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Likely causes of the recent changes in Arctic sea ice

by Judith Curry

A new paper by Polyakov, Kwok and Walsh is in press in the Bulletin of the American Meteorological Society, entitled: “Recent changes in arctic multi-year sea ice coverage and likely causes.”  This is the best paper I’ve seen on this topic, which clearly articulates the complexity of the issue.

Recent changes in arctic multi-year sea ice coverage and likely causes

Igor V. Polyakov, Ronald Kwok, and John E. Walsh

The full paper is available online [here].

From the paper’s conclusions:

This article addresses probable causes of the observed reduction of the Arctic Ocean’s 179 coverage of MYI [multi-year ice] over that past decade. There is evidence of the increasingly important role 180 of atmospheric thermodynamic forcing in shaping recent changes of the Arctic MYI. In addition to direct MYI melt due to high-latitude warming, the impact of enhanced upper- ocean solar heating through numerous leads in decaying Arctic ice cover and consequent ice bottom melting has resulted in an accelerated rate of sea-ice retreat via a positive ice-albedo feedback mechanism. The pan-Arctic role of this feedback is yet to be quantified. Analysis of satellite ice motion suggests that the role of ice export through straits connecting the Arctic Ocean with sub-polar basins may be elusive. This situation probably differs from the  situation that existed in the early to mid-1990s, when enhanced ice export through Fram  Strait was caused by anomalous winds associated with the positive Arctic Oscillation phase.  The possible long-lasting impact of anomalous winds such as those in 2004–05 or 2007  (especially when superimposed on a warming trend) on the state of MYI should not be ruled  out. An intriguing feature of the scenario described here is the potential contribution of  oceanic thermodynamic forcing to the recent changes of the high-latitude MYI coverage.  Available observations suggest a thermodynamic coupling between the heat of the ocean  interior and the sea ice. In the Canadian Basin, the impact of Pacific water warmth has been  recently documented. While vertical AW [Atlantic Water] heat fluxes are negligible in the Canadian Basin, turbulent mixing may be strong enough in the western Nansen Basin to produce a sizable  effect of AW heat on sea ice. In the eastern Eurasian Basin, double diffusion provides an  important alternative to weak turbulent mixing for upward AW heat transport. However, this contribution to sea-ice loss remains uncertain pending new field experiments that will provide estimates of upward AW heat fluxes.

The fact that the rate of MYI recovery observed in recent years shows a delay relative to thermodynamic forcing indicates that MYI is resistant to recovery. However, the relative roles of dynamic and thermodynamic factors in recent changes of the Arctic MYI cover remains to be determined. Quantifying these roles is a high priority if we are to develop reliable forecasts of the future state of Arctic ice coverage.

JC comment:  This paper clearly and authoritatively describes the complex interactions among ocean dynamics and heat transport, sea ice dynamics forced both by atmospheric winds and ocean currents, and atmospheric thermodynamic forcing in determining recent variations in multi-year sea ice extent.  Hence sorting dynamical versus thermodynamic factors and attribution to increased greenhouse gases is not at all straightforward.  Of more relevance than attribution is the development of reliable forecasts of the Arctic sea ice over the next few decades, which clearly requires consideration and integration of all these processes.

The Fat Lady has sung

Neven has declared that the fat lady is singing in terms of having reached the minimum sea ice extent.  NSIDC has the following announcement:

Arctic sea ice appears to have reached its lowest extent for the year. The minimum ice extent was the second lowest in the satellite record, after 2007, and continues the decadal trend of rapidly decreasing summer sea ice.

Please note that this is a preliminary announcement. Changing winds could still push ice flows together, reducing ice extent further. NSIDC scientists will release a full analysis of the melt season in early October, once monthly data are available for September.

What is relevant right now from my perspective is how rapidly the freeze-up will occur and with what spatial distribution; this is largely at the whim of weather patterns.  The recent uptick in sea ice extent is intriguing.  My research group has just submitted a paper for publication on the subject of autumn sea ice patterns as a precursor for wintertime snowfall and surface temperatures in the Northern Hemisphere.

New paper on the NCAR sea ice model

Improved sea ice shortwave radiation physics in CCSM4:  The impact of melt ponds and aerosols on Arctic sea ice

Marika M. Holland, David A. Bailey, Bruce P. Briegleb, Bonnie Light, Elizabeth Hunke

Abstract.  The Community Climate System Model, 4 has revisions across all components. For sea ice, the most notable improvements are the incorporation of a new shortwave radiative transfer scheme and the capabilities that this enables. This scheme uses inherent optical properties to define scattering and absorption characteristics of snow, ice and included shortwave absorbers and explicitly allows for melt ponds and aerosols. The deposition and cycling of aerosols in sea ice is now included and a new parameterization derives ponded water from the surface meltwater flux. Taken together, this provides a more sophisticated, accurate, and complete treatment of sea ice radiative transfer. In preindustrial CO2 simulations, the radiative impact of ponds and aerosols on Arctic sea ice is 1.1 W/m2 annually, with aerosols accounting for up to 8 W/m2 enhanced June shortwave absorption in the Barents/Kara Seas, and with ponds accounting for over 10 W/m2 in shelf regions in July. In 2XCO2 simulations with the same aerosol deposition, ponds have a larger effect whereas aerosol effects are reduced, thereby modifying the surface albedo feedback. While the direct forcing is modest, because aerosols and ponds influence the albedo, the response is amplified. In simulations with no ponds or aerosols in sea ice, the Arctic ice is over a meter thicker and retains more summer ice cover. Diagnosis of a 20th century simulation indicates an increased radiative forcing from aerosols and melt ponds, which could play a role in 20th century Arctic sea ice reductions. In contrast, ponds and aerosol deposition have little effect on Antarctic sea ice for all climates considered.

The paper is in press in the Journal of Climate, abstract available [here].  The full paper is not available on line.  Complete documentation of the sea ice model is provided [here].
.
JC conclusions:  Whereas sea ice models are becoming quite sophisticated, most recently in terms of the radiative transfer, melt ponds, and aerosols, prediction of sea ice is hostage to predictions of the chaotic atmospheric and oceanic dynamics.
In the current sea ice regime since 2007 (see my previous sea ice post), there has been return to a large amplitude annual cycle (with an increase in the wintertime max), but with a an overall shift to lower summertime values.  The regime shifts noted in my previous post seem to be associated with shifts in the multidecadal ocean circulation regimes (e.g. AMO, NAO, PDO).  Given the apparent importance of the multidecadal ocean circulations in determining the seasonal and interannual variations in sea ice extent, it is very difficult to discriminate a global warming signal from the data because of the short data record.

 

Comments

141 responses to “Likely causes of the recent changes in Arctic sea ice”

  1. Ecotretas

    The recent uptick is really intriguing. Looking at the graphs, it seems it’s the earliest recovery in the decade…
    But since I believe in the “Gore effect”, it could even go down in the next days…

    Reply
    1. David L. Hagen

      Good graphic review and compilation of numerous factors affecting arctic ice: Arctic ice refreezing after falling short of 2007 recordBy Joseph D’Aleo, CCM, AMS Fellow
      E.g., Soon comparing Solar vs CO2 driving Arctic ice and
      annual TSI and annual PDO+AMO track together with arctic temperatures.

      Reply
  2. Oliver K. Manuel

    Thank you, thank you, Professor Curry, for your role in restoring some semblance of honesty to the field of climatology.

    My main concern now is that we have been deceived by government propaganda about global climate change in order to distract us from seeing that we were actually losing:

    a.) Integrity of government science, and
    b.) Citizen’s control over the government

    With kind regards,
    Oliver K. Manuel

    Reply
  3. tonyb

    Judith

    These are Intriguing articles.

    I have been taking SSTs locally in order to be able to further discuss factual observations with the Met office following on from my article on the subject here a few months ago.

    I was surprised at the considerable effect that direct sun had on rapidly raising the temperature of the water, the effect of clouds/clear sky in retaining heat or helping to reduce temperatures further during the night, and the effect that the cloudiness of water had on the depths to which the water was warmed.

    As a skier i can also observe the dramatic effect that the sun has on melting snow/ice particularly according to the inclination of the sun or the surface on which it is shining.

    I do appreciate that we are not comparing like for like but taking all the factors described above into account I have no doubt as to the dramatic effect that the sun can have on both the water temprerature and the ice and wondered if there are any records that show the number of sun hours and cloud in the Arctic area over a significant period-say the last fifty years and whether it is partly a cause of the observed melting?

    Tonyb

    Reply
    1. steven mosher

      You can probably pull some cloud data from satillites. your period is going to be less than 50 years obviously. You will also need to learn to deal with GIS datasets.

      Reply
      1. tonyb

        Hi Mosh

        All very well, but is the hypothesis worth spending time on?

        tonyb

      2. Dallas

        http://www.arctic.noaa.gov/detect/climate-clouds.shtml

        It would be interesting. Arctic clouds tend to retain more heat I would imagine and diffused sunlight is still a pretty source of energy. The noaa link above stops in 2004, just adding to the present would be nice to see.

      3. Steven Mosher

        Hmm. I’d probably start by looking at the arctic ocean anomalies

        http://i43.tinypic.com/2e4m62r.png

        Bob Tisdale can probably point you in the correct direction to look at those..

        No simple answers but the warm water making its way to the arctic was warmed some other place. I would imagine that late in the season when the water opens up, you at least have the possibility of the limited sunlight in the arctic playing a role for a short time..

