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 physics and hydrology Ocean circulation Atmospheric circulation and radiation Land physics and hydrology Ocean ecology and chemistry Atmospheric circulation and radiation Allows Interactive CO 2 Ocean circulation Plant ecology, land use, and Biogeochemistry Climate Model Earth System Model Sea Ice

CO 2 DiagnosticPrognostic Global Climate ModelEarth 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 examples  Anthropogenic land cover change  Photosynthesis-transpiration  Leaf area index Multi-disciplinary Science

History

Heterogenity

Dynamic Global Vegetation Model (DGVM)

Vegetation dynamics Competition (10 days) Broadleaf Tree C3 Grass Shrub Soil Plant functional type (PFT) Deciduous, evergreen trees Shrub Grass Crop

Phenology LAI (Model)

Simulated Carbon

Annual cycle of LAI in ESMs Observation (GIMMS New LAI) Amplitude of LAI annual cycle climatology ( ) [Jeong et al., in preparation]

Poor performance

Uncertainties in phenology [Optimal parameterization] [parameter] [structure] [hypothesis] [species] [DGVM group1] EX 4m EX 5m Day of year Net ecosystem productivity Parameter: -1.2 days -1.0 days Structure: -0.5 days days Hypothesis: -1.5 days -2.0 days Species: -9.7 days days DGVMs: -9.2 days days Budburst date Carbon uptake commencement [DGVM group2] [Jeong et al., 2012]

Potential solution Species [Jeong et al., 2013b; Jeong and Medvigy, in review] EarlyMid 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 irrigation Red: 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. CO2 ConcentrationVegetation Activity How will changes in phenology affect the variations in annual cycle of atmospheric CO2?