Topic 4.4 Climate Change

Question 1

Greenhouse gases

Answer 1

makes up less than 1% of the earth’s atmosphere / the gases with the largest warming effect within the atmosphere are water vapor and carbon dioxide

Question 2

Two factors to determine how much impact a greenhouse gas will have in warming the atmosphere

Answer 2

Ability to absorb long-wave radiation

Concentration within the atmosphere

Question 3

The greenhouse effect

Answer 3

natural process whereby the atmosphere behaves like a greenhouse to trap and retain heat

Question 4

How the greenhouse gas effect works

Answer 4

The greenhouse effect functions to trap heat within the atmosphere and hence prevent rapid temperature fluctuations

• Incoming radiation from the sun is shorter wave radiation (ultraviolet radiation and the visible spectrum)
• The surface of the Earth absorbs short wave radiation and re-emits it at a longer wavelength (i.e. infra-red / heat)
• Greenhouse gases absorb and re-radiate this longer wave radiation and hence retain the heat within the atmosphere

Question 5

Increase of greenhouse gas emission

Answer 5

Deforestation and increased farming / agriculture

Question 6

Main cause of greenhouse gas

Answer 6

combustion:

When fossil fuels (e.g. coal, oil, gas) are combusted to release energy, carbon dioxide gas is released as a by-product

The increased reliance on fossil fuels following the industrial revolution has resulted in ~38% increase in CO2 levels

There are now efforts to reduce our reliance on fossil fuels by exploiting alternative energy sources (e.g. solar power)

Question 7

Greenhouse gases impact on global temperatures

Answer 7

it has a pivotal role in determining global temperatures and climate patterns due to their capacity to retain heat

Question 8

The ocean and carbon

Answer 8

The oceans are a major carbon sink and absorb roughly a third of all human produced (anthropomorphic) CO2 emissions

Question 9

Carbon dioxide in the ocean

Answer 9

• Carbon dioxide will combine with water to form carbonic acid, which dissociates into hydrogen ions and hydrogen carbonate
• H+ ions will lower the ocean pH (acidification) and will also combine with free carbonate ions to form more hydrogen carbonate
• With less free carbonate ions in the water, marine organisms are less able to produce calcium carbonate (via calcification)
• Calcium carbonate is used to form the hard exoskeleton of coral and is also present in the shells of certain molluscs
• Hence increasing concentrations of dissolved carbon dioxide threatens the viability of coral reefs and certain molluscs

Question 10

CO2 Emissions and Ocean Acidification

Answer 10

Rising levels of atmospheric carbon dioxide are causing a decrease in the pH of ocean water (ocean acidification)

• An increase in the concentration of H+ ions means there are less free carbonate ions available for calcification
• Shells and coral exoskeletons are also likely to begin to dissolve when ocean conditions are more acidic
• Experiments have shown that increasing water acidity correlates with the significant thinning of shells over several weeks
• Corals, sea urchins and shelled molluscs do not exist in regions with high levels of dissolved CO2 (e.g. near hydrothermal vents)