        None of the buoy data I skimmed had any ground truth data on insolation..but I didnt look very hard

    2. vukcevic

      The SST data have suffered extensive corrections
      ftp://ftp.wmo.int/Documents/PublicWeb/amp/mmop/documents/JCOMM-TR/J-TR-13-Marine-Climatology/REV1/joc1171.pdf
      ftp://ftp.astr.ucl.ac.be/publi/2011_08_03-08h24-hugues.goosse-14.pdf
      but it main appear to be OK:
      http://www.vukcevic.talktalk.net/SST-NAP.htm
      despite this odd curiosity
      http://www.vukcevic.talktalk.net/Data.htm
      which may be welcomed by 60 (65 anyway) year cycle hunters.

      Reply
      1. tonyb

        Vuk

        You will remember my article on SSTs carried here a few months ago. The more I delve into the subject the more I become completely baffled as to how anyone can believe that we have a global SST back to 1850 that is accurate to tenths of a degree.

        For the most part we have only a vague idea of very approx temperatures which were often collected using a very dubious method-buckets etc.

        Some SSTs back in time are dervied from a single reading in a grid square for the year which is then extrapolated..

        We may be able to gain an idea of approx Sea surface temperature for brief periods of time in small areas of the most travelled bits of ocean but for the most part the use of SSTs is highly flawed and should have no place in the IPCC reports.

        i reserve judgement on figures derived over the last half century or so where methods have changed but prior to this date we are deluding ourselves to believe they are a ‘scientific’ measure.

        tonyb

      2. vukcevic

        I tried to understand the methods of correction they applied (see two links above), I think you are right, it’s all a bit of a ‘fiddle’. For the North Atlantic the SST trends agree well with those of the CET with about a decade delay, so a ‘clever reconstruction’ would be based on the CET, using the latest SST more accurate data as a reference for backdating the rest.
        I’m more interested in the trend rather than a decimal point or two, and as you can see my North Atlantic precursor (‘birth’ of which you are aware) links well together the N.A’s SST, CET and to some degree SSN, but it is not caused by any of the above:
        http://www.vukcevic.talktalk.net/SST-NAP.htm
        http://www.vukcevic.talktalk.net/CDr.htm
        The ‘magic’ of reconstruction is ‘apparent’ in here:
        http://www.vukcevic.talktalk.net/Data.htm

      3. vukcevic

        forgot this bit:
        For the Northern Hemisphere, there is some divergence between the seasons prior to 1890. Such seasonal differences could be reduced by modifying the correction procedure, either by changing the exposure time, or by changing the assumed fraction of un-insulated buckets prior to 1905. However, this would increase the seasonal differences in the Southern Hemisphere and tend to make both hemispheric means less consistent with the land data.
        http://icoads.noaa.gov/Boulder/Boulder.Jones.pdf

      4. vukcevic

        Tony
        Here I compared the AMO ( SST derivative) NOAA’s file, the CET, and what I think drives the SST, all normalised to the AMO data.
        http://www.vukcevic.talktalk.net/ACS.htm

  4. Wagathon

    Facts are facts. Overall, the extent of global sea ice has been about the same for 30 years: the extent of Arctic sea ice is essentially unchanged over the last decade; and, the extent of Antarctic sea ice has risen steadily over the last 30 years. You would think that even a global warming alarmists must admit such facts if they are to have any credibility. Sadly, however, it is an embedded part of the social structure of AGW True Believer religion that the members of the cult simply refuse to admit any fact that conflicts with their preconceived and superstitious notions about the catastrophic consequences of AGW.

    Reply
    1. R. Gates

      Wagathon,

      Your “facts” are yours alone, and have no relationship to what has actually tranpired. Suggest you might try doing a bit more research.

      Reply
  5. Chip Knappenberger

    It may be worth considering that if climate models are underplaying the actual amount of Arctic sea ice loss, and if Arctic sea ice loss is a positive feedback on global temperature, then, the observed rate of Arctic sea ice loss ought to be applying a warming pressure over and above that from greenhouse gas emissions.

    We explore this issue over at World Climate Report in an article here.

    -Chip Knappenberger

    Reply
    1. curryja

      Thanks Chip, this is a very interesting article.

      Reply
      1. Chip Knappenberger

        Judith,

        Any thoughts about Governor Deal’s re-alignment of the Georgia State Climatology Office?

        I think is was a poor decision (to say the least).

        -Chip

      2. curryja

        Chip, I’ll probably bring this up in week in review.

      3. maksimovich

        There is an interesting paper in discussion at Earth system dynamics Climate sensitivity in the Anthropocene M. Previdi et al.

        The arguments are of a heurestic nature,ie anthropocentric as opposed to geometric ( read dynamics) eg Jaynes on Logic

        It seems that mankind has always been occupied with the problem of how to deal with ignorance.Primitive man, aware of his helplessness against the forces of Nature but totally ignorant of their causes, would try to compensate for his ignorance by inventing hypotheses about them. For educated people today, the idea of directing intelligences willfully and consciously controlling every detail of events seems vastly more complicated than the idea of a machine running; but to primitive man (and even to the uneducated today) the opposite is true. For one who has no comprehension of physical law, but is aware of his own consciousness and volition, the natural question to ask is Not What is causing it?”, but rather Who is causing it?”

        The answer was to invent Gods with the same consciousness and volition as ourselves, but with the additional power of psychokinesis; one in control of the weather, one in control of the seas, and so on. This personication of Nature must have been going on for thousands of years before it started producing permanent written records, in ancient Egypt and Greece. It appears that the adult citizens of those times really believed very literally in all their local Gods.

        This oldest of all devices for dealing with one’s ignorance, is the first form of what we have called the Mind Projection Fallacy”. One asserts that the creations of his own imagination are real properties of Nature, and thus in effect projects his own thoughts out onto Nature. It is still rampant today, not only in fundamentalist religion, but in every field where probability theory is used.

        The first significant problem is the lamarkian inference for the carbon cycle eg Le Quere rigorously buried in the 30’s by Fisher, Komologorov and the martyrs Vavilov and Bauer.

        http://www.earth-syst-dynam-discuss.net/2/531/2011/

        Interesting group of authors.

    2. Rob Starkey

      Chip

      Isn’t there only a concern if sea level rise as a result of melting?

      The melting of the ice itself is actually not an issue.

      Reply
      1. Chip Knappenberger

        Rob,

        The decrease in albedo that accompanies the loss of sea ice is the phenom that underlies “arctic amplification” (as you point out, it has nothing directly to do with sea level rise). What I am saying is that if Arctic sea ice loss is occurring faster than models predict, then, all else being equal, the earth should be warming faster than models predict. But it is not (and, of course, all else is not equal). But, in the haste to explain why models are overpredicting the global warming rate, some folks tend to not account for reasons why the models should be underpredicting the observed warming rate–like a higher than anticipated rate of Arctic sea ice loss.

        -Chip

      2. Rob Starkey

        Chip

        I agree that our climate models are by no means mature. I have been writing that point here for quite some time.

        I guess I am just trying to point out to people to try to consider what is really important and not get lost in every detail.

        As far as an impact to humanity- the ice melting is a good thing–unless it result in a secondary harm such as a sea level rise. There is no evidence of a secondary harm that I am aware of–at least not one of much interest.

      3. manacker

        Chip Knappenberger

        You wrote:

        The decrease in albedo that accompanies the loss of sea ice is the phenom that underlies “arctic amplification” (as you point out, it has nothing directly to do with sea level rise).

        OK. Let’s look at the magnitude of this phenomenon.

        Let’s say the summer sea ice extent has diminished by 20% since the satellite record started (2006-2010 July/August/September average versus 1979-2000 baseline)
        ftp://sidads.colorado.edu/DATASETS/NOAA/G02135

        Millions of square kilometers sea ice extent
        Month – last 5 years – baseline
        End July – 8.73 – 10.10
        End Aug – 6.04 – 7.67
        End Sep – 5.02 – 7.04
        Average – 6.60 – 8.27
        Difference 1.67 million square kilometers (msk)
        Cumulated loss = 20%

        I believe we all agree that sea ice has an empirically observed higher albedo than sea water, so that a significant net melting of sea ice should lower the average albedo of Earth.
        Sea ice albedo = 0.5 to 0.7 (Wiki); other estimates put this as high as 0.75

        Sea water is said to have an average albedo of 0.2
        http://issmes.enes.org/uploads/media/easyms-pres_final.pdf

        However, a study shows that this varies strongly with latitude and degree of waviness, with waviness having a lesser effect on sea water albedo at higher latitudes than at lower ones.
        http://www.terrapub.co.jp/journals/JO/JOSJ/pdf/2104/21040148.pdf

        Sea water albedo at Arctic latitudes is shown to be between 0.4 and 0.6, depending on waviness.

        Using a value of 0.75 for sea ice and an average of 0.45 for sea water at Arctic latitudes, and assuming that there are no clouds, one can calculate an upper limit for the albedo impact of the reduced Arctic sea ice.

        Surface area of Earth = 510,072,000 km2; exposed to sun = 255,036,000 km2
        Average albedo of Earth is estimated to be 0.367.

        So the reduction in summer arctic sea ice (3 months per year) represents:

        [0.25 * 1,670,000 * (0.75 – 0.45)] / (255,036,000 * 0.367) = 0.134% increase in our planet’s albedo, i.e. from 0.3670 to 0.3675.

        This does not appear to be a big deal.

        Taking the pessimistic assumption that there would eventually be an “ice free summer” in the Arctic, I come up with a future reduction of the average albedo of the Earth of:

        [0.25 * 8,670,000 * (0.75 – 0.45)] / (255,036,000 * 0.367) =
        0.69% increase in our planet’s albedo, i.e. from 0.3670 to 0.3696.

        Again, I do not see much to get excited about here, particularly when considering that the albedo increase from a 1% increase in cloud cover would more than offset this decrease.

