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Earth System Asymptotics* Neil Edwards (Open University) with thanks to

Earth System Asymptotics* Neil Edwards (Open University) with thanks to. GENIE team and others, esp. James Annan, David Cameron, Julia Hargreaves, Tim Lenton, Bob Marsh, Simon Müller, Andrew Price, Andy Ridgwell, Jonty Rougier, John Shepherd* , Mark Williamson, Andrew Yool, .

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Earth System Asymptotics* Neil Edwards (Open University) with thanks to

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  1. Earth System Asymptotics*Neil Edwards (Open University)with thanks to • GENIE team and others, esp. James Annan,David Cameron, Julia Hargreaves, Tim Lenton, Bob Marsh, Simon Müller, Andrew Price, Andy Ridgwell, Jonty Rougier, John Shepherd*, Mark Williamson, Andrew Yool,

  2. Extreme Climate Systems Neo-proterozoic Snowball Earth Equator -500 Myrs?

  3. Extreme Climate Systems Cretaceous Greenhouse Arctic -55 Myrs?

  4. Extreme Climate Systems • Last ~10 kyears extraordinarily equable • Coincides with development of civilisation • Consequence? Cause? • In contrast: • 80% of last million years much colder • 80% of last 500 million years much warmer • Earth history is full of extremes • Near future may be similarly extreme

  5. Going to extremes • Asymptotics ~ going to extremes • Classic first test of a system eg • Mathematics • y = x2 + 1/x2 • Engineering • testing to destruction • Human body • pathology - study of disease

  6. y = x2 + 1/x2

  7. y =x2 + 1/x2

  8. y = x2 + 1/x2

  9. Engineering testing to destruction

  10. Complex systems,knowledge of the body - from disease

  11. Earth System Asymptotics • Definition (nre): study extremes of ES and connect with a single (realistic) model • HadCM3 - high-res. 3-D • Snowball (Lewis) to Cretaceous (Valdes) • appropriate?

  12. High-res. modelling (OCCAM) surface potential temperature & ice thickness

  13. Glacial-interglacial dynamics Wolff et al. DESIRE proposal

  14. Earth System Asymptotics • Definition (nre): study extremes of ES and connect with a single (realistic) model • HadCM3 - high-res. 3-D (bottom-up) • snowball (Lewis) to Cretaceous (Valdes) • appropriate? • CLIMBER - low-res. 2.5-D (top-down) • accurate?

  15. What’s wrong? • Bottom-up inappropriate • Top-down inaccurate • Big model error  • y = x +  • Problem is prediction: has dynamics • Usual approach - compare models

  16. Multi-model - means?

  17. Multi-model - means? + + = ? Types of model error / uncertainty (a) inputs (b) parameters (c) structure (GENIE-1) . (GCM)

  18. Multi-model - means? + + = ? Types of model error / uncertainty (a) inputs (b) parameters (c) structure .

  19. Parametric error • Main source of uncertainty? • Atmosphere: initial conditions > parameters? • Ocean: parameters ~ initial conditions? • Calibrate parameters by fitting to data • Huge dimensional parameter space • Define error function and minimise • Need prior estimates of parameters (pdfs)

  20. Simplified models: GENIE

  21. IPCC AR4: 63 ensembles of 52 simulations Atlantic overturning (Sv) year

  22. Types of model error / uncertainty (a) inputs (b) parameters (c) structure (1) . (2) reality = ? (∞) Very hard to measure - need hierarchies Rougier (2005)

  23. Hierarchies of models simple few cells complex many cells Understanding Confident prediction Accuracy One guess

  24. Hierarchy (Lowerarchy*) Ocean resolution (Bern3-D) *A. Wirth (LEGI)

  25. Bridges required models data photo Lukas Witschi

  26. Bridges required top down models data bottom up photo Lukas Witschi

  27. Bridges required top down models data bottom up physics biology timescales, lengthscales, domains, cpu photo Lukas Witschi

  28. Earth System Modelling

  29. www.genie.ac.uk • Grid Enabled Integrated Earth system model(s) • Atmosphere: Valdes - Reading IGCM T21 (EBM) • Vegetation+soil: Cox - Moses-Triffid (ENTS) • Ice sheets: Payne - GLIMMER • Ocean biogeochemistry+sediments: Ridgwell • Ocean+sea ice: N. Edwards - C-GOLDSTEIN

  30. GENIE-1 • Grid Enabled Integrated Earth system model • Atmosphere: Valdes - Reading IGCM T21 (EBM) • Vegetation+soil: Cox - Moses-Triffid (ENTS) • Ice sheets: Payne - GLIMMER • Ocean biogeochemistry+sediments: Ridgwell • Ocean+sea ice: N. Edwards - C-GOLDSTEIN

  31. Snowball Earth hypothesis

  32. Massive transient overturning at snowball initiation, very large flows in steady state

  33. Surface equatorial divergence creates leads, where large fluxes drive circulations below

  34. Millennial climate change scenarios 15k (exotic fuels) 8k (intermediate) 4kfast (all known fuel) 4kslow min Lenton et al. 2006

  35. Veg. C change (kgC/m2) Soil C change (kgC/m2) min 15k -5 0 5 -12 0 12

  36. Earth System Asymptotics • Bridges extremes across: Earth history; data-model; top-bottom • Tests climate models more thoroughly • Addresses whole system: ESMs and IAMs • Models predict models that predict climate • Lowerarchies: understanding to prediction

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