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Arctic Sea Ice Volume: PIOMAS, Prediction, and the Perils of Extrapolation

Filed under: — group @ 11 April 2012

Guest Commentary by Axel Schweiger, Ron Lindsay, and Cecilia Bitz

We have just passed the annual maximum in Arctic sea ice extent which always occurs sometime in March. Within a month we will reach the annual maximum in Arctic sea ice volume. After that, the sea ice will begin its course towards its annual minimum of both extent and volume in mid-September. This marks the beginning of the ritual of the annual sea ice watch that includes predictions of the extent and rank of this year’s sea ice minimum, as well as discussion about the timing of its eventual demise. One of the inputs into that discussion is the “PIOMAS” ice-ocean model output of ice volume – and in particular, some high-profile extrapolations. This is worth looking at in some detail.

Prediction methods for the sea ice minima range from ad-hoc guesses to model predictions, from statistical analyses to water-cooler speculation in the blogosphere. Many of these predictions are compiled in the SEARCH-sponsored “sea ice outlook“.

This year’s discussions however will be without the input of the father of modern sea ice physics, Norbert Untersteiner, who recently died at the age of 86. Much of the physics in PIOMAS and global climate models can be traced to Norbert’s influence. Norbert was sober-minded and skeptical about the prospects of skillful short-term sea ice predictions, but even he couldn’t help but be drawn into the dubious excitement around the precipitous decline of arctic sea ice and regularly added his own guestimate to the sea ice outlook. Norbert’s legacy challenges those of us who engage in predictions to prove our skill and to understand and explain the limitations of our techniques so they are not used erroneously to misinform the public or to influence policy…more about that later and here.

PIOMAS

PIOMAS is the Panarctic Ice Ocean Modeling and Assimilation System. It belongs to the class of ice-ocean models that have components for the sea ice and the ocean, but no interactive atmosphere. There is an active community (AOMIP) engaged in applying and improving these types of models for Arctic problems. Without an atmosphere, inputs that represent the atmospheric forcing (near surface winds, temperature, humidity, and downwelling short and longwave radiation) need to be provided. Typically those inputs are derived from global atmospheric reanalysis projects. The advantage of such partially-coupled models is that they can be driven by past atmospheric conditions and the simulations match well the observed sea ice variability, which is strongly forced by the atmosphere.

This is in contrast to fully-coupled models, such as those used in the IPCC projections, which make their own version of the weather and can only be expected to approximate the mean and general patterns of variability and the long-term trajectory of the sea ice evolution. Another advantage of ice-ocean models is that they don’t have to deal with the complexities of a fully-coupled system. For example, fully-coupled models have biases in the mean wind field over the Arctic which may drive the sea ice into the wrong places, yielding unrealistic patterns of sea ice thickness. This has been a common problem with global climate models but the recent generation of models clearly shows improvement. Because sea ice is strongly driven by the atmosphere, model predictions depend on the quality of the future atmospheric conditions. Therefore an ice-ocean model, like PIOMAS, is much more accurate at hindcasts, when the atmospheric conditions are simply reconstructed from observations, than for forecasts, when atmospheric conditions must be estimated. That is not to say that PIOMAS can’t be used for predictions, it can (Zhang et al. 2008, Lindsay et al. 2008 , Zhang et al. 2010) but it is important to recognize that performance at hindcasts does not necessarily say much about performance at forecasts. This point often gets confused.


Figure 1: PIOMAS mean monthly arctic sea ice volume for April and September. Dashed lines parallel to linear fits represent one and two standard deviations from the trend. Error bars are estimated based on comparison with thickness observations and model sensitivity studies (Schweiger et al. 2011)

PIOMAS was developed and is operated by Jinlun Zhang at the University of Washington. It is the regional version of the global ice-ocean model of Zhang and Rothrock (2003). The sea ice component represents sea ice in multiple categories of thickness and accounts for changes in thickness due to growth and melt as well as mechanical deformation of ice (Thorndike et al. 1975, Hibler 1980).
It has evolved with continual improvements, including the addition of data assimilation capabilities (Zhang et al. 2003, Lindsay et al. 2006) and the development of sister models for new applications (BIOMAS for biology) or specific regions (BESTMAS for the Bering Sea and GIOMAS for the entire globe) (publications). As a modeler working among observationalists from a variety of disciplines, Jinlun has never been short of tire-kickers who probe, push, and challenge his model from all sorts of different angles and identify warts and beauty spots. This is one of the reasons why PIOMAS has evolved into one of the premier ice-ocean models (Johnson et al. 2012), particularly when it comes to the representation of the sea-ice cover.

PIOMAS has been used in a wide range of applications but arguably the most popular product has been the time series of total Arctic sea ice volume which we have been putting out since March 2010 (see also Fig 1). The motivation for this time series is to visualize the fact that the long term Arctic-wide loss of sea ice is not only happening in extent, which is well measured by satellites, but also in thickness, which isn’t. Ice volume, the product of sea ice area and thickness, is a measure for the total loss in sea ice and the total amount of energy involved in melting the ice. Though this is a very small part of the change of global energy content, it is regionally important and investigations into the cause of sea ice need to pin down the sources of this energy.

But why use PIOMAS to show the decline in ice volume when our group of researchers has been involved in measuring, rescuing, and collecting sea ice thickness data from in-situ observations for 30-some years? The answer is that even though wide-spread thickness losses from observations alone have been apparent for some areas or time periods, Arctic-wide thickness losses are more difficult to document because of the sparse sampling in time and space. The problem can be visualized by constructing a “naïve” sea ice thickness time series from in-situ observations:



Figure 2 Naïve sea ice thickness time series. Sea ice thickness observations from the sea ice thickness climate data record (small grey dots), averages for all observations in a given year (large grey dots), and 5-year running mean through those observations. The same calculation for the corresponding PIOMAS simulations at the location and time of observation is shown by the big red dots and line.

Before those claiming that global warming stopped in 1998 have a field day with this figure, they should appreciate that our total volume time series and the naïve thickness time series are entirely consistent. The sampling issues arise from the fact that sea ice is highly dynamic with lots of spatial and seasonal variability so that measurements from individual moorings, submarine sonar tracks, and aircraft flights can only construct an incomplete picture of the evolution of the total Arctic sea ice volume. Progress towards establishing ice thickness records from satellite (ICESat, Envisat, and CryoSat-2) will change this over time, but these sources won’t yield a record before these measurements began and satellite retrievals of ice thickness have their own issues.

PIOMAS is not normally run as a freely-evolving model, but rather it assimilates observations. Ice concentration and sea surface temperature are currently assimilated and we have experimented with the assimilation of ice motion (Zhang et al. 2003, Lindsay et al. 2006). Assimilation helps constrain the ice extent to observations and helps improve the simulation of sea ice thickness. Ice thickness observations are not assimilated into the model. Instead, ice thickness and buoy drift data are used for model calibration and evaluation. So using a model constrained by observations is quite possibly the best we can do to establish a long-term ice volume record.

Model calibration is of course necessary. We need to determine parameters that are not well known, deal with inadequately modeled physics, and address significant biases in the forcing fields. Parameters changed in PIOMAS calibration are typically the surface albedo and roughness, and the ice strength. Once calibrated, the model can be run and evaluated against observations not included in the calibration process. Evaluation does not only mean showing that PIOMAS says something useful but also establishes the error bars on the estimated ice thickness. To establish this uncertainty in the ice-volume record (Schweiger et al. 2011), we spent a significant effort drawing on most types of available observations of ice thickness thanks to a convenient compilation of ice thickness data (Lindsay, 2010). We have also compared PIOMAS estimates with measurements from ICESat and conducted a number of model sensitivity studies. As a result of this evaluation our conservative estimates of the uncertainty of the linear ice volume trend from 1979-present is about 30%. While there is lots to do in improving both measurements and models to reduce the uncertainty in modeled ice volume, we can also say with great confidence that the decline in observed ice thickness is not just an effect of measurement sampling and that the total sea ice volume has been declining over the past 32 years at astonishing rates (for instance a 75% reduction in September volume from 1979 to 2011).

