As part of the Climate Dialogue, there is the usual but but but, and one of the buts has been pointing to the role of clouds (Sgt. Schultz knows nothing, nothing)
The past 25 years of carbon dioxide increase has contributed to less than 1 W m-2 in radiative forcing. There is no simple calculation to be made of the effect of the sea ice albedo change on the global energy balance. The better comparison is with a change in fractional cloud cover (which is highly variable), which dominates the planetary albedo far more than the arctic sea ice.but to be fair, and you know that Eli is always fair, others, such as Rob Dekker point out that
Here, I noticed that GCM projections are lagging some 20 years (CMIP5) to 40 years (CMIP3) behind actual Arctic sea ice decline. Apparently, we are currently experiencing Arctic “climate” conditions that were not expected until another 40 – 80 ppm increase in CO2 concentration (which implies some 0.5 – 1.0 W/m^2 forcing).And in the middle of this, the Rabett remembered something, the further north you go, the larger the annual CO2 cycle
flask sample data from Alert (in the blue, purple is Mauna Loa) , it's about a 15 ppm swing from early spring (April, May) to late summer (August, September) and about 8-10 ppm more of a swing than ML.
And the latest measurements from Barrow show a difference of 20 ppm
Applying the normal equation for CO2 forcing, 5.35 ln (C/Co), where Co is 280 ppm, that is a difference of a bit more than 0.25 W/m^2, in other words, significant when compared to the total average increase of 0.5 to 1 W/m^2 in the past 25 years. Moreover, the net effect is to limit cooling in the winter as compared to using the average carbon dioxide mixing ratio, increase melting in the spring and force less melting in the late summer. Over the year, the average concentrations are about the same at ML and Alert.
It takes about six to seven years before the low mixing ratio catches up with the high at Alert (e.g. the minimum in 2007 matched the maximum in 2000.
To tell the truth, Eli has not a clue as to whether this is included in models or evaluations of the Arctic ice, but it looks interesting. Just thought the bunnies might like to know