Chapter 1:  Earth’s Changing Atmosphere

Big Idea:  Earth’s atmosphere is a blanket of gases that supports and protects life. 

Key Concept 1.4:  Human activities affect the atmosphere.

I.  Vocabulary

A.  air pollution- smoke and other harmful materials that are added to the air and spread by wind from place to place

B.  particulates- tiny particles or droplets that are mixed in with air

C.  fossil fuels- fuels formed from the remains of prehistoric animals and plants

D.  smog- a combination of smoke and fog

II.  Human activity can cause air pollution

         A.  Types of pollution

                  1.  Pollutants-  types of air pollution

2.  Gas pollutants:  carbon monoxide, methane, ozone, sulfur oxides, nitrogen oxides

a.  These are pollutants only when they are harmful

b.  Ozone gas is good in the stratosphere, but harmful to breathe if in the troposphere

                  3.  Particle pollution:  particulates can be easier to see than gas pollutants

                           a.  Include:  dust, dirt, pollen, and sea salt, all carried by the wind

         B.  Pollution in cities/suburbs

                  1.  Most comes from the burning of fossil fuels (oil, gasoline, coal)

                           a.  In the 1800s, coal burning (smoke) and weather conditions (fog) produced smog

b.  Today’s smog:  sunlight causes the fumes from gasoline, car exhausts, and other gases to react chemically, forming new pollutants like ozone (these can create a brownish haze)

         C.  Effects of pollution

                  1.  Health problems:  eye, nose, throat and lung irritation

                           a.  Foul smells can make it hard to breathe

                           b.  Gases or particulate chemicals can move from your lungs to other body parts

                           c.  Over time:  lung disease

                           d.  Especially dangerous for young children, elderly folks, and those who have asthma

                  2.  Environmental problems

                           a.  Particulates can stick to plants, buildings, and other objects outdoors, damaging them

                           b.  Dusty air or dust storms can darken the sky and make seeing difficult

c.  Particulates can be carried high into the atmosphere, where they can reflect or absorb sunlight and even affect the weather

d.  Rain may clear the air of pollutants, but then they are carried to the ground

                  3.  Controlling pollution

                           a.  Smog alerts:  cities may ask people to limit their driving

b.  National, state, and local governments work together to reduce air pollution and protect people from its effects

c.  Clean Air Act- limits the amount of air pollution that factories and power plants are allowed to produce;  sets rules for making car exhausts cleaner

d.  The Environmental Protection Agency (EPA) measures air pollution and works to enforce laws passed by Congress

III.  Human activities are increasing greenhouse gases

         A.  Sources of greenhouse gases    (Remember:  most greenhouse gases occur naturally)

                  1.  Carbon dioxide

                           a.  From use of fossil fuels in power plants, cars, factories, and homes

                  2.  Methane

                           a.  From cattle and other livestock, bacteria in rice fields, and landfills

                  3.  Nitrous oxide

                           a.  From fertilizers and chemical factories

                  4.  Water vapor

                           a.  Comes mostly from the weather, which can be altered by pollution

         B.  Global Warming

                  1.  CO2 can stay in the atmosphere for over 100 years, so it just keeps adding up

                  2.  The air contains 30% more CO2 now than it did in the mid 1700s (+0.4% per year)

                  3.  Temperatures have risen in recent decades

                           a.  It is hard to know how much of a part greenhouse gases have played in this

b.  Scientists make computer models to understand their effects and to predict what might happen in the future

c.  These models predict that the average global temperature will continue to rise another 2-10 degrees F by the year 2100—this could have big effects

d.  Food sources, water amounts, and human health could all be affected

         C.  Reducing greenhouse gases

                  1.  Global warming is a worldwide issue

2.  Kyoto Protocol- an international agreement to limit the amounts of greenhouse gases, requires nations to limit emissions to 1990 levels

3.  The United States is the only nation that has not ratified the protocol.  We also have not committed to any CO2 reduction

4.  Exploration of alternative energy sources

IV.  Human activities produce chemicals that destroy the ozone layer

A.  Chlorine, when released and carried into the stratosphere, can start a series of chemical reactions that break ozone apart into oxygen

B.  Chlorofluorocarbons have been used in cooling systems, spray cans, and foam for packaging

         1.  These chemicals break down in the stratosphere and release chlorine and other ozone enemies

C.  The Montreal Protocol

1.  Since 1987, over 180 nations have signed to comply with a plan to stop making and using ozone-harming chemicals

         2.  If the protocol is followed, ozone levels will return to normal in 50 years