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Climate Change: The Move to Action
(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 2012
January 26, 2012
Class News
• Ctools site: AOSS_SNRE_480_001_W12
• 2008 and 2010 Class On Line:
– http://climateknowledge.org/classes/index.php
/Climate_Change:_The_Move_to_Action
Reading Response: Due Jan 31, 2012
• The World Four Degrees Warmer
– New et al. 2011
• Reading responses of roughly one page (singlespaced). The responses do not need to be
elaborate, but they should also not summarize
the reading. They should be used by you as
think pieces to refine your questions and insight
from the readings. They must be submitted via
CTools at least two hours before the start of
lecture for the relevant readings.
The Current Climate (Released Monthly)
• Climate Monitoring at National Climatic
Data Center.
– http://www.ncdc.noaa.gov/oa/ncdc.html
• State of the Climate: Global
• Plant Hardiness - 2012
Some Project Ideas
• Education
– Strategies when policy requires teaching “denial”
– Incorporation into engineering curriculum
– Earth science in K-12; admission to college
•
•
•
•
Cities (esp Great Lakes) Adaptation
Climate in the Keystone Pipeline
Great Lakes
Seasonal forecast information / Long-term
projections / Use of information / Effectiveness
of communication efforts
Today
• Scientific investigation of the Earth’s
climate: Foundational information
– Aerosols
– Feedbacks
Scientific investigation of Earth’s climate
SUN
EARTH
PLACE AN
INSULATING
BLANKET
AROUND
EARTH
FOCUS ON
WHAT IS
HAPPENING
AT THE
SURFACE
EARTH: EMITS ENERGY TO SPACE  BALANCE
Today
• Scientific investigation of the Earth’s
climate: Foundational information
– Radiative Balance
– Earth System
– Aerosols
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 particulate matter in the
atmosphere.
– They impact the radiative budget.
– They impact cloud formation and growth.
Aerosols: Particles in the Atmosphere
Aerosols: Particles in the atmosphere.
• Water droplets – (CLOUDS)
• “Pure” water
• Sulfuric acid
• Nitric acid
• Smog
•…
• Ice
• Dust
AEROSOLS CAN:
• Soot
REFLECT RADIATION
• Salt
ABSORB RADIATION
• Organic hazes
CHANGE CLOUD DROPLETS
Earth’s aerosols
Dust and fires in Mediterranean
Forest Fires in US
The Earth System
Aerosols (and 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 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
Current Anthropogenic Aerosol Extreme
• South Asian Brown Cloud
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
Natural Aerosol
Earth’s aerosols
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
The Earth System
Aerosols (and clouds)
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
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
Scientific investigation of Earth’s climate
Today
• Scientific investigation of the Earth’s
climate: Foundational information
– Aerosols
– Feedbacks
More consideration of radiative energy in the atmosphere
• FEEDBACKS ....
– The idea that one thing causes a second thing
to happen.
• That second thing then does something to the first
thing
– It damps it, negative feedback
– It amplifies it, positive feedback
– Technical Reference: Soden and Held
The Earth System: Feedbacks 1
Infrared Proportional to Temperature
Top of Atmosphere / Edge of Space
Assume that greenhouse gases remain the same
• Infrared emission is proportional to temperature
• Temperature increases  emission increases
T
 H  T  0
t
H
T
ATMOSPHERE

(infrared)
SURFACE
The Earth System: Feedbacks 2
Water Vapor
When it gets warmer more water, a greenhouse gas,
will be in the atmosphere
Top of Atmosphere / Edge of Space
• Higher temperature increases evaporation from land
and ocean
• Higher temperature allows air to hold more water
• Increase of water increases thickness of blanket –
increases temperature more
• This could runaway!
• Natural limit because of condensation  clouds, rain?
• Compensating circulation changes?
• Think deserts …
ATMOSPHERE
(infrared)
SURFACE
The Earth System: Feedbacks 3
Ice - Albedo
When it gets warmer less ice
Top of Atmosphere / Edge of Space
• Less ice means less reflection  warmer
• Warmer means less ice
• This could runaway!
• Cooler works the other way  ice-covered
ICE
The Earth System: Feedbacks 4
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: Feedbacks 5
Something with the Ocean?
Is there something with the ocean and ice?
• Land ice melting decreases ocean salinity (density)
• Sea-ice impacts heat exchange between ocean and
atmosphere
• Sea-ice impacts solar absorption of ocean
• North Atlantic sea-ice and ocean interaction very
important to the climate
• Think Gulf Stream
• Think climate and people and economy
• Is there a natural feedback that stabilizes climate?
• Even if there is, it would be very disruptive, perhaps
not stable from a societal point of view.
Cloud-Ice-Atmosphere Feedback
• Some carry away messages
– This is where much of the discussion about scientific
uncertainty resides.
– The Earth is at a complex balance point
• That balance relies on water to exist in all three phases.
– Too warm could run away to “greenhouse”
– Too cold run away to “snowball” ice
vapor
– How clouds change is not well understood and much
argued.
• The Iris Effect?
– Is there something in all of this that changes the sign;
namely, that CO2 warming will be compensated by
more cooling?
Earth System: Ice
SUN
ICE:
• Very important to reflection of solar radiation
• Holds a lot of water (sea-level rise)
• Insulates ocean from atmosphere (sea-ice)
Ice impacts both radiative
balance and water – oceans
and water resources on land.
.
• Large “local” effects at
pole.
• Large global effects
through ocean circulation
and permafrost melting.
• Might change very
quickly.
OCEAN
CLOUD-WORLD
ATMOSPHERE
LAND
ICE
(cryosphere)
The Earth System: ICE
(Think a little more about ice)
non-polar
polar
glaciers
glaciers
and
(Greenland)
snow
(Antarctica)
sea-ice
Impacts regional
water supply,
agriculture, etc.
Solar reflection,
Ocean-atmosphere
heat exchange
Solar reflection,
Ocean density,
Sea-level rise
(Tour of the cryosphere, Goddard Scientific Visualization Studio)
The Cryosphere
• TOUR OF CRYOSPHERE: MAIN NASA
SITE
Let’s think about the Arctic for a while
• WWF: Arctic Feedbacks Assessment
Projected Global Temperature Trends: 2100
2071-2100 temperatures relative to 1961-1990.
Special Report on Emissions Scenarios Storyline B2 (middle of the road warming).
IPCC 2001
The Thermohaline Circulation (THC)
(Global, organized circulation in the ocean)
(The “conveyer belt”, “rivers” within the ocean)
Blue shading, low salt
Where there is localized
exchange of water between
the surface and the deep
ocean (convection)
Green shading, high salt
Warm, surface currents.
Cold, bottom currents.
From Jianjun Yin, GFDL, see J. Geophysical Research, 2006
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
Scientific investigation of Earth’s climate
SUN
EARTH
WHAT HAPPENS
IF WE HAVE AN
IMPULSE OR
PERTURBATION
TO THE
SYSTEM?
EARTH: EMITS ENERGY TO SPACE  BALANCE