US CLIVAR Symposium – 14 July 2008 (Photo credit: Arthur Greene) Model Predictions/Projections Model Predictions/Projections for 2018 for 2018 : What is Being : What is Being Planned and Planned and What Could They Tell Us? What Could They Tell Us? [Summary of AGCI workshop] [Summary of AGCI workshop] US CLIVAR Symposium – 14 July 2008 Lisa Goddard – PPAI International Research Institute for Climate & Society The Earth Institute of Columbia University
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US CLIVAR Symposium – 14 July 2008 (Photo credit: Arthur Greene) Model Predictions/Projections for 2018: What is Being Planned and What Could They Tell.
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US CLIVAR Symposium – 14 July 2008
(Photo credit: Arthur Greene)
Model Predictions/Projections for 2018Model Predictions/Projections for 2018: : What is Being Planned and What is Being Planned and What Could They Tell Us? What Could They Tell Us?
[Summary of AGCI workshop][Summary of AGCI workshop]
US CLIVAR Symposium – 14 July 2008
Lisa Goddard – PPAIInternational Research Institute for Climate & Society
The Earth Institute of Columbia University
US CLIVAR Symposium – 14 July 2008
OUTLINE
Summary of AGCI Workshop
Efforts at specific research institutions
Other coordinated efforts within the EU
Experimental [Dynamical] Decadal Predictions
US CLIVAR Symposium – 14 July 2008
AGCI Workshop – Climate Prediction to 2030: Is it possible, what are the scientific issues, and how would those predictions be used?
Meeting Goals:1) Experimental design originally discussed in 2006 for AR5
that explicitly included short-term climate predictions to be performed for assessment by the international climate modeling community. The 2008 AGCI session carried this concept to the next level by tackling the formidable science issues involved with designing and running short term climate projections (now more commonly referred to as "decadal prediction”).
2) Address the important issues of the utility and applications of this information for decision support and impacts research.
25 June 2008 US CLIVAR Symposium – 14 July 2008
Global Climate Change Projections
Source: IPCC 4th Assessment Report, Working Group 1: The Physical Science Basis for Climate Changehttp://ipcc-wg1.ucar.edu/wg1/wg1-report.html
2030
US CLIVAR Symposium – 14 July 2008
Coordinated Decadal Prediction for AR5
Basic model runs:
1.1) 10 year integrations with initial dates towards the end of 1960, 1965, 1970, 1975, 1980, 1985, 1990, 1995 and 2000 and 2005 (see below).- Ensemble size of 3, optionally increased to O(10)- Ocean initial conditions should be in some way representative of the observed anomalies or full fields for the start date.- Land, sea-ice and atmosphere initial conditions left to the discretion of each group.
1.2) Extend integrations with initial dates near the end of 1960, 1980 and 2005 to 30 yrs.- Each start date to use a 3 member ensemble, optionally increased to O(10)- Ocean initial conditions represent the observed anomalies or full fields.
US CLIVAR Symposium – 14 July 2008
Coordinated Decadal Prediction for AR5
Additional model runs:
1.3) 10 year integrations each year in Argo era from near end of 2001, 2002, 2003, 2004, 2006 (2007, ..)
1.4) For models w/ 20th century runs, run additional ensemble members that extend to 2035. These runs form a “control” against which the value of initializing short-term climate and decadal forecasts can be measured.
1.5) For models which do not have 20th century and other standard runs, suggest making a 100 year control integration, and a 70 year run with a 1% per year increase in CO2. These integrations will allow an evaluation of model drift, climate sensitivity and ocean heat uptake, and give some idea of the natural modes of variability of the model.
