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Wilkins ice shelf collapse

Filed under: — gavin @ 6 April 2009

Since people are wanting to talk about the latest events on the Antarctic Peninsula, this is a post for that discussion.

The imagery from ESA (animation here) tells the recent story quite clearly – the last sliver of ice between the main Wilkins ice shelf and Charcot Island is currently collapsing in a very interesting way (from a materials science point of view). For some of the history of the collapse, see our previous post. This is the tenth major ice shelf to collapse in recent times.

Maybe we can get some updates and discussion of potential implications from the people working on this in the comments….?

613 Responses to “Wilkins ice shelf collapse”

  1. 251

    Steve Missal (#50):

    <I’d still like to hear an actual theory [of why the Wilkins disengaged] from Dawn or any other skeptic. Something other than armchair stuff.>

    This is so obvious. I can’t believe you so-called “scientists” missed this.

    It’s polar bears. They held a conference. They identified the problem: not enough ice. They came up with the solution: go get some from the other end. It’s just that simple.

  2. 252
    sidd says:

    Re: Ocean Heat Content Data and corrections:

    To those who have objections to the corrections. It is quite clearly laid out in th Levitus(2008) paper and others. Please do read these and post your objections. Let us discuss the science.

  3. 253
    Jim Norvell says:

    I know where the Wilkins Ice Shelf is. I don’t see how this collapse potends anything catastrophic.

    Jim N

    [Response: If you know where it is, then you also know that sea ice declines have been very large in that region. That is the answer to your original question. Who said this was catastrophe? (except in the technical sense of a catastrophic failure of the ice which it clearly is). – gavin]

  4. 254
    Hank Roberts says:

    Gavin replied inline:
    “a mechanically induced failure rather the surface melt induced collapse”

    Hm — may I speculate further?
    On Wilkins the ice sheet was halted by contact with the islands, sat there moving up and down. It would get those straight cracks where ice flexed in the water alongside its grounding lines, and I’m guessing it had a grounding line on the shortest distance where that long persistent ice bridge. So it’d have parallel fractures on either side of the shallow area I”m imagining, with the persistent ice bridge over it.

    On Ross the ice was being extruded slowly into the bay, and flexed at the grounding line as it extruded across that linear feature. So it’d have a different pattern of cracks reflecting a different pattern of flexing.

    Just, again, trying to empathize with the ice sheet…. and tempt those reading who have done the science to comment.

    I wonder if there are other places this might also play out.

  5. 255
    Marcus says:

    Jim Norvell: Another difference between general Antarctic sea ice and the various ice-shelves is that the ice-shelves are hindering glacial land-ice flow. Therefore, collapse of ice shelves may have an impact on sea level rise in a manner unlike other sea-ice changes.

    Having said that, the same conditions which lead to large Antarctic sea ice extent would seem to me (perhaps naively) to make it unlikely that there would be simultaneous persistent mass loss from Antarctic ice. But I also don’t expect the Antarctic sea ice extent to remain larger than average for more than another decade or two, while it does seem like loss of Peninsula ice shelves is becoming a trend. But that is more speculative, and I am not an Antarctic expert.

  6. 256
    Hank Roberts says:

    Ok, interesting stuff out there on structure:

    Structure of Eastern Antarctic Peninsula Ice Shelves and Ice Tongues from Synthetic Aperture Radar Imagery


    Examination of synthetic aperture radar data collected over the southeastern Antarctic Peninsula shows that features sometimes mapped as ice shelves are more likely composed of numerous ice tongues interspersed within a matrix of fast ice and icebergs. The tongues are formed by the seaward extension of numerous small mountain glaciers that drain from the Antarctic Peninsula. Once afloat, the tongues intermingle with a matrix of fast ice and brash. Examination of 1997 Radarsat-1 image mosaics shows that southeastern Antarctic Peninsula composite-ice-shelves covered an area of about 3500 km2. Similar to ice tongues around the rest of Antarctica, these features are highly fragmented and likely to be susceptible to mechanical failure.

    Mercer (1978) postulated that Antarctic ice shelves would be the component of the Antarctic glacier system most responsive to “greenhouse” warming. He predicted a southerly retreat of ice shelf margins starting with the ice shelves in the Antarctic Peninsula (figure 1). His ideas seem especially prescient given the rapid disintegration of the Wordie Ice Shelf during the 1980s (Doake and Vaughan, 1991), retreat of the Wilkins and George VI ice shelves (Luchitta and Rosanova, 1998), and retreat and catastrophic collapse of Larsen A Ice Shelf in 1995 (Skvarca, 1993; Rott and others, 1996; Vaughan and Doake, 1996) and the Larsen Ice Shelf B in 2002
    (MacAyeal and others, 2003) …
    —–end excerpt—–

    This was the search:
    Lots more.

  7. 257
    Lawrence Brown says:

    Elijah, the prophet visited our table this evening, drank of his goblet of wine, and went on to innumerable other supper tables, to partake of same,but before departing he did some prophesizing to me about the fouling of our nest.