        Max

      4. Jim D

        The normally accepted albedo for water is only 8%. Why do you think it is 40-60%? This would make it brighter than the land surface, which we know from satellite images is not true.

      5. manacker

        Jim D

        You write:

        The normally accepted albedo for water is only 8%. Why do you think it is 40-60%?

        Please refer to the two papers I cited.

        The first suggests a global average albedo of sea water of around 0.2 (rather than 0.08).

        The second goes into more detail for sea water albedo values at various latitudes and water conditions, from still to windy.

        It points out that sea water albedo is much higher at higher latitudes (lower angle of the sun):

        “…it is to be noted that the value of albedo on the windroughened surface may take a maximum in the range when the sun is 0°~10°.

        From the figures I took an average value of 0.45 – but, hey, if you prefer to assume 0.35, that’s OK, because it will not change the conclusion that the observed Arctic sea ice melt has not appreciably changed our planet’s total albedo, and that a very small change in cloud cover would have a far greater effect.

        And that was my point.

        Max

      6. Fred Moolten

        “So the reduction in summer arctic sea ice (3 months per year)… = 0.134% increase in our planet’s albedo, i.e. from 0.3670 to 0.3675. This does not appear to be a big deal.”

        Max – It would be a very big deal indeed, if a reduction in Arctic sea ice managed to increase the planet’s albedo.

        Is it a “big deal” if instead, it reduces the albedo? I think this should be put in context. First, one can’t compute the actual reduction from back of the envelope calculations. Models, for all their imperfections, are needed to account for all the variables. If the reduction were actually as large as you calculate, it would be of great importance. Most estimates of the current planetary radiative flux imbalance place it at less than 0.9 W/m^2. Your albedo change represents a value of about 0.17 W/m^2, which if correct, would make Arctic sea ice reduction in recent years potentially a major contributor to ongoing imbalances. However, that value is almost certainly too large. For example, while you have probably overestimated the albedo of Arctic seawater during summer months, when the solar zenith angle is relatively low (the sun is closer to overhead and daylight hours are long), this factor is outweighed by the fact that you have used the maximum (September) sea ice reduction rather than the summer average, as well as the fact that the sun doesn’t shine at night, and that clouds mask a significant portion of the albedo effects during Arctic summer. A more realistic quantitation would probably place the contribution of Arctic sea ice reduction to global temperature change at a smaller level, although not an insignificant one. Total global snow/ice/albedo effects of course encompass far more than the Arctic sea.

        On the other hand, the Arctic sea ice albedo reduction does contribute significantly to polar amplification of globally averaged temperature changes.

      7. Jim D

        I think this is the albedo for sun glint. If you look at visible satellite pictures you see the reflection of the sun over a small area, and the brightness could be from albedos in this range.
        Also, Earth’s average albedo is near 30%, not 36%. How can the ocean albedo exceed the average albedo when water clearly is dark on visible satellite pictures? Albedo values of 0.08 come from direct satellite measurements, while your papers seem to apply to limited conditions and one looks like a hypothetical 0.2 albedo.

      8. manacker

        Fred Moolten

        Sorry for typo. This should have read:

        So the reduction in summer arctic sea ice (3 months per year) represents:

        [0.25 * 1,670,000 * (0.75 – 0.45)] / (255,036,000 * 0.367) = 0.134% DEcrease in our planet’s albedo, i.e. from 0.3670 to 0.3665.

        This does not appear to be a big deal.

        And the next statement is OK as is:

        Again, I do not see much to get excited about here, particularly when considering that the albedo increase from a 1% increase in cloud cover would more than offset this decrease

        So how big a deal is it?

        A 1% change in our planet’s albedo has a radiative effect of 3.4 W/m^2. This is roughly the same as a doubling of CO2, So the 0.134% change resulting from the decrease in late-summer Arctic sea ice represents 0.46 W/m^2 equivalent.

        Cloud albedo results in reflection of around 14% of the incoming SW radiation, resulting in cooling estimated to be 48 W/m^2. (Ramanathan and Inamdar 1989) So a 1% decrease in cloud cover has a slightly higher radiative effect as all the observed loss of Arctic sea ice to date has had.

        To your other points, I used the average summer extent (not just September, as you write).

        The seawater albedo values at Arctic latitudes came from the study I cited, and the sea ice albedo values came from Wiki.

        Obviously, even at very high latitudes, sea water has a lower albedo than sea ice, so a net reduction of end-summer ice extent will result in a small reduction of our planet’s overall albedo, as indicated

        To be sure, it’s a rough approximation, but it does point out that changes in end-summer Arctic sea ice have not had a very large impact on our planet’s total albedo.

        If you want to talk about albedo, talk about clouds, instead (that’s where the action is).

        Max

      9. tempterrain

        Max,

        Albedo means “whiteness” right? So, doesn’t a reduction in ice and snow cover in the Arctic mean decreased albedo.

        Your back of envelope calculation shows an increase? Why’s that?

        Incidentally, 20% ice reduction in the Arctic since 1978 is a slight underestimate:

        http://nsidc.org/images/arcticseaicenews/20100907_Figure3.png

      10. manacker

        Jim D

        Earth albedo:

        The albedo of the Earth is 0.367.

        http://www.universetoday.com/25819/albedo-of-the-earth/

        Another source (Goode et al. 2001) puts it at 0.30.

        As far as the relative impact of changes in sea ice versus changes in clouds:

        A 1% decrease in cloud cover has a slightly higher radiative effect as all the observed loss of Arctic sea ice to date has had.

        The Earthshine observations (Pallé et al. 2006) showed

        The overall decrease in cloud amount from 1985 to 2000 is about 4–5% with a recovery of about 2–3% from 2000 to 2004.

        so these impacts have been several times as important as the observed cumulated loss of summer ice.

        Max

      11. Fred Moolten

        Max – I believe you did some of the math wrong by using only half of the Earth’s surface to compare with all of the area with reduced sea ice, which is why you seem to have overestimated the W/m2 reduction. However, even a smaller figure (I had calculated about 0.17 W/m^2 based on your inflated figure for total planetary albedo, but you can check it out) is still significant when compared with the total flux imbalance, which I think is a more informative comparison than an arbitrarily selected change in cloud cover, because it compares the sea ice reduction with the effects of all climate variations that have been operating in recent years..

      12. Jim D

        manacker, everyone in climate is using 0.3 for albedo. This is where 255 K comes from for the equilibrium radiative temperature, where .367 would give only around 249 K. The Kiehl-Trenberth diagram is uncontroversial in using 0.3. Your reference is an outlier, I think.

      13. Fred Moolten

        Also, if you want to compare the percent change in albedo of 0.134 (too high, but assume it correct for the moment) with a 1% reduction, the latter would be 1% of about 100 W/m^2, not 1% of 340 W/m^2, and would yield a value of about 1 W/m^2. That’s because the 0.134 was something you calculated on the basis of the albedo fraction of solar radiation and not total solar radiation. It would take a 1% reduction in total solar to amount to about 3.4 W/m^2.

      14. Fred Moolten

        Regarding albedo, the accepted value is about 0.30 for the Bond albedo, which is the fraction of incident solar radiation scattered/reflected at all angles from the Earth. A “geometric albedo” representing the fraction that would be reflected from a flat surface is higher, at about 0.367.

        About half of the albedo comes from clouds, with the surface and Rayleigh scattering by atmospheric molecules contributing the rest. Cloud variations are obviously an important element on a global scale, but the effects of Arctic ice melting are important locally and also a non-trivial fraction of global albedo feedbacks, which are a contributor to total feedback that is smaller than those from water vapor and probably from cloud feedbacks, but not insignificant.

      15. Fred Moolten

        In my last comment, “global albedo feedbacks” was meant to refer specifically to global snow/ice albdeo feedbacks.

      16. Chief Hydrologist

        The forcing from sea ice decline is minor – 0.1W/m^2 change from 1979. About the same as sulphides this century.

        http://www.agu.org/pubs/crossref/2011/2011JD015804.shtml

        Although it may be difficult to disentangle clouds.

        Albedo changes from about 0.5 in a snowball earth to 0.25 in a blue green planet with lots of forest. It also changes over the shorter term as a result of cloud changes.

        http://scienceofdoom.com/2010/07/04/the-earths-energy-budget-part-four-albedo/
        http://hal.archives-ouvertes.fr/docs/00/30/12/40/PDF/acpd-4-2671-2004.pdf

        About a 2.3W/m^2 form 1979 to 1998 decrease in reflected SW- 2W/m^2 increase since. Cloud changes are the biggest source of decadal climate change in the record.

    3. Fred Moolten

      Chip – As far as I can tell from Recent NSIDC Data, the models appear to have overestimated rather than underestimated sea ice decline, since recent September value exceed 4 million square kilometers.

      Reply
      1. Fred Moolten

        I should have used the Zoom before commenting, because I didn’t correctly read the dates on the x-axis. The results to date do support your point that the model projections underestimated the overall trend. On the other hand, recent years have not shown much decline, and so it’s hard to know to what the extent the observations signify a trend difference as opposed to an inherent fluctuation in the data.

      2. Fred Moolten

        However, I have a problem with the use in your analysis of an equilibrium climate sensitivity value to compute annual responses to a change in the radiative flux balance. That is probably an inappropriate use of an equilibrium climate sensitivity parameter and would therefore overstate the short term temperature impact. What am I missing?

