1. Climate Change: The Move to Action (AOSS 480 // NRE 480)
Richard B. Rood
Cell:
2525 Space Research Building (North Campus)
Winter 2014
February 6, 2014

2. Reading: The World Four Degrees Warmer
Class News
Ctools site: AOSS_SNRE_480_001_W14
Reading: The World Four Degrees Warmer
New et al. 2011
Something I am playing with
Politics of Dismissal Entry
Uncertainty Description
Model

3. First Reading Response
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 simply summarize the reading. They should be used by you to refine your questions and to improve your insight into climate change.
They should be submitted via CTools by next Tuesday and we will use them to guide discussion in class on Thursday. Assignment posted with some questions to guide responses.

4. This lecture: Projects? Energy Aerosols
Tuesday work on teams and specifics
Energy
Absorption
Reflection
Aerosols

5. Let’s focus on the balance of the energy at the Earth’s surface

6. The sun-earth system (What is the balance at the surface of Earth?)
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).
Radiative Balance. This is conservation of energy. Energy is present in electromagnetic radiation.
But the Earth’s surface temperature is observed to be, on average, about 15 C (~59 F).
Earth

7. 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.

8. 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

9. 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

10. 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

11. 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”

12. 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?

13. 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)

14. 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)

15. 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

16. 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

17. 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

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

19. 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

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

21. 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, ….

22. 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.

23. 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.

24. 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, ….

25. 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.

26. 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.

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

28. 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

29. This lecture:
Energy
Absorption
Reflection
Aerosols

30. The Earth System SUN ATMOSPHERE ICE OCEAN (cryosphere) LAND
CLOUD-WORLD
ATMOSPHERE
OCEAN
ICE
(cryosphere)
LAND

31. Where absorption is important
The Earth System
SUN
CLOUD-WORLD
Where absorption is important
ATMOSPHERE
OCEAN
ICE
(cryosphere)
LAND

32. Where reflection is important
The Earth System
SUN
Where reflection is important
CLOUD-WORLD
ATMOSPHERE
OCEAN
ICE
(cryosphere)
LAND

33. The Earth System SUN Solar Variability ATMOSPHERE ICE OCEAN
CLOUD-WORLD
ATMOSPHERE
OCEAN
ICE
(cryosphere)
LAND

34. Possibility of transport of energy down from the surface
The Earth System
SUN
CLOUD-WORLD
ATMOSPHERE
OCEAN
ICE
(cryosphere)
LAND
Possibility of transport of energy down from the surface

36. Lean: Living with a Variable Sun
Earth System: Sun
SUN:
Source of energy
Generally viewed as stable
Variability does have discernable signal on Earth
Impact slow and small relative to other changes
Lean, J., Physics Today, 2005
Lean: Living with a Variable Sun
CLOUD-WORLD
ATMOSPHERE
Solar variability is often a flash point in the climate change discussion. Some claim that climate scientists ignore and dismiss the role of the sun. This is not true. However, there is an enigma here; the terrestrial signal attributed to solar variability is larger than that modeled given our estimates of solar energy variability. Still, it is small compared to other sources of variability.
OCEAN
LAND
ICE
(cryosphere)

37. Earth System: Atmosphere
SUN
Earth System: Atmosphere
The Atmosphere:
Where CO2 is increasing from our emissions
Absorption and reflection of radiative energy
Transport of heat between equator and pole
Weather: Determines temperature and rain
What are the most important greenhouse gasses?
Water (H2O)
Carbon Dioxide (CO2)
Methane (CH4)
CLOUD-WORLD
ATMOSPHERE
Change CO2 Here
OCEAN
LAND
ICE
(cryosphere)

38. Cloudy Earth

39. Earth System: Cloud World
SUN
Earth System: Cloud World
Cloud World:
Very important to reflection of solar radiation
Very important to absorption of infrared radiation
Acts like a greenhouse gas
Precipitation, latent heat
Related to motion in the atmosphere
Most uncertain part of the climate system.
Reflecting Solar Cools
Largest reflector
Absorbing infrared Heats
CLOUD-WORLD
ATMOSPHERE
In the absence of clouds the albedo would be closer to 0.1 rather than 0.3.
OCEAN
LAND
ICE
(cryosphere)

40. Earth System: Land SUN Land: Absorption of solar radiation
Reflection of solar radiation
Absorption and emission of infrared radiation
Plant and animal life
Impacts H2O, CO2 and CH4
Storage of moisture in soil
CO2 and CH4 in permafrost
Land where consequences are, first and foremost, realized for people.
What happens to atmospheric composition if permafrost thaws?
Can we store CO2 in plants?
Adaptability and sustainability?
CLOUD-WORLD
ATMOSPHERE
Land use is critical to how people get along with the environment as a whole. What we do also impacts the climate system. It is especially true that what happens on the land can impact the local and regional climate.
OCEAN
LAND
Change Land Use Here
ICE
(cryosphere)

41. Doney: Ocean Acidification
SUN
Earth System: Ocean
Ocean:
Absorption of solar radiation
Takes CO2 out of the atmosphere
Plant and animal life
Impacts CO2 and CH4
Takes heat out away from surface
Transport of heat between equator and pole
Weather regimes: Temperature and rain
What will the ocean really do?
Will it absorb all of our extra CO2?
Will it move heat into the sub-surface ocean?
Changes in circulation?
Does it buy us time? Does this ruin the ocean? Acidification
CLOUD-WORLD
ATMOSPHERE
Issues of salinity and ocean chemistry are also important to circulation, sustainability, etc.
OCEAN
LAND
ICE
(cryosphere)
Doney: Ocean Acidification

42. Today
Scientific investigation of the Earth’s climate: Foundational information
Radiative Balance
Earth System
Aerosols

43. Following Energy through the Atmosphere
We have been concerned about, almost exclusively, greenhouse gases.
Need to introduce aerosols
Continuing to think about
Things that absorb
Things that reflect

44. Aerosols are particulate matter in the atmosphere.
They impact the radiative budget.
They impact cloud formation and growth.

