Removing the Mystery of Removing the Mystery of Predicting Climate Predicting Climate

ChangeChange

Duane WaliserDuane WaliserJPL JPL

101 Lecture Series101 Lecture SeriesJuly 19, 2006July 19, 2006

Your connections to climate change predictionsYour connections to climate change predictions

1.1. What does he mean by “climate What does he mean by “climate change”?change”?• Observations

2.2. Build a Simple Climate ModelBuild a Simple Climate Model• Greenhouse Gases• Climate Feedback; “What If”?• Model Predictions

3.3. State of the Art Climate ModelsState of the Art Climate Models• Computation Challenges• Do They Work?

4.4. Reducing the UncertaintiesReducing the Uncertainties1. Faster Computers2. More/Better Satellite Data

Today’s LectureToday’s Lecture•Bad NewsBad News•Good NewsGood News

__________________________________________________________________________________________________________________________________________________________

- Only ONE Test Question!!- Includes Physics/Math

Boo

Boo

What Kind of Climate Change What Kind of Climate Change Are We talking about?Are We talking about?

Natural VariationsNatural VariationsGeological Changes - Ice Ages - NoGeological Changes - Ice Ages - No

El Nino <-> La Nina - NoEl Nino <-> La Nina - NoVolcanic Induced - No…Volcanic Induced - No…Solar Variations - No…Solar Variations - No…

The Kind in “Day After Tomorrow” - Definitely NotThe Kind in “Day After Tomorrow” - Definitely Not

Anthropogenic = Man-MadeAnthropogenic = Man-MadeCFCs & Ozone Destruction - NoCFCs & Ozone Destruction - No

Enhanced Greenhouse Gases (e.g., COEnhanced Greenhouse Gases (e.g., CO22) - Yes) - Yes

Why AllWhy AllThe The

Concern?Concern?

““Hockey Stick”Hockey Stick”

Rarely If EverSo Warm

Rarely if Ever So Fast

Far and Far and AwayAway

One of One of The MostThe MostImportantImportantClimateClimateDataDataSetsSets

What MIGHT be causing this warming?What MIGHT be causing this warming?

ExtendedExtendedUsingUsingProxyProxyDataDatae.g.e.g.

Ice CoresIce Cores

Industrial Age

So, How is the Warming & COSo, How is the Warming & CO2 2 Connected?Connected?

What about the Future?What about the Future?

Yes, this is Yes, this is where the where the

physics and Math physics and Math come income in

Past Experience SuggestsStarting with a Simple

Model

TTEE44

Sun Heats the EarthSun Heats the Earth

Earth Emits Radiation to CoolEarth Emits Radiation to Cool

Total Solar Radiation = Total Terrestrial Radiation

Simple Climate ModelSimple Climate Model

(aka Infrared, Thermal)

ObservationsObservationsSolar “constant”Solar “constant”

~335 W/m~335 W/m22

Physics + MathPhysics + MathStefan-Boltzmann Law: 1884

Emitted Radiation T4

101 - Take Away MessageTemperature ↑

Emitted Radiation ↑↑↑↑

Simple Climate ModelSimple Climate Model

TE4

Earth Surface

Solve For TSolve For TEE => 277 K = 4 C ~ 40 F => 277 K = 4 C ~ 40 F

Real Global Average Real Global Average Temperature = 288 K = 15 C ~ 59 FTemperature = 288 K = 15 C ~ 59 F

Not Bad - But We Missed TwoNot Bad - But We Missed TwoReally Important ThingsReally Important Things

Clouds, Ice, Snow, Clouds, Ice, Snow, Desert and DustDesert and Dust

ReflectsReflectsSunlightSunlightBack to Back to SpaceSpace

Improve Our Simple Climate ModelImprove Our Simple Climate Model

Earth Surface

Now Solve For TNow Solve For TEE => 254 K = -19 C ~ -2 F => 254 K = -19 C ~ -2 FFreezing Cold!!!Freezing Cold!!!

Pretty Bad - But We Still Have Pretty Bad - But We Still Have Something Very Important to Include Something Very Important to Include

TE4

Ice/SnowIce/SnowCloudsCloudsDesertsDeserts

A = “Albedo” ~ 0.30A = “Albedo” ~ 0.30

Greenhouse Earth

Greenhouse Analogy

Gases such asGases such asHH22O, COO, CO22, CH, CH44

Are Known AsAre Known AsGreenhouse Greenhouse

GasesGases

More Improvements to our Climate ModelMore Improvements to our Climate Model

Now Solve For T => 286 K = 13 C ~ 55 FNow Solve For T => 286 K = 13 C ~ 55 F

Surface, TE

Ice/SnowIce/SnowCloudsCloudsDesertsDeserts

Greenhouse Gases, H2O, CO2 Atmosphere, TA

90% Solar 90% Solar Passes Passes ThruThru

20% Terrestrial 20% Terrestrial Passes Thru; RestPasses Thru; Rest

Heats the AtmosphereHeats the Atmosphere

AtmosphereAtmosphereCools AsCools As

TTAA44

Back to the Math & PhysicsBack to the Math & PhysicsNow, We Balance Energy (i.e. & ) at the Top of the Atmosphere and at theSurface - 2 Equations & 2 Unknowns.

