The Enhanced Greenhouse Effect

Question 1

what is the greenhouse effect?

Answer 1

• the sun emits radiation which travels through space
• some is reflected by the earth’s atmosphere but some passes through and is absorbed by the surface of the earth
• this warms the earth, which then emits infra-red (IR) radiation
• some IR radiation passes through the atmosphere into space, but some gases in the atmosphere absorb the IR radiation, preventing it from escaping back into space
• this leads to more energy being held by the atmosphere, heating it

Question 2

which gases cause the enhanced greenhouse effect?

Answer 2

• water vapour
• carbon dioxide
• methane
• nitrous oxides
• CFCs

Question 3

what would happen without the greenhouse effect?

Answer 3

the entire planet would be frozen - it is essential for life on earth

Question 4

what has suggested that the Earth has been through cycles of global warming and cooling?

Answer 4

records from ice cores and fossilised tree rings

Question 5

what is the name for the greenhouse effect caused by human activity?

Answer 5

enhanced greenhouse effect

Question 6

what do humans do to cause a source of carbon dioxide?

Answer 6

• burning fossil fuels
• slash and burn forest clearance

Question 7

what do humans do to cause a source of methane?

Answer 7

• generated by bacteria in anaerobic (low oxygen) conditions, for example:
• ruminants such as cattle produce large volumes of methane from the anaerovic activity of bacteria in their gut - this largely comes out from their mouths
• bacteria in waterlogged paddy fields for rice cultivation give off methane

Question 8

what do humans do to cause a source of nitrous oxides?

Answer 8

• burning fossil fuels

Question 9

what do humans do to cause a source of CFCs?

Answer 9

• until the 1990s CFCs were used as a solvent for aerosols such as deodorants - they were also used in fridges and freezes
• CFCs were also blamed for the hole in the ozone layer - do not confuse the effect with the greenhouse effect