2.2 - Australian Drought 'The Big Dry'

Question 1

What are La Niña conditions?

Answer 1

• Same as normal but more extreme

Question 1

What are normal conditions in the Pacific?

ENSO cycle

Answer 1

• HP in S America, LP in Australia
• Warm moist air in Australia rises = rainfall
• Dry conditions in S America
• Warm water in Australia, cold water in S America = upwelling of nutrients etc

Question 2

What are El Niño conditions?

Answer 2

• Reverses
• High pressure in Australia, low in S America
• Dry conditions in Australia, wet in S America
• Cold water in Australia, warmer in S America = less upwelling of nutrients

Question 3

‘The Big Dry’

Answer 3

• 12 years (1997-2009)
• Annual rainfall 12.4% below mean
• Murray-Darling Basin felt heaviest impact - agricultural heartland
• Disastrous impact on wheat, wool, meat exports
• Prevailing El Niño conditions explain 2/3 of rainfall deficit but also human causes

Question 4

Human causes

Answer 4

• 90% og. vegetation removed = reduced transpiration = reduced precipitation = reduced SRO so increased GW consumption
• Anthropogenic climate variability adding to natural variabilities
• Groundwater extraction

Question 5

Why is there conflict?

Answer 5

• 3.5 million people depend on Murray-Darling basin
• Introduction of water cap overshadowed by illegal overuse by farmers
• Conflict with environmentalists over wetland water availability