45. Aerosols: Particles in the Atmosphere
Water droplets – (CLOUDS)
“Pure” water
Sulfuric acid
Nitric acid
Smog …
Ice
Dust
Soot
Salt
Organic hazes
AEROSOLS CAN:
REFLECT RADIATION
ABSORB RADIATION
CHANGE CLOUD DROPLETS

46. Earth’s aerosols

47. Dust and fires in Mediterranean

48. Forest Fires in US

49. The Earth System Aerosols (and clouds)
Clouds are difficult to predict or to figure out the sign of their impact
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
Top of Atmosphere / Edge of Space
CLOUD
ATMOSPHERE
(infrared)
SURFACE

50. The Earth System: Aerosols
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.
Top of Atmosphere / Edge of Space
ATMOSPHERE
AEROSOLS ?
(infrared)
SURFACE
Composition of aerosols matters.
This figure is simplified.
Infrared effects are not well quantified

51. South Asia “Brown Cloud”
But don’t forget
Europe and the US in the 1950s and 1960s
Change from coal to oil economy

52. 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

53. Current Anthropogenic Aerosol Extreme
South Asian Brown Cloud

54. Aerosol: South & East Asia

55. Reflection of Radiation due to Aerosol

56. Atmospheric Warming: South & East Asia
WARMING IN ATMOSPHERE, DUE TO SOOT (BLACK CARBON)

57. Surface Cooling Under the Aerosol

59. Natural Aerosol

60. Earth’s aerosols

61. Alan Robock: Volcanoes and Climate Change (36 MB!)
Department of Environmental Sciences

62. Department of Environmental Sciences
Explosive
backscatter
absorption (near IR)
Solar Heating
More Reflected
Solar Flux
absorption (IR) IR
Heating
emission
IR Cooling
More
Downward
IR Flux
Less
Upward
Stratospheric aerosols
(Lifetime » 1-3 years)
H2S
SO2
® H2SO4
NET HEATING
Heterogeneous ® Less
O3 depletion Solar Heating
CO2
H2O
forward scatter
Enhanced
Diffuse
Flux
Reduced
Direct
Less Total
Solar Flux
Ash
Effects
on cirrus
clouds
Tropospheric aerosols
(Lifetime » 1-3 weeks)
This diagram shows the main components of non-explosive and explosive volcanic eruptions, and their effects on shortwave and longwave radiation.
Quiescent
Indirect Effects on Clouds
SO2 ® H2SO4
NET COOLING
Alan Robock
Department of Environmental Sciences

63. Superposed epoch analysis of six largest eruptions of past 120 years
Year of eruption
Superposed epoch analysis of six largest eruptions of past 120 years
Significant cooling follows sun for two years
Robock and Mao (1995)
Robock and Mao (1995) removed the ENSO signal, and averaged the temperature change for the six largest recent eruptions, showing the anomaly from the preceding 5-year period. The cooling follows the sun for two years after the eruptions, but is displaced north of the Equator because there is more land in the Northern Hemisphere, so the cooling is larger there. The volcanic aerosol clouds were fairly evenly distributed in latitude.
Robock, A. and J. Mao, The volcanic signal in surface temperature observations, J. Climate, 8, , 1995.
Alan Robock
Department of Environmental Sciences

64. The Earth System Aerosols (and clouds)
Aerosols impact clouds and hence indirectly impact radiative budget through clouds
Change their height
Change their reflectivity
Change their ability to rain
Change the size of the droplets
Top of Atmosphere / Edge of Space
CLOUD
ATMOSPHERE
(infrared)
SURFACE

65. Aerosols and Clouds and Rain

66. 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

67. Iconic and Fundamental Figures

68. Scientific investigation of Earth’s climate
SUN: ENERGY, HEAT
EARTH: ABSORBS ENERGY
EARTH: EMITS ENERGY TO SPACE  BALANCE

69. Sun-Earth System in Balance
PLACE AN INSULATING BLANKET AROUND EARTH
The addition to the blanket is CO2
FOCUS ON WHAT IS HAPPENING AT THE SURFACE
EARTH: EMITS ENERGY TO SPACE  BALANCE

70. Increase of Atmospheric Carbon Dioxide (CO2)
Primary increase comes from burning fossil fuels – coal, oil, natural gas
Data and more information

71. Temperature and CO2: 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”

72. The Earth System SUN ATMOSPHERE ICE OCEAN (cryosphere) LAND
CLOUD-WORLD
ATMOSPHERE
OCEAN
ICE
(cryosphere)
LAND

73. Radiation Balance Figure

74. Radiative Balance (Trenberth et al. 2009)