Comparison of Recent European Climate Trends

and Extremes with RegCM3 Future Projections

Jeremy Pal

Abdus Salam International Centre for Theoretical PhysicsTrieste, Italy

Contributors: Xunqiang Bi, Elfatih Eltahir,Raquel Francisco, Xuejie Gao, Filippo Giorgi

Premises/Objectives of the studyPremises/Objectives of the studyClimate variability and extremes are of

fundamental importance for an assessment of the impacts of climate change.

Because of their relatively high spatial and temporal resolution Regional Climate Models (RCMs) can be especially useful in the study of climate variability and extremes.

Carry out climate change simulations over the European region for different emission scenarios using an RCM driven by boundary conditions from time-slice GCM simulations

PART I: Regional Climate ModelingBrief Overview

PART II: Reference SimulationMean Climate

PART III: A2 & B2 Scenario SimulationsMeanInterannual VariabilityExtreme Events

PART I:PART I:Regional Climate ModelingRegional Climate Modeling

Brief Overview

GCMGlobal Climate Model (GCM)RCM Nesting

GCM forces RCM at the lateral boundaries and the sea surface.

Added Value of using a Regional Climate Added Value of using a Regional Climate Model for Climate Change Studies.Model for Climate Change Studies.

Increased resolution compared to the driving GCM. Fine scale forcing (e.g. topography, landuse, coastlines,

lakes, aerosol sources). Mesoscale circulations (e.g. North American Monsoon

System). Improved representation of physical processes.

Clouds and precipitation, biosphere, boundary layer, radiation, etc.

Increased confidence for impacts studies. Can include additional processes not present in the

driving GCM. Landuse changes, aerosol effects, lake desiccation, etc.

Summary of RegCM3 CoreSummary of RegCM3 CoreDynamics:

MM5 Hydrostatic (Grell et al 1994)Non-hydrostatic (in the works)

Radiation:CCM3 (Kiehl 1996)

Large-Scale Clouds & Precipitation:SUBEX (Pal et al 2000)

Cumulus convection:Grell (1993); AS74 & FC80 closureAnthes-Kuo (1977)Betts-Miller (1993)Emanuel (1991)

Boundary Layer:Holtslag (1990)

Tracers/Aerosols:Qian et al (2001); Solmon

Land Surface:BATS (Dickinson et al 1993)SUB-BATS (Giorgi et al 2003)CLM0 (Dai et al 2003)

Ocean FluxesZeng et al (1998)BATS (Dickinson et al. 1986)

ComputationsParallel Code (Yeh & Gao)User friendlyMultiple platforms

(Giorgi et al 1993ab, Pal et al 2005ab)

Dynamics:MM5 Hydrostatic (Grell et al 1994)Non-hydrostatic (in the works)

Radiation:CCM3 (Kiehl 1996)

Large-Scale Clouds & Precipitation:SUBEX (Pal et al 2000)

Cumulus convection:Grell (1993); AS74 & FC80 closureAnthes-Kuo (1977)Betts-Miller (1993)Emanuel (1991)

Boundary Layer:Holtslag (1990)

Tracers/Aerosols:Qian et al (2001); Solmon

Land Surface:BATS (Dickinson et al 1993)SUB-BATS (Giorgi et al 2003)CLM0 (Dai et al 2003)

Ocean FluxesZeng et al (1998)BATS (Dickinson et al. 1986)

ComputationsParallel Code (Yeh & Gao)User friendlyMultiple platforms

1993 Midwest Summer Flood

USHCN ObservationsUSHCN Observations

RegCM3RegCM3

Ancient Nilometer(Mississippimeter)

Date back 1800 B.C.

This one calibrated insubjective terms byPliny the Elder

(Dooge 1988)

Disaster

Abundance

Security

Happiness

Suffering

Hunger

• Record high rainfall Record high rainfall (>200 year event)(>200 year event)

• Thousands homelessThousands homeless• 48 deaths48 deaths• $15-20 billion in Damage$15-20 billion in Damage

1993

1988

1988 Great North American

Drought

CRU ObservationsCRU Observations

RegCMRegCM

Ancient Nilometer(Mississippimeter)

Date back 1800 B.C.

