Climate change and the hydrological cycle

Question 1

What are the impacts of climate change on 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 degrees 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

What are the impacts of climate change on evaporation and evapotranspiration?

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 changed is soil moisture and precipitation.

Question 3

What are the impacts of climate change on soil moisture?

Answer 3

Uncertain, as soil moisture depends on many factors, of which climate is only one.
Where precipitation is increasing, it is likely that soil moisture will also increase.

Question 4

What are the impacts of climate change on surface runoff and stream flow?

Answer 4

More low flows (droughts) and high flows (floods)

Increased runoff and reduced infiltration

Question 5

What are the impacts of climate change on groundwater flow?

Answer 5

Uncertain, because of abstraction by humans

Question 6

What are the impacts of climate change on reservoir, lake and wetland storage?

Answer 6

Changes in wetland storage cannot be conclusively linked to climate change.
It appears that storage is decreasing as temperatures increase.

Question 7

What are the impacts of climate change on permafrost?

Answer 7

Deepening of the active layer is releasing more groundwater.

Methane is released from thawed lakes may be accelerating change.

Question 8

What are the impacts of climate change on snow?

Answer 8

Decreasing length of snow-cover season
Spring melt starting earlier
A decreasing temporary store

Question 9

What are the impacts of climate change on glacier ice?

Answer 9

Strong evidence of glacier retreat and ice sheet thinning since the 1970’s.
Less accumulation because more precipitation falling as rain.
A decreasing store.

Question 10

What are the impacts of climate change on oceans?

Answer 10

More data on surface temperatures needed.
Where there is ocean warming, there will be more evaporation.,
Possibly ocean warming leads to the generation of more cyclones.
Storage capacity being increased by meltwater
Rising sea level.