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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 24, 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.
Supporting Reading
• Next Reading: Radiative Balance
– Radiative Forcing of Climate Change:
Expanding the Concept and Addressing
Uncertainties (2005)
Board on Atmospheric Sciences and Climate
(BASC) Chapter 1
• http://www.nap.edu/books/0309095069/html
• From class website
– Executive Summary
– Chapter 1: Radiative Forcing
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
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
– Radiative Balance
– Earth System
– Aerosols
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
Focus attention on the surface of the Earth
Simple earth 1
GO TO
Radiation Balance Figure
Radiative Balance (Trenberth et al. 2009)
Let’s build up this picture
• Follow the energy through the Earth’s
climate.
• As we go into the climate we will see that
energy is transferred around.
– From out in space we could reduce it to just
some effective temperature, but on Earth we
have to worry about transfer of energy
between thermal energy and motion of wind
and water.
The sun-earth system
(What is the balance at the surface of Earth?)
SUN
Based on conservation of energy: If the
Earth did NOT have an atmosphere,
then, the temperature at the surface of
the Earth would be about -18 C ( ~ 0 F).
Welcome Back
Earth
But the Earth’s surface temperature is
observed to be, on average, about 15 C
(~59 F).
Radiative Balance. This is
conservation of energy, which is
present in electromagnetic
radiation.
Building the Radiative Balance
What happens to the energy coming from the Sun?
Top of Atmosphere / Edge of Space
Energy is coming from the sun.
Two things can happen at the surface. In can be:
Reflected
Or
Absorbed
Building the Radiative Balance
What happens to the energy coming from the Sun?
Top of Atmosphere / Edge of Space
We also have the atmosphere.
Like the surface, the atmosphere can:
Reflect
or
Absorb
Building the Radiative Balance
What happens to the energy coming from the Sun?
Top of Atmosphere / Edge of Space
In the atmosphere, there are clouds which :
Reflect a lot
Absorb some
Building the Radiative Balance
What happens to the energy coming from the Sun?
RS
Top of Atmosphere / Edge of Space
For convenience “hide” the sunbeam
and reflected solar over in “RS”
Building the Radiative Balance
What happens to the energy coming from the Sun?
RS
Top of Atmosphere / Edge of Space
Consider only the energy that has
been absorbed.
What happens to it?
Building the Radiative Balance
Conversion to terrestrial thermal energy.
RS
Top of Atmosphere / Edge of Space
1) It is converted from solar
radiative energy to terrestrial
thermal energy – the motion of
molecules.
(Like a transfer between accounts)
Building the Radiative Balance
Redistribution by atmosphere, ocean, etc.
RS
Top of Atmosphere / Edge of Space
2) It is redistributed by the
atmosphere, ocean, land, ice, life.
(Another transfer between accounts)
Building the Radiative Balance
Terrestrial energy is converted/partitioned into three sorts
Top of Atmosphere / Edge of Space
RS
It takes heat to
• Turn ice to water
• And water to “steam;”
that is, vapor
3) Terrestrial energy ends up in
three reservoirs
(Yet another transfer )
CLOUD
ATMOSPHERE
PHASE
TRANSITION
OF WATER
RADIATIVE
ENERGY
(infrared)
(LATENT HEAT)
SURFACE
WARM AIR
(THERMALS)
Building the Radiative Balance
Which is transmitted from surface to atmosphere
Top of Atmosphere / Edge of Space
RS
3) Terrestrial energy ends up in
three reservoirs
CLOUD
CLOUD
(LATENT HEAT)
(infrared)
SURFACE
ATMOSPHERE
(THERMALS)
Building the Radiative Balance
And then the infrared radiation gets complicated
Top of Atmosphere / Edge of Space
RS
1) Some goes straight to space
2) Some is absorbed by atmosphere
and re-emitted downwards
3) Some is absorbed by clouds and
re-emitted downwards
CLOUD
CLOUD
(LATENT HEAT)
(infrared)
SURFACE
4) Some is absorbed by
clouds and atmosphere
and re-emitted upwards
ATMOSPHERE
(THERMALS)
Put it all together and this what you have got.