Lets Spare the Details…..

Pretty Good! .Pretty Good! .The GH’effect Changes This The GH’effect Changes This

To This . To This .

So Why The “Global Warming”?So Why The “Global Warming”?

Surface, TE

Ice/SnowIce/SnowCloudsCloudsDesertsDeserts

Greenhouse Gases, H2O, CO2 Atmosphere, TA

Recall, CORecall, CO22 Has Been Increasing Has Been Increasing

So Why The “Global Warming”?So Why The “Global Warming”?

Surface, TE

Ice/SnowIce/SnowCloudsCloudsDesertsDeserts

Greenhouse Gases, H2O, CO2 Atmosphere, TA

This Part is Well EstablishedThis Part is Well Established

Greenhouse Gases, H2O, CO2 Atmosphere, TA

More GHGs, More Trapping, Higher TemperaturesMore GHGs, More Trapping, Higher Temperatures

TE

So Why Are We Uncertain?So Why Are We Uncertain?Climate Feedbacks!!Climate Feedbacks!!

Ice/Snow-Albedo Feedback

Water VaporFeedback

CloudFeedback

Climate FeedbacksClimate FeedbacksPositive or or Negative

Te : Ice/Snow Melt : Reflection : Te +Te : Water Vapor : GHG : Te +Water Vapor : ?Clouds : Reflection : Te - Depends on the type of cloud, its height, ice/water, etc.!

Surface, TE

Ice/SnowIce/SnowCloudsCloudsDesertsDeserts

Greenhouse Gases, H2O, CO2 Atmosphere, TA

The balance of these The balance of these feedbacks, feedbacks, and MANY and MANY othersothers, have to be , have to be properly representedproperly representedIn Climate ModelsIn Climate Models

Ice/Snow-Albedo Feedback

Water VaporFeedback

CloudFeedback

How do We Do this in State-How do We Do this in State-of-the-Art Climate of-the-Art Climate

Modeling?Modeling?•Divide the Atmosphere Into Boxes Divide the Atmosphere Into Boxes (How many - as many as possible)(How many - as many as possible)

•Do the type of calculations for each Do the type of calculations for each Box like we did in our simple model.Box like we did in our simple model.

•Use Conservation of Mass, Energy, Use Conservation of Mass, Energy, and Momentum and the Ideal Gas Law.and Momentum and the Ideal Gas Law.

Test QuestionDid our model use Conservation of

1) Mass2) Energy 3) Momentum

__________________________________________________________________________________________________________________________________________________________

Climate Model Computer “Grid”Climate Model Computer “Grid”

Similar for Ocean,Similar for Ocean,Land & Ice SystemsLand & Ice Systems

<- Longitude -> <- Latitude ->

<- Height ->

<- Time ->

Scope of numerical problem in Excel terms Scope of numerical problem in Excel terms

360 Longitude * 180 Latitude * 30 in Height * 20+ Variables (e.g., Temp, Water Vapor, Wind, Clouds, Radiation, etc) = ~40 Million; Then make a calculation of these to step forward in time for 20 minutes until you get to 100 years.

TemperatureOther files for q,U, V, W, P, etc.

That’s Why We Need That’s Why We Need Super-ComputersSuper-Computers

JPL Dell Xeon Clustercosmos.jpl.nasa.gov

What Can These Climate Models Do?What Can These Climate Models Do?

NaturalNatural&&

Man-MadeMan-MadeInducedInducedChangesChanges

VolcanoesSolar

GreenhouseOzone

VolcanoesSolar

GreenhouseOzone

ModelModelHindsightHindsightPrettyPrettyGoodGood

Predicting the FuturePredicting the Future

ScienceScience, , PoliticsPolitics & & SocietySociety

Plausible Plausible ““Scenarios”Scenarios”

For COFor CO22 EmissionsEmissions

Climate Model ProjectionsClimate Model ProjectionsIntergovernmental Panel on Climate Change (IPCC, 2001)Intergovernmental Panel on Climate Change (IPCC, 2001)

While there is While there is considerableconsiderable

disagreement, disagreement, ALLALL models predict models predict WARMINGWARMING for for ALLALL

plausible plausible scenarios.scenarios.

Where does the warming occur?Where does the warming occur?IPCC, 4th (newest) Assessment ReportIPCC, 4th (newest) Assessment Report

ProjectedProjectedTemperatureTemperature

ChangeChangeIn 2100In 2100

2099-2070Minus

1999-1970

How About Our Backyard?How About Our Backyard?IPCC, 4th (newest) Assessment ReportIPCC, 4th (newest) Assessment Report

Systematic WarmingSystematic Warming1.5 - 3.0 C1.5 - 3.0 C2.7 - 5.4 F2.7 - 5.4 F

Relatively AgreeableRelatively Agreeable

+/- 20%+/- 20%Much Less CertainMuch Less Certain

Why do the Model Why do the Model Predictions Differ?Predictions Differ?