      3. Chip Knappenberger

        Fred,

        Unfortunately, Hudson didn’t compute a temperature change, so I kind of had to back-of-the-envelope a value from his results. Singarayer et al. (2005, Journal of Climate) and Parkinson et al. (2001, Journal of Climate) came up with some temperature numbers, but again, they are hard to apply directly but they seem to be in the ballpark of my estimate from Hudson’s work. Admittedly, the effect is probably not particularly large, but neither are some of t the effects being proffered for the lack of warming. At the very least, the faster-than-expected sea ice decline should be included in the net calculations.

        But from reading all these papers, it striking how large the disconnect is between how much you hear about “arctic amplification” and how small the effect on the global temperature appears to be.

        -Chip

      4. Chip Knappenberger

        Fred,

        I am not so much talking about this year or last year, but the general trend overall. See Figure 3 at this link which shows a comparison of model projections of the evolution of Arctic sea ice with the observations overlaid (updated from Stroeve et al., 2007).

        -Chip

      5. Fred Moolten

        Chip – I agree that the projections diverge from the observations, at least short term, but that wasn’t my point. The article you cite states: So to convert the radiative forcing changes in Figure 1 to global temperature changes, we multiply by 0.75°C/W/m2. That would be correct if you wait 500 years for the temperature changes to fully manifest themselves, but the temperature changes expected over the few years cited would be much smaller. The article, as far as I can tell, therefore seriously overstates the impact of the divergence between the modeled and observed sea ice decline.

      6. manacker

        Fred

        You are right in writing that the most recent years (since 2007) show a net gain in Arctic sea ice, using end-August data, 2007-2011.

        But the long-term trend is one of decline of around 0.7 million square km per decade (or ~10% per decade).

        I would be very surprised if the most recent trend of “recovery” continued for very long, but who knows?

        Max

    4. Raving

      It may be worth considering that if climate models are …. (doing whatever),…. | follow on reasoning deliberately ignored

      It’s all very confusing. Then I read hunter’s comment | September 16, 2011 at 6:03 pm

      Stupidity is much more common than cunning plots.
      The AGW community demonstrates this daily.

      It was a Eureka!™ moment. One of many flashes of insight gained while struggling to creatively build overgenerously parametrized models of complicated processes in the hopes of capturing some intricacy.

      I failed every time. I even failed when it seemed that I had succeeded.

      Crafty plots tend to fail because the dynamics of the ‘creatively rigged simulations’ were controlled by only a few relevant parameters. That generous excess of parameter choice served as mere ornament to the overall design.

      AGW models seem to suffer from the excessively inspired, over-tweaked defect … Eventually the model(s) cannot be salvaged.

      Prediction: It will become increasingly difficult to adjust the AGW models to accommodate future climate data

      Prediction: The AGW models will mis-estimate temperature, CO2 levels, sea level and sea ice extent with increasing severity.

      Reason: With complicated simulation model, there is a tendency to get hoisted on the petard of it’s own internal structural entropy

      Cunningly crafting a model to prove AGW risks collapsing to reveal runaway AGW to an extent that it (the model) can no longer be fixed.

      Reply
      1. hunter

        Raving,
        Glad to help.
        I agree with your predictions.
        As reality declines to cooperate more and more, the divergenece will grow.
        Think of Web and his career in promoting a peak that does not exist as he perceives it.

    5. Neven

      How well is warming in the Arctic reflected in the observations?

      Reply
      1. Kermit

        Is there enough data for the Arctic? satellite photos have only been around ~30 years, haven’t they? Before that I don’t think there is accurate measurements are there?

  6. Coalsoffire

    Wagathon,

    I don’t understand your comment. My observation is that AGW believers don’t always ignore the facts, rather they tend to adopt every fact as evidence of their meme. So just as more cold and more warmth are both evidence of AGW so is Arctic sea ice decline proof of AGW and Antarctic sea ice increases are also proof of AGW. And not to worry, if Arctic sea ice reverses the trend and begins to increase, that will be proof of AGW too. And if that line in the sand seems to waiver they just morph their argument into “climate change” (what could that possibly even mean?) or go for “climate disruption” (isn’t that really just “weather”) and ignore the GW part.

    Anyway I learned last night on good authority that we ought not to get bogged down in the metrics. Sea ice is really just a lot of metrics. Don’t worry about it, just know that it’s really catastrophic and that it’s enough to just believe.

    Reply
    1. Wagathon

      –> “… rather they tend to adopt every fact as evidence of their meme.”

      How do they explain the fact that AGW has become a Left vs. right issue: e.g., do they believe the Left wants to save the Earth from humanity whereas the right denies that the human race should be aborted?

      Reply
  7. Fred N.

    The 2010/2011 Northern Hemiphere winter saw a very late start to the eastern Canadian Arctic/Hudson Bay freeze due to primarily due to the extended period and location of a strongly negative AO (NSIDC discusses it here: http://nsidc.org/arcticseaicenews/2011/020211.html). Undoubtly that affected the summer melt extent as thick ice did not have a chance to form.

    Reply
  8. Rob Starkey

    I have been closely watching arctic ice for several years now and have reviewed the 2011 data pretty closely over the course of the year. That written as a background, maybe a few here can help me with a basic question.

    Why is the potential melting of the arctic such a concern when there is not an associated rise in sea level? We know that sea level is rising at between 2.5 mm and 3 mm per decade-which is a nonissue- so what is the net problem with less ice in the arctic?

    Reply
    1. DaveJR

      I’m sure you already realise that it’s just a PR issue. It’s the simple meme that an increase in ice melting must be caused by rising atmospheric temperatures. So regardless of whether atmospheric temperatures, SSTs or OHC fails to increase, and ignoring the multitude of complexities involved, reduced ice extent is clear evidence of AGW.

      Reply
    2. John Carpenter

      The polar bears will become extinct.

      Reply
      1. Rob Starkey

        John

        are you serious?

      2. John Carpenter

        LOL… No…. but others…?

    3. Jim D

      The reason the Arctic is warming faster than anywhere else is the ice albedo feedback, so this is a critical measure of how that is proceeding.

      Reply
  9. pokerguy

    NIcely said Coals. I’m looking forward to how the next 2 decades of substantial cooling will be proof of AGW as well.

    Reply
  10. John from CA

    “Of more relevance than attribution is the development of reliable forecasts of the Arctic sea ice over the next few decades, which clearly requires consideration and integration of all these processes.”

    Well said and the new satellite observations should help to supply some of the missing data over time. The current data represents what may be only one half of the normal cycle so our concern over multi-year ice formation and its flushing from the Arctic may be misplaced. For instance, are there any studies which clearly show multi-year ice older than the typical 30 year cycle?

    The one factor that’s rarely discussed is fresh water input and salinity’s role in the seasonal melt. Have we altered the climate system with other factors like dams?

    Fascinating topic, thanks for the article.

    Reply
  11. Wagathon

    Can we just get real for a moment? There has been essentially no warming since 1995.

    Currently, we are in a period of global cooling and “Arctic sea ice extent … for April 2010 was the largest for that month in the past decade.” The oceans are cooling.

    Some scientists predict global cooling for a decade or more–perhaps for the next 30 years. The globe may experience another ice age before the end of the century.

    The Earth has been locked in ice age conditions for more than 80% of the time over the last one million years. Those are the facts. All of the rest is dogma and self-loathing.

    Unfortunately, too many of America’s homegrown little Eichmanns and disciples of Mao and Al Gore — blinded by irrational fears of Thermageddon — have lost the ability to repress their natural instinct to tell everyone else what to think, what to do and how to live. With extreme environmentalism as their new religion, they don’t give two-schitts about the Constitution or personal liberty and responsibility.

    Reply
    1. Norm Kalmanovitch

      Since the last of the continental ice sheet melted over 10,000 years ago the world has warmed for about 5,000 years and has been on a long cooling trend ever since. In the past 3500 years each warm period as been cooler than the previous one with the currennt warm period being cooler than the Medieval Warm Period which was cooler than the Roman Warm Period which was cooler than the Minoan Warm period.
      Ice ages come on slowly as the albedo from greater and greated snow coverage increases causing greater and greater cooling, but end rapidly as the melt back rapidly decreases the albedo.
      We can be pretty comfortable that there won’t be another full ice age for several thousand years but we should be rather uncomfortable that the solar cycle 24 is mimicking the Dalton Minimum that brought an extension of the Little Ice Age around 1810 from which we were recovering but might return to.
      It is very comforting to see someone like you with a bit of common sense stand up to this AGW idiocy

      Reply
      1. Wagathon

        Some good questions to ask are, why is this happening in the West and only in the West and why now? And, the answer just may be as simple as, understanding the nature and symptoms of a dysfunctional societal zeitgeist:

        “Friedrich Nietzsche was the first to notice that religious emotions, like guilt and indignation, are still with us, even if we’re not religious. He claimed that we were living in a post-Christian world–the church no longer dominates political and economic life–but we, as a culture, are still dominated by Judeo-Christian values. And those values are not obvious–they are not the Ten Commandments or any particular doctrine, but a general moral outlook.

        “You can see our veiled value system better if you contrast it with the one that preceded Christianity. For the pagans, honor and pride were valued, but for the Christians it is meekness and humility; for the pagans it was public shame, for Christians, private guilt; for pagans there was a celebration of hierarchy, with superior and inferior people, but for Christians there is egalitarianism; and for pagans there was more emphasis on justice, while for Christians there is emphasis on mercy (turning the other cheek). Underneath all these values, according to Nietzsche, is a kind of psychology–one dominated by resentment and guilt.

