Transcript AOSS_NRE_480_L05_CO2_Energy_Balance_20120119.ppt
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 19, 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
CLIMATE CHANGE TOWN HALL DISCUSSION • FRIDAY EVENING, Friday January 20, 6:30 – 8:00 pm Cures for Climate Confusion: Breaking Through in our Neighborhoods and in the Nation – – – Blau Auditorium at the University of Michigan Ross School of Business, 701 Tappan Street* Submit a Question: http://erb.umich.edu/blog/2012/01/04/town-hall-cures-for-climate-confusion-live-stream/
Speakers:
Rep. Bob Inglis, former US Congressman (R-SC) Rev. Canon Sally Bingham, President, Interfaith Power and Light, Steven W. Percy, former CEO of BP America (retired 1999) Andrew Hoffman, Director, Erb Institute for Global Sustainable Enterprise, University of Michigan Peter Frumhoff, Director of Science and Policy, Union of Concerned Scientist * Moderator:
*Tim Mealey, Co-Founder and Senior Partner, Meridian Institute*
• View Live Stream Beginning at 6:30: http://erb.umich.edu/blog/2012/01/04/town-hall-cures-for-climate-confusion-live-stream/
Reading Response: Due Jan 31, 2012
• The World Four Degrees Warmer – New et al. 2011 • Reading responses of roughly one page (single spaced). 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
From Reading of IPCC Summary
• The structure of the IPCC and the makeup of the panel • Objective wording (i.e. "virtually certain", "very likely") • Alarmed by observations (80% of heat absorbed by ocean, cause sea-level rise)
Some questions, based on the responses
• What do you think the goal of the summary is?
• Is it successful at reaching this goal? • Who is the audience? • Is the summary well structured and formatted? • What parts did you find confusing?
The Current Climate
• Climate Monitoring at National Climatic Data Center .
– http://www.ncdc.noaa.gov/oa/ncdc.html
• State of the Climate: Global
Today
• Scientific investigation of the Earth’s climate: Foundational information – Project Discussion – Radiative Balance – Earth System
What are the mechanisms for production and loss of CO 2 ?
Movement of carbon dioxide by land use changes
+1
Were you counting?
• Net sources into the atmosphere
5.5 + 1 = 6.5
• Net removal from the atmosphere
2+1 = 3
Conservation
• We have just done an accounting of carbon dioxide (CO 2 ) – This could be called a budget.
– In words: How much CO 2 we have tomorrow equals how much we have today plus how much we add minus how much we take away.
Conservation
• In words: How much CO 2 we have tomorrow equals how much we have today plus how much we add minus how much we take away.
• In symbols: CO 2 tomorrow = CO 2 today + Production - Lost
Conservation: A familiar concept
Some algebra and some thinking
(M
today -
M
yesterday
)
/
N = I
–
E
If difference does NOT change with time, then
I
=
E Income equals Expense
With a balanced budget, how much we spend,
E
, is related to how much we have:
E
= eM
(M
today -
M
yesterday
)
/
N = I
– eM
Some algebra and some thinking
(M
today -
M
yesterday
)
/
N = I
– eM If difference does NOT change with time, then M = I/e
Amount of money stabilizes Can change what you have by either changing income or spending rate
All of these ideas lead to the concept of a budget: What you have = what you had plus what you earned minus what you spent
This picture is conservation of energy
SUN: ENERGY, HEAT EARTH: ABSORBS ENERGY EARTH: EMITS ENERGY TO SPACE BALANCE
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
Conservation (continuity) principle
I
ncome
M
today =
M
yesterday +
I
-
E
Earth at a certain temperature, T Let’s get some money and buy stuff.
E
xpense
(proportional to T)
Some jargon, language
• Income is “production” is “source” • Expense is “loss” is “sink” • Exchange, transfer, transport all suggest that our “stuff” is moving around.
The first place that we apply the conservation principle is energy • Assume that Energy is proportional to temperature, T, if the average temperature of the Earth is stable, it does not vary with time.
T next year T last year 0 Production Loss change in time Production Loss • We are starting with the idea that Earth’s climate is in balance. Looking at changes to that balance.
