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chapter 8 introduction essential questions global climate change are sea levels rising?
Lessons on the Lake -> Chapter 8 -> Global Climate Change

GLOBAL CLIMATE CHANGE

The earth’s atmosphere is a thin blanket of gases which serves many important functions. It protects the planet from harsh ultraviolet (UV) rays from the sun, and it warms the Earth’s surface and modifies our climate. This naturally occurring phenomenon is called the greenhouse effect.


Earth’s atmosphere is made up of about 78% nitrogen, 21% oxygen, and about 1% of trace gases that absorb infrared radiation. These trace gases, which trap heat to warm the earth, are known as the greenhouse gases. The two most
important ones in producing the insulating effect of Earth’s atmosphere are carbon dioxide (CO2) and water vapor (H20), but others include methane (CH4), chlorofluorocarbons (CFC’s), nitrous oxide (N20), and ozone (03). The following chart lists the major greenhouse gases and their sources.


Greenhouse Gases

Natural Sources

HumanMade Sources

Carbon Dioxide
CO2

• respiration of animals
and plants
• volcanic eruptions
• decay of organisms

• burning of fossil fuels
• clearing land for
agriculture
• cement manufacturing

Methane
CH4

• livestock
• wetlands
• termites

• landfills
• coal mines
• rice paddies
• natural gas leaks
• burning of biomass

Chlorofluorocarbons
CFC’s

• none

• refrigerators
• auto air conditioners
• solvents
• insulation
• aerosols

Nitrous Oxide
N2O

• soil microbes’ digestion

• burning coal and wood
• chemical fertilizers

Ozone
O3

• lightning
• pine trees

• photochemical reaction
between nitrogen
oxides and organic
compounds

Water Vapor
H2O

• evaporation
• transpiration

• will increase as evaporative
effect rises proportionally
to increasing
amounts of other
greenhouse gases


Atmospheric Greenhouse Gases

Range from Dawn of Humans to 1750 A.D.

concentration in 2005 A.D.*
(from 2007 IPCC SPM)

Annual Rate of Increase

Carbon Dioxide
CO2

180-295 parts per million (ppm)

379 ppm

25%

Methane
CH4

0.3-0.8ppm

1.7 ppm

115%

Nitrous Oxide
N2O

0.27-0.29 ppm

0.32 ppm

9%

CFC-11

not invented yet

0.28 ppm (1990)

--

CFC-12

not invented yet

0.48 ppm (1990)

--

*note: table updated from the 2007 International Panel on Climate Change's Summary for Policymakers

During those same time periods, the human population of the planet increased
from 760 million people in 1750 to 5.3 billion people by 1990.

HOW DO YOU THINK THIS AFFECTED THE AMOUNTS OF GREENHOUSE GASES?

What other sources of greenhouse gases can be associated with increasing human
population growth? Refer to the chart above for help.

The amount of carbon dioxide in the atmosphere has been increasing rapidly, as has
methane, which traps heat 20-30 times more efficiently than carbon dioxide. One CFC
molecule traps 20,000 times the heat of one carbon dioxide molecule.

There is much concern about the negative effects on our climate which can be
produced by these atmospheric changes. The increase in the amount of heat trapped by
the greenhouse effect due to higher greenhouse gas concentrations will make the earth’s
climate warmer than it would otherwise be.

This is called global warming.

none for this page

Herons nest in large groups called heronries.

  1. Introduction
  2. Essential Questions
  3. Global Climate Change
  4. Are Sea Levels Rising?
  5. Subsidence and Erosion in the Basin
  6. Activity: Thinking at Right Angles
  7. Activity: Linking Lake Factors
  8. Hurricanes
  9. Activity: Subsidence and Erosion
  10. Activity: C-Mail
  11. Activity: The Pontchartrain Picayune
  12. Activity: Multimedia Presentation
  13. Activity: Help! I'm Up to my Hips in Water!