2) Further studies which would be of interest• Comparison of initialization strategies • Repeat of the 1.1 2005 forecast with a high and/or low anthropogenic aerosol
scenario• Repeat of the 1.1 2005 forecast with an imposed “Pinatubo” eruption in 2010• Impact of Interactive Ozone chemistry• Air quality
US CLIVAR Symposium – 14 July 2008
Coordinated Decadal Prediction for AR5
Participating (/represented) Modeling Groups:BoM - Australia
CCCMA - Canada
COLA - USA
GFDL - USA
UKMO/Hadley Centre – UK
IMF-GEOMAR – Germany
MPI - Germany
NCAR - USA
RSMAS - USA
JMA & U. Tokyo - Japan
US CLIVAR Symposium – 14 July 2008
Coordinated Decadal Prediction for AR5
Main Scientific Issues:• Initialization
- Assimilation issues/products; initialize ocean models with anomalies vs full values vs forced by atmosphere; etc.
• Ensemble Generation Strategy
- perturb ocean and/or atmosphere; perturb model physics
• Ensemble Size
• External Forcing, particularly volcanoes
• Verification
- Modes of variability (e.g. ocean - AMO, PDO), regional surface climate, probabilistic v deterministic, ‘trend’ v ‘natural variability’
US CLIVAR Symposium – 14 July 2008
OUTLINE
Summary of AGCI Workshop
Efforts at specific research institutions
Other coordinated efforts within the EU
Experimental [Dynamical] Decadal Predictions
Predictability of MOC• In COLA CGCM, MOC decadal variability is forced by
weather noise.– If this conclusion is general, the only paths towards improving
prediction of MOC and related surface climate variability are:• More accurate ocean initial conditions
• Improved models on climate time scales
– Reduced biases in climate statistics
– More realistic coupled feedbacks
(Source: Ed Schneider, COLA)
US CLIVAR Symposium – 14 July
2008
MOC in 20th Century Ensemble Integrations
PI CONTROL
(Courtesy: Joe Tribbia, NCAR)
NCAR:Short-term Simulations/Forecasts
• Use higher 0.5o resolution atmosphere and land.
• Run from 1980 – 2000 using observed forcing, and then from 2000 – 2030 using the A1B scenario.
• Have just interpolated 1980 atmosphere and land ICs from 20th Century run using ~2o resolution.
• Do need to initialize the ocean for these runs?
• Idea is to improve near-term projections over USA.
Experiment protocol developed at the July ‘08 Aspen workshop(Stockdale, et. al) with a focus on evaluating hindcast skill. Use GFDL CM2.1 model (AR4 vintage) for short-term climate predictions.
Continue exploring questions of decadal climate predictability (e.g., mechanisms underlying decadal variability, model dependence,
•10 members DePreSys and sub-sampled, 4 members NoAssim
•Max overturning at 30N
2007 obs 1980 obs 1960 obs
(Source: Doug Smith, Hadley Centre)
Future activities at IFM-GEOMARFuture activities at IFM-GEOMAR
1. Investigate methods to extend simple initialisation schemes:
– Perfect model experiments to develop better understanding of the utility of SST restoring
– Investigate methods to account/include salinity variations
– Investigate statistical methods for using SST data
2. Understand the mechanisms for Atlantic multi-decadal variability using model hierarchy
(Source: Noel Keenlyside, IFM-GEOMAR)
Prospect for future climate prediction studies in Hamburg
CLISAP: Integrated Climate System Analysis and Prediction Large scale 5 year research project at U. Hamburg with participation of
MPI-M Plans to develop a climate monitoring and prediction system
CSC: Climate Service CentreBMBF funded 5-year project, possible tasks: dissemination of data Regionalization large scale or quasi-operational simulations for the German research
community
BMBF program for climate prediction (scheduled for 2009 – ? )
“COMBINE” proposal to European commission: Develop/test different initialization and bias correction methods, climate predictions and sensitivities to model improvements (stratosphere, …)
“Storm” project of German research consortium: Explore benefits of high spatial resolution for climate simulation and climate prediction (Atmosphere > T250, Ocean ~0.1°)
(Source: Marco Giorgetta, MPI)
US CLIVAR Symposium – 14 July 2008
OUTLINE
Summary of AGCI Workshop
Efforts at specific research institutions
Other coordinated efforts within the EU
Experimental [Dynamical] Decadal Predictions
US CLIVAR Symposium – 14 July 2008
● Three systems: multi-model (ECMWF, GloSea, DePreSys, Météo-France, IfM-Kiel, CERFACS, INGV), stochastic physics (ECMWF) and perturbed parameters (DePreSys).
