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The Modeling of Climate and Climate Change; can we trust model predictions?. University of California, Irvine 21 February 2003 by John Houghton. Outline. Introduction Cloud Radiation Feedback Ocean Interactions The Carbon Cycle The Climate of the 20th Century

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The modeling of climate and climate change can we trust model predictions

The Modeling of Climate and Climate Change;can we trust model predictions?

University of California, Irvine

21 February 2003

by

John Houghton


Outline
Outline

  • Introduction

  • Cloud Radiation Feedback

  • Ocean Interactions

  • The Carbon Cycle

  • The Climate of the 20th Century

  • Climate Projections for the 21st Century

  • Regional Climate Modeling

  • Patterns of Climate Response


The greenhouse effect

Solar radiation

Long-wave

radiation

236 Wm-2

236 Wm-2

Equivalent T = 255 K (-18ºC)

390 Wm-2

T = 255 K (-15ºC)



The enhanced greenhouse effect
The Enhanced Greenhouse Effect Nimbus 3

S L

236 236

S L

236 232

S L

236 236

S L

236 236

Solar (S) and longwave (L) radiation in Wm-2 at the top of the atmosphere

T = -18°C

CO2 x 2

+ Feedbacks

H2O (+60%) Ice/Albedo (+20%)

Cloud?

Ocean?

CO2 x 2

CO2 x 2

TS = 15°C

TS = 15°C

DTS ~ 1.2K

DTS ~ 2.5K



The development of climate models past present and future
The Development of Climate models, Past, Present and Future Nimbus 3

Mid 1980s

Early 1990s

Late 1990s

Present day

Early 2000s?

Mid 1970s

Atmosphere

Atmosphere

Atmosphere

Atmosphere

Atmosphere

Atmosphere

Land surface

Land surface

Land surface

Land surface

Land surface

Ocean & sea-ice

Ocean & sea-ice

Ocean & sea-ice

Ocean & sea-ice

Sulphate

aerosol

Sulphate

aerosol

Sulphate

aerosol

Non-sulphate

aerosol

Non-sulphate

aerosol

Carbon cycle

Carbon cycle

Atmospheric

chemistry

Sulphur

cycle model

Non-sulphate

aerosols

Ocean & sea-ice

model

Off-line

model

development

Strengthening colours

denote improvements

in models

Land carbon

cycle model

Carbon

cycle model

Ocean carbon

cycle model

Atmospheric

chemistry

Atmospheric

chemistry


Predicting impacts of climate change
Predicting impacts of climate change Nimbus 3

Scenarios from population, energy,

economics models

Emissions

Concentrations

CO2, methane, sulphates, etc.

Global climate change

Temperature, rainfall, sea level, etc.

Regional detail

Mountain effects, islands, extreme weather, etc.

Impacts

Flooding, food supply, etc.

Carbon cycle and chemistry models

Coupled global climate models

Regional climate models

Impacts models

The main stages required to provide climate change scenarios for assessing the impacts of climate change.

Hadley Centre - PRECIS brochure


Coupled atmosphere / ocean climate model Nimbus 3

Radiation

Atmosphere: Density

Motion

Water

Heat

Exchange of: Momentum

Water

Ocean: Density (inc. Salinity)

Motion

Sea

Ice

Land


30km Nimbus 3

19 levels in

atmosphere

2.5

lat

3.75

long

THE HADLEYCENTRETHIRDCOUPLEDMODEL -HadCM3

1.25

1.25

20 levelsin ocean

-5km


Physical feedbacks
Physical Feedbacks Nimbus 3

  • Water vapour

  • Ice albedo

  • Clouds

  • Oceans

  • Ice sheets






Effect of cloud feedback formulation on climate prediction
Effect of cloud feedback formulation on climate prediction Nimbus 3

  • Feedback scheme Global Av Temp change,C for doubled CO2

    • RH 5.3

    • CW 2.8

    • CWRP 1.9

    • after Senior & Mitchell, Hadley Centre


Net cloud forcing january to july
Net cloud forcing: January to July Nimbus 3

Hadley Centre


Ship tracks under cloud
SHIP TRACKS UNDER CLOUD Nimbus 3

Washington

state





Modelled transport of water in Atlantic conveyor belt Atlantic.

