Transcript aerosols - climateknowledge.org

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 2010
February 9, 2010
Class News
• Ctools site: AOSS 480 001 W10
• On Line: 2008 Class
– Reference list from course
• Rood Blog Data Base
• Reading
Make Up Class / Opportunity
• Make up Class on March 8, Dana 1040,
5:00 – 7:30 PM, Joint with SNRE 580
– V. Ramanathan, Scripps, UC San Diego
– Please consider this a regular class and make
it a priority to attend.
• Pencil onto calendar on April 6, Jim
Hansen, time TBD.
Class Projects
• Think about Projects for a while
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The role of the consumer
Energy efficiency / Financing Policy
Science influence on policy, Measurements of carbon, influence
Role of automobile, transportation, life style
Water, fresh water, impact on carbon,
Geo-engineering, public education, emergency management,
warning,
Water, insurance, Midwest development, Michigan, regional
Dawkins, socio-biology
What leads to a decision
What does it really mean in the village
Geo-engineering, urban sustainability
US Policy, society interest, K-12, education
Projects; Short Conversation
• Finance/Energy Efficiency/Development of
Technology/Reduction of Emissions
• “Geo-engineering” --- managing heating in
the near-term/Role of Attribution/Managing
the climate, what climate information is
needed
Next week
• Groups that have organized a short
presentation, discussion
– Title
– Your vision
– What disciplines are present in your group
Today
• Foundation of science of climate change
(continued)
Summary Points
Theory / Empirical Evidence
CO2 and Water Vapor Hold Heat Near Surface
Correlated Observations
CO2 and Temperature Observed to be strongly
related on long time scales (> 100 years)
CO2 and Temperature not Observed to be strongly
related on short time scales (< 10 years)
Observations
CO2 is Increasing due to Burning Fossil Fuels
Theory / Conservation Principle
Mass and Energy Budgets
 Concept of “Forcing”
Let’s look at just 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.
{
Note that on this scale, with more time
resolution, that the fluctuations in
temperature and the fluctuations in CO2
do not match as obviously as in the
long, 350,000 year, record.
What is the cause of the temperature
variability? Can we identify
mechanisms, cause and effect? How?
Important Concept
• We are working with, calculating budgets, for
existing, “stable” systems. They are in balance.
• We are interested in changes in the balance.
– What we are changing:
• CO2 in atmosphere (ocean-land-fossil fuel burning)
– How does this change?
• Phase of water in current climate (vapor, liquid, ice)
• Energy and exchange of energy within the Earth’s system
• ?????
Radiative Balance of The Earth
• Over some suitable time period, say a year,
maybe ten years, if the Earth’s temperature is
stable then the amount of energy that comes
into the Earth must equal the amount of energy
that leaves the Earth.
– Energy comes into the Earth from solar radiation.
– Energy leaves the Earth by terrestrial (mostly
infrared) radiation to space.
• (Think about your car or house in the summer.)
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.
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
Energy doesn’t just come and go
• The atmosphere and ocean are fluids. The horizontal
distribution of energy, leads to making these fluids move.
That is “weather” and ocean currents and the “general
circulation.”
Transport of heat poleward by atmosphere and oceans
• Weather ... The weather is how we feel the
climate day to day.
– It is likely to change because we are changing
the distribution of average heating.
– It is likely to change because warm air can
hold more water, which also changes the
distribution of energy.
To complete the basic picture we need
• Aerosols
• Internal Variability
• Feedbacks: Response to a change in forcing
• Important details that we have to remember
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Land surface / land use changes
Other green house gases
Air quality
Abrupt climate change
Following Energy through the Atmosphere
• We have kept in our mind, mostly,
greenhouse gases.
– Need to introduce aerosols
• We have been thinking about
– Things that absorb
– Things that reflect
– Responses to energy  Feedbacks
The Earth System
SUN
CLOUD-WORLD
ATMOSPHERE
ICE
(cryosphere)
OCEAN
LAND
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
• Reflecting Solar Cools
• Largest reflector
• Absorbing infrared Heats
CLOUD-WORLD
ATMOSPHERE
OCEAN
LAND
ICE
(cryosphere)
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
Earth’s aerosols
Current Anthropogenic Aerosol Extreme
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
Earth’s aerosols
Natural Aerosol Extreme
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
Let’s take a breath
• We have now seen the basics of the climate
change problem
– reduced it to an energy balance that alters absorption
and reflection
• greenhouse gases
• changes at the Earth’s surface
• aerosols
– seen that there is significant natural variability in the
climate
– identified the role of the major components of the
physical climate system
– exposed the role of water in the physical climate
Radiative Forcing IPCC 2007
Let’s look at just 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.
{
Note that on this scale, with more time
resolution, that the fluctuations in
temperature and the fluctuations in CO2
do not match as obviously as in the
long, 350,000 year, record.
What is the cause of the temperature
variability? Can we identify
mechanisms, cause and effect? How?
Sources of internal variability
• This is, in principle, natural variability.
• That does not mean that these modes of
variability remain constant as the climate
changes.
Internal Variability?
• There are modes of internal variability in the
climate system which cause global changes.
– El Nino – La Nina
• What is El Nino
– North Atlantic Oscillation
• Climate Prediction Center: North Atlantic Oscillation
– Annular Mode
– Inter-decadal Tropical Atlantic
– Things we have not observed?
Changes during El Nino
Times series of El Nino (NOAA CPC)
EL NINO
LA NINA
OCEAN TEMPERATURE
EASTERN PACIFIC
ATMOSPHERIC
PRESSURE
DIFFERENCE
Some good El Nino Information
• NOAA Climate Prediction: Current El Nino
/ La Nina
• NOAA CPC: Excellent slides on El Nino
– This is a hard to get to educational tour. This
gets you in the middle and note navigation
buttons on the bottom.
GISS Temperature 2002
1997-98 El Nino
An interesting time to study?
Internal Variability
• Definitely Important: Must be accounted
for in determining trends
– El Nino – La Nina
• What is El Nino
– North Atlantic Oscillation
• Climate Prediction Center: North Atlantic
Oscillation
ENOUGH!
Taking a breath
• We have not
– Looked at what the atmosphere and ocean
look like
– Talked about how we measure climate
change
– Talked about how we predict climate change
– Talked about how we make attributions of
climate change to greenhouse gases
– Addressed the role of “abrupt” climate change
Abrupt climate change
• The predictions and observations so far
are either in the sense of:
– Relatively small changes in the dynamic
balance of the climate system
– Incremental changes to the stable climate.
• What about “abrupt” climate change?
Note to professor: Force students to think and speak
• What might cause something to change
abruptly in the climate system?
• Lamont-Doherty: Abrupt Climate Change
• NAS: Abrupt Climate Change
• Wunderground.com: Abrupt Climate
Change
What is a stable climate?
LIQUID - ICE
NOAA Paleoclimate
Schlumberger
Younger Dryas
POSSIBLE EVIDENCE
OF CHANGE IN OCEAN
CIRCULATION
WHAT DOES THIS
MEAN?
Next time: Fundamental Science of Climate
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