The greenhouse effect and global warming

For teachers
This content is for teachers
For students
This content is for students
For technicians
This content is for technicians

A garden greenhouse keeps plants warmer than they would be outside. It does this because the glass traps some of the Sun’s radiation energy. The atmosphere keeps the Earth warm in a similar way. Without the greenhouse effect the earth would be about 33 °C cooler than today’s pleasant average of 15 °C. Greenhouse gases include carbon dioxide, oxides of nitrogen, methane, chlorofluorocarbons (CFCs) and water.

Questions

1. If the greenhouse effect did not exist, what would the normal temperature of the earth be?
2. What do you think is meant by global warming?
3. List all the things you can think of that give off greenhouse gases – eg cars.

Looking at the data

Temperature changes over the last century

Study the graphs, published by the International Panel of Climate Change (IPCC) and then answer the questions. These are temperatures above and below the average for the period 1961–1990.

1980–2000 data

Global average temperatures for 1980-2000

1. Describe how the temperature of the earth has changed over the period 1980-2000.
2. By how much has the temperature changed in that period?
3. Draw a sketch graph to show what you expect the average temperature to change by over the twenty years from 2000–2020.

Global average temperatures for 1940-1960	Global average temperatures for 1960-1980

4. Compare how the temperature of the earth changed between 1960 and 1980 and between 1940 and 1960.

5. Based on the new information from question 4, draw a second sketch graph to show what you expect the temperature to change by over the twenty years, 2000–2020.

For more information see the USAEPA website.