IPCC Third Assessment Report


Projected changes in annual temperatures for the 2050s
Projected changes in annual temperatures for the 2050s Atlantic.

The projected change in annual temperatures for the 2050s compared with the present day, when the climate model is driven with an increase in greenhouse gas concentrations equivalent to about 1% increase per year in CO2

BW 11

The MetOffice. Hadley Center for Climate Prediction and Research.


Changes in surface air temperature, relative to the present day, 20 years after the hypothetical collapse of the thermohaline circulation.

Hadley Centre


Combined effect of THC collapse (2049-2059) and global warming

Surface Temperature

Cooling over UK: 1-3°C





Partitioning of co 2 uptake using o 2 measurements
Partitioning of CO warming2 uptake using O2 measurements


Global co 2 budgets in gtc per year
Global CO warming2 budgets in GtC per year

1980s 1990s

Atmospheric increase 3.3 ± 0.1 3.2 ± 0.1

Emissions (fossil fuel, cement) 5.4 ± 0.3 6.3 ± 0.4

Ocean-atmosphere flux -1.9 ± 0.6 -1.7 ± 0.5

Land atmosphere flux -0.2 ± 0.7 -1.4 ± 0.7

partitioned as follows:

Land-use change 1.7 (0.6 to 2.5) NA

Residual terrestrial sink -1.9 (-3.8 to 0.3) NA

IPCC Third Assessment Report



Change in carbon content of soil (top) and vegetation (bottom)

between 1860 and 2100

- predicted by Hadley Centre climate model

Hadley Centre


Simulated changes in the global total soil and vegetation carbon content (Gt C) between 1860 and 2100.

Hadley Centre


Influence of ENSO on CO carbon content (Gt C) between 1860 and 2100.2 Variability

  • Annual changes in atmospheric CO2 are dominated by ENSO

    • after removing anthropogenic rise

    • rise during El Nino

    • fall during La Nina

CO2 - black, Nino3 - red


Influence of Volcanoes on CO carbon content (Gt C) between 1860 and 2100.2 Variability

  • 2 notable exceptions to ENSO correlation

  • CO2 levels lower than expected

  • Coincide with major volcanic eruptions

El Chichon

Pinatubo

CO2 - black, Nino3 - red


Constraint from enso sensitivity
Constraint from ENSO Sensitivity carbon content (Gt C) between 1860 and 2100.

  • Model with q10=2 has realistic sensitivity to ENSO.

  • Reconstructions for range of q10.

  • Infer q10=2.1±0.7.


Constraint from sensitivity to volcanoes
Constraint from Sensitivity to Volcanoes carbon content (Gt C) between 1860 and 2100.

  • Model with q10=2 has realistic sensitivity to Pinatubo.

  • Reconstructions for range of q10.

  • Infer q10=1.9±0.4


Enso and pinatubo variations as a constraint on climate carbon cycle feedback
ENSO and Pinatubo Variations as a constraint on climate-carbon cycle feedback

Model with

C cycle

Feedback

(q10= 2)

Grey region is estimate of uncertainty

related to q10 parameter for soil respiration

Model without

C cycle

Feedback

q10= 3

q10= 1


Photo: Tim Hewison climate-carbon cycle feedback


Estimated carbon uptake if suitable arable land north of 30º N were to be replaced with trees.

The additional effect on climate of the changes in surface reflectivity when trees are planted on suitable arable land north of 30º N, expressed as equivalent carbon emissions.

The difference between the two diagrams above. Negative values show where the net effect of planting trees is to warm climate.