Prediction

The seasonal prediction issue and the prediction of the long-term trajectory are fundamentally different problems. Seasonal prediction, say predicting September ice extent in March, is what is called an initial value problem and the September ice extent depends both on the weather, which is mostly unpredictable beyond 10 days or so, and the state of the ocean and sea ice in March. Improving observations to better characterize that state, and improving models to carry this information forward in time is our best hope to improve seasonal predictability. The prediction of the long-term trajectory, depends on the climate forcing (greenhouse gases, aerosols, solar variability) and how the model responds to those forcings via feedbacks. A recent model study showed that the crossover between initial-value and climate-forced predictability for sea ice occurs at about 3 years (Blanchard-Wrigglesworth et al. 2011). In other words, a model forgets the initial sea ice state after a few years at which point the main driver of any predictable signal is the climate forcing. In fact, coupled model simulations have shown that even removing all the sea ice in a particular July has little lasting impact on the trajectory of the ice after a few years (Tietsche et al. 2011).

PIOMAS has been run in a forward mode (and hence without data assimilation) to yield seasonal predictions for the sea ice outlook (Zhang et al. 2008) and has also provided input to statistical forecasts (Lindsay et al. 2008) and fully-coupled models. We have also done experiments with PIOMAS in a climate projection mode by scaling atmospheric forcing data from a reanalysis to 2xC02 projections from the CMIP3 models (Zhang et al. 2010). This setup provides more realistic wind fields and spatial thickness distribution but cannot account for important atmosphere-ocean feedbacks.

Global climate model projections (in CMIP3 at least) appear to underestimate sea ice extent losses with respect to observations, though this is not universally true for all models and some of them actually have ensemble spreads that are compatible with PIOMAS ice volume estimates and satellite observations of sea ice extent. With error bars provided, we can use the PIOMAS ice volume time series as a proxy record for reality and compare it against sea-ice simulations in global climate models. This provides another tool in addition to more directly observed properties for the improvement and evaluation of these models and is in our view the best use of PIOMAS in the context of predicting the long-term trajectory of sea ice.

Predictions of a seasonally ice-free Arctic Ocean

The eventual demise of the summer sea ice is a common feature of nearly every climate model projection (the exceptions are models with very inappropriate initial conditions). But the question of when the Arctic will be ‘ice-free’ is imprecise and calls for a clear definition of what ice-free means. Does it mean completely ice-free, or is there a minimum threshold implied? Does it mean the first time the summer sea ice goes beneath this threshold or does it imply a probability of encountering low-ice conditions over a period of time? (e.g. high likelihood of Septembers with less than 106 km2 of ice in a 10-year period). Regardless of whether the concept is actually useful for any practical purpose (say for planning shipping across the Arctic), it is nevertheless a powerful image in communicating the dramatic changes that are under way in the Arctic.

Once defined, predictions of when an ice-free Arctic will occur seem justified. In the published literature there are several papers specifically targeting such predictions (Zhang and Walsh, 2006, Wang and Overland, 2009, Boe et al. 2009, Zhang et. al. 2010) while others include discussion about the timing of ice-free summers (e.g. Holland et al. 2006). Some address the fact that the CMIP3/IPCC AR4 simulations show sea ice declines less rapid than the observations and attempt to correct for it. Published projections, though with varying definitions of what constitutes ice-free, all project an ice-free Arctic ocean somewhere between 2037 (Wang and Overland, 2009) and the end of the century. Predictions of earlier ice-free dates so-far seem to be confined to conference presentations, media-coverage, the blogosphere, and testimony before to the UK parliament.

Extrapolation

A different class of predictions are based on simple extrapolation using historical sea ice extent, concentration, or volume. An example is included in the materials presented by the so-called ‘Arctic Methane Emergency Group’ who show extrapolations of PIOMAS data and warn about the potential of a seasonally ice-free Arctic ocean in just a few years. So does it make sense to extrapolate sea ice volume for prediction? In order to do a successful extrapolation several conditions need to be met. First, an appropriate function for the extrapolation should be chosen. This function needs to either be based on the underlying physics of the system or needs to be justified as appropriate for future projections beyond just fitting the historical data.

But what function should one choose? Since we don’t really have data on how the trajectory of the Arctic sea ice evolves under increased greenhouse forcing, model projections may provide a guide about the shape of appropriate function. Clearly, linear, quadratic or exponential functions do not properly reflect the flattening of the trajectory in the next few decades seen for example in the CCSM4 (Fig 3). The characteristic flattening of this trajectory, at first order, arises from the fact that there is an increasingly negative (damping) feedback as the sea ice thins described by Bitz and Roe (2004) and Armour et al. (2011). The thick ice along the northern coast of Greenland is unusually persistent because there are on-shore winds that cause the ice to drift and pile-up there. So extrapolations by fitting a function that resembles a sigmoid-shaped trajectory may make more sense, but even that, as shown in the figure, yields a much earlier prediction of an ice-free Arctic than can be expected from the CCSM4 ensemble.



Figure 3. CCSM4 AR4 ensemble and PIOMAS September mean arctic ice volume. Exponential and sigmoid (Gompertz) fits to PIOMAS data are shown. Note that the 1979-2011 September mean of the CCSM4 ensemble has about 30% higher sea ice volume than PIOMAS. To visualize the difficulty in choosing an appropriate extrapolation function based on PIOMAS data we shifted the CCSM4 time series forward by 20 years to roughly match the mean ice volume over the 1979-2011 fitting period.

But there is a second issue that may foil prediction by extrapolation: The period over which the function is fit must be sufficiently long to include adequate long-term natural variability in the climate system. The goodness of fit over the fitting period unfortunately may be misleading. Whether or not this is the case for sea ice extent or volume is an open question. The sea ice trajectory shows considerable natural variability at various time scales on top of the smoother forced response to changes in greenhouse gases. Periods of rapid decline are followed by slower periods of decline or increases. By fitting a smooth function to a sea ice time series (e.g. PIOMAS) one might easily be tempted to assume that the smooth fit represents the forced (e.g. greenhouse) component and the variation about the curve is due to natural variability. But natural variability can occur at time scales long enough to affect the fit. We have to remember that part of the observed trend is likely due to natural variability (Kay et al. 2011, Winton, 2011) and may therefore have little to do with the future evolution of the sea ice trajectory. This is visualized in figure 4 where ensemble members from the CCSM4 AR4 runs are fit with S-shaped (Gompertz) functions using the 1979-2011 period to estimate the parameters. The differences between the ensemble members, reflecting natural variability, yield vastly different extrapolated trajectories. Natural variability at these time scales (order of 30 years) may very well make prediction by extrapolation hopeless.



Figure 4. CCSM4 AR4 ensemble with sigmoid (Gompertz) fits. Light vertical lines represent fitting period for ensemble members (1979-2011).

In summary, we think that expressing concern about the future of the Arctic by highlighting only the earliest estimates of an ice-free Arctic is misdirected. Instead, serious effort should be devoted to making detailed seasonal-to-interannual (initial-value) predictions with careful evaluations of their skill and better estimates of the climate-forced projections and their uncertainties, both of which are of considerable value to society. Some effort should also target the formulation of applicable and answerable questions that can help focus modeling efforts. We believe that substantially skillful prediction can only be achieved with models, and therefore effort should be given to improving predictive modeling activities. The best role of observations in prediction is to improve, test, and initialize models.