This one calibrated insubjective terms byPliny the Elder

(Dooge 1988)

Disaster

Abundance

Security

Happiness

Suffering

Hunger

1993

1988

• Driest/warmest since 1936Driest/warmest since 1936• ~10,000 deaths~10,000 deaths• $30 billion in Agricultural $30 billion in Agricultural

DamageDamage

Precipitation over East Asia:

CRU Observations RegCM3

September 1994 thru August 1995

Scenario SimulationsScenario Simulations

Design of Numerical Experiments

Socio-Economic Assumptions

Emissions Scenarios

Concentration CalculationsBiogeochemical/Chemistry Models

Global Climate Change SimulationAOGCMs, Radiative Forcing

ImpactsImpact Models

Inte

rac

tio

ns

an

d F

eed

bac

ks

La

nd

Us

e C

ha

ng

e

Po

licy

Res

po

ns

es:

Ad

ap

tati

on

an

d M

itig

ati

on

Regional Climate Change Simulations

Regionalization Techniques

Cascade of Uncertainties in Climate Change PredictionCascade of Uncertainties in Climate Change Prediction

NaturalForcings

Model Configuration

ICTP RegCM3 50 km 121 x 100 x 14 HadAMH SST, GHG

& Sulfate Aerosol effects (direct

& indirect) Simulations

Reference run 1961-1990

A2 & B2 Scenario runs 2071-2100

Mediterranean Focused

Regional Climate Model SchematicRegional Climate Model Schematic

RotatedRotatedMercatorMercatorProjectionProjection

GLCCGLCCVegetationVegetation

HadAMH3 HadAMH3 Initial and Initial and Boundary Boundary ConditionsConditions

Hadley & OISea Surface

Temperatures

USGSUSGSTopographyTopography

HadAMH3 HadAMH3 AerosolsAerosols

SCENARIOSCO2 Emissions

(Gt C)CO2 Concentrations

(ppm)

A2

A2

B2

B2

PART II:PART II:Reference SimulationReference Simulation

Comparison to Observations

Giorgi, Bi, Pal, Clim. Dynamics 2004a

Winter MeansWinter Means

Reference Period

Surface Air Temperature: Reference SimulationSurface Air Temperature: Reference Simulation

WinterRegCM3

WinterObservations

Precipitation: Reference SimulationPrecipitation: Reference Simulation

WinterRegCM3

WinterObservations

Summer MeansSummer Means

Reference Period

Surface Air Temperature: Reference SimulationSurface Air Temperature: Reference Simulation

SummerRegCM3

SummerObservations

Precipitation: Reference SimulationPrecipitation: Reference Simulation

SummerRegCM3

SummerObservations

PART III:PART III:A2 & B2 Scenario A2 & B2 Scenario

SimulationsSimulationsComparison to the Reference Simulation

Giorgi, Bi, Pal, Clim. Dynamics 2004b

Pal, Giorgi, Bi, GRL 2004

Winter MeansWinter Means

Scenarios

Temperature Change: Future-ReferenceTemperature Change: Future-Reference

WARM

HOTA2-REF Winter

RegCM3

B2-REF Winter

RegCM3

WARM

Precipitation Change: Future-ReferencePrecipitation Change: Future-Reference

WET

WET WETA2-REF Winter

RegCM3

B2-REF Winter

RegCM3

DRY

DRY

Sea Level Pressure Change: Future-ReferenceSea Level Pressure Change: Future-Reference

L H

L H

H

A2-REF Winter

RegCM3

B2-REF Winter

RegCM3

Winter Sea Level Pressure Change: B2 & A2 ScenariosWinter Sea Level Pressure Change: B2 & A2 ScenariosDJF HadAMH: B2 DJF RegCM: B2