The radiative balance
Thinking about the greenhouse
A thought experiment of a simple system.
Top of Atmosphere / Edge of Space
1) Let’s think JUST about the infrared radiation
• Forget about clouds for a while
3) Less energy is up here because it
is being held near the surface.
• It is “cooler”
ATMOSPHERE
(infrared)
2) More energy is held down here
because of the atmosphere
• It is “warmer”
SURFACE
Thinking about the greenhouse
A thought experiment of a simple system.
Top of Atmosphere / Edge of Space
1) Remember we had this old idea of a temperature
the Earth would have with no atmosphere.
•
•
This was ~0 F. Call it the effective temperature.
Let’s imagine this at some atmospheric height.
3) Up here it is cooler than T effective
ATMOSPHERE
2) Down here it is warmer than T effective
(infrared)
SURFACE
T < T effective
T effective
T > T effective
Thinking about the greenhouse
Why does it get cooler up high?
Top of Atmosphere / Edge of Space
1) If we add more atmosphere, make it thicker, then
3) The part going to space gets a little smaller
• It gets cooler still.
ATMOSPHERE
2) The part coming down gets a little larger.
• It gets warmer still.
(infrared)
SURFACE
The real problem is complicated by clouds, ozone, ….
Changes in
the sun
So what matters?
THIS IS WHAT WE
ARE DOING
Things that
change
reflection
Things that
change
absorption
If something can transport energy DOWN from the surface.
Today
• Scientific investigation of the Earth’s
climate: Foundational information
– Radiative Balance
– Earth System
– Aerosols
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
Possibility of transport of
energy down from the
surface
Earth System: Sun
SUN
Lean, J., Physics Today, 2005
SUN:
• Source of energy
• Generally viewed as stable
• Variability does have discernable signal on Earth
• Impact slow and small relative to other changes
Lean: Living with a Variable Sun
CLOUD-WORLD
ATMOSPHERE
OCEAN
LAND
ICE
(cryosphere)
Earth System: Atmosphere
SUN
What are the most important
greenhouse gasses?
• Water (H2O)
• Carbon Dioxide (CO2)
• Methane (CH4)
The Atmosphere:
• Where CO2 is increasing from our emissions
• Absorption and reflection of radiative energy
• Transport of heat between equator and pole
• Weather: Determines temperature and rain
CLOUD-WORLD
ATMOSPHERE
Change CO2 Here
OCEAN
LAND
ICE
(cryosphere)
Cloudy Earth
Earth System: Cloud World
SUN
Most uncertain part of
the climate system.
Cloud World:
• Very important to reflection of solar radiation
• Very important to absorption of infrared radiation
• Acts like a greenhouse gas
• Precipitation, latent heat
• Related to motion in the atmosphere
• Reflecting Solar Cools
• Largest reflector
• Absorbing infrared Heats
CLOUD-WORLD
ATMOSPHERE
OCEAN
LAND
ICE
(cryosphere)
Earth System: Land
SUN
Land where consequences are,
first and foremost, realized for
people.
•What happens to
atmospheric composition
if permafrost thaws?
• Can we store CO2 in
plants?
• Adaptability and
sustainability?
Land:
• Absorption of solar radiation
• Reflection of solar radiation
• Absorption and emission of infrared radiation
• Plant and animal life
• Impacts H2O, CO2 and CH4
• Storage of moisture in soil
• CO2 and CH4 in permafrost
CLOUD-WORLD
ATMOSPHERE
LAND
OCEAN
Change Land
Use Here
ICE
(cryosphere)
Earth System: Ocean
SUN
What will the ocean really do?
• Will it absorb all of our
extra CO2?
• Will it move heat into
the sub-surface ocean?
• Changes in circulation?
Ocean:
• Absorption of solar radiation
• Takes CO2 out of the atmosphere
• Plant and animal life
• Impacts CO2 and CH4
• Takes heat out away from surface
• Transport of heat between equator and pole
• Weather regimes: Temperature and rain
CLOUD-WORLD
ATMOSPHERE
Does it buy us time? Does this
ruin the ocean? Acidification
OCEAN
Doney: Ocean Acidification
LAND
ICE
(cryosphere)
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