Hadley Centre


Net effect of planting trees expressed as equivalent carbon uptake
NET EFFECT OF PLANTING TREES 30º N were to be replaced with trees.expressed as equivalent carbon uptake

50

0

50

100

150

200

tonnes of carbon per hectare

Met Office / Hadley Centre

Negative values show where the net effect of planting trees is to warm climate


Emissions and concentrations of co 2 from unmitigated and stabilising emission scenarios

20 30º N were to be replaced with trees.

1000

950

900

850

15

emissions (GtC/yr)

800

750

700

CO concentration (ppm)

10

2

650

600

2

Anthropogenic CO

550

5

500

450

400

0

350

2000

2050

2100

2150

2200

2250

2300

2350

2000

2050

2100

2150

2200

2250

2300

2350

750 ppm stabilisation

550 ppm stabilisation

Unmitigated emissions

EMISSIONS AND CONCENTRATIONS OF CO2from unmitigated and stabilising emission scenarios

Source: IPCC


The climate of the 20 th century
The Climate of the 20 30º N were to be replaced with trees.th Century


Global mean surface air temperature anomalies from 1,000 year control simulations with three different climate models, - Hadley, GFDL and Hamburg, compared to the recent instrumental record. No model control simulation shows a trend in surface air temperature as large as the observed trend. If internal variability is correct in these models, the recent warming is likely not due to variability produced within the climate system alone.

IPCC Third Assessment Report


Simulated annual global mean surface temperatures
Simulated annual global mean surface temperatures year control simulations with three different climate models, - Hadley, GFDL and Hamburg, compared to the recent instrumental record. No model control simulation shows a trend in surface air temperature as large as the observed trend. If internal variability is correct in these models, the recent warming is likely not due to variability produced within the climate system alone.

Natural forcing

Anthropogenic forcing


Simulated annual global mean surface temperatures1
Simulated annual global mean surface temperatures year control simulations with three different climate models, - Hadley, GFDL and Hamburg, compared to the recent instrumental record. No model control simulation shows a trend in surface air temperature as large as the observed trend. If internal variability is correct in these models, the recent warming is likely not due to variability produced within the climate system alone.


Ipcc statements on detection
IPCC statements on Detection year control simulations with three different climate models, - Hadley, GFDL and Hamburg, compared to the recent instrumental record. No model control simulation shows a trend in surface air temperature as large as the observed trend. If internal variability is correct in these models, the recent warming is likely not due to variability produced within the climate system alone.

  • “The balance of evidence suggests a discernible human influence on global climate” 1995 Report

  • “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities” 2001 Report


Climate projections for the 21st century

Climate Projections year control simulations with three different climate models, - Hadley, GFDL and Hamburg, compared to the recent instrumental record. No model control simulation shows a trend in surface air temperature as large as the observed trend. If internal variability is correct in these models, the recent warming is likely not due to variability produced within the climate system alone.for the 21st century


The solid line shows a GCM prediction of temperature change. Prior to 1990, historical emissions were used. Beyond 1990, the IS92a emissions scenario was used. The dashed line shows the results of scaling the model prediction to give the best fit to the most recent 50 years of observations. The shaded region is the uncertainty estimate.

Hadley Centre


Sres scenario familys
SRES scenario familys Prior to 1990, historical emissions were used. Beyond 1990, the IS92a emissions scenario was used. The dashed line shows the results of scaling the model prediction to give the best fit to the most recent 50 years of observations. The shaded region is the uncertainty estimate.

A1

More

economic

A2

B: balanced

FI: fossil intensive

T: non-fossil

More

global

More

regional

B1

B2

More

environmental


Globally averaged tempertaure change for scenario SRES B2 Prior to 1990, historical emissions were used. Beyond 1990, the IS92a emissions scenario was used. The dashed line shows the results of scaling the model prediction to give the best fit to the most recent 50 years of observations. The shaded region is the uncertainty estimate.