DJF RegCM: A2DJF HadAMH: A2

L H L H

L H L H

H H

Summer Means

Scenarios

Temperature Change: Future-ReferenceTemperature Change: Future-Reference

WARM

HOT

A2-REF SummerRegCM3

B2-REF SummerRegCM3

WARM

Precipitation Change: Future-ReferencePrecipitation Change: Future-Reference

DRY

WET

DRY

WETA2-REF SummerRegCM3

B2-REF SummerRegCM3

Sea Level Pressure Change: Future-ReferenceSea Level Pressure Change: Future-Reference

H L

HL

A2-REF SummerRegCM3

B2-REF SummerRegCM3

Winter Sea Level Pressure Change: B2 & A2 ScenariosWinter Sea Level Pressure Change: B2 & A2 ScenariosJJA HadAMH: B2 JJA RegCM: B2

JJA RegCM: A2JJA HadAMH: A2

H L H L

H

L

H

L

Interannual VariabilityInterannual Variability

Scenarios

Map of Domain & TopographyMap of Domain & Topography

SEM

Sub-region Averages

DJF, A2

DJF, B2

JJA, A2

JJA, B2

Surface Air Temperature:Surface Air Temperature:Interannual Variability ChangesInterannual Variability Changes

SEM

RegCM3: Future-REF

Sub-region Averages

Precipitation:Precipitation:Interannual Variability ChangesInterannual Variability Changes

RegCM3: Future-REF

DJF, A2

DJF, B2

JJA, A2

JJA, B2

SEM

ExtremesExtremes

How do recent climatic changes compare to scenarios?

Pal, Giorgi, Bi, GRL 2004

Recent European Extreme SummersRecent European Extreme Summers The western European summer drought of 2003 is

considered one of the severest on record. 20,000 heat related casualties in Western Europe. Worst harvest since World War II.

In contrast, during 2002, many European countries experienced one of their wettest summers on record. Weather systems brought widespread heavy rainfall to central

Europe, causing severe flooding along all the major rivers. The Elbe River reached its highest level in over 500 years of record

Both of these contrasting events resulted in severe damages and losses.

This study addresses whether these seemingly opposites in extremes are consistent the current climate change projections.

Changes in Summer500 hPa Geopotential Heights

( meters) ( meters)

B2-Reference(2071-2100) minus (1961-1990)

NCEP Reanalysis(1976-2000) minus (1951-1975)

Changes in Summer Temperature

B2-Reference(2071-2100) minus (1961-1990)

(C)(C)

CRU Observations(1976-2000) minus (1951-1975)

Changes in Summer Precipitation

B2-Reference(2071-2100) minus (1961-1990)

(% change)(% change)

CRU Observations(1976-2000) minus (1951-1975)

Changes in Summer Temperature:B2-Reference

(C)(C)

Mean Surface(2071-2100) minus (1961-1990)

Interannual Variability(2071-2100) minus (1961-1990)

Changes in Summer Extremes:B2-Reference

(% change)( Days)

Dry Spell Length(2071-2100) minus (1961-1990)

Max 5-Day Precipitation(2071-2100) minus (1961-1990)

Precipitation DistributionPrecipitation Distribution(Hypothetical)(Hypothetical)

REF

ref

ref

B2

B2

B2

MoreDroughts

MoreFloods

DrierSummers

Summary & ConclusionsSummary & Conclusions The RegCM3 reproduces the main features of observed

temperature and precipitation. A general consistency of change patterns is found between the

A2 and B2 scenarios. Warming:

2-7 oC in the A2 scenario is found over land areas. The B2 scenario is 1-2 oC lower.

Precipitation: Increases in Northern Europe during summer and winter Increases in the Mediterranean in DJF and decreases in JJA.

Interannual variability: Mostly increases in JJA Little change in DJF.

Extremes: Increases flooding in Northern Europe Increased summer flood and drought in the Mediterranean.

Projected changes of mean summer European climate are broadly consistent with the observed changes.

谢谢