But when will the Arctic be ice free then? The answer will have to come from fully coupled climate models. Only they can account for the non-linear behavior of the trajectory of the sea ice evolution and put longer term changes in the context of expected natural variability. The sea ice simulations in the CMIP5 models are currently being analyzed. This analysis will reveal new insights about model biases, their causes, and about the role of natural variability in long-term change.It is possible that this analysis will change the predicted timing of the “ice free summers” but large uncertainties will likely remain. Until then, we believe, we need to let science run
its course and let previous model-based predictions of somewhere between “2040 and 2100″ stand”

References

Bitz, C. M., and G. H. Roe (2004), A mechanism for the high rate of sea ice thinning in the Arctic Ocean, J Climate, 17(18), 3623-3632.
Boe, J. L., A. Hall, and X. Qu (2009), September sea-ice cover in the Arctic Ocean projected to vanish by 2100, Nature Geoscience, 2(5), 341-343.
Hibler, W. D. (1980), Modeling a Variable Thickness Sea Ice Cover, Monthly Weather Review, 108(12), 1943-1973.
Holland, M. M., C. M. Bitz, and B. Tremblay (2006), Future abrupt reductions in the summer Arctic sea ice, Geophys. Res. Lett, 33(23), 5.
Johnson, M., et al. (2012), Evaluation of Arctic sea ice thickness simulated by Arctic Ocean Model Intercomparison Project models, J. Geophys. Res., 117, C00D13.
Kay, J. E., M. M. Holland, and A. Jahn (2011), Inter-annual to multi-decadal Arctic sea ice extent trends in a warming world, Geophys. Res. Lett, 38.
Lindsay, R. W. (2010), New Unified Sea Ice Thickness Climate Data Record, Eos Trans. AGU, 91(44), 405-416.
Lindsay, R. W., J. Zhang, A. J. Schweiger, and M. A. Steele (2008), Seasonal predictions of ice extent in the Arctic Ocean, J.Geophys.Res., 113(C2), 11.
Lindsay, R. W., and J. Zhang (2006), Assimilation of ice concentration in an ice-ocean model, Journal of Atmospheric and Oceanic Technology, 23(5), 742-749.
Rothrock, D. A., Y. Yu, and G. A. Maykut (1999), Thinning of the Arctic sea-ice cover, Geophys. Res. Lett, 26(23), 3469-3472.
Schweiger, A. J., R. Lindsay, J. Zhang, M. Steele, H. Stern, and R. Kwok (2011), Uncertainty in modeled Arctic sea ice volume, J. Geophys. Res., 116, C00D06.
Tietsche, S., D. Notz, J. H. Jungclaus, and J. Marotzke (2011), Recovery mechanisms of Arctic summer sea ice, Geophys. Res. Lett, 38.
Thorndike, A. S., D. A. Rothrock, G. A. Maykut, and R. Colony (1975), Thickness Distribution of Sea Ice, J.Geophys.Res., 80(33), 4501-4513.
Wang, M. Y., and J. E. Overland (2009), A sea ice free summer Arctic within 30 years?, Geophys. Res. Lett, 36, 5.
Winton, M. (2000), A reformulated three-layer sea ice model, Journal of Atmospheric and Oceanic Technology, 17(4), 525-531.
Winton, M. (2011), Do Climate Models Underestimate the Sensitivity of Northern Hemisphere Sea Ice Cover?, J Climate, 24(15), 3924-3934.
Zhang, J., D. R. Thomas, D. A. Rothrock, R. W. Lindsay, Y. Yu, and R. Kwok (2003), Assimilation of ice motion observations and comparisons with submarine ice thickness data, J.Geophys.Res., 108(C6), 3170, DOI: 3110.1029/2001JC001041
Zhang, J., and D. A. Rothrock (2003), Modeling global sea ice with a thickness and enthalpy distribution model in generalized curvilinear coordinates, Monthly Weather Review, 131(5), 845-861.
Zhang, X. D., and J. E. Walsh (2006), Toward a seasonally ice-covered Arctic Ocean: Scenarios from the IPCC AR4 model simulations, J Climate, 19(9), 1730-1747.
Zhang, J., M. Steele, and A. Schweiger (2010), Arctic sea ice response to atmospheric
forcings with varying levels of anthropogenic warming and climate variability, Geophys.
Res. Lett, 37 (L20505)

302 Responses to “Arctic Sea Ice Volume: PIOMAS, Prediction, and the Perils of Extrapolation”

  1. 201
    MacDoc says:

    Have not read all the responses but great article.
    Have a question.

    Is there a point that may be coming or past that the positive feedback of additional open water in the warming in the Arctic will be discernible.

    This may be tangled up with warm additional North Pacific waterflow through newly unimpeded channels.

    Both these should be accelerants to a slow consuming burn off of the ice pack in the Arctic. Is there a discernible point, maybe in a model, that includes reduced albedo in the summer, that might show an acceleration of melting above the average temperature increase curve for the region so that ocean warmth has an increasing role over atmospheric??

    ( yeah yeah not the clearest question but hey just off 30 hours of Australia to Canada over the pole. )

  2. 202
    Ray Ladbury says:

    Paul Beckwith: “I would rather be the chess master that sees the pattern amongst all the pieces, consider the strategy and tactics that the whole board and the entirety of pieces dictates,and projects where the game is headed and what the other player Earth is liable to do,as opposed to being one of the pieces myself.”

    This attitude is precisely the problem. The human brain is a machine for recognizing patterns, whether they are there or not. Unless we constrain our pattern recognition with empirical data, we will be spectacularly wrong. What is more, since we are rationalizing animals rather than rational ones, we will merely confirm our prejudices by finding patterns in noise.

    Paul, I’ve no doubt you are a smart guy. But Freeman Dyson is a smart guy, and he is spectacularly wrong about climate change. Earth is the only chessmaster, and we are all just pieces on the board. The only difference is how much damage the pieces inflict on each other.

  3. 203

    #197–“I would rather “hand wave” and be correct rather than “mechanistic” or “statistical” and be wrong.”

    I suppose I would, too–but what are the odds that that is really the relevant choice?

  4. 204

    #200–Jim, the subject under discussion was allegedly ice-free periods in the Arctic in 1934 and 1953. While the data available does not allow a complete evaluation of the state of the ice in those years, it is more than good enough to rule out anything like an ‘ice-free’ status. Thus Gavin’s tag of “implausible” was not only justified, it was charitable.

    If you wish to discuss climate models, that is a whole other question. But at least take notice that you are attempting to change the subject.

    And on that subject, I will simply note that your assertion:

    “The warming of the 1930′s-40′s was natural, and whatever contribution of recent warming in the Arctic by CO2 is only trivial in that context.”

    …is just that–pure unsupported assertion; it doesn’t follow.

    (If we grant for the moment that the ‘model doesn’t represent reality’, then there is no basis in anything you wrote for any attribution–either to the ‘natural’ causes you claim, or to greenhouse forcings.)

  5. 205
    Hank Roberts says:

    Jim wrote:

    > ice coverage during the 1930′s to 40′s .. the source
    > … was pictures taken from submarines that surfaced
    > at the north pole with considerable open waters.

    Jim, it didn’t happen.
    Someone made it up.
    Someone fooled you.

    No submarines in the 1930s could do that.
    No submarines in the 1940s could do that.

    When the first nuclear subs did cross under the Arctic ice they tried finding open leads through which they could surface, with some successes and some failures.

    There was no extensive open water in the Arctic ice back then.

    You’ve been fooled. They can’t show you the pictures.
    The pictures you think you saw don’t exist.
    The Navy has made the original pictures and docs available.

    Why do you trust whatever source you rely on to believe what you have been repeating here?

    Where are you getting this?

  6. 206
    Radge Havers says:

    Paul Beckwith @ 197

    “I would rather “hand wave” and be correct rather than “mechanistic” or “statistical” and be wrong. Many scientists are like chess pieces on a chessboard, their knowledge and worldview is based on the given square that they occupy and the squares that they can legally move to.

    I would rather be the chess master that sees the pattern amongst all the pieces, “

    I’m sorry, I just can’t let this high-handed triteness pass.

    Look, “hand waving” refers to empty posturing designed to manipulate opinion with obfuscation and portentous overtones of “beyond-the-beyond”. It is not synthetic or h*listic. On the other hand, contrary to popular postmodernist b.s., scientific practice is a flexible and creative endeavor. And it works.

    It works.

