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Recent Climate, Energy Balance and the Greenhouse Effect
David B. ReuschPenn State/New Mexico Tech
[email protected] 7920/Geol 571
~4 x
1026
W
W = watts = power = energy/sec
~4 x
1026
W
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
1026
W
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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IR or longwaveUV & Visible
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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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LongwaveLongwave
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LongwaveLongwave
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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
1938
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