Projected Future Changes

(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Climate Models (from IPCC WG-I, Chapter 10)Climate Models (from IPCC WG-I, Chapter 10)

Projected Future ChangesProjected Future Changes

Primary Source: Primary Source:

IPCC WG-I Chapter 10 - Global Climate ProjectionsIPCC WG-I Chapter 10 - Global Climate Projections


Part 1: Projected Radiative ForcingPart 1: Projected Radiative Forcing


•A “forecast” implies that we know (or think we know) all the A “forecast” implies that we know (or think we know) all the factors that determine the future - even though we may know factors that determine the future - even though we may know them only imperfectly.them only imperfectly.

Some important factors we do Some important factors we do notnot know for the future: know for the future: What will humans do about GHG emissions, aerosol generation What will humans do about GHG emissions, aerosol generation and land use?and land use? When and where will volcanoes erupt, and how strongly? When and where will volcanoes erupt, and how strongly?

Language Problem: ForecastLanguage Problem: Forecast

IPCC does not talk about “forecasting” or “predicting” future IPCC does not talk about “forecasting” or “predicting” future climate. Why?climate. Why?


IPCC: IPCC: “A “A projectionprojection is a potential future evolution of a is a potential future evolution of a quantity or set of quantities, often computed with quantity or set of quantities, often computed with the aid of a model.”the aid of a model.”

To recognize this uncertainty, many climate scientists To recognize this uncertainty, many climate scientists describe a simulation of possible future climate as a describe a simulation of possible future climate as a projection.projection.

Terminology: ProjectionTerminology: Projection


Special Report on Emission Scenarios (SRES)Special Report on Emission Scenarios (SRES)

IPCC Working Group III produced a set of possible IPCC Working Group III produced a set of possible future emissions scenarios, described in special IPCC future emissions scenarios, described in special IPCC report (see supplemental material).report (see supplemental material).

There is no probability weighting to these scenarios: There is no probability weighting to these scenarios: each is considered equally credible.each is considered equally credible.

•The IPCC AR4 focuses on three:The IPCC AR4 focuses on three: B1 - a “low” emissions future, global cooperation B1 - a “low” emissions future, global cooperation A1B - a “medium” emissions future A1B - a “medium” emissions future A2 - a “high” emissions future, regional fragmentation A2 - a “high” emissions future, regional fragmentation


SRES Scenarios vs. TimeSRES Scenarios vs. Time


Steps from Scenario to Climate ChangeSteps from Scenario to Climate Change

Biogeochemical models

Radiation schemes and

parameterizations

Climate system models


Radiative Radiative ForcingsForcings

GCM GCM vs vs

Line-by-lineLine-by-line

What is What is

““line-by-line-by-line”?line”?



GCM GCM vs vs

Line-by-lineLine-by-line

Doubled Doubled COCO22

20% 20% increase increase in water in water

vaporvapor



SRES A1B SRES A1B 2000-21002000-2100

Longwave Longwave (infrared)(infrared)

Shortwave Shortwave (solar)(solar)

aerosol aerosol uncertaintyuncertainty


EndEndPart 1: Projected Radiative ForcingPart 1: Projected Radiative Forcing


Part 2: Projected Climate Change - Part 2: Projected Climate Change - Atmosphere & Water CycleAtmosphere & Water Cycle


Projections of Future Changes in Climate


Stabilization of Future Changes in Climate


Latitudinal Pattern of Temperature ChangeLatitudinal Pattern of Temperature Change

(2080 - 2099) minus (1980 - 1999)(2080 - 2099) minus (1980 - 1999)

Ratio: Ratio: Local change / Global average Local change / Global average TT

Actual changeActual change


Latitude-Height Temperature ChangesLatitude-Height Temperature Changes

A1B (“medium”) scenario relative to 1980-1999A1B (“medium”) scenario relative to 1980-1999

Stippling: Stippling:

multi-model ensemble mean > standard deviation between modelsmulti-model ensemble mean > standard deviation between models


Surface Temperature ChangesSurface Temperature ChangesRelative to 1980-1999Relative to 1980-1999


Latitudinal Pattern of Precipitation ChangeLatitudinal Pattern of Precipitation Change

(2080 - 2099) minus (1980 - 1999)(2080 - 2099) minus (1980 - 1999)

Actual changeActual changeRatio: Ratio: Local change / Global average Local change / Global average TT


Surface Temperature, Precipitation and Pressure ChangesSurface Temperature, Precipitation and Pressure ChangesRelative to 1980-1999Relative to 1980-1999




Changes in Changes in Cloud Cloud Cover Cover

[fraction][fraction]

A1B A1B (“medium”) (“medium”)

scenario scenario relative to relative to 1980-19991980-1999


Changes in Diurnal Temperature RangeChanges in Diurnal Temperature Range



Changes in Precipitation CharacteristicsChanges in Precipitation Characteristics


Changes in Water CycleChanges in Water Cycle


EndEndPart 2: Projected Climate Change - Part 2: Projected Climate Change -

Atmosphere & Water CycleAtmosphere & Water Cycle


Part 3: Projected Climate Change - Part 3: Projected Climate Change - Oceans & ExtremesOceans & Extremes


Latitude-Height Temperature ChangesLatitude-Height Temperature Changes





Changes in Area of Sea IceChanges in Area of Sea Ice


Changes in Distribution of Sea IceChanges in Distribution of Sea Ice


Changes in tropical Pacific SSTs and El Niño VariabilityChanges in tropical Pacific SSTs and El Niño Variability


Changes in Extremes: Very Warm Nights Changes in Extremes: Very Warm Nights

(Wehner, (Wehner, 2008)2008)

For For North North

AmericaAmerica


Changes in Extremes: Heavy Precipitation Changes in Extremes: Heavy Precipitation

(Wehner, (Wehner, 2008)2008)

For For North North

AmericaAmerica


Changes Changes in in

ExtremesExtremes

Standard deviation Standard deviation scale used to scale used to

combine results combine results from multiple from multiple

modelsmodels


Factors Factors Affecting Affecting Hurricane Hurricane

DevelopmentDevelopment

(Vecchi and Soden, 2007)(Vecchi and Soden, 2007)

A1B scenarioA1B scenario

18 GCMs18 GCMs


Changes Hurricane IntensityChanges Hurricane Intensity

(Knutson and (Knutson and Tuleya, 2004)Tuleya, 2004)

Idealized Idealized Simulations Simulations

with High with High Resolution Resolution

ModelModel

Future: 80-year Future: 80-year warming from warming from 1%/year CO1%/year CO22

increaseincrease


Sea Level Rise due to Thermal Expansion

Observed:

1961-2003: 0.4 ± 0.1 mm/yr

1993-2003: 1.6 ± 0.5 mm/yr

Models (A1B):

2000-2020: 1.3 ± 0.7 mm/yr


Local Sea Level Change due to Density and Circulation ChangesLocal Sea Level Change due to Density and Circulation Changes

““+” = greater than global average+” = greater than global average Stippling: Stippling:

ensemble mean > stdev between modelsensemble mean > stdev between models

Wind changes? Low thermal expansivity?

Freshening of water?


Sea-Level Rise: 2090-2099 from 1980-1999Sea-Level Rise: 2090-2099 from 1980-1999


EndEndPart 3: Projected Climate Change - Part 3: Projected Climate Change -

Oceans & ExtremesOceans & Extremes


ENDEND

Global Climate ProjectionsGlobal Climate Projections

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Projected Future Changes