● Hindcasts in two streams:
o Stream 1: hindcast period 1991-2001, seasonal (May and November start dates), annual (November start date) and 2 decadal (1965 and 1994), 9 member ensembles.
o Stream 2: As in Stream 1 but over 1960-2005, with 4 start dates for seasonal hindcasts, at least 1 for annual and at least one 3-member decadal hindcast every 5 years.
o Additional simulations: DePreSys_PPE carries out a 10-year hindcast every year and a 30-year hindcast every 5 years + lots of sensitivity experiments from the other contributors.
Seasonal-decadal prediction in the EU ENSEMBLES project
(Source: James Murphy, Hadley Centre)
US CLIVAR Symposium – 14 July 2008
Further EU Projects (1)
COMBINE (Comprehensive Modelling of the Earth System for Better Climate Prediction and Projection)
• Use new climate model components developed since AR4• Input to AR5• Decadal and centennial timescales• Initialisation Work Package: assess different initialisation strategies
- assimilate full values and remove bias calculated from hindcasts
- anomaly initialisation
- empirical model error correction diagnosed from assimilation runs
(Source: James Murphy, Hadley Centre)
US CLIVAR Symposium – 14 July 2008
Further EU Projects (2)
THOR (thermohaline overturning at risk?)• analyse mechanisms driving the THC• assess skill on decadal timescales (using ENSEMBLES hindcasts)• assess relative impact of greenhouse gases and initial conditions
using following hindcasts using:– A 1965 initial conditions, observed GHGs (including aerosols) from 1965
– B 1994 initial conditions, observed GHGs from 1994
– C 1965 initial conditions, observed GHGs from 1994
– D 1994 initial conditions, observed GHGs from 1965
• Idealised experiments to assess impact of observations of predictability of THC
(Source: James Murphy, Hadley Centre)
US CLIVAR Symposium – 14 July 2008
OUTLINE
Summary of AGCI Workshop
Efforts at specific research institutions
Other coordinated efforts within the EU
Experimental [Dynamical] Decadal Predictions
US CLIVAR Symposium – 14 July 2008
Experimental [Dynamical] Decadal Predictions
Few Pioneers1. Hadley Centre (Smith et al, 2007 - Science)
2. IFM-GEOMAR (Keenlyside et al, 2008 - Nature)
3. MPI/Hadley Centre (Pohlman et al, 2008 submitted)
2. Initialisation and decadal hindcasts using ECHAM5/MPI_OM coupled model(Keenlyside et al, 2008)
• 3x 20th century transient simulations (anthro, solar, volcanic forcing)
• 3 x 20th century simulations assimilating SST anomalies (same forcing)
• Decadal hindcasts started every 5 years from 1955-2005. 3 ensemble members; (anthro forcing, repeated solar cycle, no volcanoes)
2. Decadal hindcast/forecast strategyDecadal hindcast/forecast strategy (Keenlyside et al, 2008)
• Model: ECHAM5/MPIOM Climate model (IPCC AR4 version)
• Initial conditions: Coupled model SST anomalies restored to observations
• Boundary conditions: 20th century/A1B radiative forcing Nudging constant varies with latitude
0.25 days-1
Linear transition
0 days-1 (fully coupled)
Linear transition
0 days-1 (fully coupled)
30˚N
30˚S
60˚N
90˚N
60˚S
90˚S
(Source: Noel Keenlyside, IFM-GEOMAR)