    He prophesied that our species will rise up against the vested interests, and stop polluting and defiling our land, sea, and air before it’s too late. That we will stop our profligate use of scarce resources, our thoughtless burning of products that have as a necessary bi-product CO2 and other GHGs, in time to save ourselves. That we’ve done too much harm already- genug! enough! basta!.Its time to start taking action. I may not get there get there with you(I’m about James Hansen’s vintage,…and then some!) but we as a species will get there. I hope I wasn’t just hearing things or indulging in wishful thinking.

  8. 258
    Ray Ladbury says:

    Milton Fyke says: “Raw temperature data is all that is required to prove or disprove the AGW theory.”

    Great, we’ll await your thesis in the peer-reviewed literature. Do get back to us when it comes out.

    [crickets chirping]

    The Oracle of ReCAPTCHA refers to the unmasking of yet another anti-science idiot: outing Stein (Ben, I presume.)

  9. 259
    Ray Ladbury says:

    Dawn asks “Who doesn’t understand “estimating and modeling errors”?”

    Uh, well, you, evidently. The mechanism of the errors was understood. The rough magnitude of the errors was understood. Why, under those circumstances, would you not make the correction?

    Dawn, there is a veritable mountain of evidence favoring anthropogenic causation. It dates back all the way to the 1820s–nearly 2 centuries. Anthropogenic causation of the current warming epoch is an unavoidable consequence of the consensus theory of Earth’s climate. You simply cannot come up with a climate model that gives Earth-like behavior that won’t predict warming if you increase greenhouse gasses. So, every aspect of paleoclimate or modern climate that climate science can explain provides support for that model, and so for anthropogenic causation of current warming. Don’t like that conclusion? Great, come up with with a better theory that doesn’t require CO2 sensitivity of 3 degrees per doubling or so. Go ahead. We’ll wait.

    [More crickets chirping]

  10. 260
    Ray Ladbury says:

    Walt Bennett, I presume you refer to the post now numbered #206. Theo’s post contended that having found 3 or 4 errors could only be explained by incompetence or fraud.
    You have contended here and elsewhere that climate science is more interested in defending its position than advancing understanding. That is incorrect. The portion of the science that implies anthropogenic causation is simply not under threat. It has been established for decades. The state of the art in climate science concerns paleoclimate, the roles of clouds and aerosols, etc., none of which is likely to overturn the role of CO2 and other greenhouse gasses. If you concentrate only on the political controversy between scientists and denialists, you are watching the side show while the interesting stuff is primarily happening in the main ring.

  11. 261
    Doug Bostrom says:


    “I think you could have done a much better job of pointing out how my impressions of the Wilkens event and cooling ocean corrections had you simply stayed with climate science.”

    I assume you intended to include somewhere in that sentence a clause indicating I thought you were wrong? No matter, it’s irrelevant to me what you believe.

    As to sticking with science, here’s a gratuity: you’re not actually “debating” science. You’re spewing pointless entropic noise, like a broken machine that can’t be fixed. As I said, boring friction, all too familiar for anybody that checks into this site on a regular basis. Look back in the archives: examples abound of ill-prepared and poorly equipped self-styled “skeptics” latching onto some spurious talking-point and then working it absolutely beyond the bitter end, making fools of themselves in a way we’ll be able to read about and laugh at for years to come. Yet even as you’re unable to discern this, you’re helping to provide the sort of diagnostic I mentioned.

    Also, it’s “Wilkins”, not “Wilkens”.

  12. 262
    Hank Roberts says:

    > other places
    Maybe; nice illustration here, crediting NSIDC:

    From the commentary — much, much more available:

  13. 263
    RichardC says:

    230 Walter asks, “if all of antarctica’s ice melted what would we find?”

    East Antarctica is mostly above sea level and West Antarctica is a group of islands. Here’s a map:

  14. 264
    RichardC says:

    242 Nick, actually geoengineering against warming is easier because the agent (sulphur) is fairly benign in quantities needed and is short-lived. This means that one doesn’t have to get it perfect the first time. It also means that different areas of the globe can be targeted to somewhat customize the cooling effect. Squabbles will arise, lawsuits will flourish, and all the wonderful ways of mankind will make this task far more difficult.

  15. 265
    David B. Benson says:

    Somewhere I found two clear, color pix of Wilkins, one March 31, the other April 6. From the drift of sea ice between the two pix, it seems clear there was a wind/current drift to the right (and slightly up). Maybe this helps explain the form of the ice bridge collapse.

    [reCAPTHCA does not agree: “designer fertilizers”.]

  16. 266
    Ray Ladbury says:

    A Twain quote for Dawn: “You cannot depend on your eyes when your imagination is out of focus.”

  17. 267

    Jim N wrote in 247:

    How does the collapse square with the latest NSIDC data which shows an increasing Antartic ice coverage?

    Gavin inlined:

    Look in the region where this is happening.

    It really is the darnedess thing…

    The growth rate in the Ross Sea is 4.8% per decade — which is by far more than anywhere else. The most after that is in the West Pacific Ocean at 1.2%. However, the growth rate in the Bellingshausen Sea is -5.3% — so the sea ice in that region is actually dropping.

