Transcript Slide 1 - climateknowledge.org

Climate Change: An Inter-disciplinary
Approach to Problem Solving
(AOSS 480 // NRE 480)
Richard B. Rood
Cell: 301-526-8572
2525 Space Research Building (North Campus)
[email protected]
http://aoss.engin.umich.edu/people/rbrood
Winter 2015
January 27, 2015
Class Information and News
• Ctools site: AOSS_SNRE_480_001_W15
– Record of course
• Rood’s Class MediaWiki Site
–
http://climateknowledge.org/classes/index.php/Climate_Change:_The_Move_to_Action
• A tumbler site to help me remember
– http://openclimate.tumblr.com/
Resources and Recommended Reading
• NASA Resources
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Aerosols: What and Why Important
NASA/EO: Smoke and Clouds
NASA/EO: Dust and Desertification
NASA/EO: Volcanoes and Climate Change
NASA/EO: Big Effects of Aerosols
• Aerosols: Open Source Systems, Science, Solution
– NASA
– Realclimate
• Aerosols Wikipedia
• Miller et al. Onset of Little Ice Age
Outline: Class 7, Winter 2015
•
•
•
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Basics of aerosols
South and East Asian brown cloud
Aerosol relation to clouds
Volcanoes and climate
– Models and Little Ice Age
• Earth system summary
• Changes in radiative balance
Changes in
the sun
So what matters?
THIS IS WHAT WE
ARE DOING
Things that
change
reflection
Things that
change
absorption
Accumulation, transport and storage of energy in ocean, ice, land
Following Energy through the Atmosphere
• We have been concerned about, almost
exclusively, greenhouse gases.
– Need to introduce aerosols
• Continuing to think about
– Things that absorb
– Things that reflect
Aerosols
• Aerosols are fine, airborne particles
consisting at least in part of solid material
– They impact the radiative budget.
• Absorb
• Reflect
– They impact cloud formation and growth.
Particles in the Atmosphere
Clouds and Aerosols: Particles in the atmosphere.
• Water (and other) droplets and ice particles – (CLOUDS)
• “Pure” water
• Sulfuric acid
• Nitric acid
• Smog
•…
• Dust
• Soot / Black Carbon
AEROSOLS CAN:
• Salt
REFLECT RADIATION
• Organic hazes
ABSORB RADIATION
CHANGE CLOUD DROPLETS
Earth’s aerosols
Earth’s Aerosols
http://www-das.uwyo.edu/~geerts/cwx/notes/chap02/aerosol&climate.html
Dust and fires in Mediterranean
Forest Fires in US
The Earth System: Clouds
Clouds are difficult to predict or to figure out the
sign of their impact
Top of Atmosphere / Edge of Space
• Warmer  more water  more clouds
• More clouds mean more reflection of solar  cooler
• More clouds mean more infrared to surface  warmer
• More or less clouds?
• Does this stabilize?
• Water in all three phases essential to “stable” climate
CLOUD
ATMOSPHERE
(infrared)
SURFACE
The Earth System: Aerosols
Top of Atmosphere / Edge of Space
Aerosols directly impact radiative balance
• Aerosols can mean more reflection of solar  cooler
• Aerosols can absorb more solar radiation in the
atmosphere  heat the atmosphere
• In very polluted air they almost act like a “second”
surface. They warm the atmosphere, cool the earth’s
surface.
AEROSOLS
ATMOSPHERE
?
(infrared)
SURFACE
Composition of aerosols matters.
•This figure is simplified.
•Infrared effects are not well quantified
South & East Asia “Brown Cloud”
• But don’t forget
– Europe and the US in the 1950s and 1960s
• Change from coal to oil economy
Asian Brown Cloud
(But don’t forget history.)
• Coal emits sulfur and smoke
particulates
• “Great London smog” of 1952 led to
thousands of casualties.
