5.6 Impacts of Climate Change on the Global Hydrological Cycle

Question 1

5.6a Climate change affects inputs and outputs within the hydrological cycle

precipitation

Answer 1

A warmer atmosphere has a greater water-holding capacity

It is argued that the mode of precipitation may be more important than the amount in determining the impacts

Widespread increases in rainfall intensity are expected more than large increases in total amounts

Areas of precipitation increase include the tropics and high latitudes

Areas of precipitation decrease lie between 10° and 30° north and south of the Equator

The length and frequency of heatwaves is increasing in some locations and is resulting in the increased occurrence of drought

With climate warming, more precipitation in northern regions is falling as rain rather than snow

Question 2

5.6a Climate change affects inputs and outputs within the hydrological cycle

evaporation

Answer 2

Evaporation over large areas of Asia and North America appears to be increasing

Transpiration is linked to vegetation changes, which in turn are linked to changes in soil moisture and precipitation

Question 3

5.6b Climate change changing stores and flows

stores and flows

Answer 3

ADD THESE FROM TABLE IN THE HODDER TEXTBOOK

Question 4

5. 6b Climate change changing stores and flows

stores: size of snow and glacier mass

Answer 4

decreasing length of snow-cover season

spring melt starting earlier, causing changes to flows and river regimes

glacier retreat and thinning since the 1970s

less accumulation because more precipitation is falling as rain

a decreasing temporary store

albido effect

Question 5

5. 6b Climate change changing stores and flows

stores: amount of permafrost

Answer 5

deepening of the ‘active layer’ is releasing more groundwater

foundations of buildings built in to the permafrost

Question 6

5. 6b Climate change changing stores and flows

flows: soil moisture levels as well as rates of runoff

Answer 6

increased surface runoff (infiltration excess and saturated) during periods of intense precipitation

Question 7

5. 6b Climate change changing stores and flows

flows: stream flow

Answer 7

affected by changes to snowmelt

more low flows (drought) and high flows (floods) occurring

Question 8

5. 6b Climate change changing stores and flows

stores: lakes, reservoirs and wetland storage

Answer 8

a

Question 9

5.6c Climate change increasing uncertainty

factors affecting water supply

Answer 9

Increases in annual temperature lead to greater evaporation from surface water and reservoirs in summer, although spring discharge may increase

Greater rates of evapotranspiration, desiccation of forest stores

Impact of oscillations, e.g. ENSO, is leading to increasingly unreliable patterns of rainfall, e.g. less predictable monsoons

More frequent cyclone and monsoon events threaten water supplies intermittently

Increased intensity and frequency of droughts as a result of global warming and oscillation is issue for rain-fed agriculturalists

Depleted aquifers lead to problems with groundwater

Decreasing rainfall in many areas as a result of global warming

Loss of snow and glaciers as a store threatens many communities in mountain ares, e.g. Himalayas

Question 10

5.6c Climate change increasing uncertainty

short term oscillations

Answer 10

ENSO cycles

Question 11

5.6c Climate change increasing uncertainty

global warming

Answer 11

a

Question 12

5.6c Climate change increasing uncertainty

predicting water supplies

Answer 12

• distinguishing between the impacts of long-term climate change and those of the short-term oscillations associated with El Niño events
• ENSO cycles are associated both with extreme flooding in some parts of the world, and extreme drought in others
• important unknowns to be taken into account, (such as possible advances in water technology) and factors related to the demand side, (such as population growth and the rising tide of global development)