    You can see it here:

    Regional changes in Arctic and Antarctic sea ice


    If you place a round clock with the hands — not the digital kind — face up at the South Pole with the West Antarctic Peninsula at roughly 11-1, the Bellingshausen Sea will be at 10. The West Pacific Ocean will be at about 9, and the Ross Sea will be at roughly 7-8. More or less.

    It also looks like water circulates in two directions there. Warm water circulates clockwise. That is on the outside. It’s called the West Wind Drift.

    You can see it here:

    Great ocean conveyor belt
    … from 1-10: Ocean Structure and Circulation
    … by Eugene S. Takle

    However, if you look a little more closely, cold water circulates counterclockwise. That is on the inside. It’s called the East Wind Drift. And what separates the two is called the Antarctic Divergence.

    Please see:
    Antarctic Ocean Surface Currents…
    … from Antarctic Surface Water
    Antarctic Surface Water at

    So the Bellingshausen Sea is sticking out there along with the West Antarctic Peninsula and the warm West Wind Drift. The West Pacific Ocean is along continental West Antarctica and gets the cold East Wind Drift. However, the Ross Sea is almost like a bay between West and East Antarctica.


    Looks like the West Pacific Ocean and Ross Sea might be getting some fresh water from all the melting along the West Antarctic Peninsula. You also have to wonder how things will change as the storm tracks move south.

  18. 268
    Ike Solem says:

    A wide variety of data point to a steadily warming Antarctic Peninsula climate, of which the collapsing ice shelves are just one:

    March 19, 2009

    “Over the past 50 years, winter temperatures on the Peninsula have risen five times faster than the global average and the duration of sea-ice coverage has decreased. A warm, moist maritime climate has moved into the northern Peninsula region, pushing the continental, polar conditions southward.”

    “As a result, the prevalence of species that depend on sea ice, such as Adelie penguins, Antarctic silverfish and krill, has decreased in the Peninsula’s northern region, and new species that typically avoid ice, such as Gentoo and Chinstrap penguins, and lanternfish are moving into the habitat.”

    or, try this, 2006:

    Lead author Dr Gareth Marshall from the British Antarctic Survey said, “This is the first time that anyone has been able to demonstrate a physical process directly linking the break-up of the Larsen Ice Shelf to human activity. Climate change does not impact our planet evenly — it changes weather patterns in a complex way that takes detailed research and computer modelling techniques to unravel. What we’ve observed at one of the planet’s more remote regions is a regional amplifying mechanism that led to the dramatic climate change we see over the Antarctic Peninsula.”

  19. 269
    Lawrence Brown says:

    Re #202
    Dawn,corrections are made to raw data very frequently. Way back before the ships that map our coastal areas were part of NOAA, we made corrections to our fathometer(depth) readings for temperature and salinity. Without these modifications, we would have given nautical chart users faulty information.

    These corrective procedures are not unusual and in fact are necessary for consistent and,more importantly, accurate results. These are not heretical procedures in order to fudge things to bring about predetermined results. Scientifically based corrections need to be applied to field measurements in a great many cases.
    Check into your source of info and be sure whether or not this applies in the case of the ocean sensors.

  20. 270
    your mommy called says:

    Mark (post #90) I guess you didn’t pay much attention to your high school chemistry class. I do not need another thermometer to calibrate a thermometer. By definition the boiling point of water at STP is 100 deg C and a mixture of ice and water constantly stirred at STP is by definition 0 deg C. Thus I immerse my thermometer in boiling water mark the maximum rise of the column, then immerse the thermometer in a stirred mixture of ice and water and mark the minimum point. Divide the distance between your two marks into 100 evenly space divisions. My son calibrated thermometers in 7th grade science. A simple google search finds a host of elementary school lesson plans for the same exercise. Please do your homework first

  21. 271
    Phillip Shaw says:

    Re: #215


    Do you understand the difference between earthquakes, which may be tectonic or volcanic in origin, and icequakes which are caused by rifting and movement within ice such as glaciers or ice shelves? And do you understand that only volcanic quakes could even conceivably involve magma?

    It only took a few minutes to check Google Scholar and learn that no earthquakes have been recorded in recent years near the Wilkins Ice Shelf, and that the icequakes which have been recorded are entirely consistent with the breakup of the 200 to 250 meter thick ice shelf. The speculation that the ongoing breakup could be the result of volcanic activity doesn’t have a shred of data to support it.

    So for you or Jim Steven to conflate unrelated seismic phenomena is either disengenuous, flatly dishonest, or completely mistaken.

  22. 272
    Hank Roberts says:

    > geoengineering against warming is easier
    That’s treating a symptom, but not the only symptom or even the most urgent one. You know this, right?

  23. 273
    chris colose says:

    I would say geoengineering to make it warmer is a bit “easier” in theory. That’s much like what we’re doing now (the industrial revolution!), only one could find a “better” greenhouse gas than CO2 if we wanted to intentionally make it warmer quickly, particularly some gas which didn’t have overlap with other infrared absorbers and was at a very low background concentration.

