you have to explain why a) all of that other evidence needs to be ignored; or b)why the situation is different now and the same forcings no longer apply. The whole system has to stand or fall as a whole, and it is difficult for me to believe that we do as good a job at modeling a complicated system like climate with models making reasonable physical assumption purely by chance. Climate science just doesn’t resemble a nascent field where there are no physical models and the inquiry is dominated by exploration. It is a mature science. So, maybe GCR do contribute to climate–it’s a stretch to believe that a driver with only 5 particles per cm^2/sec is significant, but I’ll suspend disbelief. To think that this mechanism–completely ignored in current models–contributes more significantly than the known sources absolutely strains credulity.

  33. 233
    Dan Fregeau says:

    #230 (Ray Ladbury) Do the math

    But if this seemingly small effect is cumulative because the southern ocean’s larger heat capacity is acting as a long-term heat reservoir, what might that add up to?

    I thought that the Greenhouse Therory was likewise caused by a small cumulative effect, is it not? Why is it that the GHG effect is not discounted on the same ground as this one?

  34. 234
    Dan Fregeau says:

    #229 (Hank Roberts)

    Since the period prior was clearly one of very high CO2, then why did the ice build-up in the first place since the earth should have been plunged in a global greenhouse state, correct?

    Some of the thinking I have seen on this proposes that something caused the CO2 to drop dramatically – can you suggest the mechanism by which this would occur? My understanding is that this is not understood, but maybe I am wrong. Can you send me references that explain the mechanism for that transition.

  35. 235
    Ray Ladbury says:

    Dan, the sun is and will remain the most important energy source for climate. Fortunately, its input is easily measured. After the sun, the greenhouse effect is #2, with H2O being the greatest contributor. That too, is relatively easy to model. CO2 is #2 on the list of ghgs. Other sources are way down the list. If there were other critical components that contributed at the same order as the above components, the climate models would not come even close to getting the answer right. There are mountains of evidence that support the current model, and it’s not as if there are lots of adjustable parameters that we could twiddle to support new physics–the models are pretty well constrained by data; their main uncertainties have to do with the human response. So, it’s not just a matter of coming up with a couple of new phenomena to consider. You’d have to come up with a whole new model.

    Should these other sources be investigated? Certainly. And if they hit the jackpot, they pay off big. However, the probability of a payoff is small, so in the mean time, we have a working theory, physically reasonable and well substantiated by evidence. We should use that to guide policy.

  36. 236
    Ray Ladbury says:

    #232. Well, except that the oceans would then lose the heat to the atmosphere via evaporation and via radiation at aphelion. There’s no mechanism for transfering energy to the deep ocean where it would be somewhat insulated. The thing is that you are not changing the amount of energy incident on Earth. Nor have you proposed a mechanism for Earth to hold onto more of the incident radiation. The greenhouse effect serves as an insulating blanket, preventing some IR from radiation back into space, so it’s holding onto more of the incident energy. As to the climate and past warming and cooling epochs, no climate scientist has ever said that CO2 is only or even the most important factor in climate. If solar radiation decreased due to Milankovitch cycles, then Earth would cool because ultimately all energy in Earth’s climate comes from the sun.
    As to how CO2 could suddenly decrease–biogenic processes are the only process I know of with the right timescale, unless maybe there were a rapid overturning of cold ocean water for which CO2 solubility is high. Anybody else?

  37. 237

    I thought that the goal of science was to understand what is really happening

    Another stunning statement from the audience.

    According to our current perspective of reality, nature and the universe, we can NEVER understand what is really happening, we can only model it to higher and higher precision. What is the exact value of pi? That’s easy, it’s pi. Rather than blindly adopting a denialist position, you need to do a little research about the history of science, and of science itself. Skepticism of science must be backed up with evidence, just as science itself must.

    All things are in principle knowable, but the act of investigating reality itself changes the landscape, just as our pursuit of science on Earth has changed the landscape of Earth. That’s what we are trying to come to grips with here, and you’re flailing about mucking up what we think we know, is not producing any new knowledge. If you think you can break a paradigm, you’re going to have to try a lot harder than simply posting your reservations on an internet blog. I would encourage you to try, but I must point out that it appears that you haven’t even fulfilled the basic educational prerequisites for intelligent discussion yet.

    Search engines are your friend. Use them.

  38. 238
    Pat Cassen says:

    Re 224, 230: The flux of galactic cosmic rays is modulated over the entire extent of the heliosphere, so the difference in GCR flux from perihelion to aphelion is probably more like 1%/(size of heliosphere in AU), i.e., zilch.

  39. 239
    Paul M says:

    Science is about transistors, masers, lasers, and moore’s law. Because of Sputnik, the Government got involved and we got some healthy competition going and fufilled Kennedy’s promise of sending a man to the moon (although he did not live to see it). But the NASA glory days are over, and now medicine is the new darling. But just as the science landscape is changing, so is the global landscape, in every facet including economic. In the near future the prospective scientist will be heading to China to do research, maybe at MIT’s new facility there. Scientists love to discover, and they married the Government to do exactly this. In the new landscape scientists need to do research with no restrictions from the money source, ultimately to save the human race. In the WWII years, German scientists could have stayed where they were and could have developed nuclear weapons living a comfortable life. But they made a stand on principle—develop the bomb, but do it before the evil society does it, in a free environment. Climate scientists must make these decisions in an arena that is equally important as the nuclear one. Politics must step aside and pure science needs an environment that will solve this crisis or we cannot call ourselves civilized.

