1. 2525 Space Research Building (North Campus)
Climate Change: Demystifying the Application of Earth Systems Models for Climate Science
Richard B. Rood
Cell:
2525 Space Research Building (North Campus)
June 20, 2017

2. Some Resources
Gettelman and Rood: Demystifying Climate Models: A User’s Guide to Earth Systems Models
Springer, Open Source, (It is free.)
Introductory Material OpenClimate Mini-page
Model Introduction OpenClimate Mini-page
Rood’s Class MediaWiki Site

3. Models and Scientific Investigation Models in Climate Science
Outline
Models
Definition
Models and Scientific Investigation
Models in Climate Science
Establishing Trust: Numerical Experimentation
Looking Towards the Future
Summary
The Conservation Principle: Balancing the Budget: The conservation of energy and mass, role of atmosphere, ocean, ice, and
land; The Earth System; Modeling as budget and accounting, relation to scientific method

4. From: http://www.halfhull.com/main.jpg
Assumption
I am talking to an audience that knows what “model” means in the context of weather and climate science.
Knows the jargon of meteorology
From:

5. What is a Model? Model (Dictionary)
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

6. We live lives full of models
Models are everywhere in our lives and work
Architecture
Epidemiology
Aerospace
Computer assisted design
Games
The bridge over the Missouri River
Landing things on Mars
Investing my retirement account
How much rent can I afford
My digital thermometer
The Conservation Principle: Balancing the Budget: The conservation of energy and mass, role of atmosphere, ocean, ice, and
land; The Earth System; Modeling as budget and accounting, relation to scientific method

7. What is a Model? Model (Dictionary) Weather and Climate
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
Weather and Climate
Provide numerical approximations of the equations that describe the atmosphere, land, ocean, ice, biology of the Earth –
process definition, diagnostics, predictions, and projections
Solves conservation equations:
energy, momentum, mass

8. Models and Scientific Investigation
OBSERVATIONS
THEORY
EXPERIMENT

9. Models and Scientific Investigation
OBSERVATIONS
THEORY
PREDICTION

10. Models and Scientific Investigation
OBSERVATIONS
PROCESSES
SIMULATION

11. Computational Science (Post and Votta, PhysToday, 2005)
Computational Science & Numerical Simulation
Given what we know, can we predict what will happen, and evaluate (validate) that what we predicted would happen, happened?
Validation: Comparison with observations
Philosophy: Do we ever know if we get the right answer for the right reason?
Computational and natural science: Establish the credentials of a model to help inform us about the application for which the model was designed.

12. Models in Climate Science

13. Models and Model Infrastructure
Models & Model Simulations
Connects it all together. Critical for
- Scientific credibility
- Collaboration
- Development
- Efficiency
- Analysis
- End user
Solves the conservation equations
- Mass
- Momentum (~ weather)
- Energy (~climate)
Split into “processes”
- Fluid dynamics
- Radiation
- Moist physics
- Turbulence
Representation of the “physics,” the climate, the theory, and mathematics.
Importance of application
Integral constraints, conservation laws

14. Observations and Models: Processes
Infrastructure
Observations
Models & Model Simulations
PROCESSES
DIAG. & TEST
Define & test model “physics”
Diagnostic applications

15. Observations and Models: Weather Forecasts
Infrastructure
Observations
Models & Model Simulations
INITIAL COND.
FORECASTS
Start Forecasts
Validation
Prognostic applications

16. Observations and Models: Assimilation
Infrastructure
Observations
Models & Model Simulations
MELD
Assimilation & Reanalysis
Initial Conditions
Validation
Scientific Investigation
Data System Monitoring

17. Observations and Models: Predictions and Projections
Infrastructure
PROCESSES
PREDICTIONS
Observations
Models & Model Simulations
INITIAL STATE
PROJECTIONS
Define & test model “physics”
Diagnostic applications
Prognostic applications
Start Forecasts
Validation
Assimilation & Reanalysis

18. Complexity / Types of Models (Rood, Perspective)
Conceptual / Heuristic Models
Integrated, theory based (ex. Geostrophic balance)
Statistical models
Past behavior and correlated information used to make predictions
Physical models: First principle tenets of physics (chemistry, biology)
Mechanistic: some aspects prescribed
Comprehensive: coupled interactions, self-determining
(State Earth will Warm)
(Details of Warming, Feedbacks)