    The problem with the injection of aerosols (to offset anthropogenic warming) is that we’d have to commit to it on timescales equivalent to the CO2 lifetime (i.e, centuries to millennia), since our ancestors will get a huge warming effect if CO2 keeps rising and aerosols all of a sudden drop. Talk about abrupt climate change! Once we get to very high CO2 concentrations, continuing to keep up with aerosols is pretty impractical (costs, pollution, etc), global offsets don’t imply regional offsets, ocean acidifcation still an issue, etc. Of course, playing these kind of games with the climate system probably isn’t the best idea in the first place

  24. 274
    Dawn says:

    269 Lawrence Brown,

    I don’t know how I can be any more clear than I was upthread.
    I never said anything or indicated that I didn’t grasp that
    “corrections are made to raw data very frequently”
    I must repeat that is obvious.
    I am not disputing the decsion to make corrections.

    I am challenging the reliability and confidence level of the perceived erros and the corrections made.

    I am not saying corrections should not be made when errors are suspected to have occured.

    However, I didn’t gather there was much certainty about the errors.
    How many sensors were giving false temperature readings and to what degree appears to be unknown.
    That’s why I suggested they were guesstimating.
    Assumptions were made. In the corrections additional assumptions were made.

    Two reports showed ocean cooling and in the aftermath

    “correcting for instrumental biases of bathythermograph data, and correcting or excluding some Argo float data”

    warming appeared.

    This does not translate into a very high confidence level IMO.

    It’s quite possible that there is no warming, very little warming or even cooling.

    Yet many here are certain the errors and corrections which moved the reported cooling to continued warming is entirely sound.


    I don’t.

    I am not saying assumptions should not be made. If errors are detected or suspected “corrective procedures” should be taken.
    Accuracy varies.
    There’s margin of error.
    There needs to be some measure of confidence.

    In the full spectrum between heretical procedures in order to fudge things to high level of scientific control and measurement lies the ocean sensor errors and corrections.

    So I am inquiring as to how scientifically based the corrections were. My take is the field measurements and the corrections may be no better than somewhere in the middle.

    I could have missed something but in all of these comments I didn’t see anyone offer anything to alter that.

    [Response: Again, based on nothing better than your take, are we supposed to assume that the corrections were not scientifically based? Why not read the actual papers? In particular, those of Wijfels et al 2007 and Domingues et al 2008 and references therein. Then tell us why these scientists don’t know what they are doing. Your hunch/gut feeling/take/opinion is not the basis of any useful discussion. (PS. No one has claimed the data sets are perfect, so drop that particular strawman). – gavin]


  25. 275
    Ike Solem says:

    Dawn, are you still reading the old Pielke web pages and articles on “cooling of the global oceans?” Those are not very reliable sources. There really isn’t much evidence that supports your claim, other than one published paper (Lyman et al. with the cooling claim due to bad Argo float data). See previous discussion:

    Limited data from the Arctic and Antarctic (the regions that are expected to warm the fastest and the earliest) means that warming in these regions could have offset the rest of the reported trend. The fact that the cooling trend is reduced when the ARGO data is excluded seems to support this notion.

    – but perhaps you are overworked, so let me help you out by providing you with the full-scale denialist argument, as seen on TV.

    First, you want to start with something a little bit authoritative.

    Media contact: Alan Buis
    Jet Propulsion Laboratory, Pasadena, Calif.

    There you go – scientific ‘proof’ that the world is cooling due to a negative phase of the PDO. Or is it a big La Nina? Maybe an amplification of the AMO? The Iris effect in action cooling the ocean, as Lindzen predicted… though that would require a drying of the tropical atmosphere, not a moistening. (P.S. Always use acronyms – it makes you sound more authoritative)

    Here’s some more on our cooling world:

    “As repeatedly stated on Climate Science, the concept of global warming promulgated by the IPCC and others requires a more-or-less continuous accumulation of Joules. For the last several years this has not occurred.”

    See – no joules, no warming. Now, cite some random web sites:

    Those are not as good as respected media outlets, however. Try Andrew Revkin at DotEarth, NYT on the issue:

    Revkin: “This came by email from Don Easterbrook. I’ll be setting up the images he alludes to a bit later this week:

    Easterbrook: “Notice that cool water in the Pacific that extends from the equator all the way up the west coast of North America into the Gulf of Alaska is still firmly entrenched. This is the cool water phase of the PDO and it isn’t going to change for at least 2-3 decades (at least it never has in the past) and it is unaffected by atmospheric CO2 as shown by the three PDO switches this century that occurred before atmospheric CO2 increased significantly.”

    There you have it – Easterbrook’s proof, delivered with a smile by Andrew Revkin, no questions asked… but what do the people at JPL have to say about it?

    Willis: “The real debate is not over whether global warming exists, but how we as a society will address it. The climate system is already committed to a certain amount of warming from carbon dioxide emissions of the past, but the worst effects of global warming can still be avoided. It only requires the will to look toward the future and to curb our addiction to fossil fuels. That’s not alarmist, it’s just common sense.”

