Download AOSS_480_L09_Model_Predictions_20080131

Climate Change: The Move to Action
(AOSS 480 // NRE 501)
Richard B. Rood
734-647-3530
2525 Space Research Building (North Campus)
[email protected]
http://aoss.engin.umich.edu./people/rbrood
Winter 2008
January 31, 2008
Class News
• A ctools site for all
– AOSS 480 001 W08
• This is the official repository for lectures
• Email [email protected]
• Class Web Site and Wiki
– Climate Change: The Move to Action
– Winter 2008 Term
• Wunderground Climate Page
– Posted Introduction of the New Rough Guide
– My recent series on models
Readings on Local Servers
• Assigned
– Stott: External Forcings of 20th Century Climate
– Andronova: Anthropogenic Forcing of 20th Century
Climate
– Roe: Climate Sensitivity
• Of Interest
– IPCC Figures in PPT
– Robock: Volcanoes and Climate (powerpoit, 36MB!)
QuikClimate AOSS 605
• First specific readings for Quikclimate
(Physical Climate Course)
– Hartmann: Chapter 5: Hydrological Cycle
– Oort & Rasmusson: Chapter 12: Hydrological
Cycle
Lectures coming up
• http://www.snre.umich.edu/events
• MLK Day Keynote Speaker: Dr. Warren
Washington // Climate Modeling // Tuesday,
February 5, 2008 - 4:00pm to 5:30pm //Location:
Stamps Auditorium, North Campus, Charles R.
Walgreen, Jr. Drama Center
• Erb Speaker Series: Jim Nixon, Alcoa,
"Challenges for an Energy Intensive
Business in a Carbon Constrained World"
Tuesday, February 5, 2008 - 5:00pm to
6:30pm Ross School, Wyly 0750
Tuesday February 5
• http://www.cgd.ucar.edu/ccr/warren/
• Warren Washington will be here for
questions and discussion.
– 1) How has the discussion of climate change
varied from President to President?
– 2) What are the next steps in research an
management of the climate?
– 3) How do we change to get climate
information generated and needed for societal
needs?
Tuesday February 5
• http://www.cgd.ucar.edu/ccr/warren/
• WE STILL START PROMPTLY AT 10:30
• If schedule work we should walk into this
room about 10:20.
Outline of Lecture
• Introduction to Models
• Conservation equation
– Calculation of production and loss terms
• Volcanoes
– Internal variability
• El Nino
• The last 100 years.
• Climate Sensitivity
• Radiative Forcing
What is a Model?
• Model
– A work or construction used in testing or perfecting a
final product.
– A schematic description of a system, theory, or
phenomenon that accounts for its known or inferred
properties and may be used for further studies of its
characteristics.
• Numerical Experimentation
– Given what we know, can we predict what will
happen, and verify that what we predicted would
happen, happened?
What do we do?
• We develop models based on the
conservation of energy and mass and
momentum, the fundamental ideas of
classical physics. (Budget equations)
Symbolic Energy Balance Equation
Atmosphere:
Eat+Dt = Eat + Dt((Pa – LaEa) + (Traoil + Ma ))
Symbols
E = “Energy”
P = Production
L = Loss rate
Tr = Transfer
M = Motion
Superscripts
a is for atmosphere
o is for ocean
i is for ice
l is for land
Variables
t = time
Dt = time increment
The Earth System
SUN
CLOUD-WORLD
ATMOSPHERE
ICE
(cryosphere)
OCEAN
LAND
Symbolic Energy Balance Equation
(Earth System)
Atmosphere:
Eat+Dt = Eat + Dt((Pa – LaEa) + (Traoil + Ma ))
Ocean:
Eot+Dt = Eot + Dt((Po – LoEo) + (Troail + Mo ))
Ice:
Eit+Dt = Eit + Dt((Pi – LiEi) + (Trioal + Mi ))
Land:
Elt+Dt = Elt + Dt((Pl – LlEl) + (Trloia + Ml ))
A point
• With this model we are now existing inside of the
climate system rather than sitting out in space
looking at the global balance.
– Inside – we are especially interested in what goes on
at the surface of the Earth
– Inside – we have to worry about the climate every
day, we don’t have the benefit of the average
– Inside – we have to deal with the complexity
• Conservation is still true, but you have to think
about being embedded in the system, not a
distant observer of the system
What do we do?
• We develop models based on the conservation
of energy and mass and momentum, the
fundamental ideas of classical physics. (Budget
equations)
• We determine the characteristics of production
and loss from theory and observations of, for
instance, the eruption of a major volcano and
the temperature response as measured by the
global observing system.
Consider just the Production and Loss Rate
(We call this forcing.)
Pa – LaEa
We can divide this, conceptually, into two:
 That in absence of the influence of the “industry” of humans
• Variability of the sun
• What volcanoes put in the atmosphere
• Greenhouse gases prior to industrial revolution
• Aerosols from, for instance, sea salt and desert dust
 That which includes the influence of the “industry” of humans
• Changes in greenhouse gases due to burning of fuel
• Aerosols from “industrial” emissions
• Changes in gases due to changes in what is growing
• Change in absorption and reflection due to land use change
• More?