19. The Earth System Model: Climate Models
SUN
CLOUD-WORLD
ATMOSPHERE
BIOLOGY
OCEAN
ICE
(cryosphere)
BIOLOGY
LAND

20. Establishing Trust: Numerical Experimentation
Hindcasting
Historical simulation

21. Let’s look at observations from 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.
Temperature starts to follow CO2 as CO2 increases beyond approximately 300 ppm, the value seen in the previous graph as the upper range of variability in the past 350,000 years.
Medieval warm period
“Little ice age”

22. 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 one-to-one.
What is the cause of the temperature variability? Can we identify mechanisms, cause and effect? How?
This is an important point in the ultimate argument, on short time scales co2 and T are not so well correlated. T responds to other factors. These factors will be evaluated based on modeling experiments, which follow from (imperfect) observations of cause and effect as determined by observable events, e.g. volcanos.

23. 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 (forcing) 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 simulate 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.

24. Schematic of a model experiment.
Observations
Model prediction with
forcing and source of
internal variability, for example, El Nino, Pacific Decadal Oscillation T
Model prediction with
forcing
Start model prediction
Model prediction without
forcing T
Statistical representation – not deterministic

25. After 1800 need to consider the impact of man
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.

26. Let’s look at the “modern” record.
Modern ~ Industrial Revolution
~ Last half of 1800s
When we have direct temperature measures

27. Figure TS.23 20th Century Simulations Example of Attribution
Figure TS.23. (a) Global mean surface temperature anomalies relative to the period 1901 to 1950, as observed (black line) and as obtained from simulations with both anthropogenic and natural forcings. The thick red curve shows the multi-model ensemble mean and the thin lighter red curves show the individual simulations. Vertical grey lines indicate the timing of major volcanic events. (b) As in (a), except that the simulated global mean temperature anomalies are for natural forcings only. The thick blue curve shows the multi-model ensemble mean and the thin lighter blue curves show individual simulations. Each simulation was sampled so that coverage corresponds to that of the observations. {Figure 9.5}
Example of Attribution

28. 20th Century Simulations
Meehl et al., J. Climate (2004)

29. Look towards the future.
Surface temperature anomaly
Intergovernmental Panel on Climate Change (IPCC, every ~ 5 years)
IPCC assesses, does not “do” research
Coupled Model Intercomparison Project (CMIP)
Scientist community designs protocol to evaluate and establish trustworthiness of climate models
CMIP is not the same as IPCC, but are often conflated.

30. IPCC (2007) projections for the next 100 years.
Figure SPM.5. Solid lines are multi-model global averages of surface warming (relative to 1980–1999) for the scenarios A2, A1B and B1, shown as continuations of the 20th century simulations. Shading denotes the ±1 standard deviation range of individual model annual averages. The orange line is for the experiment where concentrations were held constant at year 2000 values. The grey bars at right indicate the best estimate (solid line within each bar) and the likely range assessed for the six SRES marker scenarios. The assessment of the best estimate and likely ranges in the grey bars includes the AOGCMs in the left part of the figure, as well as results from a hierarchy of independent models and observational constraints. {Figures 10.4 and 10.29}

31. Summary: Models
Basic scientific principle or law used in climate science is conservation of energy
Models are an accounting, or calculating the budget, of
Energy
Mass
Momentum
Credibility established by representation of the past, and, when possible, evaluating predictions and projections
The Conservation Principle: Balancing the Budget: The conservation of energy and mass, role of atmosphere, ocean, ice, and
land; The Earth System; Modeling as budget and accounting, relation to scientific method

32. Summary: Energy Balance of Planet
Earth’s energy balance
Energy from Sun
Energy sent back to space
Things that absorb
Things that reflect
Moving energy around
Storing energy at the surface of the Earth
Greenhouse gases hold the energy a while
Oceans pick it up and hold it longer
Ice takes it up and melts  balances change
The Conservation Principle: Balancing the Budget: The conservation of energy and mass, role of atmosphere, ocean, ice, and
land; The Earth System; Modeling as budget and accounting, relation to scientific method

33. A fundamental conclusion
Based on the scientific foundation of our understanding of the Earth’s climate, we know with virtual certainty
The average global temperature of the Earth’s surface has risen and will continue to rise due to the addition of gases (esp, carbon dioxide) into the atmosphere that hold heat close to the surface. The increase in greenhouse gases is due to human activities, especially, burning fossil fuels.
Historically stable masses of ice on land have melted and will continue to melt.
Sea level has risen and will rise.
The weather has changed and will change.