And the conservation of CO
2 • Assume that total CO 2 is balanced. It sloshes between reservoirs and gets transported around.
CO 2 next year CO 2 last year 0 Production Loss change in time Production Loss
Equilibrium and balance
• We often say that a system is in equilibrium if when we look at everything production = loss. There might be “exchanges” or “transfers” or “transport,” but that is like changing money between a savings and a checking account.
– We are used to the climate, the economy, our cash flow being in some sort of “balance.” As such, when we look for how things might change, we look at what might change the balance.
Need to think about our “system”
• How might we change this balance?
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
One of my rules
• In the good practice of science, of problem solving, to first draw a picture.
Conservation (continuity) principle
Energy from the Sun
Stable Temperature of Earth could change from how much energy (
production
) comes from the sun, or by changing how we emit energy.
Earth at a certain temperature, T
Energy emitted by Earth (proportional to T)
SUN The Greenhouse Effect (Is this controversial?) 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).
But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F).
Earth
This greenhouse effect in not controversial.
This surface temperature, which is higher than expected from simple conservation of energy, is due to the atmosphere. The atmosphere distributes the energy vertically; making the surface warmer, and the upper atmosphere cooler, which maintains energy conservation.
SUN The Greenhouse Effect (Is this controversial?) 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).
But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F).
Earth
This greenhouse effect in not controversial.
This surface temperature, which is higher than expected from simple conservation of energy, is due to the atmosphere. The atmosphere distributes the energy vertically; making the surface warmer, and the upper atmosphere cooler, which maintains energy conservation. We are making the atmosphere “thicker.”
Some aspects of the greenhouse effect
• Greenhouse warming is part of the Earth’s natural climate system.
– It’s like a blanket – it holds heat near the surface for a while before it returns to space.
• Water is the dominant greenhouse gas.
• Carbon dioxide is a natural greenhouse gas.
– We are adding at the margin – adding some blankets • Or perhaps closing the window that is cracked open.
• N 2 0, CH 4 , CFCs, ... also important. But in much smaller quantities.
– Molecule per molecule stronger than CO couple of centuries now.
2 • We have been calculating greenhouse warming for a
Greenhouse gases (GHG)
• Earth's most abundant greenhouse gases – water vapor (H 2 O) – carbon dioxide (CO 2 ) – methane (CH 4 ) – nitrous oxide (N 2 O), commonly known as "laughing gas" – ozone (O 3 ) – chlorofluorocarbons (CFCs) • Ranked by their contribution to the greenhouse effect, the most important ones are: – water vapor, which contributes 36–70% – carbon dioxide, which contributes 9–26% – methane, which contributes 4–9% – ozone, which contributes 3–7% • What are the atmospheric lifetimes of the GHGs?
The theoretical foundation is the conservation of energy • If we change a greenhouse gas e.g. CO 2 , we change the loss rate. For some amount of time we see that the Earth is NOT in balance, that is Δ
T
/ Δ
t
is not zero, temperature changes. temperatur
H
e difference time difference Heating Production
T
t
T
Cooling Loss
H
T
Conservation (continuity) principle
Energy from the Sun
Stable Temperature of Earth could change from how much energy (
production
) comes from the sun, or by changing how we emit energy.
Earth at a certain temperature, T
Energy emitted by Earth (proportional to T)
The first place that we apply the conservation principle is energy • We reach a new equilibrium
T
t
0
H
Production -
T
Loss
T
H
Changing a greenhouse gas changes this
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).
What else could be happening in this system?
Earth
But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F).
This greenhouse effect in not controversial.
Conservation of Energy
• The heating could change. That is the sun, the distance from the sun, ... .
T
t H
H
Heating
T
T
Cooling Production Loss Loss
The first place that we apply the conservation principle is energy • We reach a new equilibrium
T
t
0
H
Production -
T
Loss
Can we measure the imbalance when the Earth is not in equilibrium?
T
H
Changes in orbit or solar energy changes this
Still there are many unanswered questions
• • • • We know that CO 2 in the atmosphere holds thermal energy close to the surface. Hence, more CO temperature?
2 will increase surface temperature.
– Upper atmosphere will cool.
