U2 T2

Question 1

The major anthropogenic sources of greenhouse gases

Answer 1

• Carbon dioxide
• Methane
• Oxides of nitrogen
• Chlorofluorocarbons (CFCs)
• Tropospheric ozone

Question 2

Carbon dioxide - human activity

Answer 2

Combustion of fossil fuels, deforestation (Deforestation –>tropical rainforests => stops photosynthesis occurring, so that less atmospheric carbon dioxide is fixed into organic material, + likely to be more organic material being burned or decomposed –> + CO2 is being released into the air

Question 3

Methane - human activity

Answer 3

Anaerobic bacteria in paddy fields, landfill sites and the intestines of livestock. Methane is produced during the formation of fossil fuels and released by the ventilation of coal mines, leaks from natural gas field and pipelines

Question 4

Oxides of nitrogen - human activity

Answer 4

Oxygen and nitrogen from the air react at high temperatures a in vehicle engines and power stations. They are then released into the atmosphere in the exhaust gases

Question 5

Chlorofluorocarbons (CFCs) -human activity

Answer 5

CFCs were used as aerosol propellants, fire extinguishers, refrigerants, solvents and in expanded foam plastics

Question 6

Tropospheric ozone - human activity

Answer 6

Produced by the photochemical breakdown of NO2 and subsequent reaction with oxygen

Question 7

Carbon dioxide - approximate relative effect per molecule

Answer 7

1

Question 8

Methane - approximate relative effect per molecule

Answer 8

25

Question 9

Oxides of nitrogen - approximate relative effect per molecule

Answer 9

2000

Question 10

CFCs - approximate relative effect per molecule

Answer 10

5600

Question 11

Tropospheric ozone - approximate relative effect per molecule

Answer 11

25000

Question 12

Consequences of global climate change

Answer 12

• sea level rise (thermal expansion + melting land ice)
• changes in climate ( wind patterns + precipitation)
• Ocean current changes (el niño + La niña (+ the North Atlantic Conveyor))
• Ecological changes (temperatures + etc)

Question 13

Explain what temperature rise may cause to plants

Answer 13

Temperature rise may cause plants to grow faster. This could provide more food for herbivores such as butterflies and moth caterpillars. But many plants produce toxins that build up in their leaves to protect them from being eaten. If plants growth begin earlier in the year, the toxins may build up sooner, which could kill the caterpillars.

Question 14

Explain what could happen to plants in drier period

Answer 14

Plants with shallow roots may cope less well with drier periods than those with deeper roots.

Question 15

Explain how ecological changes , such as changes in temperatures, could affect hibernating animals

Answer 15

Species that hibernate may benefit by being able to feed for more of the year, or suffer by being disturbed more frequently when they should be asleep

Question 16

Precipitation changes may cause wetland habitats to…

Answer 16

Enlargement or shrink

Question 17

What may happen to dormouse hibernation?

Answer 17

Dormouse hibernation may be disturbed by warmer winters, causing them use up stored fat. They may starve before spring arrives, when they could start feeding again.

Question 18

What could happen to oak trees in drier period?

Answer 18

Oak trees have deep roots and will be able to survive droughts better than shallow- rooted beech trees,whose actually dry leaves may die during dry weather.

Question 19

Explain how geese migration may changes

Answer 19

Geese that breed in Arctic areas during the summer may not need to migrate so far south if winters become warmer

Question 20

What could happen to coastal salt marsh habitats if sea levels rise?

Answer 20

A rise in sea level would flood the coastal salt- marsh habitats needed by many wading birds, such as dunlin

Question 21

The distribution of species may change as conditions change and they colonise areas that have become suitable. For some species this may not be possible for the following reasons

Answer 21

• they may colonise new areas more slowly than they disappear from their old range, this is very likely for species that grow slowly, such as trees
• suitable areas may not be available
• human land use may block movement
• species live in interdependent communities of species. All the species will not be able to move at the same speed

Question 22

Say a few reasons why it is difficult to predict climate change

Answer 22

• difficult to tell whether an event is caused by human actions or not
• difficult to identify trends are there may be limited historical data (some cannot be trusted)
• many natural effect are interconnected so one change may have unexpected effects
• somme changes are very slow
• may occur at different locations at different times
• we do not fully understand how all the Earth’s climate systems work

Question 23

Say 5 positive feedback mechanism about raised temperatures

Answer 23

• increase the rate of composition
• reduce size the area of ice and snow –> less sunlight is reflected
• methane can eventually be released from methane hydrate in marine sediments
• melting permafrost releases methane gas bubbles that were trapped in ice
• forest + areas with peat soils to become drier -> fires more often and loger

Question 24

2 negative feedback mechanism for raised temperatures

Answer 24

• increased rate of photosynthesis –> store more carbon in biomass
• increase evaporation –> formations of low level clouds –> increase albedo

Question 25

Explain what is El Niño year

Answer 25

In some years the winds that create the surface currents change direction so that the ocean currents reverses. This prevents the nutrients upwelling off South America so that rich food web collapses. Rainfall in eastern Australia drops while coastal parts of South America that are normally desert may have heavy rain and floods.

Question 26

Explain, La Niña year

Answer 26

Name given to periods when the normal currents flows more strongly and the normal climate is exaggerated. During these periods east coast Australia gets more rain than usual while the west coast of South America gets less.