Earth System Science Dan Lunt, Prof. Paul Valdes, Prof. Tony Payne

1. Earth System Science Dan Lunt, Prof. Paul Valdes, Prof. Tony Payne

2. How do these systems work? What are the key drivers? How do the different parts interact? How do we measure and predict climate? What will happen in the near future? What has happened in the past? Big Picture

3. Course aims and objectives • Introduce the study of the “Earth System” • Understand the processes important in influencing the Earth System • Understand the inter-connectivity of the major components of the Earth system • Develop an appreciation of the methods used for studying climate • Understand how and why we use climate models to inform our understanding of the climate system

4. Lecture 1: Introduction. Lecture 2: Future modelling and the IPCC. Lecture 3: Past Climate Changes Lecture 4: Geoengineering Lecture 5: Atmospheres Lecture 6: Energy balance modelling Lecture 7: Basics of General Circulation Modelling Lecture 8: Oceans Lecture 9: Ice sheet dynamics (1) Lecture 10: Ice sheet dynamics (2) + practical sessions Lecture series

5. Based on practicals Write a brief report (in the style of a Nature paper) on your investigations with the climate model (e.g. a past or future simulation). Assessment

6. To help see the “overall” picture, you may wish to look at: IPCC Working Group 1: Summary for Policymakers IPCC Working Group 1: Technical Summary IPCC Working Group 1: Individual chapters (All available at http://ipcc-wg1.ucar.edu/wg1/wg1-report.html) Plus: McGuffie K. and Henderson-Sellers A., 2005. A Climate Modelling Primer. 3rd Ed. Wiley. Barry R.G. and Chorley R.J , 2003. Atmosphere, weather and climate. 8th Ed. Routledge. Bigg G.R. , 1996.The oceans and climate. 2nd Ed. Cambridge University Press. Benn D.I. and Evans D.J.A., 1998. Glaciers and glaciation.Hodder Arnold. Kump L.R., Kasting J.F., Crane R.G., 2004. The Earth system: an introduction to Earth systems science. 2nd Ed.Prentice Hall. Ruddiman W.F., 2001. Earth’s climate : past and future. W.H. Freeman and Company. Holton, J.R.: An Introduction to Dynamic Meteorology. Academic Press. 4th Ed. Peixoto & Oort “Physics of Climate” Text books

7. Media

8. Government “Urgent action is needed to combat climate change” “Above all, climate change is the greatest challenge facing this generation.” “Internationally, we will work for an ambitious, fair and legally binding climate change agreement”

9. Atmospheric CO2

10. CO2 emissions Oceans absorb approx. 25% of emissions, and land (plants) absorb a further 25% Leaving 50% of emissions to increase atmosphere concentration

11. The Greenhouse Effect

12. The Earth System Oldfield, p4

13. General Circulation Models (GCMs)

14. History of GCMs 1990 1990 1995 1995 2001 2001 2007 2007

15. Surface Temperature: observations Surface Temperature: HadCM3 How good are GCMs? (1) temperature

16. Seaice: observations vs models Precipitation: observations Precipitation: HadCM3 How good are GCMs? (2) Precip and seaice

17. How good are GCMs? (3) El Nino

18. Radiative Forcing – anthropogenic component

19. Historical Forcing and response (century)

20. Historical Forcing and response (millenium)

21. Attribution (global)

22. Attribution (regional)

23. The future – climate sensitivity

24. Predicting the Future "Prediction is very difficult, especially if it's about the future." --Nils Bohr, Nobel laureate in Physics "Those who have knowledge, don't predict. Those who predict, don't have knowledge. " --Lao Tzu, 6th Century BC Chinese Poet "This is the first age that's ever paid much attention to the future, which is a little ironic since we may not have one. " --Arthur C. Clarke http://www.met.rdg.ac.uk/cag/forecasting/quotes.html

25. SRES (special report on emissions scenarios) storylines

26. SRES storylines Economic growth rapid Population peak 2050 Technological growth rapid Capacity building A1F1: fossil intensive A1T: non-fossil energy A1B: Balance Economic development regional - disparity Population continues rising Technological growth - slow, fragmented Self reliance, heterogeneity Economic development intermediate Population continues rising slowly Technological growth - diverse Local and regional solutions to environment/equity Economic shift - services/information Population peak 2050 Technology -clean/efficient Global solutions to sustainability/equity No Additional climate initiatives

27. SRES storylines summary A1F1 BAD B1 GOOD From Jo House

28. SRES storylines summary Radiance calibrated lights obtained from night satellite imagery. Situation in 1995/1996 (bottom panel) and illustrative simulation for the SRES A1 scenario's implied GDP growth for 2070 (top panel). IPCC SRES

29. SRES storylines in more detail IPCC TAR

30. SRES: Emissions Also include emissions scenarios for other greenhouse gases and aerosols. IPCC TAR synthesis report 2001

31. How to go from emissions to concentrations? Need to consider the components of the carbon cycle important on these timescales – ocean, land, and human pertubations. IPCC TAR

32. How to go from emissions to concentrations? However, we still don’t fully understand the Vostok CO2 curve!! Petit et al, Nature, 399, 429-436, 1999. From Andy Ridgwell

33. CO2 concentration projections IPCC use relatively simple models to give CO2 concentration scenarios….. IPCC TAR

34. The IPCC Process - summary

35. Future Climate Predictions - global

36. Future Climate Predictions – regional(1) temperature

37. Future Climate Predictions – regional(2) Precipitation and cloud cover[stippling – at least 80% agree on sign of change]

38. Future Climate Predictions – regional(3) Ocean circulation

39. Summary The atmospheric composition has changed over the last century. The climatic consequences of these variations can be represented using numerical models. These models do a relatively good job of the last century (millenium) compared to observations. Climatic change over the last century is predominantly anthropogenic. Future scenarios of atmospheric composition have been developed. Some modelled consequences of these future changes are robust, others less so.