    As for chess, WTF! The skill set required to play chess at the masters’ level is intense but very narrowly “mechanistic”, patterns and all. You must be thinking of backgamm*n where lucky idiots can occasionally beat masters, and then spout baloney about why that happens.

    Climate science is science. Science works. It works better than anything else we’ve got. Deal with it.

  7. 207
    Hank Roberts says:

    Some numbers on forcing (posted in reaction to the AMEG suggestion that of relaxing “pollution” [sic] rules for sulfates might be a wise move).
    Note their timing–hearings open on the new EPA coal plant rule

    http://www.springerlink.com/content/lm0024kv72t3841w/
    “The simulated magnitude of hydrological changes over land are much larger when compared to changes over oceans in the recent marine cloud albedo enhancement study since the radiative forcing over land needed (−8.2 W m−2) to counter global mean radiative forcing from a doubling of CO2 (3.3 W m−2) is approximately twice the forcing needed over the oceans (−4.2 W m−2). Our results imply that albedo enhancement over oceans produce climates closer to the unperturbed climate state than do albedo changes on land when the consequences on land hydrology are considered. Our study also has important implications for any intentional or unintentional large scale changes in land surface ….”

    (Are those reasonable numbers for the change needed in forcing?)

    “Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents. However, we note that the changes in precipitation, evaporation and P-E are dominated by small but significant areas, and given the highly idealized nature of this study, a more thorough and broader assessment would be required for proposals of altering marine cloud properties on a large scale.” http://www.springerlink.com/content/9569172415150486/
    Climate Dynamics
    Volume 37, Numbers 5-6 (2011), 915-931, DOI: 10.1007/s00382-010-0868-1
    Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle
    G. Bala, Ken Caldeira, Rama Nemani, Long Cao, George Ban-Weiss and Ho-Jeong Shin

    (Caldeira is listed by the AMEG as having contributed to their work; I wonder if he agrees with whatever it is they plan to propose sometime)

    http://www.int-res.com/abstracts/cr/v42/n2/p155-160/
    “… a relatively simple, environmentally acceptable, double-acting mechanism for increasing the earth’s albedo emerges. It is a low-level environmental intervention that enhances a mechanism already active in nature by increasing the foam fraction of the ocean surface. Bubble rafts increase the optical reflectivity of the ocean and when bubbles burst, they launch seasalt particles that loft and increase the number concentration of cloud droplets in the marine boundary layer, thus increasing the reflectivity of stratocumulus. A strategy based on recent research for producing microbubbles appears to be the best option for large-scale use.”

    Picture the ocean covered with rafts of foamy bubbles instead of ice.
    Imagine what that will do to photosynthesis in the upper ocean layers.

    See generally articles citing Bala: Problems with geoengineering schemes to combat climate change

    See also Taleb on “Black Swans” — “… everybody knows that you need more prevention than treatment, but few reward acts of prevention.”

    See also There Was An Old Lady Who Swallowed A Fly

  8. 208

    #200, Jim Steele,

    It seems to me that you are missing the point.

    In figure 4d the anomaly appears, but at a different time (they state the X axis in that plot is arbitrary). This is explained in the adjacent column at the top of page 4 – assuming you’re using the Tellus copy and not a pre-print.

    The point of this is that; the forced response should appear in all ensemble members as a consistent feature but incidents of internal variability should appear at different times or not at all*. Johanessen et al conclude that the consistent appearance of recent warming with GHGs simulated supports the interpretation that the current warming is a forced response to GHGs, of which the increase is overwhelmingly human driven. Whereas the appearance of similar warming events to the 1920/30s event at different times, with that warming event not being consistenly present in all ensemble members at the same times is evidence that it was an outcome of internal variability, not a forced response. Furthermore as Johanessen et al point out the spatial structure of the two warmings is different, a point also stressed by Overland et al, 2008, “”The recent Arctic warm period”, Tellus.

    *See also Gillett et al, 2008, “Attribution of polar warming to human influence” wherein figure 1a shows the same behaviour.

    Finally it is not an ‘arbitrary’ amount of sulphate aerosols.
    http://cera-www.dkrz.de/WDCC/ui/Compact.jsp?acronym=MP01GS01

    None of this technical discusssion changes the salient fact that the authors of the papers you cite do not agree with the conclusions you draw.

  9. 209
    Jim Steele says:

    Hank,

    Why do you persist in talking condescendingly to me like I was duped by false photographs. It was never the point of my argument and was something I myself said provided little weight to the discussion. The picture I referred to as creating the “speculation” of open water was not fabricated but is part of the naval archives, http://www.navalhistory.org/wp-content/uploads/2010/11/uss_skate_north_pole1.jpg Their caption along with the picture was “The only USS Skate (SSN-578) made submarine history on 11 August 1958 when it became the first submarine to surface at the North Pole.” The misinterpretations you want to focus on is merely the date of when that picture was taken. Whatever the date of the picture, it has a too limited scale to advance an argument one way or another, but you continue to drag this straw dog throughout the thread. Perhaps you lack any other ammunition.

    If you want to discuss Arctic conditions and open waters, then we must address the natural warm temperatures that Arctic scientists clearly observed in the 1930’s and 40’s. We must be able to discuss how those warm water incursions that lay below the surface for 15 years can affect sea ice. Or how freezing winds can open the waters, as well as remove multi-year ice, built from converging winds, that resisted annual melting. CO2 radiative heating only contributed a trivial amount of warming and has had no impact on expanding Antarctic Ice. Much of the Arctic’s open waters in the west were created by winds off the coast of Siberia that were so cold that any added heat from CO2 would be meaningless. Read Rigor 2002. Changes in the PDO and NAO speed up the gyres and increase the flow of warm waters entering the Arctic . In the North Atlantic sector it is this inflow to the Barents Sea and subsequent feedbacks that Bengstonn 2004 refers to as maintaining open waters and Arctic warmth. Furthermore removal of ice not only allows greater heat flux but re-couples the atmosphere to the oceans thereby generate more turbulence that brings warmer waters to the surface. As Rigor rightfully asked “are warmer temperatures due to less ice, or did warmer temperatures cause less ice?” No one has yet to definitively proven the latter. As the PDO has gone negative, so have the warm incursions from the Pacific and the Bering Sea is now showing signs of growing sea-ice. Nature will soon reveal the power of CO2 versus oscillation in the next 20 years as those oscillations trend negative and deny the Arctic with warm waters.

    But you do not discuss that science. instead yo choose to hang your hat on “debunking” the date that the Skate surfaced at the North Pole, like that proves anything one way or another. You are purposely obscuring the issues.

  10. 210

    Jim Steele@209: “Why do you persist in talking condescendingly to me like I was duped by false photographs.”

    Here’s why:

    From your comment #179: “Indeed, there is no way to truly compare ice coverage during the 1930′s to 40′s but the source of that speculation was pictures taken from submarines that surfaced at the north pole with considerable open waters.”

    Maybe you misspoke.

  11. 211
    tamino says:

    Re: #209 (Jim Steele)

    It’s not just that the date of the photograph is different than has been claimed. It’s that the photograph was not taken at the north pole. If you can show us any photograph of a submarine surfacing at the north pole in open water, please do so. Be sure to provide documentation of its location, because at this site we’re real skeptics, not fake ones.

    As for refusing to discuss the science, you seem to be the one doing that. I’ve already pointed you to data for Arctic sea ice coverage which contradicts the claim that ice cover was anywhere near as low as today. You don’t seem to want to discuss that. I also pointed you to data for Arctic temperature which shows that it has warmed considerably over just the last decade, so that presently the Arctic is far warmer than it ever was in the 20th century. You don’t seem to want to discuss that either.

    If you get the impression that people are treating you condescendingly, perhaps it’s because you have been evasive and mendacious. When you fail to acknowledge, let alone address, proof that your claims are false — what do you expect?

  12. 212

    #209–“You are purposely obscuring the issues.”

    So why are you, Jim, choosing to respond to the submarine issue, but not to specific citations regarding the state of the ice?

    If you wish to discuss the various things you list, perhaps a good start would be to specify the sources of your information

    –Which scientists observed Arctic warmth? Where and when? How warm exactly was it?

