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useful for global systems 2.2.1-Changing Landscapes: Sea Level Change -…
useful for global systems 2.2.1-Changing Landscapes: Sea Level Change
Kiribati & Sea Level Rise:
Background: 32 atolls - most barely above 2m sea level - Tarawa, 1/2 of residents live here (60,000) - Gov lacks funds for long-term infrastructure
Solutions:
Residents build coral walls to protect to increase in floods & storms
Floods cause sanitation issues
Gov purchased land on Fiji for re-housing
Mangroves planted to act as buffer against storm + prevent soil erosion
Every family supplied with water filter from international aid
Problems:
Livable land = sparse - migration to Tarawa = over-popualtion = over-crowding = disease & no jobs
Second largest village on island of Abaiang now uninhabiated as flooded by sea level rise
Groundwater used for drinking from wells now flooded with sea water = undrinkable
Population concentration in certain areas led to increase is fishing as job - leading to lack of stocks
Signs of degradation in coral reefs becuase of pollution
Could see islands washed away in next 50 years
Impacts of sea level rise on UK:
Areas of Eastern England face coastal flooding by 2050
Intense low pressure = sea driven ashore by strong winds - if coincides with high tide - effects = devastating
Storm surge 1953: wrecked towns in East of England - killed 300+ - see minimal on Happisburgh
Hemsby to small for gov flood defence - nothing will be done to stop storms destorying houses built on sand dunes
Flood damage cost UK £1.3b year
Solutions in UK:
Intro better flood warning sys
Modify buildings/homes to help withstand floods
Construct buildings aboev flood level
increase flood spending - has fallen 20% (in real terms) since 2010
More flood barriers (permanent & temp)
Isostatic Change
Sea level change due to increase (sea levels fall) or decrease (sea levels rise) in height of the land
Local sea level change
Compression: Occured in ice age as ice on land weighed land down slightly causing sea level to rise
Decompression/Isostatic rebound: when ice melted at end of ice age land v. slowly began to rise (Dongarie, Isle of Arran, Scotland still rebounding from last ice age)
Eustatic & Isostaic processes can occur at the same time
Eustatic Change:
Sea level change due to change in the volume of water in oceans or shape of ocean basin
Always global effect
Shape of basins change due to tectonic movement - if basin become larger volume of oceans become larger but overall sea level decrease - same amount of water in larger space
In ocean basin reduces, sea levels rise
At start of ice age, temp falls water freezes in glaciers inland and goes into clouds and falls as snow then gets compressed as ice - water taken out of ocean - fall in sea level - happening over thousands of yrs
Ice age ends enters inter-glacial period, temps rise water stored in glaciers inland melts and re-enters hydrological cycle, increasing sea level - warming from cc is also exacerbating this (arguably seeing sea level rise due to eustatic change at greater level than ever before seen)
Facts:
when freshwater ice (Greenland Ice Sheet) more water added to oceans - however, melting of ice caps has no effect on sea level rise as sea ice is already displacing oceans
During 20th century sea levels rose 20cm, if greenhouse gas emissions dont slow may rise by 41cm by 2080
Impacts in the Maldives:
Could see 80% of 1000 islands submerged within 100 yrs = 370,000 people homeless
Erosion of sand banks - 4 homes collapsed
Rise in sea temp = signif as affects fishing stocks (second biggest industry)
Tourism directly commands 1/3 of GDP - slow destruction of reefs = impact of tourism diving + beaches
Solutions for Maldives:
2008 - President Nasheed produced plan to buy up land for citizens to relocate should islands submerge
New artifical islands built using sand from sea bed - built well above 2m
Affordable social housing on other islands for specific groups e.g those displaced due to sea level rise