Lesson 18: Degradation of the Water Cycle Flashcards
Describe how rising temperatures will affect precipitation patterns
-Existing weather patterns will get stronger (wet places will get wetter and dry places will get drier).
-This is because warm air traps more moisture
Define river regimes
‘the annual variation in discharge or flow, at a particular point’
Describe how rising temperatures will affect river regimes
-Increased temperatures = more snow/glacier melt, and an increased in the amount and intensity of precipitation
-Increased evapotranspiration - more precipitation
Describe how rising temperatures will affect water stores
-Cryosphere has been losing mass as ice sheets and glaciers melt.
-Arctic temperatures have risen twice as fast as global averages in the past 20 years.
-This means huge implications for ocean currents, air -circulation, sea level rise and flooding.
Where is the Yukon?
A territory in the far northwest of Canada and a significant part of it lies within the Arctic Circle
Between which years did winter precipitation increase in the Yukon?
1950-98
What is happening to river regimes in the Yukon?
Snowmelt is occurring earlier and snow cover is decreasing. Brings earlier peak flows to most river basins
By what % did the total ice area shrink by in the Yukon between 1958-2008?
22%
By what % have inflows increased by in the Yukon since 2000?
39%
What has happened to the ice sheets in Antarctica and Greenland in the last 20 years?
Ice sheets have been losing mass
Snow cover is decreasing in extent and thickness
How much have Arctic temperatures risen by in the past few decades?
Risen twice as fast as global averages
How much have temperatures risen by in Alaska and Northern Canada?
3-4 degrees
What could temperatures in the Arctic soon increase by?
Another 4-5 degrees over land and 7 degrees over the ocean
What are the impacts of rising temperatures on the water cycle?
-Warm water flowing into the Arctic from the Pacific and Atlantic.
-Rising local temperatures – increased evaporation.
-Shrinkage of sea ice; the Arctic ice cap averages only 3m thick and melting is increasing faster than anticipated.
-Run-off of fresh, cold water which will alter marine ecosystems and food chains dependent on the saline waters; predicted to affect areas outside the Arctic Ocean by 2100.
-Funnelling of more cold water into the oceanic conveyor belt
What are the impacts of rising temperatures on the carbon cycle?
-Increased or new emissions of: CH4 (methane) from destabilisation of wetlands and sea floor deposits containing methane hydrate
-Increased or new emissions of: mainly CH4 and some CO2 from thawing permafrost.
-Increased or new emissions of: CO2 from increased forest fires as boreal forests dry out; they may also absorb CO2 and CH4 from the atmosphere
Where are mangroves found?
Along tropical and sub-tropical coasts of Africa, Australia, Asia and the Americas
How much carbon do mangroves sequester per hectare, per year?
1.5 metric tonnes
How is it that very little carbon is respired into the atmosphere by mangroves?
Their soils are anaerobic (without oxygen), bacteria and microbes can’t survive without oxygen so decomposition of plant matter is slow
In what ways do mangroves protect coastlines?
They absorb and disperse storm surges
How much of global mangrove forests have been lost since 1950?
50%
What percentage of forests have been lost due to draining and clearing mangrove forests for tourism, shrimp farming and aquaculture?
25%
How many people does fishing support?
500 million
Where do 90% of these people live?
Developing countries
Fish provide 16% of the annual protein consumption for how many people?
3 billion people