    –Which “warm water incursions”, and when did this happen?

    –Which ‘freezing winds?’ When?

    –When was ‘CO2 radiative heating’ a ‘trivial’ contribution? How was this measured?

    –When did ‘winds off the coast of Siberia’ create open waters? And how is this attribution made?

    As it is, it’s very unclear what you are trying to say. Though again, you do seem to be changing the subject; now it’s not ice so much, nor submarines, but ‘freezing winds’, the NAO and the PDO.

    At least you did cite Rigor 2002, and Bengstonn 2004. Off to see what they have to say.

  13. 213
    dhogaza says:

    Jim Steele:

    Whatever the date of the picture, it has a too limited scale to advance an argument one way or another

    Bullshit. It’s clear she found a lead in the ice and surfaced in the lead, surrounded by pack ice.

    FROM THE VERY PAGE YOU CITE:

    USS Skate (SSN-578) hung below the Arctic ice like a matchstick suspended an inch from the ceiling of a large room. A knot of sailors in the control room stared intently at an instrument inscribing patterns of parallel lines on a rolling paper tape. The pattern looked like an upside down mountain range.

    “Heavy ice, ten feet,”said one of the sailors.

    Suddenly the lines converged into a single narrow bar. “Clear water!” the sailor called out.

    A wrong move or a miscalculation would endanger the mission or even the ship. Calvert continued to peer through the eyepiece. When the top of the periscope came within sixty feet of the surface, he spotted heavy ice to the side. He flipped the prism to look straight up, but saw nothing except the same blurred aquamarine. Sweat appeared on his forehead as he felt all eyes in the control room bear down upon him. If the sub rose too slowly, it could drift away from the opening. If it rose too quickly and struck ice, the collision could tear open the pressure hull and send the sub and all ninety men on board to the bottom.

    The submarine’s black hull stood out in stark relief against the deep blue of the calm lake in which the ship now floated. Beyond the lake, stretching to the horizon in every direction, was the stark white of the permanent polar ice pack. The officer who had climbed to the bridge with Calvert called the skipper’s attention to the port side of the ship. There a full grown polar bear was climbing slowly out of the water and up onto the ice.

    Now what were you saying about the experience of the USS Skate not being sufficient to disprove claims that the North Pole was ice free in 1958?

    I’m sure you read the entire page, Jim, not just the single line you quote.

    ‘Fess up.

  14. 214
    MARodger says:

    Jin Steele @209
    Who ever introduced this ‘straw man’ and what ever his age (1930/40s or 1959), he (the straw man) is no friend of mine. Can we please now shoot him dead and bury him?
    Yes, the photo you link to @209 is a picture of USS Skate. The USS Skate did surface at the North Pole in 1959 as the photo caption says but the picture was not taken there.
    The link below has pictures (below the graphs & maps) of the Skate at the North Pole in 1959. There is no open water that I can see.
    http://www.science20.com/chatter_box/arctic_ice_october_2010

  15. 215
    dhogaza says:

    Jim Steele:

    If you want to discuss Arctic conditions and open waters, then we must address the natural warm temperatures that Arctic scientists clearly observed in the 1930′s and 40′s.

    <a href="http://tamino.wordpress.com/2011/09/17/cold-cherries-from-joe-daleo/&quot;Except it wasn’t as warm in the arctic in the 1930s and 1940s as it is today.

    Take-home image for people like Jim Steele who like pictures unfettered with context.

    Regarding your citing decade-old papers pointing out that the proximate cause of the loss of arctic ice isn’t solely due to warming air temps in the arctic, but rather warm water incursion, etc, well, yes, that’s the mainstream view and isn’t controversial. You have a point?

  16. 216

    Any help on “Bengstonn 2004?” Couldn’t turn it up.

  17. 217
    dhogaza says:

    Jim Steele:

    Their caption along with the picture was “The only USS Skate (SSN-578) made submarine history on 11 August 1958 when it became the first submarine to surface at the North Pole.”

    That’s not a caption. It’s the lead paragraph to the article. The photo itself is captionless.

  18. 218
    sidd says:

    Mr. Steele writes on the 21st of April 2012 at 1:29 pm:
    “CO2 radiative heating only contributed a trivial amount of warming…

    “…winds off the coast of Siberia that were so cold that any added heat from CO2 would be meaningless.”

    What do you imagine that the radiative warming due to CO2 over the rest of the globe is doing to the temperature of the ocean in the far north ? Oddly enuf, a new paper by Levitus et al in GRL answers that in Figure 3.

    “…the flow of warm waters entering the Arctic .”

    Do you imagine that the flow of warm water into the Arctic is not due to global radiative imbalance caused by CO2 ?

    “Nature will soon reveal the power of CO2 versus oscillation in the next 20 years as those oscillations trend negative and deny the Arctic with warm waters.”

    Why yes, you do! Very well: You predict that the loss of sea ice will halt and reverse over the next two decades. I have a counter prediction: that we will see a seasonally ice free arctic before two decades are done.

    Now as to the Levitus paper: it is quite amazing to see that the extreme north Pacific and Atlantic keep warming in spite of the 5e19J/yr absorbed by the 300Gt/yr ice melt from PIOMASS or even the similar amount that it takes to melt Greenland at 250Gt/yr . Globally the oceans are warming at surface and at depth. I do not see how a perennial arctic icecap can survive very long.

    sidd

  19. 219
    dhogaza says:

    Jim Steele:

    If you get the impression that people are treating you condescendingly, perhaps it’s because you have been evasive and mendacious.

    Googling for his posts at WUWT won’t do anything to change your opinion, either. Just sayin’ :)

  20. 220
    dhogaza says:

    The link below has pictures (below the graphs & maps) of the Skate at the North Pole in 1959. There is no open water that I can see.

    No, no, she really did surface in a lead at the Pole in 1958. The problem is that the official account makes it clear that it was a small lead that was barely large enough for her to surface in, and that she had to surface very carefully after carefully searching for a suitable lead.

    That’s why her sail was strengthened, and why subsequent nuke subs have strengthened sails: the only *reliable* way to surface in winter in the midst of the Arctic Sea is to smash through the ice.

    The whole experience screams “those who claim the north pole [or pretty much anywhere else in the Arctic Ocean] was ice free in winters in the 1950s” is full of it. If the Skate’s experience supported such claims they wouldn’t’ve bothered spending the money to retrofit her sail, or to increase the expense of future subs by doing the same (sail and planes, actually).

  21. 221
    Hank Roberts says:

    https://duckduckgo.com/?q=Bengston++2004+climate

    ANNEX 1 : Climate Change Projections for the Arctic & the North
    Arctic Climate Impact Assessment , Cambridge University Press, 1042 pp. Johannessen, O.M., L. Bengston, et al., 2004. Arctic climate change, observed and modeled temperature …
    http://ccrm.cier.ca/downloads/Annex_1_Climate_Change_Projections_for_the_Arctic_and_the_North.pdf

  22. 222
  23. 223
    Hank Roberts says:

    http://www.agu.org/pubs/crossref/pip/2012GL051094.shtml

    Observations reveal external driver for Arctic sea-ice retreat

    Key Points

    Internal variability as estimated from observations can’t explain sea-ice loss
    Superposition of a linear trend and internal variability explains sea-ice loss
    Observational sea-ice record shows no signs of self-acceleration

    Dirk Notz, Jochem Marotzke

    “The very low summer extent of Arctic sea ice that has been observed in recent years is often casually interpreted as an early-warning sign of anthropogenic global warming. For examining the validity of this claim, previously IPCC model simulations have been used. Here, we focus on the available observational record to examine if this record allows us to identify either internal variability, self-acceleration, or a specific external forcing as the main driver for the observed sea-ice retreat. We find that the available observations are sufficient to virtually exclude internal variability and self-acceleration as an explanation for the observed long-term trend, clustering, and magnitude of recent sea-ice minima. Instead, the recent retreat is well described by the superposition of an externally forced linear trend and internal variability. For the externally forced trend, we only find a physically plausible strong correlation with increasing atmospheric CO2 concentration. Our results hence show that the observed evolution of Arctic sea-ice extent is consistent with the claim that virtually certainly the impact of an anthropogenic climate change is observable in Arctic sea ice already today.”