        “Every culture feels the call of conscience–the voice of internal self-criticism. But Western Christian culture, according to Nietzsche and then Freud, has conscience on steroids, so to speak. Our sense of guilt is comparatively extreme, and, with our culture of original sin and fallen status, we feel guilty about our very existence. In the belly of Western culture is the feeling that we’re not worthy… All this internalized self-loathing is the cost we pay for being civilized.” (Stephen Asma)

    2. Steven Mosher

      when you want to understand how a region of the globe is responding you need to look at REGIONAL SST. That is, the arctic ocean is warming, other basis are warming less, and some are cooling. The global average is somewhat flatish, but there are regional variations. Here is a nice slide ( by a skeptic no less ) that illustrates why your comment gets a D-

      http://i43.tinypic.com/2e4m62r.png

      Reply
      1. kuhnkat

        Round about 2005 the trend reversed yet again. Trends usually do that eventually. That is why your comment gets a F.

    3. Chief Hydrologist

      The see-sawing pattern in the Quaternary (2.58 million years) are better known as glacials and interglacials.

      Reply
    4. Pooh, Dixie

      Decades of cooling? Sunspot Magnetism—Livingston & Penn (39 pages of posts)
      http://solarcycle24com.proboards.com/index.cgi?board=general&action=display&thread=855

      The “Umbral Magnetic Field” (here, UMF) of sun spots has been declining since about the year 2001. So what? According to Livingston, Penn and Svalgaard, sunspots become invisible below about 1500 gauss. Again, so what? The Maunder and Dalton Minima are associated with a dearth of visible sunspots. Causation? No. Association with conditions that do affect climate and temperatures? Possibly yes.

      At any rate, extrapolation suggests we will know more between 2015 and 2023 when the UMF declines below 1500 and we have contemporary observations.
      http://solarcycle24com.proboards.com/index.cgi?action=gotopost&board=general&thread=855&post=73604
      1) Possibly of interest, a summary:
      http://www.leif.org/research/Livingston-Poster.jpg
      2) Currently:
      http://www.leif.org/research/Livingston%20and%20Penn.png
      3) Data and Findings to date:
      http://www.leif.org/research/Livingston-Penn%20Data%20and%20Findings%20so%20far.ppt

      “HMI” explained:
      The primary goal of the Helioseismic and Magnetic Imager (HMI) investigation is to study the origin of solar variability and to characterize and understand the Sun’s interior and the various components of magnetic activity. The HMI investigation is based on measurements obtained with the HMI instrument, one of the three instruments that make up the Solar Dynamics Observatory (SDO) mission. … HMI observations will help establish the relationships between internal dynamics and magnetic activity. In turn this will lead to better understanding of solar variability and its effects.
      http://hmi.stanford.edu/Description/hmi-overview/hmi-overview.html

      Reply
  12. andrew adams

    Can we just get real for a moment? There has been essentially no warming since 1995.

    These sentences do not belong together.

    http://www.woodfortrees.org/plot/hadcrut3vgl/from:1995/to:2011/plot/hadcrut3vgl/from:1995/to:2011/trend

    Reply
    1. Dave in Canmore

      According to the data set you cite, it’s cooler now than 1995! If you plot satellite data (UAH or RSS) over same years there is no trend to speak of after a margin of error is included.

      Reply
    2. nandhee jothi

      thanks andrew. I always had a problem with this one.
      whenever i go to that site, i see this option to see “raw” data. when i click on that i get this heavily processed, possibly biased/worked over/tortured/waterboarded temp anamoly. There is nothing raw about it, except it gets on my raw nerves.

      Is there a place where i can get raw temp ( not anamoly ) from a bunch of sites? with no UHI correction applied.

      thanks in advance

      Reply
      1. steven mosher

        See my R packages

    3. hunter

      Talk to Dr. Jones at CRU on this if yo udo not like it.

      Reply
  13. Fred

    What is happening with Arctic Ice Mass and Arctic Air temps?

    While ice extent is entertaining, the mass of ice would be more appropriate for energy transfer calculations.

    Reply
    1. Steven Mosher

      yes and given that the heat capacity of water is greater than air it would be better to start by looking at arctic SST..

      http://i43.tinypic.com/2e4m62r.png

      Or better.. water temps under the ice

      http://www.oc.nps.edu/~stanton/fluxbuoy/deploy/buoy22.html

      http://www.oc.nps.edu/~stanton/fluxbuoy/deploy/buoy22_deltaT.html

      And the ocean to ice heat flux

      http://www.oc.nps.edu/~stanton/fluxbuoy/deploy/buoy18_deltaT.html

      Reply
      1. hunter

        Steven,
        Can you explain that last link a bit?
        It looks very intriguing.

      2. steven mosher

        Its flux data. you wanna understand bottom melt, I’d look at that for starters..

      3. kuhnkat

        Steven,

        where is the paper that computes how many joules it takes to melt all the ice each year and how much is provided by the water and air in the arctic. You really need to pay attention to the research that tells us that the ice is melted OUTSIDE the Arctice after being shipped their by Gore and his Polar Bear buddies, er, currents and wind.

  14. Norm Kalmanovitch

    The only thing for certain in all this is the sea ice is not changing because of changes to the insulating capacity of the atmosphere from CO2 emissions. Since insulation does not supply any heat energy but merely slows down the rate at which heat energy is transmitted through it; there is no heat generated to supply the 80cal/gm of latent heat of fusion necesary to melt ice so the oly possible sources for this heat are the sun and geothermal heat transfer.

    Reply
  15. Jim Cripwell

    Judith you write “The recent uptick in sea ice extent is intriguing.”

    Maybe I am being naive, but recent temperatures in the Arctic Ocean have been quite cold for the time of year. Maybe this uptick will last as long as these temperatures stay below normal.

    Reply
  16. David Wojick

    This statement is nonsensical propaganda: “The minimum ice extent was the second lowest in the satellite record, after 2007, and continues the decadal trend of rapidly decreasing summer sea ice.” If this year is higher than 2007 how can it be continuing a decadal trend of rapidly decreasing ice?

    Note too that the press headlines have already told us that this year’s ice extent was the lowest on record (and also in 8000 years apparently):
    http://www.guardian.co.uk/environment/2011/sep/11/arctic-ice-melting-at-fastest-pace

    Icegate?

    Reply
    1. tempterrain

      David Wojick,

      You ask ” If this year is higher than 2007 how can it be continuing a decadal trend of rapidly decreasing ice?”

      Perhaps, because 2007 and 2011 are single years? Not decades.

      Didn’t you know that?

      In any case, its like arguing that the US$ is higher today than it was a week ago and therefore the relative decline we’ve seen in the US$ over the past few years is definitely over

      Reply
      1. David Wojick

        The key word here is trend. Staying low and continuing a trend are two very different hings. Conflating them is an AGW rhetorical trick. It is just like saying we are still warming just because it is still warm.

      2. Dallas

        If you extend the time out long enough and smooth the data enough there are no trends. If you were to put your prognostication hat on, what appears to be a neutral trend developing would be interesting. Then predicting things long after we are dead and buried does take the pressure off, don’t it?

  17. dp

    There are several references to heat moving from place to place but it isn’t made clear if this is sequestered heat on the move, or newly arrive heat on the move, or both. There is no explanation if this represents a movement of water mass or a mixing exchange of heat. If it is a movement of water mass then where is the replacement water coming from, and what is the temperature of that? To put a fine point on it, I see evidence that the energy content is consistent but the distribution is changing. That is not a picture of global warming that has its roots in my SUV’s tailpipe. What I see is the planet has fluid components that shift about and it is a travesty we don’t know why.

    Reply
    1. Ged

      It is, without a doubt, chocolate flavored heat.

      Reply
      1. dp

        I have a morbid fear that yours is the most cogent post in this thread. If I have any regret at all it is that nobody answered the question.

    2. Wagathon

      –>”That is not a picture of global warming that has its roots in my SUV’s tailpipe.”

      Sometimes it is, as when an ‘official’ thermometer is located on the tarmac in jet exhaust at an airport in France in the winter with a snowplow idling a few feet away. The land temperature record is to global warming as a burning anus from crapping out hot chiles is to the flu.

      Reply
      1. hunter

        That is a memorable and disturbing anaology…. ;^)

      2. Wagathon

        When the history of Western civilizaation during the final decades of the 20th century are one day written, it will be concluded that,

        “It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to heaven, we were all going direct the other way — in short, the period was so far like the present period, that some of its noisiest authorities insisted on its being received, for good or for evil, in the superlative degree of comparison only.”

        ~Charles Dickens, The opening paragraph of A Tale of Two Cities, 1859

      3. dp

        I was hoping for an educated word from Dr. Hansen, but I suppose Dickens will do.

        Of all the things I was sure of, those I was wrong about are the greatest surprise and the least expected.

        ~dp, Thoughts from the laundry chute of my life

      4. dp

        TMI, bud. Definitely.

      5. Wagathon

        —> “… isn’t made clear if this is sequestered heat on the move, or newly arrive heat on the move, or both,,,”

        SUN, yo: sequestered in the oceans, lakes and subsurface clays, and the heat is on the move, and the heat continually arrives as we all know based on anciet scrolls — i.e.: the heat it arrives via a flaming chariot drawn by four winged horses that are flogged by GOD

  18. Chief Hydrologist

    To put into a wider context – both temperature and ice extent seem correlated to the Atlantic Multi-decadal Oscillation.

    http://i1114.photobucket.com/albums/k538/Chief_Hydrologist/arcticice-1.gif

    http://i1114.photobucket.com/albums/k538/Chief_Hydrologist/chylek09.gif

    ‘What is relevant right now from my perspective is how rapidly the freeze-up will occur and with what spatial distribution; this is largely at the whim of weather patterns. The recent uptick in sea ice extent is intriguing. My research group has just submitted a paper for publication on the subject of autumn sea ice patterns as a precursor for wintertime snowfall and surface temperatures in the Northern Hemisphere.’

