GEOL 437 Global Climate Change 5/1/18: Climate sensitivity

Transcription

1 GEOL 437 Global Climate Change 5/1/18: Climate sensitivity How sensitive is the climate to external radiative forcing? FAQ 12.3 Fig 1 in: Collins, M., R. Knutti, J. Arblaster, J.- L. Dufresne, T. Fichefet, P. Friedlingstein, X. Gao, W.J. Gutowski, T. Johns, G. Krinner, M. Shongwe, C. Tebaldi, A.J. Weaver and M. Wehner, 2013: Long-term Climate Change: Projections, Commitments and Irreversibility. Chapter 12 In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Accessed via internet: acc 2/3/2014. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Accessed via internet: acc 2/3/2014; hereafter Stocker et al (2013).

2 GEOL 437 Global Climate Change Climate sensitivity 5/1/18: Climate Sensitivity Equilibrium climate response Transient climate response Key concepts

3 Climate Sensitivity Analytical expression: climatic response per unit forcing Bindoff et al, 2013, Detection and attribution of climate change: from global to regional, Ch 10 in Climate Change 2013: The Physical Science Basis, Contribution of WG1 to the fifth assessment report of the IPCC (Stocker et al, eds), Ch ; Box 12.2 in: Collins et al 2013.

4 Climate Sensitivity Analytical expression: climatic response per unit forcing Can it be observed from observations and simulations? Quantitative, physically (model) linking radiative forcing to climatic response Observational estimates of the forcing and the response Bindoff et al, 2013, Detection and attribution of climate change: from global to regional, Ch 10 in Climate Change 2013: The Physical Science Basis, Contribution of WG1 to the fifth assessment report of the IPCC (Stocker et al, eds), Ch ; Box 12.2 in: Collins et al 2013.

5 Radiative forcing of the climate system (3/27/18) Instantaneous change in the radiative balance at the top of the troposphere, and originating from outside the climate system, relative to that estimated for the global and annual average for An instantaneous RF does not account for temperature change in the stratosphere. S. Planton (ed), AR5 WGI Glossary (Annex III), p

6 ERF and equilibrium climate response (3/27/18) Instantaneous change in the radiative balance at the top of the troposphere, and originating from outside the climate system, relative to that estimated for the global and annual average for An instantaneous RF does not account for temperature change in the stratosphere. ECS: equilibrium change in annual mean global surface temperature following a doubling of the atmospheric CO 2 concentration. S. Planton (ed), AR5 WGI Glossary (Annex III), p. 1460; Collins et al (2013), Box 12.2.

7 ERF and transient climate response Instantaneous change in the radiative balance at the top of the troposphere, and originating from outside the climate system, relative to that estimated for the global and annual average for An instantaneous RF does not account for temperature change in the stratosphere. Transient climate response Flux imbalance being erased Temperatures adjusting everywhere TCR: mean global surface temperature change at the time of CO2 doubling following a linear increase in CO2 forcing over a period of 70 years. S. Planton (ed), AR5 WGI Glossary (Annex III), p. 1460; Collins et al (2013), Box 12.2.

8 Observed and simulated patterns of surface temperature change (3/27/18): ECR or TCR? Bindoff, Stott et al (2013), FAQ 10.1, Fig 1

9 Equilibrium and transient climate response Collins et al (2013) Fig 12.43, 12.44

10 Equilibrium and transient climate response Collins et al (2013) Fig 12.43, 12.44

11 Summary Equilibrium climate sensitivity estimates take into account slow processes, but for non-equilibrium conditions, transient climate response may be a better near-term indicator of climate change. Next: Thurs: Discussion of Paleosens (2012) Figs 1,4

12 Observed patterns of surface temperature change Bindoff, Stott et al (2013), Fig 10.2

13 Simulated patterns of surface temperature change All forcings Bindoff, Stott et al (2013), Fig 10.2

14 Simulated patterns of surface temperature change Natural forcings Bindoff, Stott et al (2013), Fig 10.2