  24. 224
    Jim Steele says:

    dhogaza re:Take-home image for people like Jim Steele who like pictures unfettered with context.

    I really appreciate how simplify things for me, but you really do need a tad more context to your pictures. What latitudes for example may be helpful. What stations were used and what were omitted. And what homogeneity algorithms did they run. NASA always gets the same shape for all its graphs. Do you think Bengstonn and others were deceiving us with their graphs that tell a different story?

  25. 225
    Hank Roberts says:

    Looks like a reply didn’t make it in? Try “Bergston 2004”
    AppendixA:References–DraftFinalReport
    Appendix A. References. 2004. Impacts of a Warming Arctic: Arctic Climate Impact Assessment. Cambridge: Cambridge University Press. http://www.acia.uaf.edu.
    climatechange.alaska.gov/aag/docs/aag_A-A_27Jan10.pdf

  26. 226

    #209, Jim Steele,

    CO2 radiative heating only contributed a trivial amount of warming [to the Arctic] and has had no impact on expanding Antarctic Ice.

    With regards the Arctic: As Gillett et al and Johanessen et al show – in models without the anthropogenic increase of greenhouse gasses the Arctic warming does not occur, add the GHG effect and the warming occurs in all ensembles. This is also apparent in Wang & Overland’s 2009 study “A sea ice free summer Arctic within 30 years?” Figure 1 of that study is shown here, showing September sea ice extent vs time:

    http://farm8.staticflickr.com/7275/7035602167_eeb93a8cae_o.jpg

    You can see that in all the models the natural forcing runs are level (grey trace) whereas the runs including anthropogenic forcings (coloured lines) decline. As I’ve shown, this is a common feature virtually all models, and I only say ‘virtually’ in case there is a model that doesn’t show this effect. So whilst the anthropogenic forcing is strongly amplified by processes in the Arctic, it is required to explain the changes in the Arctic.

    With respect to Antarctic sea ice Zhang 2006 “Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions.” identifies a possible mechanism that explains the increase in that sea-ice due to warming and increase in downwelling long wave radiation. The warming being a secondary effect of increased GHGs, the increased downwelling long wave a primary impact. In essence Zhang proposes that the warming factors reduce the growth of sea ice which reduces ocean overturning allowing increased stratification of the ocean which in turn reduces ocean heat flux available to melt ice. Hence the sea-ice grows.

    Read Rigor 2002…

    As Rigor rightfully asked “are warmer temperatures due to less ice, or did warmer temperatures cause less ice?” No one has yet to definitively proven the latter.

    I’ve read it, I’ve also read some 170 papers on the changes in the Arctic, it’s my hobby. As I’ve hammered home the point above – the changes in the Arctic don’t happen without anthropogenic forcings. And as I’ve also tried to inform you in post #208, there are two papers that find the 1920-30s warming is markedly different from the current warming. These papers were published after Rigor 2002.

    Warm waters from the Atlantic are a factor, however as Spielhagen et al shows the recent influx of Atlantic waters is exceptional in the context of the last 2000 years. Coincidence?.

    Warm waters from the Pacific are also a factor, however the recent influx and role in 2007 is not due to the PDO but the Arctic Dipole (AD) (Zhang J et al, Wang et al). And the AD has become the dominant mode of variability in the Arctic since 2003 replacing the AO (Zhang X). Coincidence?.

    The warming in the Arctic reverses a long term cooling and is exceptional in the context of the last 2000 years (Kaufman et al). Coincidence?.

    The recession of the Arctic sea-ice is exceptional in the context of the last 1400 years (Kinnard et al). Coincidence?.

    The reason you like papers from the late 1990s and early 2000s is that then it was possible to view the changes as possibly due to natural factors. There has been a lot of further research since then.

    Nature will soon reveal the power of CO2 versus oscillation in the next 20 years as those oscillations trend negative and deny the Arctic with warm waters.

    Stop waving your hands around and be specific. I’ll start for you.

    We know the AO/NAO hasn’t driven the warming and ice loss of the 2000s. It had a role due to increased ice fluxes through the Fram Strait in the early 1990s, when the AO/NAO was very positive. But since then it has gone neutral (ref). The PDO has been in a positive phase, now it is clearly going negative (ref), yet the losses continue – 2011 nearly matched 2007 despite the weather not being as favourable for ice loss. The AMO has been negative then gone positive during the period of ice loss (ref 3rd graph down), that is if we are to believe in the AMO at all (ref).

    So where is the consistent pattern of coincident natural ‘oscillations’ and how do they generate such exceptional changes in the Arctic. Why didn’t they do so before? Why is it that the last time Arctic sea ice was in a worse state than now was in the early to mid Holocene, when an external forcing (insolation) was substantially higher than now? Doesn’t this suggest that such extreme and exceptional conditions are driven by external forcings like insolation, or indeed greenhouse gas emissions?.

    Kaufman et al, 2009, “Recent Warming Reverses Long-Term Arctic Cooling.”

    Kinnard et al, 2011, “Reconstructed changes in Arctic sea ice over the past 1,450 years.”

    Spielhagen et al, 2011, “Enhanced Modern Heat Transfer to the Arctic by Warm Atlantic Water.”

    Wang et al, 2009, “Is the Dipole Anomaly a major driver to record lows in Arctic summer sea ice extent?”

    Zhang J et al, 2008, “The role of Pacific water in the dramatic retreat of arctic sea ice during summer 2007.”

    Zhang X et al 2008, “Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system.”

  27. 227

    Thanks, Hank. It’s in the references of the Annex you linked. The reason it was so hard to find is that “Bengstonn”–really “Bengston,” if this is the correct reference–is not the lead author. The correct citation appears to be:

    Johannessen, O.M., L. Bengston, et al., 2004.
    Arctic climate change, observed and modeled
    temperature and sea ice variability, Tellus
    56A.4:328-341.

    That the one, Jim?

  28. 228

    And from the abstract:

    SAT observations and model simulations indicate that the nature of the arctic warming in the last two decades is distinct from the early twentieth-century warm period. It is suggested strongly that the earlier warming was natural internal climate-system variability, whereas the recent SAT changes are a response to anthropogenic forcing. The area of arctic sea ice is furthermore observed to have decreased ∼8 × 105 km2 (7.4%) in the past quarter century, with record-low summer ice coverage in September 2002. A set of model predictions is used to quantify changes in the ice cover through the twenty-first century, with greater reductions expected in summer than winter. In summer, a predominantly sea-ice-free Arctic is predicted for the end of this century.

    Link:

    http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0870.2004.00060.x/abstract

  29. 229
    dhogaza says:

    Jim Steele:

    I really appreciate how simplify things for me, but you really do need a tad more context to your pictures. What latitudes for example may be helpful.

    Well, Tamino and I both provided links to his full article, why don’t you read it?

    And if you have questions about his methodology, or want to argue he’s wrong, why you can comment over there and he’ll engage you directly.

    He’s a professional statistician who specializes in time-series analysis, though, who suffers fools badly, so you might not find the experience particularly enjoyable.

    Enjoying your time outside the alternative-universe cocoon of WUWT? The real world’s a rather harsher place, isn’t it?

  30. 230
    Hank Roberts says:

    I’m still looking for “Bengstonn 2004” — what’s that refer to?

    Google Scholar: – “Bengstonn 2004” – did not match any articles.

    So I have no idea what you’re looking at, Jim. Sorry, but this is the reason for citing sources. What’s your source?

    Could it be this?
    Johannessen OM, Bengtson L, Miles MW, Kuzmina SI, Semenov VA, Alekseev
    GV, Nagurnyi AP, Zakharov VF, Bobylev LP, Pettersson H, Hasselmann K,
    Cattle HP (2004) Arctic climate change: observed and modeled temperature and
    sea-ice variability. Tellus 56(A):328-341

    Jim, when you post these claims and don’t tell us where you’re getting them, it’s a snipe hunt — highly entertaining for the snipe, but not helpful for the conversation.

