Oceans
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what do oceans and the atmosphere do?
flow to redistribute heat around the globe - driven by surface winds, salinity variations, Coriolis effect and land masses
what is global over turning circulation?
cold, dense waters from N Atlantic and around Antarctica through cooling and ice formation. generally upwelled in S ocean. warm, surface currents flow to complete the cycle (takes 1000years), so deep oceans act as a long term store for heat and CO2 and help dampen global warming.
what causes coral bleaching?
change in ocean temp, runoff and pollution, overexposure to sunlight, extreme low tides
what is coral bleaching?
algae and coral depend on each other to survive (symbiotic relationship), if stressed algae leaves the coral and coral is left bleached and vulnerable
minimum time for coral bleaching?
temp increase of only one degree C for only 4 weeks can trigger bleaching events
what causes sea level rise?
thermal expansion (30%) and water from melted ice sheets(30%) and land water storage reduction(10%)
larsen C ice shelf split from antarctica
2017 5,800sq km
is sea level change new?
no - raised beaches the rate of it now is alot quicker tho
why is sea level rise not evenly distributed?
• gravitational pull • ocean currents and winds • fresh water • El nino
short term causes for sea level change
tides, storms, tectonics (earthquake/tsunami), currents, winds, temp, salinity
long term causes for sea level change
non-uniform weathering, salinity variations, wind shifts, melting ice sheets, changes in land surface
what do the IPCC predict?
rise. rise by 2300 will be less than 1m for radiative forcing corresponding to co2 conc below 500ppm, but 1-3m for 700-1500ppm
what % of coastlines are projected to experience sea level change within 20% of the global sea level change
70%
how much of the worlds population live 150km from the coast
2/3rds
most of the top ? largest cities are near the coast
10
what will the average global ocean rise be with warming of 2degrees C
20cm - more than 90% will experience more risks
what degree rise will see the Maldives flooded and gone
1.5
why else are coastal regions vulnerable?
increase and intensify weather patterns across world
solutions?
shoreline management plans
whats coastal squeeze?
eroding shoreline approaches hard, immobile, structures e.g. sea wall or a cliff