5-13 The Greenhouse Effect

The Earth's climate is in constant change.  The climate of the Earth has changed over millions of years with ice ages, long warming periods, volcanic eruptions, orbital changes, and energy changes in the Sun.  Beginning in the 18th century with the Industrial Revolution, humans have significantly contributed to the composition of the Earth's atmosphere.  All these things are influencing the Earth's climate.

The burning of fossil fuels, as in coal and gasoline, has created high concentrations of heat-trapping "greenhouse gases" in the atmosphere.  These gases prevent heat from going into space.  Deforestation, the cutting of many trees, also contributes to the greenhouse effect.  Some greenhouse gases are necessary for life on Earth because they keep the planet's surface warmer than it would otherwise be.  But high levels of greenhouse gases cause the Earth's surface to heat up, resulting in a rise in the Earth's surface temperature.

The Earth's average temperature has begun to rise over the past 100 years.  Although the average increase is less than one degree, the warmest years have been during the past decade.  Other noticeable changes are occurring in rainfall patterns, snow and ice cover at the North and South Poles, and changes in the sea level.

Climate models are beginning to predict increases in the Earth's surface temperature of 3 to 7 degrees.  Most scientist agree that human activities are changing the composition of the atmosphere and that increases in the greenhouse gases will change the Earth's climate.  Some predict the changes could melt the Earth's ice caps causing a rise in sea level.  This rise in sea level will effect many cities built along the ocean's shorelines.  Many of these cities could be underwater in the future.

The reduction of carbon dioxide gases from the burning of fossil fuels can help reduce the greenhouse effect but this will take the efforts of many governments and communities around the world.  Everyone will need to pitch in by searching out ways to become "green" in their daily activities.

The Environmental Protection Agency has a web site that provides suggestions about " What You Can Do" to reduce your contributions.

1.  The Earth's climate changes because of

volcanic eruptions.

orbital changes.

human activity.

All of the above

2.  Fossil fuels are

hydroelectric.

solar energy.

coal and gasoline.

All of the above

3.  The burning of fossil fuels can create high levels of

oxygen.

greenhouse gases.

snow fall.

None of the above

4.  The Earth's average surface temperature has

begun to rise over the past one hundred years.

begun to fall over the past one hundred years.

leveled off over the past one hundred years.

All of the above

5.  Climate models predict

a fall in the Earth's surface temperature.

surface temperatures will remain constant.

a rise in the Earth's surface temperature.

None of the above

6.  A rise in the Earth's surface temperature may cause

ice caps to melt.

sea levels to rise.

changes in precipitation.

All of the above

7.  A reduction in carbon dioxide gas from fossil fuels will

raise the Earth's surface temperature.

reduce greenhouse gases.

increase the melting of ice caps.

All of the above

8.  Increases in human activity influences the Earth's .

9.  If the Earth's ice caps melt and sea levels rise, many cities on the ocean's shoreline could be .

10.  , the cutting of many trees, also contributes to the greenhouse effect.