Arctic Dive?

Arctic sea ice has been flirting with record lows all winter long, and many days has actually plunged below previous records. But now, it seems to be going even lower.

NSIDC (National Snow and Ice Data Center) is cross-calibrating a new instrumental record, and we still have data from JAXA (Japan Aerospace eXploration Agency) . Provisional data from NSIDC show the recent decline (the red line, with dashes showing the provisional data) dipping well below previously existing the 2-standard-deviation limit:


As for JAXA data, it shows the recent dive quite prominently (in red):


It’s also evident in anomaly values (with the seasonal cycle removed, using the entire time span as a baseline):


JAXA data don’t start until 2002, but we can get a more complete record by aligning it with NSIDC data the same we we did before. Then the sea ice extent looks like this:


Anomaly values are here (again using the entire time span as a baseline):


Any way you look at it, Arctic sea ice during May has fallen far below previous May values.

We won’t know until September just how low it will go this year. In the past, the correlation between May extent and the annual minimum hasn’t been very strong (beyond the overall downward trend over the years), but then, we haven’t seen May extent go this low, or this far below previous values, either. Whether or not this May’s Arctic sea ice nosedive is a harbinger of things to come, remains to be seen.

This much is sure: Arctic sea ice is disappearing, not just in summer/fall, but all through the year. The astoundingly high temperatures in the Arctic this winter are likely part of the reason for the extremely low sea ice extent. And, with so much more area exposed to the sun which is open ocean rather than highly reflective ice (a million square kilometers or so), yet more heat will be absorbed in the Arctic and temperatures may rise even higher.

It also remains to be seen how the extreme low May sea ice will affect patterns of atmospheric circulation. It has been argued that we’re already seeing major changes to circulation patterns because of the decline of sea ice, and the recent change might make that effect more prominent.

Which puts us in the midst of a climate experiment on a grand scale. Unfortunately, all of humanity is stuck in the same “test tube” along with all of life on earth. This kind of uncontrolled experiment seems to me to be far too great a risk, for no reason other than our inability even to listen to the dire warnings climate scientists have been issuing for decades, let alone to heed those warnings.

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19 responses to “Arctic Dive?

  1. Listening to the warning signs and heeding them enough to advocate for environmental justice will (unfortunately in this political kabuki theater) get one labeled as a religious alarmist.
    Fact checking has given way to infotainment.
    OTOH, where there’s life there’s hope.

  2. Philippe Chantreau

    Glad to see that they’re bridging the data. I hope Cryosphere Today follows suit, they have been publishing very spurious fluctuations that are not helpful, even though they have a disclaimer figuring prominently on the home page.

  3. Another positive feedback mechanism or tipping point that I hadn’t personally considered was the metastable perching of cold fresh(er) water on top of warmer more saline water throughout much of the Arctic Ocean. The freshwater lens is derived from melting of sea ice, land-based ice sheets, and rivers draining into the Arctic Ocean.

    Loss of sea ice and increased mixing via wind and wave action over open water could remove this permanently. There was a recent lengthy and well-written comment at Neven’s explaining this that I unfortunately failed to bookmark. Maybe other readers can fill in.

  4. Yes, the present Arctic melting season will surely be something extraordinary..
    Another good place to follow the development is the danish Polar Portal:
    It shows ice extent, thickness, volume, etc,
    It is quite impressing to see the ice thickness animation, showing for instance the gyre creating open water in the Beaufort Sea, and the ice transport through Fram and down along Greenland’s east coast.

  5. Extremely helpful to have Tamino presentation, and that looks awful. I’ve been struggling with trying to avoid exaggeration while facing the disastrous obviousness of it all.

  6. Windchaser

    Magma, The freshwater lens is derived from melting of sea ice, land-based ice sheets, and rivers draining into the Arctic Ocean.

    If I understand correctly, the freshwater lens is also created via thermodynamic pumping during freezes. The surface loses heat more easily, so it freezes first. But fresher water freezes more easily, so the dropping temperatures during the winter acts as a chemical pump that actually pushes the salt out.

    In terms of thermodynamics, it’s energetically easier to push some of the salt out of the surface water than it is to freeze the water with the salt in there. So that’s what happens. The water separates into fresh and salty as it freezes.

    (Incidentally, this is also how Yankees used to make applejack — by allowing fermented cider to thaw and freeze over the winters and removing the ice at intervals. The ice has a higher concentration of H2O, so the alcohol concentrates in the liquid).

    What this means is that the freshwater cap in the Arctic won’t ever fully go away — it’ll be created anew every spring, as the ice from the previous winter melts.