Estimating “Unresolved” Estimating “Unresolved” and and ComplexComplex Processes Processes

Difficulty with Clouds, Climate and Computer GridsDifficulty with Clouds, Climate and Computer Grids

Consider drawing a picture of this cloudConsider drawing a picture of this cloud

We would like to We would like to Have a sharp pencilHave a sharp pencil

For most clouds weFor most clouds wehave a BIG CRAYONhave a BIG CRAYON

CRAYOLA

Clouds - and other Clouds - and other features - have features - have very fine scalesvery fine scales

How do youRealisticallyRepresent

this with ONE number?

1)1) Get More NumbersGet More Numbers2)2) Make Sure it is a Good Make Sure it is a Good NumberNumber

1)1) Get More NumbersGet More Numbers

10km Grid10km GridOur Excel ~ 100 kmOur Excel ~ 100 km1000 X More Work 1000 X More Work

LongestLongestSimulationsSimulations

A Few A Few Months Months

1)1) Get More NumbersGet More Numbers

Get More Get More NumbersNumbersWhere YouWhere YouMost NeedMost NeedThem Them

“Nesting”Or

“Downscaling”

2) Make Sure it is a Good 2) Make Sure it is a Good Number Number That’s where satellite data are That’s where satellite data are

crucialcrucial

CloudFeedback

ICE

LIQUID

ICE

RAIN

SNOWMIXED

LIQUID

ICE

IPCC Models: Global Average Ice Water Path

0.000.010.020.030.040.050.060.070.080.090.10

bccr

cccmat47cccmat63

cnrmcsirogfdl20gfdl21gissehgisseriapinmcm

ipsl

mirochrmirocmr

mpimrincar

ukmocm3ukmogem1

Cloud Ice Path (kg/m^2)

ModelModel

Factor of ~7 DifferenceFactor of ~7 Difference

IPCC Models: Global Average Total Cloud IceIPCC Models: Global Average Total Cloud IceIPCC Models: Global Average Ice Water Path

0.00

0.05

0.10

0.15

0.20

0.25

bccr

cccmat47cccmat63

cnrmcsirogfdl20gfdl21gissehgisseriapinmcm

ipsl

mirochrmirocmr

mpimrincar

ukmocm3ukmogem1

Cloud Ice Path (kg/m^2)

ModelModel

Factor of ~20 DifferenceFactor of ~20 Difference

IPCC Models: Global Average Total Cloud IceIPCC Models: Global Average Total Cloud Ice

Cloud Ice Cloud Ice

Strong Influence on ClimateStrong Influence on Climate

Cloud Ice: Models vs ObservationsCloud Ice: Models vs ObservationsLi et al. 2005

AURA/MLS provides the first vertical profiles AURA/MLS provides the first vertical profiles of Cloud Ice in the upper troposphere -> of Cloud Ice in the upper troposphere -> Extremely Valuable Information to Improve Extremely Valuable Information to Improve

Climate Models.Climate Models.

Observations?

AIRS

Climate ModelsClimate ModelsAnd The And The MJOMJO

NCEP/NCAR ~ Observations

Day 0

Day 10

Day 20

Day 30

Day 40

Influence WeatherInfluence WeatherHurricanes,Monsoons & Hurricanes,Monsoons &

El NinoEl Nino

Models Do PoorlyModels Do PoorlySimulating & PredictingSimulating & Predicting

the MJOthe MJO

Tian et al. 2006

ICE

LIQUID

ICE

RAIN

SNOWMIXED

LIQUID

ICE

Tropical Thunderstorms / Convective CloudsTropical Thunderstorms / Convective Clouds• Produce The Cloud IceProduce The Cloud Ice• Big Temperature Variations Big Temperature Variations • Very Important for Water & Energy CyclesVery Important for Water & Energy Cycles• HardestHardest to Get Right in Climate Models to Get Right in Climate Models• Need more information on composition & Need more information on composition & StructureStructure

CloudSat : Fabulous!CloudSat : Fabulous!

In SummaryIn Summary

• Warming is Evident in the ObservationsWarming is Evident in the Observations

• The Result of Incorporating our Scientific The Result of Incorporating our Scientific Knowledge (Theory+Data), and in some cases our Knowledge (Theory+Data), and in some cases our Intuition, into Climate “Models”, Intuition, into Climate “Models”, Unequivocally Indicates the Warming is Unequivocally Indicates the Warming is Anthropogenic in Nature and Likely to ContinueAnthropogenic in Nature and Likely to Continue

• How Much? How Much?

1.1. Depends on Interplay of Society, Economics Depends on Interplay of Society, Economics and Politics and Politics (Highly Uncertain).(Highly Uncertain).

2.2. Model Predictions Are Our Most Objective Model Predictions Are Our Most Objective Guide Guide (Better Means to Establish & Reduce (Better Means to Establish & Reduce Uncertainty).Uncertainty).

Reducing Reducing RemainingRemaining UncertaintiesUncertainties

• Better/More Better/More MeasurementsMeasurements

• Faster/Better Faster/Better Computers & Computers & InfrastructureInfrastructure

•Continued FocusContinued Focus