    ‘Digging deeper, the researchers found that local wind patterns, which occurred in 2007-2008 (but not the preceding winter), may have played a role. In particular, storms tended to track farther to the south, pulling cold air off the ice edge of eastern Canada into the Labrador Sea. The same storms also continued past Cape Farewell at the southern tip of Greenland, creating a phenomenon known as Greenland tip jets: High winds from the west deflect around the glacial slopes of Greenland, accelerating as they draw cold, ocean-chilling air into a relatively small area over the southern Irminger Sea.’

    http://www.whoi.edu/page.do?pid=12455&tid=441&cid=85090&ct=61&article=54347

    ‘A final clue emerged. Analyzing satellite and in-situ ocean data, the researchers said a large amount of pack ice and fresh water was exported into the northwest Labrador Sea in the summer of 2007. This froze the following winter, significantly extending the ice edge farther offshore. As a consequence, cold air from the North American continent traveled farther over ice, instead of warmer ocean waters, remaining cold until it hit warmer open water in the middle of Labrador Sea. The resulting temperature contrast helped trigger the sinking process.’

    So we have a link between the Northern Annular Mode and THC. This is an intriguing feedback.

    Reply
  19. Roy Weiler

    Dr Curry

    Yes, Yes…more like this!!

    Roy Weiler

    Reply
  20. tempterrain

    I thought I’d just try to tie together a few of the comments from the more “skeptical” of the commentators on this subject.

    Would it be fair to say that the ‘consensus’ of you guys would be that Arctic ice isn’t decreasing. That stopped in 2007? But if it is decreasing it is a cyclical phenomenon connected to ocean oscillations? But if its not due to ocean oscillations, it could be just due to unusual wind conditions? If not, and it is due to warmer conditions in the Arctic, then these warmer conditions cannot be linked to warmer conditions globally? But if they can be linked to warmer conditions globally, then these would be most likely caused by solar variations or cosmic rays, a recovery from the LIA and certainly not due to increases in CO2 levels, which aren’t caused by human emissions anyway. If none of the above, then its probably a good thing there’s less ice in the Arctic.

    Would it also be fair to say that you are happy to say you don’t know what’s happening in the Arctic, you are happy not to know, and you don’t particularly care, providing of course, the changing conditions aren’t used to justify CO2 emissions reduction?

    Reply
    1. Rob Starkey

      I would not agree with your summary of people’s beliefs

      I would agree that it is possible that arctic ice is declining long term, but it does not seem to be doing so at any alarming rate, ( about the same as 2007) and there does not seem to be any alarming developments as a result of it in any case.

      Reply
      1. hunter

        Rob,
        tt is not actually summarizing anything. He is trying to control the discussion, in his usual helpful way.
        Maybe Joshua will fixate on this and really add some legs to it.

    2. Chief Hydrologist

      You talking to me? Are you talking to me?

      This is a technical – apart from wags waxing poetical and you going all political. So it (nearly) all about peer reviewed and authoritative sources and a serious discussion. So why don’t you go play somewhere else for a while so the adults can talk.

      Reply
      1. tempterrain

        “You talking to me”? You ask.

        No, not particularly. I’m just being my normal helpful self and I thought I’d just try to clarify what you guys were actually saying. Its not an easy task as there are a variety of competing arguments, which, incidentally, don’t seem to cause problems between you all. Those who feel that the cooling is part of a long term cyclical process seem to be on remarkably good terms with those who feel the evidence for any change at all in the Arctic is somewhat lacking.

        Isn’t that heartwarming? If only those of us who felt that it was all part of an AGW problem could learn to be so charitable.

      2. Chief Hydrologist

        Still – it would be better if you actually had something relevant to say.

      3. Steven Mosher

        Common enemy,brings together fractious factions.

        Want to split the factions and make them weaker?

        you will need different tactics.

        It’s pretty clear what they are. You wont get them. Neither will Gore

      4. tempterrain

        Steven Mosher,

        Why “common enemy”?

        However, you do seem to have grasped a point that was lost on Chief Hydrologist. True scepticism is more than just about discrediting one line of scientific argument, it is about promoting a better one. Its just not scientific to say Theory X is not acceptable, but any other will do.

      5. Chief Hydrologist

        I not sure I understand what point that is tt.

        My comment was in relation to an obscure point involving blocking patterns in the north Atlantic and THC. This is one of the questions I ask myself. Is it possible that warming and melting sea ice can cause a collapse of THC and feedbacks that plunge the worlds into a glacial? It is one of those natural philosophy question that grab my attention.

        I was discrediting anything – oher than perhaps in linking to some graphs from Polyakov 2003. Here is the full study. We know what the pattern 20th century Arctic temps are – here is the paper in question – sea ice from Russian observations has the same temporal pattern.

        http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172.4878&rep=rep1&type=pdf

        ‘Examination of records of fast ice thickness (1936–2000) and ice extent (1900–2000) in the Kara, Laptev, East Siberian, and Chukchi Seas provide evidence that long-term ice thickness and extent trends are small and generally not statistically significant, while trends for shorter records are not indicative of the long term tendencies due to large-amplitude low-frequency variability. The ice variability in these seas is dominated by a multidecadal, low-frequency oscillation (LFO) and (to a lesser degree) by higher-frequency decadal fluctuations. The LFO signal decays eastward from the Kara Sea where it is strongest. In the Chukchi Sea ice variability is dominated by decadal fluctuations, and there is no evidence of the LFO. This spatial pattern is consistent with the air temperature–North Atlantic Oscillation (NAO) index correlation pattern, with maximum correlation in the near-Atlantic region, which decays toward the North Pacific. Sensitivity analysis shows that dynamical forcing (wind or surface currents) dominates ice-extent variations in the Laptev, East Siberian, and Chukchi Seas. Variability of Kara Sea ice extent is governed primarily by thermodynamic factors.’

        ‘ Understanding Arctic temperature variability is essential for assessing possible future melting of the Greenland ice sheet, Arctic sea ice and Arctic permafrost. Temperature trend reversals in 1940 and 1970 separate two Arctic warming periods (1910–1940 and 1970–2008) by a significant 1940–1970 cooling period. Analyzing temperature records of the Arctic meteorological stations we find that (a) the Arctic amplification (ratio of the Arctic to global temperature trends) is not a constant but varies in time on a multi-decadal time scale, (b) the Arctic warming from 1910 – 1940 proceeded at a significantly faster rate than the current 1970 – 2008 warming, and (c) the Arctic temperature changes are highly correlated with the Atlantic Multi-decadal Oscillation
        (AMO) suggesting the Atlantic Ocean thermohaline circulation is linked to the Arctic temperature variability on a multi-decadal time scale.’
        http://www.lanl.gov/source/orgs/ees/ees14/pdfs/09Chlylek.pdf

        But is there any point in quoting peer reviewed science to a technically challenged space cadet such as yourself? Not so much. The world is quite obviously not warming – something that is obvious and becoming more obvious as time goes by.

        Frankly – I consider you part of the problem and not part of the solution. Lies and delusions in the service of a ‘limits to growth’ ideology. I do support reductions long term in carbon emissions – as I explained endlessly. But your nonsense will see derail any progress for a generation. You are utterly pathetic.

      6. kuhnkat

        temp baby,

        when the man is promoting the theory that the moon is made of green cheese I will accept the person simply refuting his declaration with facts and not require a theory of planetary creation to do so.

      7. tempterrain

        CH : “The world is quite obviously not warming – something that is obvious and becoming more obvious as time goes by.”

        NASA: http://imagesofglobalwarming.org/wp-content/uploads/2011/04/Nasa-Global-Warming-Images1.gif

        So who to believe? Mr Chief or NASA?

        I’d say that this graph may be subject to a slightly higher degree of peer review that anything you might have to say on this blog. But is there any point in quoting peer reviewed science to a technically challenged right wing ideologue such as yourself ?

      8. steven mosher

        TT
        The common enemy of “skeptics” is of course, CAGW. So, they don’t worry about having a coherent attack. On one day the dragon slayers say one thing, on another day ‘coolists” say another thing.. common foe binds them together.

        True skepticism my friend is not about advancing anything. Very few people can pull it off with consistency.

      9. tempterrain

        Steven Mosher,

        Your argument makes perfect sense from a political POV but does it make sense scientifically?

        I say it doesn’t. Would you agree?

      10. Chief Hydrologist

        At least use the right graph – http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.gif

        1998, 2005 and 2010 are well within limits of error shown on the graph. So no warming since 1998 – seems quite obvious.

        Here are all the sources with monthly data points – http://en.wikipedia.org/wiki/File:Satellite_Temperatures.png

        Here is a useful discussion – http://www.worldclimatereport.com/index.php/2008/12/02/will-the-un-chill-out-on-climate-change/

        Peer reviewed?

        ‘Given the widely noted increase in the warming effects of rising greenhouse gas concentrations, it has been unclear why global
        surface temperatures did not rise between 1998 and 2008.’ http://wattsupwiththat.files.wordpress.com/2011/07/pnas-201102467.pdf

        ‘Because of the resultant increase in anthropogenic sulfur emissions, there is a0.06 W∕m^2 (absolute) increase in their cooling effect since 2002. This increase partly reverses a period of declining sulfur
        emissions that had a warming effect of 0.19 W∕m2 between 1990 and 2002. The increase in sulfur emissions slows the increase in radiative
        forcing due to rising greenhouse gas concentrations (Fig. 1).
        Net anthropogenic forcing rises 0.13 W∕m^2 between 2002 and
        2007, which is smaller than the 0.24 W∕m2 rise between 1997
        and 2002. The smaller net increase in anthropogenic forcing is
        accompanied by a 0.18 W∕m2 decline in solar insolation caused
        by the declining phase of the eleven year solar cycle, such that the
        sum of modeled forcings increases little after 1998 and declines
        after 2002 (Fig. 1). This cooling effect is amplified by a net
        increase in the Southern Oscillation Index (SOI).’

