Global Climate Change -- Fiction, Facts, Uncertainties and Challenges
David D. Houghton
Lecture Notes
Atmospheric and Oceanic Sciences
U.W. Madison
Space Place - November 12, 2002

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I. Introduction

A. Climate change is here -- show bottle
B. My background

1. Research career on climate and weather
2. WMO Education and Training book on "climate change"
3. Talks to scientific and public groups

C. My motivation

1. Facilitate understanding and discussion in general public
2. Balance the "opposition"
News media is filled iwht articles and opponents are organized

D. Purpose of talk

1. Share my perspective and background on climate change science
2. Promote discussion and interest in the issues

E. Organization of talk

1. What the "opponents" are saying
2. Facts
3. Uncertainties
4. Challenges
5. What can we do about it

II. What the unconvinced people are saying

A. "Theory remains entirely unproved"
B. "One-in-three chance...that experts are wrong"
C. "Models are incapable of handling...water vapor"
D. Troposphere should be warming faster than than the surface
E. "If the weather fold can't figure out what's happening for the rest of the week, how can they tell us what the climate will be like for the next 50 years?"
F. "Guess what? Antarctica's getting colder, not warmer."
G. "Global warming is still just a theory."

III. Facts

A. Global mean temperature has been going up in the last 140 years ( see #1 reference page )
B. The magnitude of this variability does not exceed natural variability ( see #2 )
C. Concentration of carbon dioxide has been going up as well as other greenhouse gases ( see #3 )
D. Radiative theory of atmospheric gases (greenhouse) and aerosols is important ( see #4 )
E. Climate change ivolves the entire "earth system" not just the atmosphere ( see #5 )
F. Future projections face uncertainties in emission production, modeling, and impacts
G. A large number of scintists from all over the world have been involved (several thousand scientists from 40+ countries)

IV. Uncertainties

A. Human induced forcing changes to present ( see #6 )
B. Future emission levels

1. Driving forces ( see #7 )

Population ( see #8 )

2. Scenarios

A1F1: fossil fuel intensive energy system
A1T: non-fossil
A1B: no one energy source relied on
A2: self-reliant economy, preservation of local identities
B1: service and information economy, clean technology, global solutions
B2: B1 with local solutions, increasing population, less technology

3. Forcing variations to 2100 ( see #9 )

C. Model predictions - global mean ( see #10 and #11 )

D. Model predictions - local conditions

E. Impacts

1. Terrestrial ecosystems

a. Agriculture ( see #12 )
b. Forests
c. Deserts adn desertification
d. Hydrology and water resources

2. Ocean systems

a. Sea level
b. Coastal zones and marine ecosystems

3. Human "systems"

a. Settlements, energy and industry
b. Economic, insurance, and other financial services
c. Human health

1). Vector borne diseases ( see #13 )
2). Water-borne and food-borne diseases
3). Food supply
4). Air pollution
5). Ozone and ultraviolet radiation

4. Atmospheric systems (weather, storms, floods, droughts, extremes)

V. Challenges

A. Nature of climate system

1. Analysis must consider entire climate system and all of humanity
2. There is extensive natural climate variability
3. There are global connections for both climate forcing and climatic response
4. Uncertainties in outcomes involve uncertainties in numerous components
5. A small change in global means can translate to large changes in local means/extremes

B. Needs for research

1. Improve data - longer data, error analysis, more global coverage
2. Improve theory - radiation-aerosol, cloud drops-aerosol
3. Improve models - parameterization for small scale components
4. Separating naturally-induced fluctuations from anthropogenic effects ( see #14 )

C. Nature of people

1. Implement controls on human impacts on the environment
2. World cooperation

VI. What can we personally do about climate change

A. Why should we care?
B. Modify our own life style

1. Reduce our overall energy use ( see #15 )
2. Reduce our energy use - transportation
3. Examples for CO2 savings ( see #16 )

C. Mitigation and adaptation
D. Modify national and global practice ( see #17 )
E. Influencing public policy