6.3 human activities and the carbon cycle

Question 1

greenhouse effect

Answer 1

The Earth’s natural temperature control system, where shortwave radiation from the sun and long wave radiation re-emitted from the Earth’s surface are trapped by the atmosphere and regulate the Earth’s temperature. Some radiation escapes back out in to space to ensure that the Earth doesn’t heat up too much.

Question 2

fossil fuel combustion

Answer 2

The burning of non-renewable fuels such as coal, oil and gas. This is one of the greatest contributors to enhancing the greenhouse effect.

Question 3

ecosystem

Answer 3

A community of animals, plants and micro-organisms, together with the habitat where they live.

Question 4

shortwave radiation

Answer 4

High energy emissions (e.g. UV light) from the sun which enter our atmosphere along with visible light.

Question 5

longwave radiation

Answer 5

Lower energy emissions radiated by the Earth, in the form of infra red rays.

Question 6

greenhouse gases

Answer 6

Includes carbon dioxide (CO2), methane (CH4), nitrous oxide (N2), tetrafluoromethane (CF4) and sulphur hexaflouride (SF6) (23,500 times more potent than CO2).

Question 7

anthropocene

Answer 7

The current geological era, the Holocene, is also known as this due to the impact humans have had on the Earth (e.g. CO2 has increased by 40% in the last 300 years).

Question 8

CO2 fertilisation

Answer 8

Increased CO2 in the atmosphere should, in theory, increase the rate of photosynthesis in plants (and consequently NPP). But limiting factors, such as nutrient availability, will prevent equivalent rates of plant growth.

Question 9

tundra

Answer 9

Highest density of carbon storage in permafrost, but lowest levels of primary productivity due to cold temperatures

Question 10

tropical rainforest

Answer 10

Highest levels of primary productivity (i.e. plant growth) due to high levels of humidity/rainfall and warm temperatures. Most carbon is stored in biomass above ground.

Question 11

shallow water/oceans

Answer 11

High nutrient inputs and higher light levels lead to higher levels of productivity compared to deeper water.

Question 12

soil erosion

Answer 12

Organic carbon is predominantly stored in surface soil layers, which are easily eroded by surface run off. This is a major threat to carbon storage.

Question 13

climate forcing

Answer 13

Causes/drivers of climate change (e.g. fossil fuel combustion).

Question 14

ocean acidification

Answer 14

Since the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. The pH scale is logarithmic, so this represents approximately a 30 percent increase in acidity.