    Where are you getting the 1930s and 1940s Arctic submarine story?
    Where are you getting whatever the 2004 paper is?

    If all you have is a second- or third-hand anecdote, fine, but WHERE IS IT?
    We can look stuff up, given the least clue about what you’re relying on.

    Patience furthers.

  31. 231
    dhogaza says:

    And, Jim, no “thank you” for your being skewered on the USS Skate’s experience not being sufficient to argue one way or another about the north pole being ice-free in the late 1950s, now that it’s been exposed as bullshit for 1958 by your very own link and 1959 by a photo of the ash-scattering ceremony?

    If you can’t bring yourself to say “thank you”, a sincere “I’ll never lie about this again” would be sufficient.

    You can make the same statement regarding arctic temps over at tamino’s after you read the article and thank him (over there) for his excellent analysis.

  32. 232
    dhogaza says:

    Jim Steele:

    NASA always gets the same shape for all its graphs. Do you think Bengstonn and others were deceiving us with their graphs that tell a different story?

    Not only NASA, but others including some of the more intelligent skeptics that inhabit lucia’s blog, “The Blackboard”.

    It’s an interesting mindset … “NASA always gets the same shape” (therefore they’re wrong).

    As far as the paper you continuously mention, where’s a link? We have no idea as to what it says. Even if you represent the paper’s results correctly, though, there’s only one reason that you’d pin your faith on a single paper rather on the vast amount of work done by many other scientists that are in broad agreement on a different conclusion:

    Ideology.

    When one paper’s an outlier, it’s usually wrong, especially if it’s an older paper (2004) whose conclusions have not been supported by more recent work.

    However, since you apparently can’t provide a link to the paper’s contents, I can safely assume that 1) it doesn’t exist or 2) it doesn’t say what you think it says or 3) it’s been thoroughly refuted or outdated by subsequent work.

    Given that your link to the naval history account of the USS Skate’s surfacing at the north pole skewered your claims about the possibility of the north pole having been ice free in 1958, I’ll take door number two from the choices above.

  33. 233
    Hank Roberts says:

    My best guess is:

    http://journals.ametsoc.org/doi/abs/10.1175/1520-0442%282004%29017%3C4045:TETWIT%3E2.0.CO%3B2
    Bengtsson, Lennart, Vladimir A. Semenov, Ola M. Johannessen, 2004: The Early Twentieth-Century Warming in the Arctic—A Possible Mechanism. J. Climate, 17, 4045–4057.
    doi: http://dx.doi.org/10.1175/1520-0442(2004)0172.0.CO;2

    “The huge warming of the Arctic that started in the early 1920s and lasted for almost two decades is one of the most spectacular climate events of the twentieth century. During the peak period 1930–40, the annually averaged temperature anomaly for the area 60°–90°N amounted to some 1.7°C. Whether this event is an example of an internal climate mode or is externally forced, such as by enhanced solar effects, is presently under debate. This study suggests that natural variability is a likely cause, with reduced sea ice cover being crucial for the warming. A robust sea ice–air temperature relationship was demonstrated by a set of four simulations with the atmospheric ECHAM model forced with observed SST and sea ice concentrations. An analysis of the spatial characteristics of the observed early twentieth-century surface air temperature anomaly revealed that it was associated with similar sea ice variations. Further investigation of the variability of Arctic surface temperature and sea ice cover was performed by analyzing data from a coupled ocean–atmosphere model. By analyzing climate anomalies in the model that are similar to those that occurred in the early twentieth century, it was found that the simulated temperature increase in the Arctic was related to enhanced wind-driven oceanic inflow into the Barents Sea with an associated sea ice retreat. The magnitude of the inflow is linked to the strength of westerlies into the Barents Sea. This study proposes a mechanism sustaining the enhanced westerly winds by a cyclonic atmospheric circulation in the Barents Sea region created by a strong surface heat flux over the ice-free areas. Observational data suggest a similar series of events during the early twentieth-century Arctic warming, including increasing westerly winds between Spitsbergen and Norway, reduced sea ice, and enhanced cyclonic circulation over the Barents Sea. At the same time, the North Atlantic Oscillation was weakening.”

    No surprise there, that I can find.

    Or are you referring to something else?

  34. 234
    Hank Roberts says:

    PS for Jim — if you are referring to
    http://journals.ametsoc.org/doi/abs/10.1175/1520-0442%282004%29017%3C4045%3ATETWIT%3E2.0.CO%3B2
    then you should page down and read the citing papers, or at least scan them.

  35. 235

    Sorry I’ve not really paid much attention to this issue of what paper is Bengtsson et al 2004 as mentioned by Jim Steele in post #179. As can be seen from my reply to him, post #184 I’ve known precisely what that paper was all along.

    Yes Hank, you’ve got it, and you’re quite right – no surprises although it is interesting nonetheless. The paper basically proposes a mechanism for the Arctic warming of the 1920s and 1930s, it supports the idea that what is going on now cannot be naively used to ‘excuse’ GHGs from what is going on now.

    There’s a paywall free pdf of it here:
    http://www.nerc-essc.ac.uk/~olb/PAPERS/len19.pdf

  36. 236
    dhogaza says:

    Having skimmed Bengtsson et al 2004 …

    1. The anomaly they’re studying (arctic warming of 1.7C from 1920-1940) matches the amount of warming for the same period shown in Tamino’s analysis linked to above. If Jim rejects the last few decades of that analysis he’ll have to explain why the analysis matches his beliefs for 1920-1940 (and the mainstream reconstructions). It would be fun to see him do so at Tamino’s blog.

    2. The paper does not suggest that the anomaly in 1940 was higher than the anomaly when the paper was written (2003). Not sure why Jim cited the paper as evidence for his claim as it doesn’t appear to address the question.

    3. I think Jim’s arguing against a strawman view of climate science, i.e. the typical one that science ignores natural variation, changes in solar activity, etc in a belief that only changes in CO2 can affect climate. That’s silly if that’s what he believes science says.

    4. The paper states that the warming seen in 1920-1940 is about what’s expected over the next few decades due to increased CO2 forcing. ON TOP OF the warming already seen when the paper was written (2003), when it was already warmer than the arctic than in 1940.

    5. As is usual when a denialist quotes a mainstream paper claiming that it challenges the scientific consensus, the paper does no such thing. The authors accept mainstream views on climate sensitivity, indeed, one of their arguments for natural variability being the cause for the 1920-1940 warming is that if increased CO2 forcing was the cause, then climate sensitivity to increased CO2 must be far higher than the consensus range. In other words, their explanation based on natural variability for this period of time *supports* the consensus view on climate sensitivity to increased CO2, if anything.

  37. 237
    Susan Anderson says:

    Changing the subject is a fake skeptic’s stock in trade. You will never pin them down to statements they made because they will blame the questioner for being “condescending” or some such.

    This is a serious website where some of the world’s best scientists are willing to engage with questions, even silly ones. Rather than come in with a chip on your shoulder big enough to sink you through all that ice, try an open mind and some true skepticism.

    It’s not painful to look at the truth. It’s unfortunate that so many people seem to need to come in with attitude and leave in ignorance when such a wealth of material is available to the interested reader.

    The rest of us, and those not speaking up, are learning more from this conversation about how people with stiffened bias are unable to take the fearful step toward reality.

  38. 238
    dhogaza says:

    Chris Reynolds, thanks for that link. The text-only version I skimmed doesn’t have the figures.

    Jim Steele:

    Shame on you! Figure 1 in the paper you worship shows that by 2000 arctic temps were much WARMER than the peak in 1940! How DARE you to cite it in support of your claim that “the temperatures in the Arctic during that time were remarkably similar to this current period and the subject of several peer reviewed papers”.

    That’s a pants-on-fire there, Jim.

