recent climate, energy balance and the greenhouse effect david b. reusch penn state/new mexico tech...

Recent Climate, Energy Balance and the Greenhouse Effect

David B. ReuschPenn State/New Mexico Tech

dreusch@ees.nmt.eduCVEEN 7920/Geol 571

~4 x

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W = watts = power = energy/sec

~4 x

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W = watts = power = energy/sec

W = watts = power = energy/sec

~4 x

1026

W

W = watts = power = energy/sec

Basic BalanceBasic BalanceBasic BalanceBasic Balance

342 W/m342 W/m22 of shortwave radiation input of shortwave radiation input from the Sun is balanced by…from the Sun is balanced by…

Earth outputs totaling 342 W/mEarth outputs totaling 342 W/m22 of of Reflected/scattered shortwaveReflected/scattered shortwave Absorbed/re-emitted longwaveAbsorbed/re-emitted longwave

So what temperature is that?So what temperature is that?

342 W/m342 W/m22 of shortwave radiation input of shortwave radiation input from the Sun is balanced by…from the Sun is balanced by…

Earth outputs totaling 342 W/mEarth outputs totaling 342 W/m22 of of Reflected/scattered shortwaveReflected/scattered shortwave Absorbed/re-emitted longwaveAbsorbed/re-emitted longwave

So what temperature is that?So what temperature is that?

Earth’s Average TemperatureEarth’s Average TemperatureEarth’s Average TemperatureEarth’s Average Temperature

An input of 342 W/mAn input of 342 W/m22 translates to a translates to a mean surface temperature of -18 °Cmean surface temperature of -18 °C

We know that TWe know that TAA is actually 15 °C so is actually 15 °C so

what’s missing?what’s missing? The short answer: an atmosphere which The short answer: an atmosphere which

provides the natural greenhouse effectprovides the natural greenhouse effect

An input of 342 W/mAn input of 342 W/m22 translates to a translates to a mean surface temperature of -18 °Cmean surface temperature of -18 °C

We know that TWe know that TAA is actually 15 °C so is actually 15 °C so

what’s missing?what’s missing? The short answer: an atmosphere which The short answer: an atmosphere which

provides the natural greenhouse effectprovides the natural greenhouse effect

E = T4

~4 x

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W = watts = power = energy/sec

Natural Greenhouse EffectNatural Greenhouse EffectNatural Greenhouse EffectNatural Greenhouse Effect

What Wavelength?What Wavelength?What Wavelength?What Wavelength?

Sun ~6000 K, Earth ~288 KSun ~6000 K, Earth ~288 K Dominant WavelengthDominant Wavelength

Inversely related to temperature (Wien’s)Inversely related to temperature (Wien’s) Hotter -> shorter wavelengthHotter -> shorter wavelength Sun @ 0.48 Sun @ 0.48 m (480 nm; visible)m (480 nm; visible) Earth @ 10 Earth @ 10 m (infrared or IR)m (infrared or IR)

Radiation emitted over a range of Radiation emitted over a range of wavelengthswavelengths

Sun ~6000 K, Earth ~288 KSun ~6000 K, Earth ~288 K Dominant WavelengthDominant Wavelength

Inversely related to temperature (Wien’s)Inversely related to temperature (Wien’s) Hotter -> shorter wavelengthHotter -> shorter wavelength Sun @ 0.48 Sun @ 0.48 m (480 nm; visible)m (480 nm; visible) Earth @ 10 Earth @ 10 m (infrared or IR)m (infrared or IR)

Radiation emitted over a range of Radiation emitted over a range of wavelengthswavelengths

2897

T*10 6m

Note: shape of Earth’s spectrum. It’s modified by the atmosphere!

Solar Peak

TerrestrialPeak

What Happens To Insolation?What Happens To Insolation?What Happens To Insolation?What Happens To Insolation?

ReflectionReflection ScatteringScattering AbsorptionAbsorption TransmissionTransmission

ReflectionReflection ScatteringScattering AbsorptionAbsorption TransmissionTransmission

ReflectionReflectionReflectionReflection

Change in direction of a wave on Change in direction of a wave on encountering an interfaceencountering an interface

Atmosphere, clouds and surfaceAtmosphere, clouds and surface Measured by albedoMeasured by albedo

Change in direction of a wave on Change in direction of a wave on encountering an interfaceencountering an interface

Atmosphere, clouds and surfaceAtmosphere, clouds and surface Measured by albedoMeasured by albedo

Reflection (and albedo)Reflection (and albedo)Reflection (and albedo)Reflection (and albedo)

5-85%

= 35-75%

ScatteringScatteringScatteringScattering

Random redirection of light by the Random redirection of light by the atmosphereatmosphere

Wavelength and particle concentration Wavelength and particle concentration dependencedependence

Rayleigh (blue skies) and Mie (white Rayleigh (blue skies) and Mie (white clouds) are main processesclouds) are main processes

Random redirection of light by the Random redirection of light by the atmosphereatmosphere