– Caused by cold inversion layer
 pollutants didn’t disperse +
Londoners burned large amounts of
coal for heating
• Demonstrated impact of pollutants and
played role in passage of “Clean Air
Acts” in the US and Western Europe
Aerosol: South & East Asia
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html
Reflection of Radiation due to Aerosol
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html
Atmospheric Warming: South & East Asia
WARMING IN ATMOSPHERE, DUE TO SOOT (BLACK CARBON)
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html
Surface Cooling Under the Aerosol
http://earthobservatory.nasa.gov/Newsroom/NasaNews/2001/200108135050.html
Aerosol relation to clouds
The Earth System
Aerosols and Clouds Interactions
Aerosols impact clouds and hence indirectly impact
radiative budget through clouds
Top of Atmosphere / Edge of Space
• Change their height
• Change their reflectivity
• Change their ability to rain
• Change the size of the droplets
CLOUD
ATMOSPHERE
(infrared)
SURFACE
Aerosols and Clouds and Rain
Less
Volcanoes and Climate
• Alan Robock: Volcanoes and Climate
Change (36 MB)
Alan Robock
Department of Environmental Sciences
More Reflected
Solar Flux
Stratospheric aerosols
(Lifetime  1-3 years)
Less
Upward
IR Flux
backscatter
absorption
(near IR)
H2S  H SO
2
4
SO2
CO2
H2O
Solar Heating
IR
Heating
Heterogeneous Less
O3 depletion Solar Heating
emission
IR Cooling
absorption (IR) emission
forward scatter
Ash
Reduced
Direct
Flux
Enhanced
Diffuse
Flux
Tropospheric aerosols
(Lifetime  1-3 weeks)
SO2  H2SO4
Indirect Effects
on Clouds
Alan Robock
Department of Environmental Sciences
Effects
on cirrus
clouds
Less Total
Solar Flux
More
Downward
IR Flux
Superposed
epoch
analysis of
six largest
eruptions of
past 120
years
Significant
cooling follows
sun for two years
Robock and
Mao (1995)
Year of eruption
Alan Robock
Department of Environmental Sciences
Some important things to know about aerosols
• They can directly impact radiative budget through both reflection and
absorption.
• They can indirectly impact radiative budget through their effects on
clouds  both reflection and absorption.
• They have many different compositions, and the composition
matters to what they do.
• They have many different, often episodic sources.
• They generally fall out or rainout of the atmosphere; they don’t stay
there very long compared with greenhouse gases.
• They often have large regional effects.
• They are an indicator of dirty air, which brings its own set of
problems.
• They are often at the core of discussions of geo-engineering
Models and Little Ice Age
Temperature and CO2: The last 1000 years
Surface temperature and CO2 data from the
past 1000 years. Temperature is a northern
hemisphere average. Temperature from
several types of measurements are consistent
in temporal behavior.
 Medieval warm period
 “Little ice age”
Schematic of a model experiment.
Observations or “truth”
T
T
Start model prediction
Model prediction without
forcing
Model prediction with
forcing
Model prediction with
forcing and source of
internal variability
Eat+Dt = Eat + Dt((Pa – LaEa) + (Traoil + Ma ))
Little Ice Age
• Miller et al. Onset of Little Ice Age
– Numerical Experiment based on observational
evidence of decades long period of high
volcanic activity
• 50 years 4 major eruptions
• Sea-ice/ocean feedbacks
• No requirement of large changes solar energy
Earth-system Summary
The Earth System
SUN
CLOUD-WORLD
ATMOSPHERE
ICE
(cryosphere)
OCEAN
LAND
The Earth System
SUN
CLOUD-WORLD
ATMOSPHERE
Where
absorption is
important
ICE
(cryosphere)
OCEAN
LAND
The Earth System
SUN
CLOUD-WORLD
Where
reflection is
important
ATMOSPHERE
ICE
(cryosphere)
OCEAN
LAND
The Earth System
Solar Variability
SUN
CLOUD-WORLD
ATMOSPHERE
ICE
(cryosphere)
OCEAN
LAND
The Earth System
SUN
CLOUD-WORLD
ATMOSPHERE
ICE
(cryosphere)
OCEAN
LAND
Storage and transport of
energy. Influences
surface air temperature
The Earth System
Increase greenhouse gases reduces cooling rate  Warming
SUN
Solar
variability
Cloud feedback?
Aerosols cool?
ATMOSPHERE
Water vapor feedback
accelerates warming
Cloud feedback?
OCEAN
ICE
LAND
Changes in land use impact absorption and reflection
Ice-albedo feedback
accelerates warming
Changes in Radiative Forcing
Radiative forcing:
Changes to absorption and reflection
• Earth's most abundant greenhouse gases
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–
–
–
–
–
water vapor (H2O)
carbon dioxide (CO2)
methane (CH4)
nitrous oxide (N2O), commonly known as "laughing gas"
ozone (O3)
chlorofluorocarbons (CFCs)
• Long-lived, well mixed
• Short-lived, regional variability
• Aerosols, short-lived and regional
Radiative Forcing Changes
Interesting History of This Plot at RealClimate
Summary: Class 7, Winter 2015
• Aerosols
– Absorb
– Reflect
– Human and natural
– Regional
– Short lived
• Asian brown cloud demonstrate aerosol
effects
– Likely “masking” warming
Summary: Class 7, Winter 2015
• Aerosols change clouds
– Precipitation
– Characteristics of absorption and reflection
• Volcanoes
– Important natural drivers of climate variability
– Provide one of our best “controlled” experiments
• Considering all source of radiative forcing
– Warming from greenhouse gases
– Aerosols in net cooling  black carbon
management
– Cloud-aerosol effects are cooling
Outline: Class 7, Winter 2015
•
•
•
•
Basics of aerosols
South and East Asian brown cloud
Aerosol relation to clouds
Volcanoes
– Models and Little Ice Age
• Earth system summary
• Changes in radiative balance