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Re: [climate-change-forum] Re: Siberian permafrost - addendum

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  • Alex Harvey
    ... John, this conversation is becoming ridiculous. 1) Let s pretend that civilian aircraft are causing 10 W m-2 of forcing in the global average. 10 W m-2
    Message 1 of 51 , Mar 6, 2013
      On 7 March 2013 11:30, Mitchell J <oski00@...> wrote:
       
      > John, the suggestion that civilian aircraft are causing a negative forcing
      > of 10 W m-2 in the present climate is obviously absurd. The fact that you
      > are actually willing to believe this speaks volumes. Now if you have
      > another look at the abstract:

      Yes it does speak volumes. It means that there is a missing cooling effect, not captured in the models, that is clear for all to see in the current temperature and emissions data. The attempt to quantify a warming signal to Black Carbon that is much higher than what is actually there is an attempt to balance out the models when, in actuality, the real issue is a missing cooling signal that has yet to be quantified, that, when quantified, will show that the GHG forcing is much higher than we had previously thought.

      Instead, they are failing to recognize the cooling effects that have been, as yet, unidentified, are then attributing some of the warming signal to black carbon, and reducing the other effects.

      The reason that this approach is wrong is found in the increasing arctic amplification in the last 15 years.

      John, this conversation is becoming ridiculous.

      1)  Let's pretend that civilian aircraft are causing 10 W m-2 of forcing in the global average.  10 W m-2 is around 10 times larger than the consensus value for aerosol forcing, which is closer to 1 W m-2.  The positive RF from one doubling of CO2 is well known to be 3.6 W m-2, which means your value of 10 is almost enough to fully cancel out 3 doublings of CO2 or an atmospheric concentration of 2240ppmv!  Given you believe in massive positive feedbacks and massive climate sensitivity, this should have pushed us well into another ice age.  So how come the earth is still warming?  You see, John, you can't just make up scary numbers - they have to actually make sense.

      2)  Do you believe the models get the polar amplification factor wrong or don't you?  If you do, doesn't it imply that they are getting the poleward heat transport wrong?  That's the only hypothesis vaguely compatible with your desire to simultaneously believe in massive negative aerosol cooling.  In order for the theory to make sense, you need small negative RF (to be consistent with the 16 year global average temperature hiatus) combined with a much larger polar amplification caused by the heat transport.

      3)  If the RF is wrong by a factor of 10 then how come the Arctic isn't warming faster by a factor of even more than 10?  You admitted that the aerosols are causing warming at the Arctic. 

    • Mitchell J
      ... Read it again Alex, E&W09 says, a sea-ice bifurcation threshold (or tipping point ) caused by the ice–albedo feedback is not expected to occur They
      Message 51 of 51 , Mar 10, 2013
        --- In climate-change-forum@yahoogroups.com, Alex Harvey <alexharv074@...> wrote:
        >
        > On 10 March 2013 08:46, Mitchell J <oski00@...> wrote:
        >
        > > **
        > >
        > > Conclusions. Our analysis suggests that a sea-ice bifurcation
        > > > > threshold (or "tipping point") caused by the ice–albedo feedback
        > > > > is not expected to occur in the transition from current perennial
        > > > > sea ice conditions to a seasonally ice-free Arctic Ocean, but that
        > > > > a bifurcation threshold associated with the sudden loss of the
        > > > > remaining seasonal ice cover may occur in response to further
        > > > > heating.
        > >
        > > Eisenman and Wettlaufer, 2009
        > >
        >
        > And that is contradicted by Tietsche who do *not* find evidence for "*a
        > bifurcation threshold associated with the sudden loss of the remaining
        > seasonal ice cover*". You seem to be amazingly good at averting your gaze
        > from statements that contradict your thinking.

        Read it again Alex,

        E&W09 says, "a sea-ice bifurcation threshold (or "tipping point") caused by the ice–albedo feedback is not expected to occur"

        They are in agreement.


        They are also in agreement with my original point:

        The step level change in surface air temperature I was speaking of is only during the summer months after the sea ice is gone and is modeled in both papers. In E&W they model a 5-7K increase, in Teitsche '12 they model an 11K increase but only when sea ice is gone by june 1 in the seasonal cycle.

        I assert to you that this extra step increase in arctic temperatures will wreak havoc with the currently weakening polar jet and lead to massive heat transport into the arctic of mid-latitude moisture (as well as push the Hadley cell further north and possibly lead to a complete collapse of the Arctic cell into the Ferrell cell (though that might not happen until the arctic reaches a mesothermic state between 2065 and 2100.
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