Wavelength and particle concentration Wavelength and particle concentration dependencedependence

Rayleigh (blue skies) and Mie (white Rayleigh (blue skies) and Mie (white clouds) are main processesclouds) are main processes

ScatteringScatteringScatteringScattering

AbsorptionAbsorptionAbsorptionAbsorption

Energy taken up by object (photon is Energy taken up by object (photon is absorbed and destroyed)absorbed and destroyed)

Anything absorbed must be re-emitted Anything absorbed must be re-emitted to maintain equilibriumto maintain equilibrium

At Earth temperatures, this converts At Earth temperatures, this converts shortwave into longwave when energy shortwave into longwave when energy is re-emittedis re-emitted

Energy taken up by object (photon is Energy taken up by object (photon is absorbed and destroyed)absorbed and destroyed)

Anything absorbed must be re-emitted Anything absorbed must be re-emitted to maintain equilibriumto maintain equilibrium

At Earth temperatures, this converts At Earth temperatures, this converts shortwave into longwave when energy shortwave into longwave when energy is re-emittedis re-emitted

AbsorptionAbsorptionAbsorptionAbsorption

AbsorptionAbsorptionAbsorptionAbsorption

Atmosphere absorbs selectively (only Atmosphere absorbs selectively (only some wavelengths)some wavelengths)

Mostly transparent in visible rangeMostly transparent in visible range Broad range of longwave absorbed by Broad range of longwave absorbed by

various greenhouse gasesvarious greenhouse gases Stratospheric OStratospheric O22 & O & O33 absorb UV absorb UV

Atmosphere absorbs selectively (only Atmosphere absorbs selectively (only some wavelengths)some wavelengths)

Mostly transparent in visible rangeMostly transparent in visible range Broad range of longwave absorbed by Broad range of longwave absorbed by

various greenhouse gasesvarious greenhouse gases Stratospheric OStratospheric O22 & O & O33 absorb UV absorb UV

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ShortwaveShortwave31% reflected directly49% absorbed by surface20% absorbed by atmosphere

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LongwaveLongwave390 W/m2 is energy from a body at 15 °C

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Balance incoming

http://www.cdc.noaa.gov/

Outgoing Longwave RadiationOutgoing Longwave RadiationOutgoing Longwave RadiationOutgoing Longwave Radiation

Additional complexityAdditional complexityAdditional complexityAdditional complexity

Earth is a rough sphereEarth is a rough sphere Slope, aspectSlope, aspect LatitudeLatitude

Time/space varying albedo (reflectivity)Time/space varying albedo (reflectivity) Vegetation, snow/ice, soils, moistureVegetation, snow/ice, soils, moisture Human land use changeHuman land use change

Atmospheric composition/structure, cloudsAtmospheric composition/structure, clouds Ocean, iceOcean, ice

Earth is a rough sphereEarth is a rough sphere Slope, aspectSlope, aspect LatitudeLatitude

Time/space varying albedo (reflectivity)Time/space varying albedo (reflectivity) Vegetation, snow/ice, soils, moistureVegetation, snow/ice, soils, moisture Human land use changeHuman land use change

Atmospheric composition/structure, cloudsAtmospheric composition/structure, clouds Ocean, iceOcean, ice

Composition: StableComposition: StableComposition: StableComposition: Stable

Main components of dry atmosphere Main components of dry atmosphere are pretty stable (~99%)are pretty stable (~99%)

78% N78% N22, 21% O, 21% O22

Long-term (geologic) rise in oxygenLong-term (geologic) rise in oxygen Changes in stable isotope ratiosChanges in stable isotope ratios

Main components of dry atmosphere Main components of dry atmosphere are pretty stable (~99%)are pretty stable (~99%)

78% N78% N22, 21% O, 21% O22

Long-term (geologic) rise in oxygenLong-term (geologic) rise in oxygen Changes in stable isotope ratiosChanges in stable isotope ratios

Composition: VariableComposition: VariableComposition: VariableComposition: Variable

Minor by volume (< 1%) but major by Minor by volume (< 1%) but major by climate effect in many cases (GHGs)climate effect in many cases (GHGs)

Reactive (S, N, Cl cycles)Reactive (S, N, Cl cycles) Non-reactive (CONon-reactive (CO22, CFCs), CFCs) Water vapor (up to 4% by volume)Water vapor (up to 4% by volume) Particulates (aerosols)Particulates (aerosols) Variation exists over many time and Variation exists over many time and

space scalesspace scales

Minor by volume (< 1%) but major by Minor by volume (< 1%) but major by climate effect in many cases (GHGs)climate effect in many cases (GHGs)

Reactive (S, N, Cl cycles)Reactive (S, N, Cl cycles) Non-reactive (CONon-reactive (CO22, CFCs), CFCs) Water vapor (up to 4% by volume)Water vapor (up to 4% by volume) Particulates (aerosols)Particulates (aerosols) Variation exists over many time and Variation exists over many time and

space scalesspace scales

Greenhouse gasesGreenhouse gasesGreenhouse gasesGreenhouse gases

Certain naturally occurring trace gases Certain naturally occurring trace gases change the atmosphere’s energy balancechange the atmosphere’s energy balance Carbon dioxide (COCarbon dioxide (CO22), Methane (CH), Methane (CH44))

