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Transcript AOSS_NRE_480_L10_Feedbacks_20100216

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]
Winter 2010
February 16, 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
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,
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
Project Teams
• Michigan Coal / Energy: Maggie Allan,
Meghan Reynard, Evan Oswald, Yoichi
• Efficiency as effective mitigation: Rebecca
Taylor, Erin Kashawlic, Rajesh Nerlikar,
Amanda Herrick
Projects; Short Conversation
• “Geo-engineering” --- managing heating in
the near-term / Role of Attribution /
Managing the climate, what climate
information is needed / Air quality
• Transportation / Automobiles / Energy /
Market /
• Weather / Extreme Events / Agriculture /
Carbon Sinks / Local Adaptation
Next week
• Groups that have organized a short
presentation, discussion
– Title
– Your vision
– What disciplines are present in your group
Today: complete the basic picture we need
• Aerosols
• Internal Variability
• Feedbacks: Response to a change in forcing
• Important details that we have to remember
Land surface / land use changes
Other green house gases
Air quality
Abrupt climate change
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)
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?
• Aerosols are particulate matter in the
– They impact the radiative budget.
– They impact cloud formation and growth.
Some important things to know about aerosols
• They can directly impact radiative budget through both reflection and
• 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
• They are often at the core of discussions of geo-engineering
Radiative Forcing IPCC 2007
Sources of internal variability
• This is natural variability.
– Solar variability
– Volcanic activity
– Internal “dynamics”
• Atmosphere - Weather
• Ocean
• Atmosphere-ocean interactions
• That does not mean that these modes of
variability remain constant as the climate
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
– Pacific Decadal Oscillation
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?
Some information on Pacific Decadal Oscillation
• Joint Institute for Study of Atmosphere and
Ocean (JISAO):
– Pacific Decadal Oscillation
• Climate Prediction Center (CPC):
– 90 Day Outlook Summary
– Weather and Climate Linkage
• National Climatic Data Center (NCDC):
– Decadal Oscillations
• Review Paper from Rood Class References
– Mantua and Hare (2002) J of Oceanography
Today: complete the basic picture we need
• Aerosols
• Internal Variability
• Feedbacks: Response to a change in forcing
• Important details that we have to remember
Land surface / land use changes
Other green house gases
Air quality
Abrupt climate change
Changes in
the sun
So what matters?
Things that
Things that
If something can transport energy DOWN from the surface.
More consideration of radiative energy in the atmosphere
– The idea that one thing causes a second thing
to happen.
• That second thing then does something to the first
– 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
 H  T  0
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 …
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
The Earth System: Feedbacks 4
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
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
• 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
– How clouds change is not well understood and much
• 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
• 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
• Large global effects
through ocean circulation
and permafrost melting.
• Might change very
The Earth System: ICE
(Think a little more about ice)
non-polar Ice Sheets
glaciers (Greenland)
Impacts regional
water supply,
agriculture, etc.
Solar reflection,
heat exchange
Solar reflection,
Ocean density,
Sea-level rise
(Tour of the cryosphere, Goddard Scientific Visualization Studio)
The Cryosphere
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
Cloud feedback?
Aerosols cool?
Water vapor feedback
accelerates warming
Cloud feedback?
Changes in land use impact absorption and reflection
Ice-albedo feedback
accelerates warming
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
• Abrupt Climate
What is a stable climate?
NOAA Paleoclimate
Younger Dryas
Next time: Fundamental Science of Climate