Thank you for your creative calculations on the possible effect of Arctic sea ice volume loss on atmospheric temperature.

I have a couple of comments on your analysis, basically to put your numbers into perspective.

First, let us look at the “ocean heat content” over the past couple of decades, and how that changed over the decades :

Notice that ocean heat content since 1995 changed by something like 1 * 10^23 J for the upper 2000 meter of oceans.

That means that heat going into the oceans since 1995 is a factor 40 or so larger than the number you calculated for sea ice volume loss. Long term sea ice volume loss is thus almost negligible in the big picture of planetary heat balance.

Alternatively, since sea ice melt is a “heat flux” from atmosphere into the oceans, you can calculate the effect of sea ice loss in terms of “flux” of “forcing” (in W/m^2). That makes it easy to compare this effect to other forcings (such as AGW).

Let’s try that : To get the “heat flux”, start with your energy number : 2.4 * 10^21.

Divide that energy number by 3600*24*365*18 seconds, to get to power (in Watt) needed to melt that ice over 18 years.

Divide that power number by surface of the planet (5 * 10^14 m^2) and you obtain 0.0084 W/m^2.

That is the “forcing” needed to melt that ice over 18 years.

Hansen 2008 rounded that to 0.01 W/m^2 if I’m not mistaken.

This makes the direct influence of sea ice volume loss on our planet’s temperature comparable to linear contrails (caused by aircraft) and a factor 10 smaller than even GHG effect of NOx changes over the same period.

Interesting is also to compare this forcing to CO2 forcing changes over the same period.

We are currently at 390 ppm, and adding some 2 ppm /year in CO2 to our atmosphere.

A doubling of CO2 will create 3.7 W/m^2 forcing, so per year, we add 3.7 * 2/390 = 0.019 W/m^2 forcing.

Over the past 18 years, we thus added some 0.34 W/m^2, a factor 40 more than sea ice loss over the same period.

Finally, for comparison, loss of ice causes the Arctic to be darker and thus absorb more heat from the sun (this is the famous albedo feedback). There have been various analysis done to express that effect in a forcing, and they all end up in the 0.13-0.15 W/m^2 range (since 1980). Here is one easily explained, by Tamino :

http://tamino.wordpress.com/2012/10/01/sea-ice-insolation/

So the increase in heat due to melted sea ice over the long run appears to be a factor 10 or so larger than the heat it takes to melt the ice in the first place. That’s some scary feedback, no ?

Any way, that was a very long comment to explain that the energy that was needed to melt sea ice over the past 18 years is not significant in the global energy balance, and thus CANNOT be responsible for any significant planetary temperature change over that period.

]]>As regards the antarctic it seems to me that the spread is caused by bottom melt of shelf and grounded ice which then flows to the periphery across the inverted landscape. Assuming a 1m average height of ice above sea level gives an average depth of 9m below sea level to the underside. Now offhand I can’t remember if its 6ft or 10ft which equals atmospheric pressure, and I don’t know the freezing temperature of water at those pressures, but my guess is that you have practically fresh water emerging at the edge of the ice sheet at below 0c easily frozen by southern winter temps, so I suspect the extra spread, or at least it’s volume, is a proxy for the hidden melt, not exact but a good indication and probably low. ]]>

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There are also other aspects reducing the “double” effect to a “more or less equal” effect.

I gave the post an overhaul. It is no more quite as spectacular but more sound. ]]>