a framework for modeling uncertainty in regional climate ... ·...

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A framework for modeling uncertainty in regional climate change

Erwan Monier, Xiang Gao, Jeff Scott, Andrei Sokolov and Adam Schlosser

Climate Modeling DOE PI Meeting May 14, 2014


Objec,ves Investigate the contributions of major sources of uncertainty to regional climate projections and provide guidance for climate impact studies.


Objec,ves Investigate the contributions of major sources of uncertainty to regional climate projections and provide guidance for climate impact studies. Examples of sources of uncertainty: •  Emissions forecasting

o  Assumptions on economic growth o  Implementation of climate policies

•  Climate system response o  Climate sensitivity o  Strength of aerosol forcing o  Ocean heat uptake rate

•  Natural variability o  Chaotic nature of the climate system

•  Model structural uncertainty o  Differences in parameterizations, resolution…


The MIT Integrated Global System Model Integrated assessment model: couples an earth system model of intermediate complexity to a human activity model.

Trace gas

and policy constraints VOCs, BC, etc.

Hydrology/ water resources

Agriculture, forestry, bio-energy, ecosystem productivity

Human health

Earth System

Emissions Prediction and Policy Analysis (EPPA)National and/or Regional Economic Development,

Emissions & Land Use

Human System

Land use change

Atmosphere2-Dimensional Dynamical,

Physical & Chemical Processes

Ocean2- or 3-Dimensional

Dynamical, Biological, Chemical & Ice Processes

Urban AirshedAir Pollution Processes

LandWater & Energy Budgets (CLM)

Biogeochemical Processes (TEM & NEM)

Coupled Ocean, Atmosphere, and Land

Sea level change

Climate/ energy demand

Solar forcing

Volcanic forcing


The MIT Integrated Global System Model Integrated assessment model: couples an earth system model of intermediate complexity to a human activity model. Representation of uncertainty: •  Emissions •  Climate system response •  Greenhouse gas cycle

Trace gas




Human health

Earth System



Human System

Land use change









Sea level change


Solar forcing

Volcanic forcing


The MIT Integrated Global System Model Integrated assessment model: couples an earth system model of intermediate complexity to a human activity model. Representation of uncertainty: •  Emissions •  Climate system response •  Greenhouse gas cycle Representation of climate policies (global carbon tax)

Trace gas




Human health

Earth System



Human System

Land use change









Sea level change


Solar forcing

Volcanic forcing


The MIT Integrated Global System Model Integrated assessment model: couples an earth system model of intermediate complexity to a human activity model. Representation of uncertainty: •  Emissions •  Climate system response •  Greenhouse gas cycle Representation of climate policies (global carbon tax) Computationally efficient framework that allows ensemble simulations with number of members in the 100s/1000s

Trace gas




Human health

Earth System



Human System

Land use change









Sea level change


Solar forcing

Volcanic forcing


Regional Climate Modeling Framework The IGSM has a 2D zonal-mean atmosphere, so we use a two-pronged approach to obtain regional changes:



•  Dynamical downscaling: The IGSM-CAM framework, which links the IGSM to the NCAR Community Atmosphere Model (CAM). -  low, median and high climate sensitivity based on its PDF -  net aerosol forcing that best reproduces historical climate change -  5-member ensemble with different representation of natural variability



•  Dynamical downscaling: The IGSM-CAM framework, which links the IGSM to the NCAR Community Atmosphere Model (CAM). -  low, median and high climate sensitivity based on its PDF -  net aerosol forcing that best reproduces historical climate change -  5-member ensemble with different representation of natural variability

•  Statistical downscaling: A pattern scaling method that extends the IGSM 2D zonal-mean atmosphere using patterns from observations and climate models. -  400-member ensemble of IGSM, with Latin Hypercube sampling of climate parameters (climate sensitivity, strength of aerosol forcing, ocean heat uptake rate) based on their PDFs -  Pattern scaling based on 17 CMIP3 models


NORTHERN EURASIA


Northern Eurasia Projec,ons No Policy


Northern Eurasia Projec,ons Stabiliza,on at 660 ppm CO2-‐eq


Northern Eurasia Projec,ons

IMPACT OF POLICY AND CLIMATE RESPONSE

HIGH_UCE

MED_UCE

LOW_UCE LOW_LS2

MED_LS2

HIGH_LS2

2081-‐2100 MEAN MINUS 1981-‐2000 MEAN


Northern Eurasia Projec,ons

IMPACT OF POLICY AND CLIMATE RESPONSE

HIGH_UCE

MED_UCE

LOW_UCE LOW_LS2

MED_LS2

HIGH_LS2 MED_LS2 MED_LS2

MED_LS2 MED_LS2

MED_LS2

MEMBER #1 MEMBER #2

MEMBER #3 MEMBER #4

MEMBER #5

IMPACT OF NATURAL VARIABILITY

2081-‐2100 MEAN MINUS 1981-‐2000 MEAN


CONTIGUOUS UNITED STATES


Uncertainty in US Temperature Projec,ons

0

1

2

3

4

5

2020 2040 2060 2080 2100

TEM

PE

RAT

UR

E (°

C)

YEAR

CLIMATE SENSITIVITY CHOICE OF POLICY

NATURAL VARIABILITY CHOICE OF MODEL


Uncertainty in US Precipita,on Projec,ons

0

0.1

0.2

0.3

2020 2040 2060 2080 2100

PR

EC

IPIT

ATIO

N (m

m/d

ay)

YEAR

CLIMATE SENSITIVITY CHOICE OF POLICY

NATURAL VARIABILITY CHOICE OF MODEL


Conclusions Wide range of temperature and precipitation changes over Northern Eurasia and the contiguous US, even using one single climate model. ⇒ need to sample the global climate system response within each model.


Conclusions Wide range of temperature and precipitation changes over Northern Eurasia and the contiguous US, even using one single climate model. ⇒ need to sample the global climate system response within each model. Each source of uncertainty considered contributes differently to the range of temperature and precipitation changes. •  For temperature:

- choice of policy and climate sensitivity •  For precipitation:

- natural variability dominates until 2050 - all four sources contribute more equally by 2100


Conclusions Wide range of temperature and precipitation changes over Northern Eurasia and the contiguous US, even using one single climate model. ⇒ need to sample the global climate system response within each model. Each source of uncertainty considered contributes differently to the range of temperature and precipitation changes. •  For temperature:

- choice of policy and climate sensitivity •  For precipitation:

- natural variability dominates until 2050 - all four sources contribute more equally by 2100

What does this mean for climate impacts? Relying on a small ensemble of climate simulations or not accounting for the major sources of uncertainty in climate projections would likely underestimate climate impacts.


IGSM-‐CAM




Ocean3-Dimensional Dynamical,

Biological, Chemical, and Ice Processes (MITgcm)



Trace gas fluxes (CO2, CH4, N2O) and policy constraints

CO2, CH4, CO, N2O, NOx, SOx, NH3, CFCs, HFCs, PFCs, SF6, VOCs, BC, etc.



Sea level change


Human health effects


Implementation of feedbacks is under development

Exchanges utilized in targeted studies

Exchanges represented in standard runs of the system

Earth System



Human System

Land use change

Wind stress

Solar forcing

Volcanic forcing

Coupled Land and Atmosphere

CAM3

Atmosphere3-Dimensional Dynamical

& Physical Processes


Solar forcing

Volcanic forcing

SSTs andsea ice cover

Land use change

CO2, CH4, N2O, CFCs, HFCs, PFCs, SF6, SOx, BC and O3


IGSM-‐pa"ern scaling

a framework for modeling uncertainty in regional climate ... ·...

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