    Revkin: “Now that last line on policy might be read by some folks as a bit of rhetorical cover to keep Dr. Willis in good standing with his colleagues. I know him and a lot of his peers, and I doubt very much he’s worried about appearances. But that’s just my perception.”

    Yes, any scientist who says that we have to quit fossil fuels is just engaging in political correctness, out of fear of offending the hive mind… scientific authoritarianism at its worst – just ask Roger Pielke Jr. at the Breakthrough Institute, aka the Rockefeller Financial Services front group:

    Hansen’s scientific authoritarianism becomes largely incoherent when he accuses political leaders of “tricking” their citizens when they say that climate policies include plans for the future development and implementation of carbon capture and storage from coal plants.

    Try and get the NYT or Washington Post to talk about the International Renewable Energy Agency, or about subtropical drought – that’s always fun. Not an acceptable subject for the U.S. media – but you can read about how the PDO is cooling the world.

    Here is the only U.S. media outlet to have published even a passing mention of the International Renewable Energy Agency:

    For rare decent reporting on the wide variety of issues impacting water supplies in the Western U.S.:

    Hope that helps, Dawn. By the way, do you ever worry that propaganda itself is a greater threat to human civilization than either nuclear weapons, biological warfare, or global warming?

  26. 276
    Hank Roberts says:

    Whoever that was above tried to lecture Mark writing:

    > By definition the boiling point of water at STP is 100 deg C …
    > Thus I immerse my thermometer in boiling water

    At STP — that is, at standard temperature and pressure.

    And you’ve checked that you’re at standard temperature and pressure.

    How did you do that?

  27. 277

    And you’ve checked that you’re at standard temperature and pressure.

    How did you do that?

    With a mercury barometer. Assuming that local gravity g is what you think it is. And that the density for mercury found in the handbooks is indeed in SI kilogrammes per SI cubic metres, traceable back to Paris or wherever it is nowadays.

    Metrology. Measuring something is never trivial. Every measurement result contains an implicit model. Sometimes several.

  28. 278
    Mark says:

    Hank, there’s also a big problem:
    “> By definition the boiling point of water at STP is 100 deg C …
    > Thus I immerse my thermometer in boiling water”

    That would get you a single point. That doesn’t calibrate. You need two to work out how much of a change would make a 1C temperature difference.

    And “Ice freezes at 0C” has a problem that this is only true for pure water.

  29. 279
    Mark says:

    “I am challenging the reliability and confidence level of the perceived erros and the corrections made. ”

    And you know so little about how they are effected, you would be unable to work out whether they were appropriate or not.

    So you’d have to rely on someone else to tell you.

    Rather like the peers who reviewed the changes.

    You didn’t believe THEM, why would we think you’d believe anyone else unless they said what you want to hear them say?

  30. 280
    Mark says:

    Oh, and to your mommy, how do you work out -200C? How about +5000C?

    Look up metrology (spelling is correct). There’s a lot there about temperature measurements. It’s nowhere near as simple as you think it is.

    But if all you know is 7th grade physics, I guess you don’t know much physics, do you.

  31. 281
    Mark says:

    “It’s polar bears. They held a conference. They identified the problem: not enough ice. They came up with the solution: go get some from the other end. It’s just that simple.”

    You have it SOOOO wrong.

    It’s the penguins. They want to invade the artic and have heard that polar bears don’t eat penguins and wish to find a new food source since we’ve taken all the bloody fish.

    This is their Invasion Force Platform.

    Be Afraid.

  32. 282
    jr says:

    Re: Timothy Chase #82

    I guess in nearly 200 posts someone has already mentioned this…It is easier to break a window by hitting it near a corner (if it has one). Stress concentrates at geometrical discontinuities like right angles, changes in section, holes etc.

  33. 283
    Mark says:

    “#236 Mark, in case it has escaped you the extinction event happened 250 million years ago.”

    I am aware of this fact. Why dost thou repeat this item?

    ” The volcanism hypothesis does have one advantage over the others and that is that it has a test case in Laki”

    And extinction by rapid climate change has several test cases, one of which is going on now.

    But you STILL HAVE NOT put what evidence shows that your hypothesis is a better fit than the mainstream one.

    YOU HAVE TO DO THAT to get your hypothesis taken as a better one than the mainstream one.

    Still haven’t done it.

    So much effort put into nothing, too.


  34. 284

    Dawn writes:

    How is that you are waiting for special delivery of an “optional theory” when you cannot point to any meaningful data which substantiates the AGW cause?

    First of all, it isn’t a “cause.” It’s a scientific theory. Here’s the meaningful data:

    1. CO2 is a greenhouse gas. This was shown in lab work by John Tyndall in 1859. No one knowledgeable disputes it. And nowadays we have a quantum mechanical explanation as to exactly how greenhouse gases work.

    2. CO2 is rising. This was proposed on logical grounds by Arrhenius in 1896, commented on with references to preliminary evidence by Callendar in 1938, and finally proved by Keeling et al. with observations from 1958 onwards. These observations have been repeated all over the world since Keeling et al. started their program at Mauna Loa.