Water vapor and others…Water vapor and others…

Contribution to warming variesContribution to warming varies By concentrationBy concentration By “radiative efficiency”By “radiative efficiency” By lifetime in the atmosphereBy lifetime in the atmosphere

Certain naturally occurring trace gases Certain naturally occurring trace gases change the atmosphere’s energy balancechange the atmosphere’s energy balance Carbon dioxide (COCarbon dioxide (CO22), Methane (CH), Methane (CH44))

Water vapor and others…Water vapor and others…

Contribution to warming variesContribution to warming varies By concentrationBy concentration By “radiative efficiency”By “radiative efficiency” By lifetime in the atmosphereBy lifetime in the atmosphere

Leading Greenhouse GasesLeading Greenhouse GasesLeading Greenhouse GasesLeading Greenhouse Gases

GasGas ConcentrationConcentration

Carbon Dioxide (COCarbon Dioxide (CO22)) 380 ppm380 ppm

Methane (CHMethane (CH44)) 1700 ppb1700 ppb

Nitrous oxide (NNitrous oxide (N22O)O) 500 ppb500 ppb

Ozone (OOzone (O33)) 70 ppb70 ppb

Note: concentrations are approximate! Mexico ~one million peopleMexico ~one million people India ~one billion peopleIndia ~one billion people

http://www.ipcc.ch/present/graphics/2001syr/large/02.01.jpg Figure SPM.1

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Seasonal Cyclein NH Biota

AnthropogenicInfluence

Solar Base = 342 W m-2

Recent ChangeRecent Changeand Variabilityand VariabilityRecent ChangeRecent Changeand Variabilityand Variability

http://www.ipcc.ch -- Climate Change 2007: The Physical Science Basis (Chapter 3)Fi gure 3. 1

Recent Climate Variations:Recent Climate Variations:Surface Air TemperatureSurface Air TemperatureRecent Climate Variations:Recent Climate Variations:Surface Air TemperatureSurface Air Temperature

Ranked Global TemperaturesRanked Global TemperaturesRanked Global TemperaturesRanked Global Temperatures

http://www.ncdc.noaa.gov/sotc

Tied

http://www.ipcc.ch -- Climate Change 2007: The Physical Science Basis (Chapter 3)

Spatial Changes in TemperatureSpatial Changes in Temperature

Muir Glacier, Alaska, August 13, 1941, photo by W.O. Field

http://nsidc.org/data/glacier_photo/repeat_photography.html

Muir Glacier, Alaska, August 31, 2004, photo by B.F. Molnia, USGS

http://nsidc.org/data/glacier_photo/repeat_photography.html

Grinnell Glacier 1938-Grinnell Glacier 1938-20052005

Grinnell Glacier 1938-Grinnell Glacier 1938-20052005

http://en.wikipedia.org/wiki/Retreat_of_glaciers_since_1850

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1981

Glacier National ParkGlacier National Park

2005

http://www.ipcc.ch -- Climate Change 2007: The Physical Science Basis (Chapter 3)

Spatial Changes in PrecipitationSpatial Changes in Precipitation

http://www.ipcc.ch -- Climate Change 2007: The Physical Science Basis (Chapter 5)Fi gure 5. 13

Recent Climate Variations: Sea LevelRecent Climate Variations: Sea LevelRecent Climate Variations: Sea LevelRecent Climate Variations: Sea Level

http://nsidc.org/sotc/sea_ice.html

Arctic Sea Ice TrendsArctic Sea Ice TrendsArctic Sea Ice TrendsArctic Sea Ice Trends

http://nsidc.org/news/press/2007_seaiceminimum/20071001_pressrelease.html

Sept 2007 All-time MinimumSept 2007 All-time MinimumSept 2007 All-time MinimumSept 2007 All-time Minimum

500 Million Years of Change500 Million Years of Change500 Million Years of Change500 Million Years of Change

http://en.wikipedia.org/wiki/User:Dragons_flight/Images

500 Million Years of Change500 Million Years of Change500 Million Years of Change500 Million Years of Change

http://en.wikipedia.org/wiki/User:Dragons_flight/Images

500 Million Years of Change500 Million Years of Change500 Million Years of Change500 Million Years of Change

http://en.wikipedia.org/wiki/User:Dragons_flight/Images

Today is DifferentToday is DifferentToday is DifferentToday is Different

Rates of change not seen in geologic Rates of change not seen in geologic recordrecord

World did not have nearly 7 billion World did not have nearly 7 billion peoplepeople

Rates of change not seen in geologic Rates of change not seen in geologic recordrecord

World did not have nearly 7 billion World did not have nearly 7 billion peoplepeople