Appendix 8.A: Lifetimes, Radiative Efficiencies and Metric Values AGWP=absolute global warming potential [see next slide for graphic explanation] *=No single lifetime can be given. The impulse response function for CO 2 is taken from Joos et al. (2013) & if you really care to know the details, click here.here

IPCC AR5 WG1 Ch8 Figure 8.28 (a) The Absolute Global Warming Potential (AGWP) is calculated by integrating the RF due to emission pulses over a chosen time horizon; for example, 20 and 100 years (vertical lines). The GWP is the ratio of AGWP for component i over AGWP for the reference gas CO2. The blue hatched field represents the integrated RF from a pulse of CO2, while the green and red fields represent example gases with 1.5 and 13 years lifetimes, respectively. (b) The Global Temperature change Potential (GTP) is based on the temperature response at a selected year after pulse emission of the same gases; e.g., 20 or 100 years (vertical lines). See Supplementary Material Section 8.SM.11 for equations for calculations of GWP and GTP. Source: %20WG1&f=Chapter%2008

Copyright © 2013 Elsevier Inc. All rights reserved. FIGURE 11.6 Concentrations of CH 4 in air extracted from Antarctic ice cores. Source: From Etheridge et al. (1998). Used with permission of the American Geophysical Union. 3

Copyright © 2013 Elsevier Inc. All rights reserved. FIGURE 11.7 Concentrations of CH 4 in air that is extracted from ice cores in Antarctica dating to 800,000 years before present. Source: From Loulergue et al. (2008). Compare to FIGURE

(a) Globally averaged CH4 dry air mole fractions determined from weekly samples in the NOAA Global Cooperative Air Sampling Network; dashed line is a deseasonalized trend fitted to the global averages. Dlugokencky E J et al. Phil. Trans. R. Soc. A 2011;369: ©2011 by The Royal Society * Decreases in gas leaks, former soviet union * Depletion of stratospheric O3, uvB increases and photodegradation via OH radicals

Copyright © 2013 Elsevier Inc. All rights reserved. TABLE 11.2 Estimated Sources and Sinks of Methane in the Atmosphere in

Figure 1. Estimated sauropod methane production compared to total modern (both natural and anthropogenic), global pre- industrial and estimated modern methane production from ruminants. Even reducing our estimate by half still predicts a major role for sauropod methane in the Mesozoic. Source: Wilkinson et al (2012) Could methane produced by sauropod dinosaurs have helped drive Mesozoic climate warmth? Current Biology 22(9):R Inputs:Sauropod Biomass 200,000 kg km -2 Reptilian rate of metabolism [as opposed to mammalian] Production Rate Estimate:CH 4 (L d -1 ) = 0.18 (body mass in kg) 0.97