    3. The new CO2 is primarily from humans burning fossil fuels. This was demonstrated from its radioisotope signature by Hans Suess in 1955. Fossil fuel carbon is so old all its carbon-14 has decayed away, whereas carbon from the ocean or the soil would have the normal complement of carbon-14. There are also clues from the 13C/12C ratio. And invetorying how much fossil fuel is being burned, and knowing how much is going into sinks, the numbers match what we get from the radioisotope analyses.

    4. The world’s temperature is rising. This is shown by land surface temperature readings, sea surface temperature readings (no urban heat islands there), borehole readings, balloon radiosonde readings, satellite readings, and effects such as melting ice caps and glaciers, tree lines moving toward the poles, earlier hatching dates for eggs of fish, frogs, insects, and birds, and earlier blooming dates for flowers and flowering trees.

    5. When I regressed NASA GISS temperature anomalies against ln CO2 for 1880-2008, I got 76% of the variance accounted for. That means all other causes of temperature variation for that 129-year period, including other greenhouse gases, caused no more than 24%. Volcanoes had a small effect (about 2%), and sunlight had no discernable effect–and I measured the sun’s influence four different ways, TSI, sunspot cycle, years since maximum, and years since minimum.

    6. The signature of greenhouse warming by carbon dioxide is that the stratosphere should be cooling while the troposphere warms. All the observations say exactly that is happening. Some of the stratospheric cooling is due to ozone depletion, but not enough to account for all or even most of it.

    Which of the above observations do you dispute?

  35. 285

    MiltonFyke posts:

    AGW alarmists still haven’t come close to proving that global warming will be apocalyptically detrimental to mankind. The mild warming of Earth, most strongly felt in the higher latitudes, will probably benefit mankind.

    Among those benefits:

    * Increased drought in continental interiors. Ask the Australians. In the 1960s, about 20% of agricultural lands around the world were in drought at any one time. Now it’s more like 30%. Would a massive collapse of our agriculture be beneficial?

    * More violent weather along coastlines. Ask the inhabitants of New Orleans. The destruction of infrastructure due to such events has been climbing exponentially for years, or so say the insurance companies.

    * The disappearance of glaciers which provide fresh water for a billion people in Asia and some in Latin America.

    * The eventual loss of trillions of dollars of infrastructure, and some whole countries (like Bangladesh), due to sea level rise.

    * The creation of hundreds of millions of “climate refugees” from the above conditions. Consider how well the USA is accepting Mexican immigration right now. Then multiply the problem by 100.

    The Atlantic Chronozone, Medieval Warm Period, and even the Eocene give examples of what Earth will be like, were some of the more extreme predictions for AGW to be realized.

    The MWP was largely confined to Europe and was not warmer than today. And what is “The Atlantic Chronozone?” Something to do with Atlantis?

    We certainly have sufficient time to absorb negative GW effects, given the gradual nature of the change.

    See above.

    I see that some of the President’s top advisors are thinking of geoengineering to fight AGW. More research should be applied to this, but also for preventing catastrophic cooling, such as a new glacial period, which would be far worse than GW.

    The next ice age would be at one of the coming Milankovic cycle “stades,” in 20,000 years and 50,000 years, though the first might be too mild. It will certainly not happen now, as our raising amb-ient CO2 by 38% will prevent it.

  36. 286
    Mike Atkinson says:

    Re #270, 276

    Also it assumes that the expansion of the thermometer liquid is linear. The (only?) way to check that assumption is to use another thermometer.

  37. 287

    Mark wrote in 90:

    Why does your thermometer need calibration? How is it done? By interpreting the volume increase of mercury as an increase in temperature.

    What happens when your thermometer is calibrated? It’s errors are corrected. Expansion of mercury is not linear, and the gas the liquid is pushing aside is pushing back…

    Nameless… wrote in 270:

    I do not need another thermometer to calibrate a thermometer. By definition the boiling point of water at STP is 100 deg C and a mixture of ice and water constantly stirred at STP is by definition 0 deg C. Thus I immerse my thermometer in boiling water mark the maximum rise of the column, then immerse the thermometer in a stirred mixture of ice and water and mark the minimum point. Divide the distance between your two marks into 100 evenly space divisions.

    Hank Roberts wrote in 276:

    At STP — that is, at standard temperature and pressure.

    And you’ve checked that you’re at standard temperature and pressure.

    How did you do that?

    I definitely wouldn’t want to create a scientific thermometer using even spacing:

    The thermal expansion of mercury is given by V(t) = V(1 + 1.82 x 10-4t + 7.8 x 10-9t2), where t is in °C, and V is the volume at 0°C.

