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PCC 586 - Winter 2010 - What the feedback? |
Reading should be completed PRIOR to the listed date |
Week 1 - Jan. 5 |
Read pages 1-11 |
Read pages 1-11 |
Read pages 1-11 |
Read pages 1-11 |
Week 2 - Jan. 12 |
Everybody reads the intro and discussion. Also read either section 2 (cloud feedbacks), section 3 (water vapor/lapse rate feedback), section 4 (cyrosphere feedbacks), or Appendix B (methods for diagnosing feedbacks) depending on which group you volunteered for. Each group should plan on giving a short (less than ten minutes) presentation on how their feedback affects the climate sensitivity (i.e. the global mean temperature response to a radiative perturbation) including the estimated uncertaintiess in the feedback. You can present this however you want; if you're using powerpoint, email to aaron@atmos.washington.edu before class. Try to give simple schematics of the relevant physical processes, recognizing that some folks are not climate dynamicist and those who are could use a refresher in the underlying processes. |
Week 3 - Jan. 19 |
We wil finish our discussion of the Bony et al. review from last week. Read the sections you didn't read last week if you so desire. |
Week 4 - Jan. 26 |
Read: Gregory, J.M., and P. M. Forster, 2008: Transient climate response estimated from radiative forcing and observed temperature change. J. Geophys. Res., 113, D23105, doi:10.1029/2008JD010405. |
Read the section entitled "Response time" (pages 103-105) in Gerard's primer on feedbacks and timescales. |
Week 5 - Feb. 2 |
1) Assuming Schwartz's numbers for C and Tau are good estimates, what is the 95% (+- 2 sigma) confidence interval for climate sensitivity under a 3.7 W/m^2 forcing (for a doubling of CO2)? How does this compare with Schwartz's conclusions on climate sensitivity as estimated by his method? How does this compare to the range given by the IPCC? 2) The plot of time constant as a function of lag (Fig. 7) shows tau is small at short lags, and asymptotically approaches 5 years at long lags. Schwartz uses this to propose that Tau = 5 years is the characteristic response time of the climate system, which he assumes behaves as a first order autoregressive process. Is this figure consistent with his assumption of an AR(1) process and a single climate response time? What should this figure look like for an AR(1) process with tau = 5 years? |
Read: Schwartz S.E., 2007: Heat capacity, time constant, and sensitivity of Earth’s climate system. J. Geophys. Res., 112, D24S05, doi:10.1029/2007JD008746. |
This paper uses Gerard's "Euler Equation of Climate Science" : and observations of tau (timescale) and C (heat capacity) to derive a value of climate sensitivity that is significantly different from other published values. The methodology has generated some controversy. Some questions for consideration, courtesy of Kyle Armour: |
Week 6 - Feb. 9 |
Read: Soden, B.J., I.M. Held, R. Colman, K.M. Shell, J.T. Kiehl, and C.A. Shields, 2008: Quantifying climate feedbacks using radiative kernels. Journal of Climate, 21, 3504-3520. |
We will not meet on Tuesday, but instead will meet with Brian Soden from 1:30- 3:00 on Friday in the QRC library. |
Week 7 - Feb. 16 |
Read the chapter 7 on biogeochemical and carbon cycle feedbacks in the National Research Council's "Understanding Climate Change Feedbacks" review. |
Week 8 - Feb. 23 |
Read: Archer, D., 2005: Fate of fossil fuel CO2 in geologic time. J. Geophys. Res. 110, C09S05, doi:10.1029/2004JC002625. |
and Torn M.S. and J. Harte, 2006: Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming. Geophysical Research Letters, 33, L10703, doi:10.1029/2005GL025540, |
Week 9 - March 2 |
We will continue our discussion of carbon cycle feedbacks with Torn and Harte (from last week). In addition... Read: Solomon S. et al., 2009: Irreversible climate change due to carbon dioxide emissions. Proceeding of the National Acedemt of Sciences of the United States of America. Volume: 106 Issue: 6 Pages: 1704-1709. |
Week 10 - March 9 |
Non-linearities in climate sensitivity Read: Crucifix M., 2006: Does the Last Glacial Maximum Constrain Climate Sensitivity? Geophysical Research Letters. VOL. 33, L18701, doi:10.1029/2006GL027137. |