        More recent work is suggesting a sulphur effect this century of 0.1W/m^2 – more stratospheric than Chinese. Solar cycle 24 is peaking next year at the lowest no. of sunspots seen since 1928 – and going lower – http://lasp.colorado.edu/sorce/total_solar_irradiance_plots/images/tim_level3_tsi_24hour_640x480.png – the last century saw a 1000 year high.

        The SOI is trending positive after 1998 and will continue in a La Nina bias for another decade or three.

        ‘A negative tendency of the predicted PDO phase in the coming decade will enhance the rising trend in surface air-temperature (SAT) over east Asia and over the KOE region, and suppress it along the west coasts of North and South America and over the equatorial Pacific. This suppression will contribute to a slowing down of the global-mean SAT rise.’ http://www.pnas.org/content/107/5/1833.full

        I am an advocate of freedom, the rule of law and democracy. You are hopeless.

      11. Jim D

        CH, if you have some idea of what is going to happen with the extra 5 W/m2 forcing in the 21st century, you need to say it, because otherwise people will just think it will simply get warmer like the last time the earth had so much CO2 which was in the Eocene epoch (a pre-Antarctic ice shelf period).

      12. Chief Hydrologist

        So Jim,

        So it I have shown by reference to peer reviewed literature that most warming was due to cloud changes, that it hasn’t warmed recently and that it won’t warm for a decade or three more? Now you want me to prove it won’t warm for the rest of the century?

        Frankly I expect that alternative and cost effective sources of energy need to be found to enable the necessary 3%/year growth in energy and food.

        So your scenario is pointless as indeed is all of what you say.

        Cheers

      13. tempterrain

        Mr Chief,

        You might think peer reviewed scientific data and papers shows a cooling in recent years but that’s not the way NASA sees it.

        http://www.nasa.gov/topics/earth/features/upsDownsGlobalWarming.html

        Maybe you’d like to write to them and put them straight? Or have you written them off as “hopeless” too?

      14. manacker

        tempterrain

        If you read it closely, you will see that there is nothing in the NASA link you cited that refutes the observed fact that global average surface temperature has stopped warming since 2001 or 1998.

        What it will do from now on out is anyone’s guess, with the Chief’s projections showing a cooling trend over the next few decades while IPCC projects warming of 0.2C per decade.

        Time will tell which projection comes closer to reality.

        Max

      15. Chief Hydrologist

        tt,

        This is the Easterling study. I actually considered quoting this myself. Most amusing.

        ‘This may sound counter-intuitive at first sight, so let’s take a closer look at the data. Figure 1 shows the change in the world’s air temperature averaged over all the land and ocean between 1975 and 2008. The warming is obvious — about 0.5° C (0.9° F) during that time. However, there are plenty of periods — 1997 to 1985 and 1981 to 1989 (see insets, Figure 1), and 1998 to 2008 — when no warming is seen, the most recent of which some global warming skeptics say is evidence that the world is actually cooling.

        What’s going on? To answer this question, Easterling and Wehner pored over global temperature records dating from 1901 to 2008 and also ran computer simulations of Earth’s climate looking back into the past and forward into the future. They concluded that in a climate being warmed by man-made carbon emissions, “it is possible, and indeed likely, to have a period as long as a decade or two of ‘cooling’ or no warming superimposed on a longer-term warming trend.”‘

        The $64 question is why? The answer suggests that they cannot rely on warming to resume.

        Cheers

      16. Chief Hydrologist

        ‘However, there are plenty of periods — 1997 to 1985,,,’ That is NASA’s typo – it should 1977.

        I wrote about it in 2007 – http://www.americanthinker.com/2007/11/enso_variation_and_global_warm.html.

        So my prediction has been confirmed by observation.

      17. tempterrain

        Mr Chief,

        Methinks you are putting your own spin on the David Easterling’s NASA paper. There is nothing to support your prediction.

        He’s saying that:

        “periods no warming or even slight cooling can easily be part of a longer-term pattern of global warming.”

        and furthermore

        “Claims that global warming is not occurring that are derived from a cooling observed over short time periods ignore natural variability and are misleading.”

        You may, of course, turn out to be correct that there will be a a period of cooling in the next few decades, but this is very much a fringe view, and not part of the mainstream consensus.

      18. Jim D

        CH, you probably have noticed that clouds work both ways, but in the background CO2 is always warming. It is easy to see which is more important on the long term, and I have no reason to believe that 2010-2020 won’t be at least 0.15 C warmer than 2000-2010, a decade which has presented a soft target to beat by having no super El Ninos, and a relatively long solar minimum.

      19. Chief Hydrologist

        The idea that sea surface temperature will moderate surface temperature over a decade or 3 is quite mainstream. Clouds seem involved – http://i1114.photobucket.com/albums/k538/Chief_Hydrologist/Wong2006figure7.gif

        Anastasios Tsonis, of the Atmospheric Sciences Group at University of Wisconsin, Milwaukee, and colleagues used a mathematical network approach to analyse abrupt climate change on decadal timescales. Ocean and atmospheric indices – in this case the El Niño Southern Oscillation, the Pacific Decadal Oscillation, the North Atlantic Oscillation and the North Pacific Oscillation – can be thought of as chaotic oscillators that capture the major modes of climate variability. Tsonis and colleagues calculated the ‘distance’ between the indices. It was found that they would synchronise at certain times and then shift into a new state.

        It is no coincidence that shifts in ocean and atmospheric indices occur at the same time as changes in the trajectory of global surface temperature. Our ‘interest is to understand – first the natural variability of climate – and then take it from there. So we were very excited when we realized a lot of changes in the past century from warmer to cooler and then back to warmer were all natural,’ Tsonis said.

        Four multi-decadal climate shifts were identified in the last century coinciding with changes in the surface temperature trajectory. Warming from 1909 to the mid 1940’s, cooling to the late 1970’s, warming to 1998 and declining since. The shifts are punctuated by extreme El Niño Southern Oscillation events. Fluctuations between La Niña and El Niño peak at these times and climate then settles into a damped oscillation. Until the next critical climate threshold – due perhaps in a decade or two if the recent past is any indication.

        As for clouds swinging both ways – I take it that is a considered analysis. We have a reference? What causes cloud change?

        I am not predicting anything. We are in a cool Pacific mode after 1998 and these tend to last for 20 to 40 years. Will the world start warming after that? Perhaps – but if this was the dominant cause of recent (1976 to 1998) warming why does it happen and what is likely to happen next? Longer term we know that ENSO varies substantially – http://i1114.photobucket.com/albums/k538/Chief_Hydrologist/lean_2008.gif – and as many people have suggested there seems to be a solar signature. So what happens when solar activity declines from a 1000 year high? More and bigger La Nina seems very likely to me – and what are the implications of that?

        Here is new model based prediction – http://www.pnas.org/content/107/5/1833.full

        It is all very mainstream science – has been for years. The NASA site suggests that we can get a decade or 2 of non warming from natural variability. Yes – that is what I am saying. But also that the variability emerges mostly from the Pacific.

        Not sure what your problems are – but I think it emerges from being space cadets.

  21. Herman Alexander Pope

    Likely cause of the recent changes in Arctic sea ice
    This is a normal cycle that has repeated, over and over again.
    The temperature during the past ten thousand years has been stable in a narrow range. The warming up to the Medieval Warming Period took several hundred years. The cooling between then and the Little Ice Age took several hundred years. The warming between the Little Ice Age and now took three hundred years. Each warming ends with Low Arctic Sea Ice Extent and is accompanied by Massive Arctic Ocean Effect Snow. The next cooling is starting and it will likely cool for several hundred years.
    We need this low sea ice extent period to build the ice for the next phase of the cycle. Look at the data. Temperature is not stable at the modern normal. Temperature is not stable at a temperature. Temperature is changing in a stable cycle. It always gets warmer than the normal and then proceeds to cooler than the normal. This is a stable cycle. Warm leads to cool and cool leads to warm. It is not stable in between or at either extreme. The Air Conditioning is on or the Air Conditioning is off. When the Air Conditioning is on, we cool. When the Air Conditioning is off, we warm. The sun provides the warm and the Arctic Ocean Effect Snow provides the Air Conditioning. Works kind of like Air Conditioning in a house or car in Houston in the Summer.

    Reply
    1. Herman Alexander Pope

      Warm melts Arctic Sea Ice and turns the Air Conditioning on.
      Cool lets the Arctic Sea Ice freeze and turns the Air Conditioning off.
      This is the Powerful Negative Feedback that is the Thermostat of Earth.

      Reply
    2. Herman Alexander Pope

      Most of you are ignoring my stable temperature cycle theory.
      Is it just because it is a simple answer that does make sense?
      If you think I am wrong, provide reasons and data.
      My data is the official Ice Core Data and official Modern Data.
      That shows temperature has been regulated in a narrow range for ten thousand years and shows that modern temperature is well inside the same stable range. There is nothing unstable about the data.
      The only unstable information is from flawed Theory and Models as they project the future.

      Reply
  22. spangled drongo

    I’ve always been fascinated by the thought of early seafarers such as Frobisher, Davis etc in the 16th c, in ungainly, vulnerable, wooden ships that could not go an inch to windward whereby on average, 50% of the navigable water was denied them, poking about the arctic with a view to navigating through to the East Indies.

    There could not have been much ice around then, either.