    Properties of Mercury

    … and as both you and Mark have pointed out, there are other problems with simply assuming you have standard pressure, the fact that the extra space in the thermometer will contain some gas that will push back, they are assuming that the water is pure, or even simply assuming that the non-linearity is small enough for the purpose of a home thermometer rather than doing some sort of scientific study or making recourse to a model or theory that might have to be abandoned at some later point. There was a reason why they didn’t quote what they were responding to.
    Oh, and there are two more things worth noting: smoke rises and it doesn’t matter how big they are — fires typically don’t cross oceans.
    Captcha fortune cookie: resent investigation

  38. 288
    Pekka Kostamo says:

    Dawn: Seems to me that it would be a good idea to spend an hour or two reading carefully through the paper in

    It explains in great detail how sea temperature errors (both high and low) were detected by comparisons of different measurement systems. It also explains how experimental scientists work. As in all work of this nature, redundancy is the key.

    There were three models of ARGO floats of different designs plus two fundamentally different ways of measuring the ocean levels(classic in-situ gauges and satellites), large numbers of expendable instruments dropped from research ships and navy vessels, recoverable temperature sensors in sea water sampling probes,radiation balance instruments onboard satellites. As is stated:

    “We need multiple, independent, overlapping sets of observations of climate processes from space and from the Earth’s surface so that we can create long-term climate records—and have confidence that they are accurate. We need theories about how the parts of the Earth system are related to each other so that we can make sense of observations. And we need models to help us see into the future.”

    Eventually a hardware calibration problem was found and was corrected.

    Redundancy is what is needed, and that is what exists also. No single system of measurement is reliable enough over the long term. It is also a well established wisdom that if a new measurement system (such as the ARGO floats) disagrees rdically with an established theory and an array of earlier sensors, is is a good idea to verify the new measurement system. Once more demonstrated here.

  39. 289
    william says:

    #284 Barton Paul Levenson
    You neglected to mention that CO2 only provides 5-15% of the “greenhouse effect” and that the great majority is provided by water vapor and a few other gases. There seems to still be some disagreement in the science community as to the whether water vapor and cloud cover are positive or negative feedbacks. If they are negative then increases in CO2 does not push global temps up much past +.6. All the GCM’s assume them as positive feedbacks which makes them all consistent but also possibly all incorrect.

    [Response: Wrong. CO2 is about 20% of the natural greenhouse effect (after accounting for overlaps). The rest is made up of water vapour (~50%), clouds (25%) and ozone/aerosols/etc. There is no scientific debate about whether water vapour is a positive feedback – it is. Specific humidity increases with surface temperature all the way to the tropopause. There is continuing discussion about cloud feedbacks which are more complicated (depending on altitude, location, type etc.). Finally, GCMs do not “assume” positive feedbacks – these are results that emerge from the interplay of all the physical assumptions (about evaporation, cloud formation, advection, convection etc.) that go into the model. – gavin]

  40. 290
    tim says:


    Hank, I’m not convinced it’s even worth replying to ill educated comments like this. Even allowing for a typo of “at STP is 100 deg C” when “at standard pressure is 100 deg C” was meant, the poster has clearly no idea that no thermometer is truly linear unlike the ideal gas laws and most are highly non-linear (e.g. PRT PRT)

    Of course, the ideal gas thermometer is linear by definition (pV=nRT), the two points need to define the kelvin scale being absolute zero and the triple point of water (273.16K). In 1954 the definition of the Celsius scale was changed to match this (absolute zero -273.15C, triple point of water 0.01C)

  41. 291
    Mark says:

    “Oh, and there are two more things worth noting: smoke rises and it doesn’t matter how big they are — fires typically don’t cross oceans.”


    Smoke only rises if the air is rising and brings the smoke particles with it. Otherwise it will layer itself with a low scale height (the denser the smoke particle, the lower the scale height).

  42. 292
    t_p_hamilton says:

    How thermometers are calibrated at NIST:

    Laboratory Thermometers (31010C-31100C)

    This service provides for the calibration of a variety of thermometers covering the range from -196 °C to +550 °C (-321 °F to +1022 °F). Thermometers belonging to the large and varied group which may be classified as laboratory, or “chemical,” thermometers are regularly accepted. These are of the liquid-in-glass type with either solid-stem or enclosed scale. Ordinary household or meteorological thermometers will not, in general, be accepted unless the scale is graduated on the glass stem itself and the thermometer can be readily detached from its mounting for insertion in a liquid bath. Every thermometer submitted must be uniquely identified by a serial number and must pass a preliminary examination for fineness and uniformity of graduation; for cleanliness of the mercury and the capillary bore; for freedom from moisture, gas bubbles, and cracks in the glass; for adequacy or omission of gas filling where needed; for insufficient annealing; and, for misnumbered graduations. When these or other serious defects are found, the thermometer is returned untested.

    The thermometers to be calibrated are placed in a constant temperature bath along with a NIST-calibrated standard platinum resistance thermometer (SPRT). The SPRT maintains calibrations traceable to the International Temperature Scale of 1990 (ITS-90), with a maximum expanded uncertainty of 0.7 mK. (See Table 6.2)

    Table 6.2. Calibration Uncertainties for Total Immersion Thermometers (omitted table)

    OMG, they have errors!