  7. Is this what you were thinking of Magma?

    There’s a simple physical process that keeps the sea ice pack in place in the Central Arctic Basin: the fresh water lens.

    This is the ~50ft deep surface layer of water with about 25 ppm or less salt content.

  8. john ramming

    There is a typo on the Arctic salt concentration in the original post. It is 2.5%, not 25ppm. Understandable typo, I’ve had my share.

  9. OT:

    JMA have released their April global temperature anomaly 2 weeks earlier than is usual. This marks the 12th consecutive month of record-breaking monthly anomalies for that series.

    GISS have also released April anomaly.

    • NOAA April anomaly is highest for any April, and 5th highest of any any month. Like JMA, this marks 12 consecutive months of record-breaking monthly anomalies for each month.

      It appears surface temperatures have peaked in (lagged) response to el Nino. Lower troposhperic temps have almost peaked, too.

      On the theme of short-term responses (and tipping the hat to the thread topic), J Francis posited in 2009 that the atmosphere may “remember” low September sea ice concentrations in the Arctic over the following months. Later work from Francis and others emphasise the uncertainty of predicting long and short-term regional responses to diminished sea ice when factoring other weather/climate phenomena. More insight may be gleaned if NH September sea ice concentration is very low this year.

  10. Ahhahha, John. Not a typo, a mistake! (I should know, I wrote it ;^) It should be “PSU”, not ppm.

    Ocean salinity is defined as the salt concentration (e.g., Sodium and Chlorure) in sea water. It is measured in unit of PSU (Practical Salinity Unit). It is equivalent to per thousand or (or g/kg.

    The 25 PSU value for sea surface salinity is important as the threshold where overturning cirulation starts to occur in a cooling water column, bringing up heat from below.

    A “fresher” layer will freeze as it cools, a saltier layer will sink forcing warmer water to the surface.

    If the warm layer is a thousand meter thick, it’s not going to freeze in a single Winter.


  11. So is this how “arctic amplification” works. The tropics don’t actually get much hotter, but the excess heat ends up being pumped to the arctic?

    • Yup! It’s all part of the atmosphere’s general circulation, a global convection process that keeps the tropics from overheating by shunting all the excess heat from there toward the poles while draining the cold air from the poles toward the tropics. The more heat in the system, the warmer the poles become because of the added heat transfer from equator to poles and the less cold air is available to drain equator-ward. And so it goes.


      • The way I think of it–and I’m saying this to invite criticism and comment that might improve ‘the way I think of it’–is that since the Arctic tends to be advective heat sink for the planet, it follows that heat loss *from* the Arctic must be dominated by the *radiative* side of the ledger. (Ie., net advective fluxes to the Arctic must by overwhelmingly positive.) That’s in contrast to the tropics, where, although the total outward radiative flux must be greater (since the tropics are the warmest portions of the planet), the heat budget should be more dominated by advective losses.

        If that’s right, then it would make sense that greenhouse warming would be felt the most in the Arctic, where radiative loss is most important.

      • Doc: the description you give is accurate from a radiation perspective and overall poleward transport, but misses a few details. Yes, the poles are locations with net radiative loss, and the equator is a net radiative gain. The transport of energy to the poles is a bit more complex, though.

        There are three main energy transports in the zonal (N-S) direction: sensible heat in the atmosphere (thermal energy, net warmer air towards the poles)), latent heat (evaporate water in one location, move it N-S and condense it at another), and ocean currents (sensible heat via ocean currents instead of air currents).

        In the 1960s, two individuals independently developed 1-d global climate models that handled this N-S transfer – Sellers, and Budyko. A reference for the Sellers one is:

        “A Global Climatic Model Based on the Energy Balance of the Earth-Atmosphere System”, William D. Sellers,
        Journal of Applied Meteorology
        1969 8:3, 392-400


        Of particular interest is the counter-intuitive result that in the sub-tropics the latent heat transfer is actually towards the equator. Strong equatorial convection is fed by trade winds towards the equator; the evaporation in the trade wind zone converts energy to latent heat, and the energy is released in the convection zone. Look at figure 3 in Sellers’ paper. (The model does show polar amplification under changing climates – read the details.)

  12. The following link displays a large number of graphs and data links on Arctic sea ice concentration, thickness and drift, SSTs, anomaly maps, jet stream, wind speeds etc. The top bar links to long-term and regional graphs, forecasts and webcams in the Arctic. It’s an excellent resource.

    You can see sea ice concentration graphs and maps from various institutes that make their work available online, including relative concentrations for the most recent 30 days (MASIE), updated in near real-time. NSIDC and JAXA, as well as other sea ice concentration products are there.