    Reply
    1. Herman Alexander Pope

      The Medieval Warm Period did end with opening the Arctic and bringing on the Arctic Ocean Effect Snow that caused the Little Ice Age which closed the Arctic until recently.

      Reply
    2. Neven

      Think again, dear friend: A Brief History of Arctic Warming

      Reply
      1. Kermit

        What about the Vikings and earlier European artefacts all over Greenland and Baffin Island?

      2. Herman Alexander Pope

        That is very interesting. Thanks! Yes, the Arctic opens and it snows more and it closes. There are major cycles that take hundreds of years and smaller cycles along the way. If it takes an ice breaker to get through, that is more closed than open. Now you can get through without and ice breaker. This is all consistent with my climate theory.

    3. manacker

      SD

      Tony Brown (who has contributed here in the past) has done some interesting historical research on past voyages through Arctic waters.

      It is clear that these passages have been more open than today during certain periods of the past and also more closed during other periods, IOW the currently observed retreat of multi-year Arctic sea ice extent is nothing unusual or unprecedented.

      The lead article here presents us some plausible hypotheses on the underlying causes for the recent changes – the observed Arctic warming is one of the possible reasons listed (among others).

      We know from earlier work by one of the same authors (Polyakov) that temperatures were as high and that sea ice extent was as low in the 1930s/1940s before reversing until the mid to late 1970s when satellite measurements started. We do not know much about earlier cycles of warming/cooling and sea ice retreat/expansion.

      Suffice it to say that there are indications that at least a major part of the current sea ice retreat is due to naturally occurring shifts in weather patterns, rather than simply to Arctic swarming caused by human GHG emissions, as some people apparently believe.

      Max

      Reply
  23. Herman Alexander Pope

    Look at the Leap Second Data on the NIST website.

    http://www.nist.gov/pml/div688/grp50/leapsecond.cfm

    Go down and read the section on Leap Seconds. During the most recent decade and more, Leap seconds have been added much less frequently. This does show that the earth is rotating faster. This means the inertia of earth has decreased due the massive snows that we have had during the past decade and more which moved water from the low latitude oceans to ice on high latitudes. This means that the ice volume at the poles and northern latitudes has increased and that means that albedo has increased and it means the oceans are dropping and not rising. The warming cycle of the past three hundred years is likely over, or nearly over and we are entering the next several hundred year cooling phase. The glaciers are still retreating because it is still warm, but they are being replenished at their source at a faster rate. Greenland and the Antarctic Continent are being replenished on top at a faster rate than they are losing from the sides. The leap seconds changes do show that.

    Reply
  24. Alistair McDhui

    You’re right about there being ‘atmospheric forcing’. It hasn’t been picked up because to admit that the ‘AIE’ is really heating for thicker clouds would be to admit that C02-AGW is near zero or even slightly negative.

    The 60-70 year Arctic oscillation period is all about bio-feedback causing clouds to transmit more energy. it’s just ending so the Arctic is set to freeze, so are we!

    The same mechanism explains why at the end of ice ages deep southern ocean heating/currents start 2000 years before any atmospheric CO2 rise.

    As I have put these ideas out, the response was first to reject them totally. The latest is to fall back to a lower CO2-AGW.

    Basically, Sagan was wrong and I’m sure some deep in NASA know this. The latest attempt to claim AIE is doubled is in my view at best self-delusion, at worst an attempt to deceive from authority.

    You can’t fool all of the people all of the time…..I’ve worked out the proper physics…

    Reply
    1. R. Gates

      You said: The 60-70 year Arctic oscillation period is all about bio-feedback causing clouds to transmit more energy. it’s just ending so the Arctic is set to freeze, so are we!

      ____
      Not likely. Yes, the Arctic will eventually refreeze this winter, but the long-term trend in seasonal summer sea ice extent, area, and volume shows no sign of recovery– quite the opposite. Expect an ice-free summer Arctic earlier rather than later this century.

      Reply
  25. hunter

    Dr. Curry,
    It is not clear what the role of carbon black and soot is in the study you have posted.
    I thought there was an emerging sense that soot and carbon black were important in ice.
    Is this not the case?

    Reply
  26. tempterrain

    Judith,

    How accurate would you say was the data is this graph which shows Arctic Sea sea ice extent back to the beginning of the 20th century?

    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seasonal.extent.1900-2007.jpg

    Reply
  27. Wagathon

    And, the beginning of the 20th century means what, exactly?

    Reply
    1. tempterrain

      You are asking whether it is 1900 or 1901?

      Reply
      1. Wagathon

        Or, maybe the halfway point from 1800 the tequila was first made in Jalisco… where it’s really hot?

  28. Rattus Norvegicus

    Judith, you may want to walk your claims of an increase in winter max back. As Tamino shows here (and in several other posts) winter max has been declining in recent years.

    Reply
    1. manacker

      Rattus Norvegicus

      Judith’s claim of ecent gain in end-winter Arctic sea ice is validated by the NSIDC data.

      As in all cases, it’s better to go back to the source rather than relying on someone else’s rehash (mine or Tamino’s) of the data:
      ftp://sidads.colorado.edu/DATASETS/NOAA/G02135

      The longer-term end-March trend since 1979 is negative, as we all know.

      If you plot it in Excel (as NSIDC does) you will see:

      Linear equation is y = -0.043x + 16.24

      We have seen a cumulated ~6.7% net loss compared to the 1979-2000 baseline (-1.14 out of 15.70 million square km).

      Over the past 5 years (2006-2011) the trend is one of net growth.

      Linear equation is y = 0.053x + 14.66

      We have seen a cumulated ~2.4% net gain compared to 2006 (+0.34 out of 14.43 million square km).

      So the short-term trend is, indeed, one of recovery, but the longer-term trend is one of overall decline.

      Check the data out yourself to be sure.

      Max

      Reply
  29. R. Gates

    I’ve been making the case for quite some time that a different metric for measuring the total energy in the Arctic environment (both oceans and atmopshere) ought to be developed. This metric would be similar to the total Atmospheric energy content measured and discussed in this peer reviewed paper:

    http://www.agu.org/pubs/crossref/2011/2011GL048442.shtml

    Under a total energy metric, one would look at all forms of energy in the Arctic including sensible heat in atmosphere and wind, enthalpy, currents, water and air temps, mass balances, salinity, etc. Under such a total energy metric, one possibility is that 2007 and 2011 would be found to be actually very similar in total energy, with only the mix being different, and thus the results being quite similar because of the similar total energy content. Under this metric, 2007 would not be seen to be an “outlier” event, but rather, the inevitable result of the gradual increase in total energy in all forms in the Arctic environment. Furthermore, the parameters for the certainty or uncertainty of continued sea ice loss can be established based on projections of total energy content in the Arctic environment.

    Reply
    1. tonyb

      R Gates

      I have posted you numerous links on previous periods of Arctic warming-the last just a couple of weeks ago on a thread at WUWT on which you were active.

      The reality is that arctic ice is highly variable from season to season and also within cycles of roughly 60 years with more accentuated ones of 120 years or so. The last great melting of the Arctc was from 1918-1940 (even captured on Pathe Newsreel) written about in great detail by my colleague Dr Anrd Bernaerts
      http://www.arctic-heats-up.com/chapter_1.html
      and the one before that around 1818-1860 which I wrote about here;
      http://wattsupwiththat.com/2009/06/20/historic-variation-in-arctic-ice/#more-8688

      Sea ice levels around the time that satellite monitoring stsrted was probably at its highest for some 100 years ore more. This coincides with the last gasp of the LIA that can be seen in global records. As you know the Arctic is virtually surrounded by land and is very prone to the wind and warm currents as was observed in a book published in 1820 during what was said to be the first scientific expedition to the Arctc and which was referenced in my article.

      There have been several great civilisations in the Arctic which Include The Vikings a thousand years ago and the Ipiatuk some thousand years previously. Long periods of warmth and shorter interludes are the norm not the exception.

      tonyb

      Reply
  30. Faustino

    Judith, I sent the following letter to The Australian newspaper in response to an article which quoted (not altogether kindly) dire warnings re AGW and ice loss from non-experts such as palaeontologist Tim Flannery, our government’s Climate Commissioner. Not published, unfortunately, it’s much easier to get snappier and less technical letters printed.

    “Changes in Arctic ice coverage are often cited by non-experts as evidence of dire global warming (Cut & Paste, 21/9). A recognised expert, Judith Curry of Georgia Tech, says that it is very difficult to find in the data reason to attribute changes in ice coverage to global warming.

    “Curry recently reviewed the latest work in this field. The papers she cites all stress the complexity of the issue. One, she says, “clearly and authoritatively describes the complex interactions among ocean dynamics and heat transport, sea ice dynamics forced both by atmospheric winds and ocean currents, and atmospheric thermodynamic forcing in determining recent variations in multi-year sea ice extent. Hence sorting dynamical versus thermodynamic factors and attribution to increased greenhouse gases is not at all straightforward.”

    “Curry notes that “prediction of sea ice is hostage to predictions of the chaotic atmospheric and oceanic dynamics. In the current sea ice regime since 2007, there has been return to a large amplitude annual cycle (with an increase in the wintertime max), but with an overall shift to lower summertime values. The regime shifts seem to be associated with shifts in the multidecadal ocean circulation regimes [e.g. the Pacific Decadal Oscillation which drives much of Australia’s climate]. Given the apparent importance of the MDCs in determining the seasonal and interannual variations in sea ice extent, it is very difficult to discriminate a global warming signal from the data because of the short data record.””

    I hope my second sentence was an accurate representation.

    Reply
  31. Taffy Hastings

    Content is genuinely king and this article is evidence of this.

    Reply
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