Global warming not caused by increased solar activity (NASA)

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13. Hansen_etal_2011

You can read Dr. Hansen's paper here (courtesy of the Goddard Institute of Space Sciences)

http://pubs.giss.nasa.gov/docs/2011/2011_Hansen_etal.pdf

For those of you who wish the 'short version' that will drive your Republican friends into a frenzy - it goes like this. (I'll go easy on the math)

Hansen's team used improved observations of heat uptake by the oceans from inbound surface radiation from our sun and compared those measurements with our instrumental record of stratospheric aerosols together against the record of solar activity.

The idea is simple - our planet is a water planet and as such the oceans represent a considerable heat sink. For a long time we did not have reliable metrics on ocean heating but once we did the scope of our planets warming began to fall into place. Aerosols, which occur naturally as the product of volcanism and by the human activity of combustion and agricultural burning, tends to shield the planet from heating but also holding some heat along the way.

Now enter the Sun. We have very good instrumental records on solar activity so we can make very good estimates of the amount of solar radiation reaching the surface.

So put simply, take the solar energy from the sun (in watts per square meter) and calculate in the amount absorbed by the oceans and the amount reflected back into space by aerosols. Keep in mind that our planet largely radiates back nearly all the energy we receive.

What the paper shows is that solar activity cannot be responsible for our observed heating and that other forcing factors, changes in non condensing green house gases (GHG) and aerosols contribute to our planets heat retention.

Two observations I found interesting in the paper were the mention that earlier models used a more aggressive ocean mixing model which would have changed the amount of heat uptake calculated, and that currently the non polar region glaciers (alpine) are estimated as a greater contributor of sea level rise.

Hansen is always quite thorough in his submissions, clocking in at 29 pages, this paper was no exception. He makes some interesting comparisons of the GISS modelE-R, the GFDL model and the NCAR CCSM3 model in terms of their climate sensitivity and response.

This paper is describing an energy balance model (EBM). The first EBM was created by Svante Arrhenius in 1896. It is his prediction that if you double the CO2 in the atmosphere that the average global temperatures will increase between 2 and 4 degrees Celsius. This paper and all other papers like it seek to fine tune that estimated heating.

While it may baffle your Republican in-laws, its important to bear in mind that the implication of non-condensing green house gases is by inference. The "skeptics" have long pointed to solar variation as the source of our planetary warming, what Hansen has demonstrated by both data and model is that this is not the case.