28 Water Cycle: Short and Long Term Changes

Question 1

What are inputs/outputs/stores like in the short term for the water cycle?

Answer 1

• In the SHORT TERM: Inputs/outputs/stores fluctuate year to year

Question 2

What are flows/stores like in the short term for the water cycle?

Answer 2

• In the LONG TERM: Flows/stores usually maintain a balance

Question 3

Describe the graph of solar radiation during the day

Answer 3

During the day solar radiation increase till it reaches its peak at midday and then goes down again

Question 4

What is the impact of climate change on the water cycle (long-timescale)?

Answer 4

• Increased evaporation and therefore water vapour in the atmosphere
• More water vapour acts as a greenhouse gas further raising temperatures, increasing evaporation and precipitation
• Increased precipitation will lead to higher runoff and greater flood risks
• Water vapour is a source of energy in the atmosphere releasing latent heat on condensation. More events such as hurricanes and mid-latitude storms become more powerful and frequent
• Accelerated melting of glaciers and ice sheets shrinks the store of water in the cryosphere
• Accelerated melting of permafrost

Question 5

What is the impact of physical factors on the water cycle (Long-timescale)

Answer 5

• Earth’s climate over the last 2 million years has been highly unstable with large fluctuations at regular intervals.
• In the last 400,000 years there have been 4 major glacial cycles (glacial then inter-glacial), each lasting around 100,000 years.
• At the height of the Last Glacial Maximum (18,000 years ago) temperatures in Britain were 5^oC lower and ice was up to 1km thick in Scotland, Wales and northern England.
• During inter-glacials temperatures have been similar to today, but on longer timescales, they have been more extreme e.g. 250 million years ago global average temperatures reached 22^oC (7-8^oC higher than today)