How predictable is the timing of a summer ice-free Arctic? 

Posted: September 1, 2016 by oldbrew in climate, Forecasting, modelling, Natural Variation, sea ice, Uncertainty
Tags:

A polar bear inspects a US submarine near the North Pole [credit: Wikipedia]

A polar bear inspects a US submarine near the North Pole [credit: Wikipedia]


‘How predictable’ assumes some predictability of a future ‘ice-free’ Arctic in summer – debatable at least.
H/T US CLIVAR – Climate Variability and Predictability Program

The strong decline in the summer sea ice cover of the Arctic over the last decades has led many to ask when the Arctic will be ice-free for the first time.

Rather than providing yet another answer to this question, in a recent Geophysical Research Letters article by Jahn et al., they focused on determining how well the occurrence of an ice-free Arctic can be predicted, due to the inherent internal climate variability of the system.

By using the newly available large ensemble of 40 simulations from the Community Earth System Model (CESM1), which all have slightly different initial conditions but are forced the same, they were able to assess the influence of natural fluctuations of the climate system on Arctic sea ice predictability.

They found that the uncertainty for the prediction of an ice-free Arctic caused by this internal climate variability amounts to around two decades. The study further showed that present-day or past sea ice conditions could not be used to narrow down the prediction uncertainty from internal variability.

Differences in the future emissions between the medium (RCP4.5) and strong (RCP8.5) emission scenarios add at least another five years to the prediction uncertainty. Hence, two of the three main uncertainties of model predictions gives a prediction uncertainty for an ice-free Arctic of around 25 years. The third main source of climate projection uncertainty, model differences, likely further add to this lower bound of prediction uncertainty.

This means that even the best climate models cannot narrow down the exact year or even the exact decade when researchers expect to see an ice-free Arctic for the first time, as the timing depends on the exact trajectory of the weather and climate variability between now and then, which can’t be predicted. 

Written by Alexandra Jahn, University of Colorado, Boulder

Source: How predictable is the timing of a summer ice-free Arctic? | US CLIVAR

Despite certain debatable angles earlier (e.g ’emissions scenarios’), the last paragraph is telling. It seems to say climate models can’t handle climate variability very well, if at all. Interesting.

Comments
  1. oldbrew says:

    ‘The study further showed that present-day or past sea ice conditions could not be used to narrow down the prediction uncertainty from internal variability.’

    None of this stops headline chasers predicting ice-free Arctic summers ‘maybe as soon as next year’ [repeat every year ad nauseam].

    ‘What’s another year?’
    http://trustyetverify.wordpress.com/2016/08/31/whats-another-year/

  2. tallbloke says:

    “or even the exact decade when researchers expect to see an ice-free Arctic for the first time”

    Well right there we have an admission that climate varies naturally on multidecadal timescales. All bets are off for global warming then, considering we got global cooling 1945-1975…

  3. husq says:

    >None of this stops headline chasers predicting ice-free Arctic summers ‘maybe as soon as next year’ [repeat every year ad nauseam].<

    The Japanese have a term for this: “Funiki zukuri – creating an atmosphere.”

    e.g.
    If a politician wishes to bring about a certain outcome which society will accept as a de facto event,
    they need to be first subconsciously and then later consciously convinced of its inevitability.
    You do not simply put forward your idea, saying this must happen.
    You approach it obliquely from various angles and through various media.
    You saturate the social atmosphere with a more or less conscious expectation and then,
    when everyone is ready to accept it, you bring it consciously forward and hey presto,
    it is accepted almost as a matter of course.”

  4. oldbrew says:

    John Daly said (around 15 years ago):
    ‘The limits on the thickness of Arctic ice are determined by how low the air temperature can get, and on how warm and fast-moving the subsurface water is. Air temperatures measured in the Arctic region show no recent warming, thus discounting the possibility that recent thinning of ice could be caused by atmospheric warming above the ice. Rather, the thinning of ice in the 1990s is clearly associated with a warming of the sub-surface ocean, as shown by the SCICEX data, caused in whole or in part by the strong NAO increasing the flow rate of Atlantic water into the Arctic Ocean. [bold added]

    There is nothing in the data to suggest anything but natural cycles at work.’
    http://www.john-daly.com/polar/arctic.htm

    In the link he has an experiment with 3 ice cubes. Basically it shows that the faster water moves over the surface of the cube, the faster the ice melts i.e. it’s important to know the flow rate.

  5. catweazle666 says:

    I just love these theories whereby cherry-picked sections of clearly cyclic processes are linearly regressed to Armageddon and the proponents run round howling about how totally doomed we are.

    Only in climate “science”…

  6. You may find a figure in my website, modified from the CLIVAR logo, to show the real TOA-surface energy balance relation:

    http://globalenergybudget.com/#Warming

  7. oldbrew says:

    “Global” warming confined to the poles, in wintertime – “much to the chagrin of people who want the Arctic ice cap to disappear … Summers are not getting warmer in the Arctic” – Joe Bastardi

    http://notrickszone.com/2016/08/30/warming-not-global-joe-bastardi-most-of-the-global-warming-is-happening-at-the-arctic-and-antarctic/

    So ‘how predictable’ is the wrong question.

  8. oldbrew says:

    Re ‘flow rate’ (see above):
    ‘Polynyas occur in areas where swiftly moving sea currents prevent the freezing of surface water.’
    http://www.aquatic.uoguelph.ca/oceans/ArticOceanWeb/ArOWaters/PolynyaForm.htm

    ‘Compared to the surrounding air, the waters of a polynya are so warm that steam billows up.’

    What is a polynya?
    http://www.aquatic.uoguelph.ca/oceans/ArticOceanWeb/ArOWaters/Polynyas.htm

    ‘polynyas can be hundreds of kilometres wide’

  9. oldbrew says:

    Ship of Fools II: Green Arctic Expedition Frustrated by Large Quantities of Ice
    http://www.breitbart.com/london/2016/09/01/green-arctic-expedition-frustrated-large-quantities-ice/

    ‘An Arctic expedition designed to raise awareness of the perils of man-made climate change is being frustrated by unexpectedly large quantities of ice.’

    What a shame🙂

    James Delingpole comments:
    ‘If idiots want to freeze their balls off, take City investment firms and insurance brokers for a ride, and make utter dicks of themselves for our delectation and amusement while making a mockery of current climate ‘science’, then I’d say they are performing a truly valuable public service.’

  10. oldbrew says:

    Tipping Points Postponed Again: Arctic Sea Ice Refuses To Melt …No Real Shrinking In 10 Years! –

    Clearly the Arctic is nowhere near a death spiral, and the polar ice has in fact defied the models and the many earlier predictions that it would disappear by 2015 altogether. With all that ice still up there, it’s time for the sea ice and global warming modelers to discard their equations – and to start over again from scratch.

    See more at: http://notrickszone.com/2016/09/06/tipping-points-postponed-again-arctic-sea-ice-refuses-to-melt-no-real-shrinking-in-10-years/

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