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Sunday, February 24, 2013

Layers of Complexity

When I first started playing with this climate puzzle I mentioned to a PhD in Thermodynamics that using a true "surface" frame of reference, the problem was simplified.  The PhD in Thermodynamics promptly told me that I wasn't using "frame of reference" correctly.  Not that I had selected a poor frame of reference, but that frame of reference just didn't matter.  My how thermodynamics have progressed since I was in college.

The CO2 portion of climate change should, with the current levels of CO2 produce between 0.2 and 1.2  C degrees of warming based on a 1900 to 1950 baseline.  Since 1900, the warming has been roughly 0.7 C degrees with some portion of that warming likely not directly related to CO2 impact.  Since there is an environmental lapse rate that varies with altitude and some degree of internal variability, selecting a frame of reference that is not very specific would likely not produce anywhere near the accuracy required to tease out individual impacts.  That is my opinion based on limited pre-turn of the century Thermodynamics.  If you pick the wrong layers, you get noise.

Since I didn't keep up with all the changes, I tend to look at things as parts instead of a whole until I figure out what makes the whole thing tick.  Using the HADCRU SST and Tropical Surface Air Temperature data I made the above chart.  I used a 12 year sequential standard deviation because it is in the ball park of the 11 year solar cycle and I didn't want to get into half years.  Compring the data, the NH doesn't play the same as the SH.  Since the HADSST2 data set doesn't include a tropical dataset that is easily accessible, I used the new HADCRU4 tropics as a reference.  The next chart is simply subtracting the NH and SH from my Tropics reference.

The blue and orange curves are that subtraction for the tropics reference.  I added the Solar yellow curve based on the Svalgaard TSI reconstruction using an 11 year sequential standard deviation since I still don't want to get into half years.  I could have done things differently, but for an illustration is doesn't really matter.

To help show what I am trying to explain I have added a linear approximation of the Solar reconstruction with two regions defined, Transition Phase and Control Phase.  Without trying for much detail, from roughly 1900 to 1960, Solar energy could be absorbed more efficiently as the systems transitioned into a new state or phase.  That is roughly a 60 year period that may or may not be cyclic. Once the Control Phase is reached, the systems respond differently to forcing.  What may have the greatest impact in the transition phase would not have the same impact in the control phase.  If the oceans had lower heat content prior to the transition phase, then the control phase could be based on a new ocean heat content limit.

That limit could be based on total ocean heat content or relative ocean heat content.  Since the NH responded differently during the transition phase than the SH, internal transfer of energy to the two hemispheres is a likely contributor to the change.  If that is the case, then in the control phase, less energy would be used to equalize the hemispheres and there would be more energy loss to the atmosphere on its way to space.  Since the NH was gaining more of the transition energy, it would have a greater atmospheric impact during the control phase.  Why?

In the NH there is more land mass and less ocean mass.  The average altitude of the air over the NH land mass is around 2000 meters in altitude which would have roughly 20% of the density of sea level air.  It take less energy to warm a lower density volume than a higher density volume.  The impact of ocean hemispheric equalization would be amplified.  The land mass also has a lower thermal capacity than the ocean mass.  Since land mass can store less energy than ocean mass, the NH response would be different than the SH response during any phase.  With the NH oceans "charged" and the lower land and air thermal capacity limiting the storage potential, more energy would be lost to space during the control phase in the northern hemisphere than in the southern hemisphere.  This may or may not trigger another phase change, depending on the energy supplied to the oceans.

There is no magic involved, the energy storage efficiency just changes.  There are dozens of different influences than might be negligible in the transition phase that would not be negligible in the control phase.  Since the internal energy transfer in all phases depends on both the ocean greenhouse effect and the atmospheric greenhouse effect, you have to consider both.  There is no single, linear climate sensitivity.

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