Rust and Thijsse have shown that global annual average temperature anomalies T(ti) vary linearly with atmospheric CO2 concentrations c(ti). The c(ti) can be related to man-made CO2 emissions F(ti) by a linear regression model whose solution vector gives the unknown retention fractions γ(ti) of the F(ti) in the atmosphere. Gaps in the c(ti) record make the system underdetermined, but the constraints 0 <= γ(ti) <= 1 make estimation tractable. The γ(ti) are estimated by two methods: (1) assuming a finite harmonic expansion for γ(t), and (2) using a constrained least squares algorithm to compute average values of γ(t) on suitably chosen time subintervals. The two methods give consistent results and show that γ(t) declined non-monotonically from ~0.6 in 1850 to ~0.4$ in 2000.
Proceedings Title: Proceedings - MAMERN09: 3rd International Conference on Approximation Methods and Numerical Modeling in Environment and Natural Resources
Conference Dates: June 8-11, 2009
Conference Location: Pau, -1
Pub Type: Conferences
atmospheric CO2, CO2 emissions, global temperatures, global warming