Earth System Model

Beyond the boundary

• A mathematical representation of the many processes that make up our climate.

• Requires:

– Knowledge of the physical laws that govern climate

– Mathematical expressions for those laws– Numerical methods to solve the mathematical

expressions on a computer (if needed)– A computer of adequate size to carry out the

calculations

Model

Observations

Hypotheses

Numerical Simulations

Why?

• Understanding of cause and effect• Predictive skill: our main tool to make predictions for the future

Evolution of Climate Science

There is no unique definition of which processes must be represented before a climate

model becomes an Earth System Model (ESM), but typically such models have at least

an interactive carbon cycle component. The development of this capability was

motivated by suggestions that the ability of terrestrial ecosystems and the ocean to

remove carbon dioxide from the atmosphere will be limited by future climate change

(e.g., Friedlingstein et al. 2006).

Definition

Climate-Carbon Feedback

[Friedlingstein et al. 2006]

if the warming leads to enhanced rates of decay of organic matter in soils, or a reduction in oceanic carbon uptake, then the concentration of CO2 in the atmosphere will rise more rapidly than it would in the absence of such (positive) feedbacks, and the rate of warming will be greater as well.

if increased CO2 in the atmosphere enhances photosynthesis and the storage of carbon in plants and soils, then CO2 levels will rise less rapidly than in the absence of this (negative) feedback, and climate change will also be slower as a result.

Climate-Carbon Feedback

Positive feedback

Negative feedback

Earth System Model (ESM)

Land physicsand hydrologyOcean circulation

Atmospheric circulation and radiation

Land physicsand hydrology

Ocean ecology andchemistry

Atmospheric circulation and radiation

Allows Interactive CO2

Ocean circulation

Plant ecology, land use, and Biogeochemistry

Climate Model

Earth System Model

Sea Ice

Sea Ice

CO2CO2

Diagnostic Prognostic

Global Climate Model Earth System Model

Carbon cycle

11

Bonan (2008) Ecological Climatology, 2nd ed (Cambridge Univ. Press)

Terrestrial ecosystems influence climate through physical, chemical, and biological processes that affect planetary energetics, the hydrologic cycle, and atmospheric composition

Earth system science spans traditional disciplines

Three examplesAnthropogenic land cover changePhotosynthesis-transpirationLeaf area index

Multi-disciplinary Science

History

Heterogenity

Dynamic Global Vegetation Model (DGVM)

autotrophic respiration(RA)

Net Primary Production(GPP- RA )

Net CO2(GPP-RA-RH)

heterotrophic respiration (RA)

Xnot coupled

yet

BIOGEOCHEMISTRY (LPJ)

PHENOLOGY (IBIS)

Daily Leaf Area Index

Plant Functional TypeHeight

Plant CarbonLitter and Soil

Carbon

ECOPHYSIOLOGYAllocationTurnoverMortality

COMPETITON LightWater

SOILLitter

Soil organic matter

FIREOccurrence (moisture, fuel load)

Mortality (fire resistance)Combustion

ESTABLISHMENTPotential rateCanopy Gap

Frost toleranceHeat stress

Winter chillingGrowing season warmth

Low precipitation

VEGETATION DYNAMICS (LPJ)

ANNUAL STATISTICSFire season length

NPP,GPP and potential GPP Minimum monthly temperature Growing degree-days above 5℃

PrecipitationGrowing degree-days above heat stress

DAILY STATISTICS10-day mean temperature

10-day mean photosynthesisGrowing degree-day accumulation

Fire probability

CANOPY PHYSICSRadiation transferEnergy balance

TemperatureAerodynamicsWater balance

CANOPY PHYSIOLOGYPhotosynthesis (GPP)Stomatal conductance

SOIL/ICE/SNOW PHYSICSEnergy and water balance

Temperature

BIOGEOPHYSICS (CLM)

At every time step (~20minute) Daily Yearly

Multi-Time step

At every time step (~20minute) Daily Yearly

Multi-Time step

Vegetation dynamics

Competition (10 days)

Broadleaf Tree

C3 Grass

Shrub

Soil

Plant functional type (PFT)

Deciduous, evergreen treesShrubGrassCrop

Phenology

Spring SummerWinter Autumn Winter

Time

Veg

etat

ion

acti

vity L

AI (M

odel)

Simulated Carbon

Annual cycle of LAI in ESMsObservation (GIMMS New LAI)

Amplitude of LAI annual cycleclimatology (1982-2005)

[Jeong et al., in preparation]

Poor performance

90 100 110 120 130 140 150-6

-4

-2

0

2

4

Uncertainties in phenology[Optimal parameterization][Optimal parameterization]

[parameter][parameter][structure][structure][hypothesis][hypothesis][species][species][DGVM group1][DGVM group1]

CTREX1EX2EX3EX4EX5EX6EX8EX4mEX5mEX 4mEX 5m

Day of year

Net

eco

syst

em p

rodu

ctiv

ity

Parameter: -1.2 days -1.0 days

Structure: -0.5 days - 0.0 days

Hypothesis: -1.5 days -2.0 days

Species: -9.7 days -11.5 days

DGVMs: -9.2 days -11.1 days

Budburst date Carbon uptake commencement

[DGVM group2][DGVM group2]

[Jeong et al., 2012]

Potential solution

Species

[Jeong et al., 2013b; Jeong and Medvigy, in review]

0

5

10

15

20

25B. papyrifera modelQ. rubra modelA. rubrum modelA. saccharum modelF. grandifolia model

A. rubrum A. saccharumQ. rubraB. papyrifera F. grandifolia

RM

S e

rror

s[d

ays]

Early Mid Late successional species

“ecological realism”

New paradigm

Managed ecosystem

Planting date

Leaf Emergence

Grain Fill

Harvest

0

LAI

Time

Phase 1 Phase 3Phase 2

Crop phenology

Green: climate, fertilization, and irrigationRed: human-decision

Tradeoff between food benefit and climatic cost

1. Extensification (land use)

2. Intensification (Irrigation, fertilization, practices)

Global Climate Model (one way)

Earth System Model (two way)

1. Extensification (land use)

2. Intensification (Irrigation, fertilization, practices)

3. Interactive crop management (planting, harvesting)

Current problem

NCAR CESM 1.0 algorithm

Sacks et al., 2010

Wheat

[Jeong et al., 2013a]

Potential solution

Summary

We need more efforts to implement ecological realism in ESMs.

Human-managed phenology is the initial stage.

We need systematic analysis on phenology and atmospheric CO2 by integrating satellite, ground, and Earth system model.

CO

2 C

on

cen

trat

ion

Veg

etat

ion

Act

ivit

y

How will changes in phenology affect the variations in annual cycle of atmospheric CO2?