    Of side interest, Tamino’s analysis of arctic temps look *remarkably* like Bengtsson et al 2004’s Figure 1, except for the fact that Tamino’s runs out another decade because, well, time has gone on (and temps have continued to rise).

    Here’s what I predicted earlier, before the paper had been rediscovered by Hank (though Chris, as he says, was well aware of it dozens of posts ago and already skewered Jim):

    However, since you apparently can’t provide a link to the paper’s contents, I can safely assume that 1) it doesn’t exist or 2) it doesn’t say what you think it says or 3) it’s been thoroughly refuted or outdated by subsequent work.

    Given that your link to the naval history account of the USS Skate’s surfacing at the north pole skewered your claims about the possibility of the north pole having been ice free in 1958, I’ll take door number two from the choices above.

    It looks like my choosing #2 – “it doesn’t say what you think it says” – basing that choice on your misrepresentation of the USS Skate’s surfacing at the north pole in 1958, was correct. Though I was overly polite in predicting misunderstanding rather than, as I suspect, outright dishonesty.

    ‘Fess up, Jim.

    Your credibility has vanished, just in case you’re wondering.

  39. 239
    dhogaza says:

    Jim Steele:

    NASA always gets the same shape for all its graphs. Do you think Bengstonn and others were deceiving us with their graphs that tell a different story?

    You really, really, need to apologize for this statement since figure 1 in Bengtsson et al 2004 clearly does *NOT* tell a different story. And to say this *after* Chris Reynolds posted a link to the full paper and stated the truth about the contents?

    Unforgiveable.

    You can get away with this crap at WUWT but not in the real world.

    Jim? We’re awaiting your apology.

  40. 240
    Hank Roberts says:

    Well, as soon as Jim wants to tell us where he got the mistaken ideas — submarines surfacing through the ice in the 1930s and 1940s, and this notion that one paper says something that’s not in it — we can look at the source and see if he misread it or it misinformed him.

    I’m betting on co2science.org — ‘fooled me once’ “source” for many people.

    Recaptcha says:
    _________________
    Libertas; eliblys

  41. 241
    350limit says:

    To Hank:
    I followed your link to Notz and Marotzke (#223). Using extent data up to 2010, they do not directly address the claim that the decline of extent in Arctic Sea Ice is linear vs the claim that it is accelerating. They address and dismiss self-acceleration via the ice-albedo effect. The section on external drivers dismisses all candidates for which data is available (solar irradiance, indices for AO and PDO, volcanoes, etc.) as being the cause of the downward trend leaving only atmospheric CO2 concentration as a plausible explanatory variable. They do not even admit the possibility of an unknown or unmeasured external driver leading to an acceleration of declining extent.
    The Sep average extent data from NSIDC for 1979-2011 has a maximum in 1996. The slope from 1979 to 1996 is -36,000 sq km. The downward slope for 1979-X for X>1996 increases every year for 15 years – acceleration for 15 years in a row. Is that a linear trend?
    This article by Axel Schweiger, Ron Lindsay, and Cecilia Bitz and the comments that follow give the strong impression that the Climate modeling community insists that this time series has a linear trend and will shout down anyone who disagrees with them. I do not understand this mindset that says, “Until we can find a way model reality, everyone else should ignore it.”

  42. 242
    dhogaza says:

    Hank Roberts:

    I’m betting on co2science.org — ‘fooled me once’ “source” for many people.

    Well, he does post at WUWT so we have a second candidate …

    I betcha a virtual beer that it’s WUWT :)

    The big question of the hour is … will he face up to his errors or run away to duplicate the same mistaken claims elsewhere?

  43. 243
    Hank Roberts says:

    Jim, I got your email claiming you’re being prevented from posting answers.

    But you didn’t include the citations in your email.

    Try again with the cites — Where did you read about the submarines-through-the-ice in the 30s and 40s? where does it say the chart in that paper shows what you said, instead of what I see in the PDF?

    You can use the same email.

  44. 244
    Hank Roberts says:

    OK, Jim, I found your cite at Spencer’s blog.
    It’s not convincing.
    At http://www.drroyspencer.com/2012/03/could-arctic-sea-ice-decline-be-caused-by-the-arctic-oscillation/#comment-41204 Jim Steele cites:

    Absence of evidence for greenhouse warming over the Arctic Ocean in the past 40 years (by title and author only, with a quote)

    Well, look — that’s from
    http://www.nature.com/nature/journal/v361/n6410/abs/361335a0.html
    Nature 361, 335 – 337 (28 January 1993); doi:10.1038/361335a0

    Jim, if this is the cite you’ve been hinting at in your email and claiming was being censored — now that I can finally look at where you got your info — that cite is from January 1993!!

    You could just have posted the actual cite and saved a whole lot of questions about where you were getting your statements — which you made sound like they were current information, mind.

    I still don’t find the source where you got the story about submarines surfacing in open water in the Arctic Ocean in the 1930s and 1940s. Have you posted it _anywhere_? I was sure I could find anything at Spencer’s that you would claim was censored at RC.

    Email still welcome. But you’ve got to give answers to support what you claim to be credible.

  45. 245
    Hank Roberts says:

    PPS — and, Jim, the scientists here who wrote the main post for this thread have cited that 1993 paper in their own published work. Overall it’s been cited 122 times in 19 years that Scholar finds. Really, it wasn’t news.

  46. 246
    Marcel Kincaid says:

    Do you think Bengstonn and others were deceiving us

    No, I think you have been deceived by cognitive dissonance.

  47. 247

    #247–Jim Steele got boreholed–and rightfully so, IMO, as his comment there was really not responsive, amounting basically to “Does too!”

    No mention, of course, of any specific sources, or any of the stuff he got called on. He’s another Pythonian “Black Knight.”

  48. 248
    Dan H. says:

    One must remember that Bengtsson, et. al., were only postulating a mechanism that could have caused the Arctic warming and sea ice reduction of the early 20th century. Their models showed that the mechanism is plausible.

    The idea that the Arctic was “ice-free” at this time seems “implausible,” to quote Gavin. The data shown from Johannessen shows that while a similar temperature rise occurred in the Arctic in the early and latter 20th century, the latter has resulted in a higher temperature (as stated by several posters). The models also suggested that the rise in Arctic temperatures at the time, corresponded with the observed reduction in sea ice. I would be curious as to how their sea ice reduction from the early 20th century compares to the recent reduction.

  49. 249

    Not only from this but from some other research we will have ice free summers for a very short time and how this will influence climate at all still we don’t know , but it won’t be positive for sure.

  50. 250
    Hank Roberts says:

    > Dan H.
    > … I would be curious as to how their sea ice reduction from
    > the early 20th century compares to the recent reduction.

    Chris posted a link to it:
    _________________
    “– no surprises although it is interesting nonetheless. The paper basically proposes a mechanism for the Arctic warming of the 1920s and 1930s, it supports the idea that what is going on now cannot be naively used to ‘excuse’ GHGs from what is going on now.

    There’s a paywall free pdf of it here:
    http://www.nerc-essc.ac.uk/~olb/PAPERS/len19.pdf
    ——————

    Look at the papers that have cited it — quite a few cites since it’s almost 20 years old. Note the names of the authors and compare them to the cites for the main post here.

    It’s odd (or not) to see such fascination with a paper mistakenly claimed to show something it doesn’t, that’s nearly 20 years old, that has no surprises in it, and that’s been part of the discussion in the field for, well, almost 20 years.

    Something special about this one for somebody. I wonder where it’s popular? Who’s the one originating the misstatements about it? And why do y’all trust whatever source you’re relying on to believe the misstatements?

    It mus be discouraging to scientists to see how aggressively people misunderstand, misstate, and confuse attempts to discuss their work.

    If only we had a two-track commenting system — one for real scientists and invited students interested in learning, and a shadow track for kibitzers.

    If someone competent to describe how the software would work well enough to guide a programmer would put it on Kickstarter or one of the many new similar science funding sites — I’d toss money at the idea. Oh, John?