5.6 Uncertainty

Question 1

How is precipitation changing with climate change

Answer 1

• As climate change mode of precipitation is changing more than the mean
• Climate change is causing increases intense rainfall events and droughts
• more precipitation now falls as rain,not snow. This is consistent with warmer atmosphere with a greater water-holding capacity

Question 2

How is climate change affecting the input of snow

Answer 2

• Due to climate change there is a decrease in the length of the snow cover season
• There is earlier spring melting
• This has led to corresponding changes in river regimes

Question 3

How is climate change affecting outputs like evaporation and evapotranspiration

Answer 3

• There is an increase in actual evaporation
• This is however counteracted by an increase in cloud cover from increased water vapour
• Transpiration changes as vegetation productivity changes->When climate changes vegetation is more productive as soil moisture and precipitation increase

Question 4

How will climate change affect run off and stream flows

Answer 4

• With climate change there are more climatic and hydrological extremes with higher incidence of high and low flows ( droughts and floods)
• An accelerated cycle with more intense rainfall will increase run off rates and reduce infiltration ( 1 degree rise in temperature could increase global run off by 40%)

Question 5

How does climate change affect groundwater flow

Answer 5

-There is no definitive link with climate change as human abstraction is the dominant influence on supplies

Question 6

How does climate change affect soil moisture

Answer 6

Soil moisture is linked to many factors

-When precipitation is increased, it is likely that soil moisture will increase

Question 7

How will reservoirs,lakes and wetland storage be affected by climate change

Answer 7

• Regional variations in lakes and reservoirs have been linked to regional changes in climate
• Wetlands are also affected by the decreased water volumes and higher temperatures climate change brings

Question 8

How is permafrost linked to climate change

Answer 8

• increasing air and ocean temperatures are leading to permafrost degradation at higher latitudes
• The deepening of the active layer due to permafrost melt impacts groundwater supplies and releases methane from thaw lakes leading to positive feedback and accelerated change

Question 9

How has climate change impacted upon ice stores

Answer 9

• Glaciers have been retreating globally since the little ice age with down-wasting( thinning of glacier due to melting of ice) accelerating
• This is due to rapid temperature increase and changes to precipitation type

Question 10

How has climate change impacted the ocean

Answer 10

• In areas of ocean warming increased evaporation will occur
• It can also create increased cyclone generation

Question 11

What type of rainfall occurs in the Sahel normally

Answer 11

• Rainfall is variable in the Sahel from 100mm-600mm per year
• annual rainfall falls up to 90% in the west African monsoon from July to September
• In the 1970s and 1980s the rains failed ( a decline of up to 40% between 1950 and 1980)

Question 12

How is climate change affecting the sahels climate

Answer 12

-Due to climate change, the extremes of the sahels climate are becoming more intense ( droughts and floods)

Question 13

How are the extremes being used to benefit though

Answer 13

• The wet years in the Sahel region ( years when floods are bad) provide an opportunity for regreening ( Conversion of dry landscapes to productive farmland)
• Regreening is a restoration technique which is popular in Malawi and Niger which involves increasing wield, regeneration of water retaining vegetation,low cost reforest inn and water harvesting techniques

Question 14

What are the problems caused by the change to the extremes however

Answer 14

• There have been droughts which have caused poverty and civil wars ( in Ethiopia and Eritrea) in counties in the Sahel
• These factors have forced many out of the Sahel and onto marginal land where there has been widespread famine

Question 15

How is climate change causing problems in California

Answer 15

• 40 million Californians are facing problems due to recent variations in rainfall
• In 2014 the Sierra Nevada region experience 3x the normal number of wildfires due to ground dryness
• 2015 marked the 4th year of continuous drought with water rationing imposed

Question 16

What are climate scientists predicting for the future of California

Answer 16

Climate scientists are forecasting intense mega droughts (lasting 30 years with decades long dry periods)
-there is a 50% chance of a mega drought hitting SW California

Question 17

Why is the climate expected to get so much worse in this way

Answer 17

• The climate is predicted to get worse due to rising temperatures leading to increase evaporation and a trend of fall in precipitation
• ‘Buisness as usual’ will not be able to reach future water demands

Question 18

What is the evidence of the problems in California

Answer 18

• Evidence of problems is shown in declining surface run off and moisture levels,
• forest reversion to shrub and grassland
• drops in precipitation levels and groundwater levels by 30%,
• falls in reservoir levels (lake Cachuma was down 9% and water storage was at 77% of average)
• Record low levels of snowpack ice ( a massive problem for California as snowpack meltwater accounts for 1/3 of the water used by Californian cities + towns)

Question 19

What is predicted to happen in the future in terms of flooding

Answer 19

• Climates are predicted to become more extreme and extreme weather will become commonplace
• For every 1 degree of temperature rise, the amount of water that can be held in the atmosphere increases by 7%
• The creates the potential for heavier precipitation - 2010 the wettest year on record created spectacular flooding
• Climate change will interlink with other factors such as land use change and population increase in order to worsen the affects of future flooding
• Winter flooding risk is set to increase by 4 1/2 by 2100

Question 20

What will happen in the future to drought risk

Answer 20

• With a change in temperature, precipitation and potential Evapotranspiration the severity and occurrence of droughts will risen
• Currently the more intense droughts have affected more people (with the droughts in Australia leading to bush fires in the south east and Day zero approaching in drought Ed South Africa
• Droughts are spreading to new areas such as Southern Europe, south western USA and the Sahel region leading to wildfires, famine, damage to the hydrological cycle and desertification
• Summer drought risk is set to increase by 3x by 2100

Question 21

What are the sources of uncertainty when it comes to discussing future climate change projections

Answer 21

• complexity of climate systems
• Natural short term oscillations e.g Noeth Atlantic oscillation such as ENSO (hard to predict) and sunspot cycles
• Biogeochemical positive and negative feedback mechanisms
• Incomplete data sets due to lack of collection

Question 22

How might warmer water caused by climate change negatively

Answer 22

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