3. Pohlmann et al., submitted to J. Climate.
Improving Decadal Climate Predictability through the Initialization of a Coupled Model with the GECCO Oceanic Synthesis
Holger Pohlmann(1,2), Johann Jungclaus(1), A. Köhl(3), D. Stammer(3), J. Marotzke(1)
(1) Max Planck Institute for Meteorology, Hamburg, Germany(2) Now at Met Office Hadley Centre, Exeter, UK(3) Institute of Oceanography, ZMAW, Univ. Hamburg, Germany
ECHAM5/MPI-OM climate model (~ MPI-M IPCC AR4 model) GECCO ocean synthesis 1952-2001 10 year hindcasts and forecasts
(Source: Marco Giorgetta, MPI)
Pohlmann et al.: Experimental design
Experiments Initialization Forcing Amount Period
Control In 1900, 1910 and 1920 from an IPCC AR4 20th century simulation
GHG + aerosol 3 1900 – 2011
Assimilation In 1952 from Control (initialized in 1900)
GHG + aerosol and T + S from ECCO
1 1952 – 2001
Hindcast At the end of every year from Assimilation
CONs• Global average• Little to no evidence of [predictable] LF climate variability at long lead PROs:• Improved projections relative to original system• View of change in uncertainty with time scale1) Uncertainty in decadal-average2) Uncertainty through a decade due tointerannual variability3) Realization of natural variability throughdecade
US CLIVAR Symposium – 14 July 2008
Smith et al (2007)
Regionality?• Ts projections improved
over many regions
Climate variability?• Ts projection worse over
N.Atlantic• Much improvement in
regional T is associated with improvement in regional H, which bears striking resemblance to regions where T is dominated by externally-forced signal.
Figure 5
Ratio of Externally-forced to Total Variance
(Courtesy: M. Ting et al, J.Climate, submitted)
US CLIVAR Symposium – 14 July 2008
Keenlyside et al (2008)
“… the initialized prediction indicates a slight cooling relative to 1994-2004 levels, while the anthropogenic-forcing-only simulation suggests a near 0.3 K rise.”
PRO:• Focus on mode(s) of
natural climate variability
CONs:• Statements/conclusions
seem at odds with evidence (ie. fcst evolution)
• Uncertainty given by spread of 3 ensemble members
• Demonstration of natural climate variability (AMOC) not obvious
Figure 4
US CLIVAR Symposium – 14 July 2008
Keenlyside et al (2008)
Regionality?• New method seems to have
greater errors in most places, especially the N. Atlantic
• What does improved performance in eastern Pacific suggest for ENSO variability?
Climate variability?• Lack of verifying observations,
so don’t really know truth• But – according to available
truth, hindcast has no skill
Supp. Figure 2c
Figure 3a
Maximum MOC Strength
Difference in RMSE (deg. K)
Pohlmann et al.: North Atlantic annual mean SST (°C)
HadISST
Assimilation
h/f castyear 1-5
Control
h/f castyear 5-10
h/f castyear 1
h/f castyear 1-10
Time series Anom. Cor. | RMSE
H-cast/HadISST
H-cast/AssimCtrl/Assim
95% CL
Persistence
(Source: Marco Giorgetta, MPI)
US CLIVAR Symposium – 14 July 2008
Predictions? / Projections?
Projections?• Yes – seems possible to provide better
estimates of near-term anthropogenic climate change (at least T), due largely to correcting biases in ICs
Predictions?• Not yet – Some evidence of potential
predictability (perfect model/ICs) and slight evidence of real experimental predictability, but very little available at regional scales (and nothing yet demonstrated for precipitation).
US CLIVAR Symposium – 14 July 2008
SUMMARY
• Considerable national and international efforts
• Numerous scientific questions remain, particularly on initialization, mechanisms and model validation
• Decadal prediction/projection is promising but in VERY EARLY stages. The climate community must first assess what we have (and don’t have) before invoking its direct use by applications and decision makers.