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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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slide1

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,
slide2

Extreme Climate Systems

Neo-proterozoic Snowball Earth

Equator -500 Myrs?

slide3

Extreme Climate Systems

Cretaceous Greenhouse

Arctic -55 Myrs?

extreme climate systems
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
going to extremes
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
earth system asymptotics
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?
high res modelling occam
High-res. modelling (OCCAM)

surface

potential

temperature

& ice thickness

slide13

Glacial-interglacial dynamics

Wolff et al.

DESIRE

proposal

earth system asymptotics14
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?
what s wrong
What’s wrong?
  • Bottom-up inappropriate
  • Top-down inaccurate
  • Big model error 
  • y = x + 
  • Problem is prediction: has dynamics
  • Usual approach - compare models
slide17

Multi-model - means?

+

+

= ?

Types of model error / uncertainty

(a) inputs (b) parameters (c) structure

(GENIE-1)

.

(GCM)

slide18

Multi-model - means?

+

+

= ?

Types of model error / uncertainty

(a) inputs (b) parameters (c) structure

.

parametric error
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)
slide21

IPCC AR4: 63 ensembles of 52 simulations

Atlantic overturning (Sv)

year

slide22

Types of model error / uncertainty

(a) inputs (b) parameters (c) structure

(1)

.

(2)

reality = ?

(∞)

Very hard to measure - need hierarchies

Rougier (2005)

hierarchies of models
Hierarchies of models

simple

few cells

complex

many cells

Understanding

Confident prediction

Accuracy

One guess

slide24

Hierarchy

(Lowerarchy*)

Ocean

resolution

(Bern3-D)

*A. Wirth (LEGI)

slide25

Bridges required

models

data

photo Lukas Witschi

slide26

Bridges required

top down

models

data

bottom up

photo Lukas Witschi

slide27

Bridges required

top down

models

data

bottom up

physics

biology

timescales, lengthscales, domains, cpu

photo Lukas Witschi

www genie ac uk
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
genie 1
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
millennial climate change scenarios
Millennial climate change scenarios

15k (exotic fuels)

8k (intermediate)

4kfast (all known fuel)

4kslow

min

Lenton et al. 2006

earth system asymptotics36
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