IPCC Third Assessment Report


Globally averaged precipitation change for scenario SRES B2 Prior to 1990, historical emissions were used. Beyond 1990, the IS92a emissions scenario was used. The dashed line shows the results of scaling the model prediction to give the best fit to the most recent 50 years of observations. The shaded region is the uncertainty estimate.

IPCC Third Assessment Report


Area averaged changes in summer rainfall for the period 2071-2100 over southern Asia as predicted by nine coupled models forced by the A2 emissions scenario (taken from Chapter 10 of the Scientific Basis of the IPCC Third Assessment Report). In other areas predictions can show much greater differences in magnitude and even sign.

Hadley Centre - PRECIS brochure


Observed and projected changes in extremes
Observed and projected changes in extremes 2071-2100 over southern Asia as predicted by nine coupled models forced by the A2 emissions scenario (taken from Chapter 10 of the Scientific Basis of the IPCC Third Assessment Report). In other areas predictions can show much greater differences in magnitude and even sign.

Changes in Phenomenon

Higher maximum temperatures and more hot days over nearly all land areas

Higher minimum temperatures, fewer cold days and frost days over nearly all land areas

Reduced diurnal temperature range over most land areas

Increase of heat indexover land areas

More intense precipitation events

Increased summer continental drying and associated risk of drought

Increase in tropical cyclone peak wind intensities

Increase in tropical cyclone mean and peak precipitation intensities

Confidence in projected changes (during the 21st century)

Very likely

Very likely

Very likely

Very likely, over most areas

Very likely, over many areas

Likely, over most mid-latitude continental interiors (Lack of consistent projections in other areas)

Likely, over some areas

Likely, over some areas

Confidence in observed

changes (latter half

of the 20th century)

Likely

Very likely

Very likely

Likely, over many areas

Likely, over many Northern Hemisphere mid- to high-latitude land areas

Likely, in a few areas

Not observed in the few analyses available

Insufficient data for assessment

IPCC Third Assessment Report



Regional climate modelling

Regional Climate Modelling 4xCO2 experiment


Schematic diagram of the resolution of the Earth’s surface and the atmosphere in the Hadley Centre regional climate model.

Hadley Centre - PRECIS brochure


Regional climate model
Regional Climate Model and the atmosphere in the Hadley Centre regional climate model.

  • High resolution (50km) over limited area (Europe, Indian subcontinent)

  • Embedded in global model, so subject to same uncertainties

  • Takes account of local characteristics, e.g. mountains, coasts

  • Better regional detail, better prediction of extremes in weather (eg flooding)

  • Everybody wants one!


The representation of the Philippines in RCMs with resolutions of 400 km (the GCM), 50 km and 25 km.

Hadley Centre - PRECIS brochure


Patterns of present-day winter precipitation over Britain. Left, as simulated with the global model. Middle: as simulated with the 50 km regional model. Right, as observed.

Hadley Centre - PRECIS brochure


The frequency of winter days over the Alps with different daily rainfall thresholds. Purple bars, observed. Dark red bars simulated by the GCM. Green bars simulated by the RCM.

Hadley Centre - PRECIS brochure


A tropical cyclone is evident in the mean sea-level pressure field from the RCM (right) but not in the driving GCM (left) for the corresponding day (from an RCM over southern Africa, developed by the Hadley Centre in collaboration with the university of Cape Town).

Hadley Centre - PRECIS brochure


Predicted changes in summer surface air temperatures between the present day and the end of the 21st century. Left, from the global model. Right, from the regional model.

Hadley Centre - PRECIS brochure


Predicted changes in monsoon precipitation over India, between the present day and the middle of the 21st century from the GCM (left) and the RCM (right).

Hadley Centre - PRECIS brochure


Is the climate chaotic

Is the Climate Chaotic? between the present day and the middle of the 21st century from the GCM (left) and the RCM (right).


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