Human Impact on Air ResourcesChapter 26.3

Global Impacts of Air PollutionA. Global Warming

- Greenhouse Effect - a natural process in which atmospheric gases trap thermal energy.

- over time, the Earth’s climate has undergone both warming and cooling trends.

- the main greenhouse gas carbon dioxide, however, has been increasing due to the increased use of fossil fuels.

- Scientists believe this rise in CO2 has caused the avg. surface temperature of the Earth to rise 0.5oC over the past century.

Video – Greenhouse Effect (2:15 min)

Question!

What is the main greenhouse gas?

B. Photochemical Smog- a yellow-brown haze that forms around heavily populated areas.- created by the reaction of car exhaust and oxygen in the atmosphere.- produces ozone (O3) which is harmful to breathe.

Video – Future Car (5:01 min)

Question!

What is the main cause of smog?

C. Ozone Depletion- ozone (O3) in the upper atmosphere protects the Earth from harmful UV light from the Sun.- chemicals called CFC’s were used in the 1960’s - 1980’s as a refrigerant in air conditioners, refrigerators, and freezers.- Scientists discovered that these chemicals were damaging the ozone layer and they are now banned from use in most of the world.- the ozone “hole” should eventually be repaired in a few hundred years as the CFC’s drift into space.

Video – Ozone Hole (5:04 min)

Question!

What chemical kills the ozone layer?

D. Acid Precipitation- burning fossil fuels that contain sulfur releases toxic sulfur dioxide and nitric oxide into the air.- these combine with moisture in the air to produce sulfuric and nitric acids.- these acids harm aquatic life, plant life, dissolve nutrients from the soil, and increase weathering of buildings and monuments.- most acid rain in the US is from the burning of coal in electrical power plants.

Question!

What kind of acid is found in acid rain?

E. Reducing Air Pollution- Government regulations have been very effective in reducing emission of air pollutants.- These include:

- emission standards for coal burning power plants and new cars.- banning the use of CFC’s.- encouraging the use of alternative energy sources.