  40. 240

    [[Some of the thinking I have seen on this proposes that something caused the CO2 to drop dramatically - can you suggest the mechanism by which this would occur? My understanding is that this is not understood, but maybe I am wrong. Can you send me references that explain the mechanism for that transition.]]

    On a long enough time scale, CO2 is reduced by weathering and deposition in sediments. For more information, try here:

    http://www.geosc.psu.edu/Courses/Geosc320/walker.pdf

  41. 241
    Ray Ladbury says:

    Paul, I disagree with your post on several grounds
    First, practical. Science costs money. Where will this money come from if government does not fund science. Business? Not likely–they’ve cut R&D to the bone.
    Second, NASA is hardly dead–there’s a Hubble Servicing Mission planned, a mission to Europa, the James Webb Space Telescope. They are looking at the sky from microwaves to gamma ray bursts and finding new stuff all the time. Hell, just yesterday, we had the announcement of the first Earth-like planet.
    Third, yes many of the scientists who built the bomb for the US were German emigres. They were also Jewish. Had they stayed in Germany, they would have died in the camps. Their stand was personal as well as principled.
    Third, the answer is not for scientists to refuse the coin of the realm. There is the old story of the Texas Legislator who said his ethis code was, “If you can’t take their money, drink their liquor and screw their women and still vote against them, you’re in the wrong place.” Now that’s ethics of a sort, but the lesson applies. Paying my salary buys my efforts, not my honor. Part of the job description of the scientist is to find the truth and to tell the truth. At one point politicians realized that despite the occasional inconvenience of having to face unpleasant truths, ultimately society benefited from supporting science. Problem is that until the people are educated enough to understand that, they won’t be able to teach it to their leaders.

  42. 242
    Hank Roberts says:

    Barton’s answered you on CO2 reduction; keyword search would be “biogeochemical cycling” and you’ll find it well studied.

    In the (geologically) shorter term, you can also watch an example of evolution in action as life evolved forms (in less than a hundred thousand years) that could make use of the surplus CO2. That’s the “bio-” part of the cycling.

    I recall one good article on that, let’s see if I can find a copy.
    It had a typo corrected later, the length of the hottest time was wrong, you can look that up.

    http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11001051&itool=pubmed_AbstractPlus

    You may find a readable copy online(if it’s not showing up later, ask your librarian)
    http://72.14.253.104/search?q=cache:YJ3oQ9MTf7AJ:courses.washington.edu/ocean450/Discussion_Topics_Papers/Schmitz_et_al.pdf+%22Plankton+Cooled+a+Greenhouse%25&hl=en&ct=clnk&cd=4&gl=us

  43. 243
    Hank Roberts says:

    Dan, don’t miss Mike’s response inline in your #223.
    Note right hand list, of postings “…With Inline Responses”

  44. 244
    Jim Cross says:

    RE #161 “As with our annual seasons, the long-term changes in insolation are most pronounced at the polar regions and higher altitudes in both hemispheres, and this reaches a maximum at the intersection of perihelion and solstices, roughly every 10,000 years, a zone that we are currently approaching.”

    Any comment on this?

    http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F1520-0442(2001)014%3C2369%3AAODTSF%3E2.0.CO%3B2

    To quote from it:

    “When the ENSO oscillation is in transition between the two regimes, and is weak and moderately regular, the system can lock to the period of the forcing (1 yr). This gives rise to the abrupt behavior shown in Fig. 1. This behavior recurs on an approximately 11-kyr timescale, when perihelion occurs either during boreal winter or summer.”

    And again:

    “The paleoclimate record shows that the pacing of abrupt climate change could be linked to the solar forcing. Heinrich (1988) found that episodes of major ice
    rafting in the North Atlantic recur on an 11-kyr timescale over the last glacial at times of boreal winter and summer insolation maxima…”

  45. 245
    William Astley says:

    Ray,

    Solar changes can affect cloud cover without a change in GCR through the mechanism of electroscavenging, where changes to the global electric current, caused by high speed solar winds, removes cloud forming ions. The negates your argument that as GCR was not trended continually down in the later portion of the 20th century, that a change in cloud cover could not be responsible for a significant portion of the 20th century warming.

    The satellite data and earthshine data (Palle 2003 & 2004) supports at a 99.5% confidence level that planetary clouds track GCR changes 1973 to 1993. 1993 to 2003 planetary clouds continue to track GCR except for a persistent reduction in cloud cover. The reduction in cloud cover is believed to be due to the electroscavenging process. Palle in his earthshine paper estimated the forcing due to the reduction in planetary cloud to be 7.5 W/m2 (for the period in question) as compared to the estimate 2.5 W/m2 for combined GHG.