35. Models and Scientific Investigation Models in Climate Science
Outline
Models
Definition
Models and Scientific Investigation
Models in Climate Science
Establishing Trust: Numerical Experimentation
Looking Towards the Future
Summary
The Conservation Principle: Balancing the Budget: The conservation of energy and mass, role of atmosphere, ocean, ice, and
land; The Earth System; Modeling as budget and accounting, relation to scientific method

36. Some Resources
Gettelman and Rood: Demystifying Climate Models: A User’s Guide to Earth Systems Models
Springer, Open Source, (It is free.)
Introductory Material OpenClimate Mini-page
Model Introduction OpenClimate Mini-page
Rood’s Class MediaWiki Site

37. Poll questions:
I was formally introduced to weather or climate models in school.
Our knowledge of climate change is adequate for us to take action to intervene to reduce carbon dioxide emissions.
Climate models provide adequate information to inform decisions about adaptation.
Climate models are trustworthy.
Provide any comments, qualifications inspired by the questions above.
Write any questions or comments about climate models and climate change you would like to make.
What do you want to get from this presentation?

38. Background Materials

39. Roles of Uncertainty / Variability at Different Times Hawkins and Sutton, 2009

40. Conservation principle
There are many other things in the world that we can think of as “conserved.” For example, money.
We have the money that we have.
If we don’t spend money or earn money, then the money we have today is the same as the money we had yesterday.
Mtoday = Myesterday
That’s not very interesting, or realistic

41. Conservation principle (with income and expense)
Mtoday = Myesterday + I - E
This is the balance equation, basic conservation. Changes come from production and loss.
Let’s get some money and buy stuff.
Expense

42. Conservation principle (with the notion of time)
Income
Mtoday = Myesterday + N(I – E)
Salary
Income per month = I
Rent
Expense per month = E
N = number of months
I = NxI and E= NxE
This is a meaningful representation of production and loss because it brings in the idea of there being a rate, a time dependency, to the production and loss. If it is just constant, it runs away with time.
Expense

43. Some algebra and some thinking
Mtoday = Myesterday + N(I – E)
Rewrite the equation to represent the difference in money
(Mtoday - Myesterday ) = N(I – E)
This difference will get more positive or more negative as time goes on.
Saving money or going into debt.
Divide by the number of months. Now we are headed to a rate in Money and a rate in Time (N). This is essentially a time derivative.
Divide both sides by N, to get some notion of how difference changes with time.
(Mtoday - Myesterday )/N = I – E

44. E = e*M Introduce a concept
The amount of money that you spend is proportional to the amount of money you have:
How do you write this arithmetically?
E = e*M

45. Some algebra and some thinking
(Mtoday - Myesterday )/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

46. Conservation principle
Energy from the Sun
Income
Mtoday = Myesterday + I - E
Earth at a certain temperature, T
Let’s get some money and buy stuff.
This is the balance equation, basic conservation. Changes come from production and loss.
Energy emitted by Earth
(proportional to T)
Expense

47. Some jargon, language
Income is “production” is “source”
Expense is “loss” is “sink”
Exchange, transfer, transport all suggest that our “stuff” is moving around.

48. 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.
Small changes might cause large changes in a balance

49. Conservation of Energy
Conceptual model of Earth’s temperature from space

50. Energy emitted by Earth
Earth: How Change T?
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
Income (Production = Energy from Sun) and Expense (Loss = Energy emitted by Earth) figure adapted to the Earth system.
Energy emitted by Earth
(proportional to T)

51. The first place that we apply the conservation principle is energy
We reach a new equilibrium
Changes in orbit or solar energy changes this

52. The first place that we apply the conservation principle is energy
We reach a new equilibrium
Changing a greenhouse gas changes this

53. Or Tomorrow? Balancing the Budget Today’s Money =
Yesterday’s Money + Money I Get – Money I Spend
Today’s CO2 =
Yesterday’s CO2 + CO2 I Get – CO2 I Spend
Today’s Energy =
Yesterday’s Energy + Energy I Get – Energy I Spend
Or Tomorrow?