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
Volcanoes and Climate
• Alan Robock: Volcanoes and Climate
Change (36 MB!)
Alan Robock
Department of Environmental Sciences
What do we do?
• We develop models based on the conservation of energy
and mass and momentum, the fundamental ideas of
classical physics. (Budget equations)
• We determine the characteristics of production and loss
from theory and observations of, for instance, the
eruption of a major volcano and the temperature
response as measured by the global observing system.
• We attempt to predict the temperature (“Energy”)
response.
• We evaluate (validate) how well we did, characterize the
quality of the prediction relative to the observations, and
determine, sometimes with liberal interpretation, whether
or not we can establish cause and effect.
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 ))
CO2 and Temperature for 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?
What do we know from model experiments and
evaluation (validation) with observations
• With consideration of solar variability and
volcanic activity, the variability in the
temperature record prior to 1800 can be
approximated.
• After 1800 need to consider the impact of man
–
–
–
–
Deforestation of North America
Fossil fuel emission
Change from coal to oil economy
Clean air act
• Only with consideration of CO2, increase in the
greenhouse effect, can the temperature increase
of the last 100 years be modeled.
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
Internal Variability?
• There are modes of internal variability in
the climate system which cause global
changes.
– El Nino – La Nina
– North Atlantic Oscillation
– Annular Oscillation
– 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.
Back to the Predictions
• So we have constructed these models.
– Defining the production and loss.
– Model the conservation laws that support
internal variability.
– We make predictions of the past and present
and work to validate performance
• There are successes
• There are failures
– Some of which are persistent.
– We draw our conclusions
Here is a strong figure
• But it has some issues
NATURAL FORCING
HUMAN-MADE FORCING
Third Assessment Report of the IPCC (2001):
General circulation model results
Pinatubo
Fig. 12-7
Attribution experiments with models
Meehl et al., J. Climate (2004)
Figure TS.23
Think about this figure
• What are the strengths and the weakness
that are represented in this figure?
1998
Climate Forcing
(-2.7, -0.6)
2001
Hansen et al: (1998) & (2001)
(-3.7, 0.0)
ICONIC FIGURE ALERT
Positive radiative forcing warms climate
Negative radiative forcing cools climate
?
ICONIC FIGURE ALERT
from Joyce Penner
Introduce the Idea of Climate Sensitivity
(Evaluating Uncertainty)
Change in Temperatur e  constant x Change in Forcing
DT  kDF
Different Models have different sensitivity.
Some show larger changes for a given change
in CO2 than others. Let’s imagine having two
groups, those with high sensitivity and those
with low sensitivity.
Let’s Split up the Model World
• High Climate Sensitivity
– High Aerosol Forcing
– Low Aerosol Forcing
• Low Climate Sensitivity
– High Aerosol Forcing
– Low Aerosol Forcing
Low climate sensitivity, low aerosol forcing
Observed temperature change
Climate model with low climate
sensitivity and small aerosol forcing
from Joyce Penner
High climate sensitivity, high aerosol forcing
Observed temperature change
Climate model with high climate
sensitivity and high aerosol forcing
from Joyce Penner
Let’s Split up the Model World
• High Climate Sensitivity
– High Aerosol Forcing (Can fit observations)
– Low Aerosol Forcing (Cannot fit observations)
• Low Climate Sensitivity
– High Aerosol Forcing(Cannot fit observations)
– Low Aerosol Forcing (Can fit observations)
Is this too much detail?
• There is a point
– We have this forcing of the energy in the climate
system; primary, change of the speed at which the
Earth cools.
• This will warm.
– The Earth will respond to this
• Change the energy transport rate between equator and pole.
• Feedbacks to the radiative budget.
– Some will enhance heating
– Some will retard heating
– Is there any reason to expect that the Earth will
respond to maintain the same equilibrium
temperature at the surface?
• Is there a feedback which essentially balances the heating?
Positive radiative forcing warms climate
Negative radiative forcing cools climate
?
HERE IS YOUR BEST CHANCE AT COOLING
from
Joyce
Penner
And in another 100 years
High climate
sensitivity and large aerosol forcing
Low Climate sensitivity
and small aerosol forcing
from Joyce Penner
Radiative Forcing IPCC 2007
Schematic Summary
~2 out of 340 W / m2
IF WE CHOOSE TO DO SOMETHING ABOUT THIS, THEN
CHANGE ENERGY BALANCE
CHANGE ABSORPTION OF RADIATIVE ENERGY
CHANGE REFLECTION OF RADIATIVE ENERGY
Start to think about the 2100 predictions
As people sitting here on earth, what climate
parameters/events do we care about?
• Temperature
• Water
– Precipitation
– Evaporation
– Humidity
• Air Composition
– Air quality
– Aerosols
– Carbon dioxide
• Winds
• Clouds / Sunlight
• Sea-level Rise
• Droughts
• Floods
• Extreme Weather
Have a good weekend
• Warren Washington on Tuesday