Student exercises on fossil fuels, global warming, and gaia

In a recent series of tutorial papers, Rust [7,8,9,10] modelled measured time series for global temperatures and fossil fuel CO2 emissions with related combinations of polynomials, exponentials, and sinusoids, using least squares fits that can be done by students well grounded in practical statistics. The analysis suggested that temperatures cycle around a monotonically increasing, accelerating baseline with a period of approximate to65 years and that the exponential growth rate Of CO2 emissions varies inversely with this cycle. The Gaia hypothesis [5] suggests that the biosphere adjusts atmospheric greenhouse gases to maintain an optimal temperature for life. The previous analysis is here extended with a series of fitting exercises designed to demonstrate that the above described inverse relation represents a Gaian feedback.