    See copy of Palle’s satellite paper. (See figure 2. Note low level clouds are reduced by minus 0.065% per year, starting in about 1993.)

    http://solar.njit.edu/preprints/palle1264.pdf

    The high speed solar winds in solar cycle 21 and 22 were caused by coronal holes that moved towards the solar equator. For cycle 23 the cycle time has increased which allowed the coronal holes to dissipate. As I said, it appears the solar radiative to convection zone boundary were it theorized that the magnetic ropes are created, that rise to the solar surface and then create sunspots, has been disturbed by the large planets which move the sun cyclically. It seems reasonable based on paleodata/solar models that this could be a precursor to a Maunder type minimum. Regardless, the solar cycle will return to normal levels which will enable the two forcing function solar GCR/electroscavenging vs GHG to be separated.

    What are your thoughts on Palle�s paper and the solar changes?

  46. 246
    Blair Dowden says:

    Re #227 – Dan Fregeau: One more try at the effect of orbital cycles. My claim about the balance in heat gain/loss between winter and summer did not take the inverse square law into account. In fact, at the present time the southern hemisphere receives 6.7% more radiation averaged over the year than the northern hemisphere.

    As you say, because the southern hemisphere is mostly ocean, which has a lower albedo, this would push global average temperature to be highest at this point in the orbital cycle (southern summer at perihelion). But the paleoclimate data shows the opposite. Maybe someone can explain this.

    But either way, this is an irrelevant influence on global warming in the 20th century. The annual change amounts to 6.7% / 5000 years (one quarter precession cycle), or 0.0013% per year. The key point is time scale – what is significant over a period of thousands of years is much less significant over a century.

  47. 247
    Richard Tol says:

    Wow, I am allowed to speak on RealClimate!

    Here is what Roger Pielke wrote:

    You are simply incorrect when you assert: “Emanuel (2005) shows that the warming SSTs are behind the increased TC intensity in the Atlantic. No impartial reading of that paper could come to any other conclusion.”

    Here is what Emanuel actually says:

    “Tropical cyclones do not respond directly to SST, however, and the appropriate measure of their thermodynamic environment is the potential intensity, which depends not only on surface temperature but on the whole temperature profile of the troposphere. . . The above discussion suggests that only part of the observed increase in tropical cyclone power dissipation is directly due to increased SSTs; the rest can only be explained by changes in other factors known to influence hurricane intensity, such as vertical wind shear.”

    Misrepresenting Emanuel is bad enough, but for a site that often underscores the importance of consensus, your favoring of one single study (on a thread about not favoring one single study) when consensus perspectives exist (WMO, IPCC) does a disservice to your readers.

    You can compare this to #51 to see the edits of RC.

    Roger posted this sorry story at Prometheus, and not everybody is impressed:
    http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/001180a_little_testy_at_re.html

    [Response: As long as one doesn't violate our comment policy, one is always free to post here. This comment would usually be screened out because it is deeply off topic. We've screened it in to make a point. There is now a full article on the topic in question and a useful discussion thread below. In the context of this fuller discussion, it should be crystal clear why Roger's comments were silly and off the mark (and were indeed edited). By the way, comments that are snarky are typically not admitted, so if you want to post here in the future, watch the snark. - mike]

  48. 248
    Ray Ladbury says:

    Re 245. I’ll take a stab at that (from a nonexpert). My understanding of the cooler summers South vs. North is the predominance of water in the south–that is water evaporates, taking with it A LOT of latent heat, which then circulates over the globe. There’s a lot of thermal mass in them there oceans. The land masses in the North heat up more. So, experts, did I come even close, or am I full of dingo’s kidneys?

  49. 249
    Dan Fregeau says:

    #238 (Pat Cassen) GCR flux is zilch

    Can you please clarify your statement further.

    The GCR flux in the earth’s atmosphere, which per Svensmark is proposed to be a causal of cloud formation and resultant albedo modulation of (regional) insolation, is modulated by the properties of the earth’s magnetosphere which is itself modulated by the solar wind(s). Together, this represents a localized electromagnetic circuit within the heliosphere that is sensitive to variations in current strength (solar cycles), to coupling distance (orbital variation), as well as other geomagnetic factors such as relative polar angle, upper atmospheric conductance, etc.

    The resultant electromagnetic GCR shielding at the poles and high latitudes takes on a complex field configuration, and the sensitivity or behavior of that shielding/field does not appear to be fully understood at this time. Is this incorrect?

  50. 250
    Dan Fregeau says:

    #244 (Jim Cross) ENSO

    This is a very relevant post.

    Note that some paleoclimatic proxies display a strong signal at half-pressional cycles, whereas other display a strong signal at full-precessional cycles, only. This suggests very different hemispheric effects to precession induced perihelion-soltice coincidence, which is why reducing analysis to insolation variation at July 65N is incomplete/misleading.

    Given the mathematical challenges of his time, I can understand why Milankovitch resorted to this simplification, combined with the fact that he was mostly interested in understanding the behavior of northern glaciation/deglaciation.


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