54. Conservation principle
Conserved Quantities:
mass (air, ozone, water)
momentum,
Energy
Need to Define System
Need to count what crosses the boundary of the system
System depends on your point of view
This is important to think about because it strongly constrains what can and cannot happen. There is just so much energy coming into the earth system, and it has to be conserved in the case of a stable climate. It will be slightly out of balance when the climate is warming (holding more energy) or cooling (losing energy). Ultimately, in the climate problem we will require a more detailed examination … namely we are talking about warming (or cooling) at the surface. Conservation will require cooling (or warming) elsewhere in the system, because ultimately, the earth needs to get rid of its energy.

55. Point of View SUN EARTH PLACE AN INSULATING BLANKET AROUND EARTH
FOCUS ON WHAT IS HAPPENING AT THE SURFACE
EARTH: EMITS ENERGY TO SPACE  BALANCE

56. Simple earth 1

57. Models and Modeling

58. Models
Blogs on Model Tutorial (Start with #3)
Models are everywhere
Ledgers, Graphics and Carvings
Balancing the budget
Point of View
Cloak of Complexity

59. What is a Model? Model Numerical Experimentation
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?

60. Models are everywhere

61. How Many Use Spread Sheets?

62. Ledgers, Graphics and Carvings
 Spreadsheets  Computers

63. Radiation Balance Figure
This is a figure where things are in balance. What goes out = what comes in.

64. 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.

65. Building the Radiative Balance
What happens to the energy coming from the Sun?
Energy is coming from the sun.
Two things can happen at the surface. In can be:
Top of Atmosphere / Edge of Space
Reflected Or
Absorbed

66. Building the Radiative Balance
What happens to the energy coming from the Sun?
Top of Atmosphere / Edge of Space
Reflect
We also have the atmosphere.
Like the surface, the atmosphere can: or
Absorb

67. Building the Radiative Balance
What happens to the energy coming from the Sun?
Top of Atmosphere / Edge of Space
Reflect a lot
In the atmosphere, there are clouds which :
Absorb some

68. 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”

69. 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?

70. 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.
(Like a transfer between accounts)

71. 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)

72. Building the Radiative Balance
Terrestrial energy is converted/partitioned into three sorts RS
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 )
CLOUD
ATMOSPHERE
WARM AIR
(THERMALS)
PHASE TRANSITION OF WATER
(LATENT HEAT)
RADIATIVE ENERGY
(infrared or thermal)
SURFACE

73. Building the Radiative Balance
Which is transmitted from surface to atmosphere RS
Top of Atmosphere / Edge of Space
3) Terrestrial energy ends up in three reservoirs
CLOUD
CLOUD
ATMOSPHERE
(LATENT HEAT)
(THERMALS)
(infrared or thermal)
SURFACE

74. Building the Radiative Balance
And then the infrared radiation gets complicated RS
Top of Atmosphere / Edge of Space
1) Some goes straight to space
4) Some is absorbed by clouds and atmosphere and re-emitted upwards
2) Some is absorbed by atmosphere and re-emitted downwards
3) Some is absorbed by clouds and re-emitted downwards
CLOUD
CLOUD
ATMOSPHERE
(LATENT HEAT)
(THERMALS)
(infrared or thermal)
SURFACE

75. Want to consider one more detail
What happens if I make the blanket thicker?

76. Thinking about the greenhouse
A thought experiment of a simple system.
Top of Atmosphere / Edge of Space
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”
(infrared or thermal)
SURFACE

77. 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
Remember this when we later look at observations of what has happened? It is part of attribution.
2) The part coming down gets a little larger.
It gets warmer still.
(infrared or thermal)
SURFACE
The real problem is complicated by clouds, ozone, ….

78. Think about that warmer-cooler thing.
Addition of greenhouse gas to the atmosphere causes it to get warmer near the surface and colder in the upper atmosphere.
This is part of a “fingerprint” of greenhouse gas warming.
Compare to other sources of warming, for example, more energy from the Sun.