– How will the Earth respond? • Is there any reason for Earth to respond to maintain the same average surface Why those big oscillations in the past?
– They are linked to solar variability.
– Release and capture of CO 2 by ocean plausibly amplifies the solar oscillation.
• Solubility pump • Biological pump What about the relation between CO 2 and T in the last 1000 years?
– Look to T (temperature) variability forced by factors other than CO 2 • Volcanic Activity • Solar variability • CO 2 increase Radiative forcing other than CO 2 ?
– Other greenhouse gases – Aerosols (particulates in the atmosphere)
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.)
Today
• Scientific investigation of the Earth’s climate: Foundational information –
Radiative Balance
– Earth System
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
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).
Earth Welcome Back Radiative Balance. This is conservation of energy, which is present in electromagnetic radiation.
But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F).
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
RS
Building the Radiative Balance
What happens to the energy coming from the Sun?
Top of Atmosphere / Edge of Space
For convenience “hide” the sunbeam and reflected solar over in “RS”
RS
Building the Radiative Balance
What happens to the energy coming from the Sun?
Top of Atmosphere / Edge of Space
Consider only the energy that has been absorbed.
What happens to it?
RS
Building the Radiative Balance
Conversion to terrestrial thermal energy.
Top of Atmosphere / Edge of Space
1) It is converted from solar radiative energy to terrestrial thermal energy.
(Like a transfer between accounts)
RS
Building the Radiative Balance
Redistribution by atmosphere, ocean, etc.
Top of Atmosphere / Edge of Space
2) It is redistributed by the atmosphere, ocean, land, ice, life.
(Another transfer between accounts)
RS
Building the Radiative Balance
Terrestrial energy is converted/partitioned into three sorts
Top of Atmosphere / Edge of Space
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 )
RADIATIVE ENERGY
(infrared)
CLOUD ATMOSPHERE SURFACE PHASE TRANSITION OF WATER
(LATENT HEAT)
WARM AIR
(THERMALS)
RS
(infrared)
Building the Radiative Balance
Which is transmitted from surface to atmosphere
Top of Atmosphere / Edge of Space
3) Terrestrial energy ends up in three reservoirs
CLOUD CLOUD ATMOSPHERE SURFACE
(LATENT HEAT) (THERMALS)
RS
(infrared)
Building the Radiative Balance
And then the infrared radiation gets complicated
Top of Atmosphere / Edge of Space
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 4) Some is absorbed by clouds and atmosphere and re-emitted upwards
CLOUD CLOUD ATMOSPHERE SURFACE
(LATENT HEAT) (THERMALS)
Put it all together and this what you have got.
The radiative balance
(infrared)
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
2) More energy is held down here because of the atmosphere • It is “warmer”
SURFACE
(infrared)
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
T < T
effective
ATMOSPHERE
T
effective
2) Down here it is warmer than T
effective
T > T
effective
SURFACE
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 – Observations of carbon dioxide (CO 2 ) – Behavior of CO 2 and Temperature – CO 2 balance in the atmosphere • Think about how to “fix” the problem – Conservation Principle – Radiative Balance –
Earth System
SUN OCEAN
The Earth System
CLOUD-WORLD
ATMOSPHERE ICE (cryosphere) LAND
SUN OCEAN
The Earth System
CLOUD-WORLD
ATMOSPHERE Where absorption is important ICE (cryosphere) LAND
SUN OCEAN
The Earth System
CLOUD-WORLD
ATMOSPHERE Where reflection is important ICE (cryosphere) LAND
SUN OCEAN
The Earth System
Solar Variability
CLOUD-WORLD
ATMOSPHERE ICE (cryosphere) LAND
The Earth System
SUN
CLOUD-WORLD
ATMOSPHERE OCEAN Possibility of transport of energy down from the surface LAND ICE (cryosphere)
From Warren Washington
Conservation equation
• Could you write the conservation equation, at least symbolically, for surface temperature and atmospheric carbon dioxide.
Scientific investigation of Earth’s climate
SUN: ENERGY, HEAT EARTH: ABSORBS ENERGY EARTH: EMITS ENERGY TO SPACE BALANCE
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