Environmental Interactions - greenhouse gases

Question 1

how does the earth get warmed?

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 earth’s surface
• this warms the earth, which then emits infra-red (IR) radiation

Question 2

what happens to the infra-red radiation which is emitted by the earth?

Answer 2

• 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
• gases which cause this effect are water vapour, carbon dioxide, methane, nitrous oxides and CFCs

Question 3

why is it called the ‘greenhouse effect’?

Answer 3

• this is because greenhouses work on a similar principle and so this effect was dubbed the ‘greenhouse effect’

Question 4

why is the ‘greenhouse effect’ needed?

Answer 4

• it is essential for life on Earth, without it the entire planet would be frozen

Question 5

what is the ENHANCED greenhouse effect?

Answer 5

• because the greenhouse effect is a natural effect of gases in the atmosphere, any extra greenhouse effect caused by human activity is called the enhanced greenhouse effect

Question 6

what is the relationship between human activity and the concentration of water vapour in the atmophere?

Answer 6

• it is difficult to measure the extent to which human activity increases the concentration of water vapour in the atmosphere
• at any rate, this varies considerably season by season
• however it is clear that human activity does increase the concentration of other greenhouse gases in the atmosphere

Question 7

how does human activity act a source to CO2?

Answer 7

• burning fossil duels
• slash and burn forest clearance

Question 8

how does human activity act a source to methane?

Answer 8

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

Question 9

how does human activity act a source to nitrous oxides?

Answer 9

• burning fossil fuels

Question 10

how does human activity act a source to CFCs?

Answer 10

• until the 1990s, CFCs were used as a solvent for aerosols such as deodorants and they were also used in fridges and freezers
• CFCs were also blamed for the hole in the ozone layer DO NOT CONFUSE THIS EFFECT WITH THE GREENHOUSE EFFECT!

Question 11

what are the potential effects of global warming?

Answer 11

• melting of polar ice caps
• destruction of habitats
• drought and desertification
• increased extreme weather events
• spread of disease
• change in crops
• increase in hear related illnesses and deaths

Question 12

explain the melting of polar ice caps.

Answer 12

• if ice shelves over land melt, such as over Greenland and Antarctica , this will lead to sea level rises, causing flooding n coastal regions worldwide

Question 13

explain the destruction of habitats.

Answer 13

• for example, grassland may turn to desert (desertification), leading to the loss of habitat for resident species
• this could lead to the extinction of species

Question 14

explain drought and desertification.

Answer 14

• can lead to crop failure and therefore to food shortages and famines

Question 15

explain increased extreme weather events.

Answer 15

• extreme weather event such as hurricanes could become more frequent as there is more energy present in weather systems due to global warming

Question 16

explain the spread of disease.

Answer 16

• as the planet warms it will be possible for disease carrying organisms such as mosquitos to survive in a wider range of countries
• this means diseases such as malaria and dengue fever are likely to become more common

Question 17

explain the change in crops.

Answer 17

• as areas warm it will become possible to grow different crops (e.g. olives and grapes in Southern England)
• this will be beneficial to some countries

Question 18

explain the increase in heat related illnesses and deaths.

Answer 18

• in recent years, there have been increases in death rates in the elderly associated with heat waves
• this may become more common