79. Think about a couple of details of emission.
There is an atmospheric window, through which infrared or thermal radiation goes straight to space.
Water vapor window
Carbon dioxide window is saturated
This does not mean that CO2 is no longer able to absorb.
It means that it takes longer to make it to space.

80. Thinking about the greenhouse
Why does it get cooler up high?
Top of Atmosphere / Edge of Space
1) Atmospheric Window
2) New greenhouse gases like N20, CFCs, Methane CH4 close windows
ATMOSPHERE
Remember this when we later look at observations of what has happened? It is part of attribution.
3) Additional CO2 makes the insulation around the window tighter.
(infrared or thermal)
SURFACE
The real problem is complicated by clouds, ozone, ….

81. So what matters? Changes in the sun THIS IS WHAT WE ARE DOING
Things that change reflection
Things that change absorption
When we think of mitigation of climate change, managing or controlling warming, we really only have two things to think about, things that change absorption and things that change reflection.
If something can transport energy DOWN from the surface.

82. Think about the link to models
energy reflected = (fraction of total energy reflected) X (total energy)
energy absorbed = total energy - energy reflected = (1-fraction of total energy reflected) X (total energy)
fraction of total energy reflected 
Clouds
Ice
Ocean
Trees
Etc.

83. Radiation Balance Figure In this figure out = in
This is a figure where things are in balance. What goes out = what comes in.

84. Energy in Earth System: Basics
Science  Observations  Evaluation  Measurement
Can we do the counting to balance the budget?
Can we measure the imbalance when the Earth is not in equilibrium?

85. Radiative Balance (Trenberth et al
Radiative Balance (Trenberth et al. 2009) In this figure out does not = in
In this figure what goes out does not equal what goes in: The Earth is warming. The amount of warming is about 1 out of 340

86. IPCC (2001) projections for the next century…
Figure SPM-10b: Variations of the Earth’s surface temperature: years 1000 to From year 1000 to year 1860 variations in average surface temperature of the Northern Hemisphere are shown (corresponding data from the Southern Hemisphere not available) reconstructed from proxy data (tree rings, corals, ice cores, and historical records). The line shows the 50-year average, the grey region the 95% confidence limit in the annual data. From years 1860 to 2000 are shown variations in observations of globally and annually averaged surface temperature from the instrumental record; the line shows the decadal average. From years 2000 to 2100 projections of globally averaged surface temperature are shown for the six illustrative SRES scenarios and IS92a using a model with average climate sensitivity. The grey region marked “several models all SRES envelope” shows the range of results from the full range of 35 SRES scenarios in addition to those from a range of models with different climate sensitivities. The temperature scale is departure from the 1990 value; the scale is different from that used in Figure SPM-2.

87. IPCC (2007) projections for the next century
Figure SPM.5. Solid lines are multi-model global averages of surface warming (relative to 1980–1999) for the scenarios A2, A1B and B1, shown as continuations of the 20th century simulations. Shading denotes the ±1 standard deviation range of individual model annual averages. The orange line is for the experiment where concentrations were held constant at year 2000 values. The grey bars at right indicate the best estimate (solid line within each bar) and the likely range assessed for the six SRES marker scenarios. The assessment of the best estimate and likely ranges in the grey bars includes the AOGCMs in the left part of the figure, as well as results from a hierarchy of independent models and observational constraints. {Figures 10.4 and 10.29}

88. IPCC (2013) projections for the next three centuries
Time series of global annual mean surface air temperature anomalies (relative to 1986–2005) from CMIP5 concentration-driven experiments. Projections are shown for each RCP for the multi-model mean (solid lines) and the 5 to 95% range (±1.64 standard deviation) across the distribution of individual models (shading). Discontinuities at 2100 are due to different numbers of models performing the extension runs beyond the 21st century and have no physical meaning. Only one ensemble member is used from each model and numbers in the figure indicate the number of different models contributing to the different time periods. No ranges are given for the RCP6.0 projections beyond 2100 as only two models are available.

89. Radiative Forcing Changes
Excellent article on history of this figure
Interesting History of This Plot at RealClimate

90. Questionnaire: Kansas City, AMS, Broadcast Meteorologists, Model Short Course