  43. 293
    Chris S says:

    #284/285 BPL

    You neglect to mention that other things may be heading poleward as well as tree lines. I’ve already posted here about Bluetongue in Sweden (a disease that prior to this century never occured north of the Mediterranean region), but see also:

    “When temperatures increase, especially in combination with more precipitation, vector borne diseases like malaria and dengue fever increase in frequency and distribution. In particular, areas where the minimum night temperatures increase provide the best conditions for the growth and spread of Anopheline spp. and Aedes aegypti mosquitoes.”

    “Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility.”

    “Curto de Casas and Carcavallo (1984) studied the southern dispersion of Triatominae species and concluded that the critical climatic factor is the number of days with temperatures above 20oC”

  44. 294
    steve says:

    The paper “Recent Bottom Water Warming in the Pacific Ocean” was pretty interesting. Thanks to Gavin for pointing it out. My question would be isn’t this a reflection of surface temperatures haven risen for so long and shouldn’t the temperatures in the deep oceans eventually show a leveling out as the sea surface temperatures have done?

    As a side note I did notice they used the phrase “small but significant”. I believe a great deal of the disparity between the percentages of scientists that believe AGW to be significant and the percentages of non scientists to believe AGW to be significant relies on how small it can be before it becomes non significant.

  45. 295
    william says:

    #289 Gavin
    Kiehl and Trenberth do not seem to agree with your percentage breakout unless you are stating only the “cloudy day” contribution of water vapor. See link at

    [Response: They didn’t do the full calculation – partly because they are using a single reference profile and very simplified cloud structure. My calculations are more appropriate, and ~20% is what you get (though I should write this up more formally). – gavin]

  46. 296
    Hank Roberts says:

    Oh, yeah, and besides all the other thermometer stuff that high school assumed, marking the boiling point and the freezing point then adding a hundred divisions between them on the outside of the glass — they also assumed a perfectly even diameter hole inside the glass.

    Perfection — start with that and you don’t have any problems.

    The political theory that disallows any human effect on global environment is like that — perfect by definition, individuals operating for their own immediate profit without knowledge beyond what they want are the ultimate measure. So anyone who thinks otherwise has to be conspiring against them.

  47. 297
    Jim Norvell says:

    [Response: Wrong. CO2 is about 20% of the natural greenhouse effect (after accounting for overlaps). The rest is made up of water vapour (~50%), clouds (25%) and ozone/aerosols/etc. There is no scientific debate about whether water vapour is a positive feedback – it is. Specific humidity increases with surface temperature all the way to the tropopause. There is continuing discussion about cloud feedbacks which are more complicated (depending on altitude, location, type etc.). Finally, GCMs do not “assume” positive feedbacks – these are results that emerge from the interplay of all the physical assumptions (about evaporation, cloud formation, advection, convection etc.) that go into the model. – gavin]

    Would you provide some reference to the claim water vapor is a positive feed back. I have seen data that is in opposition to this I.E. relative humidity is decreasing at upper altitudes. From what I have read there is a big difference of opinion on weather cloud feedback is positive or negative.

    Jim N

    [Response: You’re kidding, right? (April 1st is long past now). -mike]

  48. 298
    Mark says:

    “and shouldn’t the temperatures in the deep oceans eventually show a leveling out as the sea surface temperatures have done?”

    Why? Energy coming in has to go somewhere.

    More wind? More water vapour? Seen any of that? All else has to go as temperature somewhere.

    Maybe deep ocean is getting much warmer quicker and pulling out heat from the air. This would mean the air temperatures are going up slower (note: there is no leveling of temperatures in the atmosphere. The rate of increase is still positive) but unless the air starts sucking heat out of the deep ocean (how?) it doesn’t mean there will be a leveling of deep ocean temperatures.

    Unless you mean “leveling” as in “it’s not going up as fast as it has before, but is still positive”.

    Which isn’t really “leveling” at all.

  49. 299
    william says:

    According to the most recent NASA research, if we are concerned about warming at the poles we should forget about C02 and worry instead about aerosols.

    “We will have very little leverage over climate in the next couple of decades if we’re just looking at carbon dioxide,” Shindell said. “If we want to try to stop the Arctic summer sea ice from melting completely over the next few decades, we’re much better off looking at aerosols and ozone.”
    See link at

    [Response: Wrong. All that Drew is pointing out here is the well known ‘commitment’ problem. The residence timescale of CO2 in the atmosphere once it has been emitted is such that there is little we can do to lower the trajectory of CO2 concentrations over the next one to two decades with our current actions. That trajectory was pretty much locked in by our emissions over the past several decades. We have far more leverage *on the decadal timescale* with aerosols and other greenhouse gases that have shorter residence times. The CO2 we emit, in the meantime, will come home to roost in future decades. To argue that this is somehow a cause for less stringent controls on CO2 emissions is to profoundly not understand the nature of the problem. -mike]

  50. 300

    mark wrote in 291:


    Smoke only rises if the air is rising and brings the smoke particles with it. Otherwise it will layer itself with a low scale height (the denser the smoke particle, the lower the scale height).

    Of course. And being a tropospheric aerosol it will tend to get rained out — with a half-life of a week to 10 days.

    I like it!