SOLAR TODAY Blog

David Archer and Ray Pierrehumbert, both professors of geophysical sciences, teach an undergraduate course in global warming at the University of Chicago. Aimed at non-science majors, it's a brilliant introduction to the issues for students who will go on to influence government and corporate policy.

And the complete series of 23 lectures is available online.

Archer and Pierrehumbert introduce the principles with an historical review of the science, beginning in 1827, when the mathematician Jean Baptiste Joseph Fourier, who pioneered heat-transfer formulae, calculated how sunlight would heat an airless rocky planet and how an atmosphere would change that balance. He didn't know about the full electromagnetic spectrum, so his averages were a bit off: he figured an average of -14°C (6°F) for an airless Earth and 29°C (86°F) for the Earth with our atmosphere.

By 1859, the physicist John Tyndal was able to prove that water vapor absorbed heat from infrared light, and thus that the Earth's atmosphere does in fact work as a greenhouse.

That laid the groundwork for the work of Svante Arrhenius, who calculated heat transfer at regular latitudes from pole to pole, identified the ice-albedo feedback mechanism, and in 1896 published the prediction that a doubling of atmospheric carbon dioxide would warm the earth by 4 to 6°C (today's accepted figure is 3 to 5°C).

The preindustrial atmosphere carried about 600 gigatons of carbon; through deforestation and burning fossil fuel, we're currently increasing that by about 6 gigatons annually and continued burning of coal and oil will push us rapidly to 5,000 gigatons by the end of this century. We've already disrupted the climate for the next 10,000 years.