CHAPTER 20
THE ATMOSPHERE: CLIMATE, CLIMATE CHANGE AND OZONE DEPLETION

I. The Atmosphere

A. Atmospheric Structure
1. Locate the troposphere, tropopause, stratosphere, mesosphere, and thermosphere.
2. What is in the atmosphere? What is the chemical content of the atmosphere?

B. Troposphere
1. What are the greenhouse gases and how they act to moderate the Earth's
temperature
2. Cloud cover decreases the quantity of energy arriving from the sun.

C. Stratosphere
1. Dynamic balance between molecular oxygen and ozone.

D. Changes in Temperature as We Move Farther from Earth

II. Climate versus Weather

A. Define Weather
1.Air currents move due to convection currents creating weather.

B. Define Climate
1. Climate creates the major conditions for biomes

C. How Climate Has Changed
1. Using Ice Cores and other Data to Understand Past Climate

D. How Oceans and Atmosphere Interact to Create Climate
1. Conveyor System
Fig. 21.2 This figure shows atmospheric structure and temperature. Left-hand plot shows the layers of the atmosphere, while plot on the right shows the vertical temperature profile.
Fig. 21.3 Much of the incoming radiation from the sun is reflected back to space (30%), but the remainder is absorbed by the oceans, land, and atmosphere (70%), where it creates our weather and fuels photosynthesis.
Fig. 21.4 Evaporation and condensation occur in rising air and precipitation results, followed by the sinking of dry air. Horizontal winds are generated in the process.
III. Global Climate Change

A. Data

1. Water Vapor
a. Sources

2. Evaporation (increases in flat water surfaces  reservoirs)

3. Methane
a. Sources
·Microbial fermentation (landfills, wetlands, cattle)
·Coal and oil deposits
·Natural gas pipelines
b. Quantity: most important next to CO2

4. Ozone
a. Source: combustion
b. Primarily considered as respiratory air pollution

5. CFCs and Other Halocarbons
a. Sources
·Refrigerants
·Solvents
·Fire retardants
·Pesticides
b. Quantities have been decreasing

6. Nitrous Oxide
a. Sources
·Biomass burning
·Chemical fertilizers
·Fossil-fuel burning
b. Quantities are increasing

7. Carbon Dioxide
a. Sources
·Burning fossil fuels
·Deforestation
b. Quantities
Fig. 21.5 This figure shows mean surface temperatures. The baseline, or zero point, is the 1950-1980 average temperature; the red line represents the five-year running average. The warming trend since 1970 is conspicuous.
Fig. 21.6 Temperature patterns of the last 160,000 years, demonstrate climatic oscillations. A cold spell occurred at start of this record and dissipated about 10,700 years ago.
Fig. 21.7 Note the connections between the oceans, indicating that some heat transported by the north Atlantic originates in the Pacific.
Fig. 21.8 Salty water flowing to the north Atlantic is cooled and sinks. This deep flow extends southward and is joined by Antarctic water, where it extends into the Indian and Pacific Oceans. Surface currents then return the water to the north Atlantic.
Fig. 21. 9 Anthropogenic factors affect atmospheric warming and cooling; some gases promote global warming, others cause cooling.
Fig. 21.10 The concentration of carbon dioxide in the atmosphere fluctuates between winter and summer because of seasonal variation in photosynthesis. The average concentration is increasing owing to human activities, namely, burning fossil fuels and deforestation.
Fig. 21.11 In 1996, approximately 22 billion metric tons of carbon dioxide were emitted. (From World Energy Council data.)
B. Ecological Effects of Global Climate Change

1. What Does Modeling Tell Us?
a. What are the predicted impacts?
b. Regional climatic changes
c. Rise in sea level
d. Increase in violent weather events
Fig. 21.12 Model results with and without the effects of sulphate aerosol are compared with the actual temperature record.
Fig. 21.13 Results show the response of temperature to a doubling of greenhouse gas emissions over pre-industrial levels, with and without corrections for sulfate aerosol emissions.
C. Is Global Warming Here?

1. Historical Record
2. Temperature records are limited to no more than 150 years
3. Trend to be in Urban Areas (but have been reanalyzed to account for heat-island
effect, and the warming trend is unchanged)
4. Ice Records
a. IPCC conclusions

D. Public Policy
1. Government Actions and the Framework Convention on Climate Change
2. Precautionary Principle

IV. Ozone Depletion

A. How Does Ozone Depletion Occur?
1. Use CFC as the prototype ozone-depleting chemical and describe how ozone is
destroyed.
2. Describe the seasonal variation
3. Chlorine cycle and chlorine as a catalyst
4. The ozone layer is thinning.

B. Ozone Thinning Data
1. Initial Discovery in 1985
2. Data initially focused on Antarctica
3. NASA data on the North Pole ozone levels

C. Ecological Effects of Increased UV Radiation at the Planet Surface
1. Possible Plant Effects
2. Possible Animal Effects
3. Possible Human Effects
a. Ozone alerts in Australia

D. Public Policy
1. Montreal Protocol
2. Subsequent Amendments to Shorten the Phaseout
3. A Problem Successfully Faced
Fig. 21.15 Ultraviolet, visible light, infrared, and other forms of radiation are wavelengths of the electromagnetic spectrum.
Fig. 21.16 Ozone is produced at low latitudes and lost at higher latitudes.