Sea cliffs and global change Flashcards
What conditions do beaches need to form?
large amounts of coarse sediment delivered by rivers, large areas of shallow depth to reduce wave and tidal energy and a stable coastline over long periods.
What are the stresses placed on organisms that inhabit sea cliffs?
erosive forces of waves and sub-aerial erosion.
salinity stress
water stress
How does salinity affect plants?
High salinity reduces the rates of photosynthesis and root respiration.
where do sea cliffs form?
where the rate of uplift is greater than the rise in sea levels. e.g tectonically active coasts, volcanic islands
or where the rate of erosion is high e.g where sea level is rising rapidly.
What determines a cliffs height and shape?
height is a function of rock strength and relative sea level lowering.
shape is a function of the rock strength and erosional processes.
what are the methods of erosion acting on a sea cliff?
waves - abrasion, hydraulic induced fracturing and physically removing material.
sub-aerial - weathering, bio-erosion, chemical, mass movement
when is wave erosion most effective?
at the mean water level, or in microtidal habitats.
What are Tafoni?
these are features found in sedimentary rocks. formed from the crystallisation of salt between particles. this forces the spaces apart. crystallisation also forms a cement, holding features in place.
What are shore platforms?
these are the gentle sloping surfaces found in the intertidal zone, resulting from previous sea cliff erosion and the removal of debris by waves.
What are the 2 types of shore platform?
sloping and sub-horizontal platforms.
sloping platforms form under weak rocks where there is high energy waves.
horizontal platforms form where there is resistant rock and lower wave energy.
What affects the width of a shore platform?
greater the energy of waves and lower the rock strength, the wider the platform.
How much is sea level predicted to rise and how will this affect parts of the globe?
predicted to rise 20 - 60 cm as a result of thermal expansion by 2100, when incorporating melt water, rise could increase to 1.5 m
a 1 m rise could flood 17% of Bangladesh where 3000 people live per m2, and reduce rice crops by 50% due to salt water intrusion.
Small island nations are further at risk of flooding and contaminated groundwater due to salt water intrusion.
What are dead zones, how will climate change affect these?
dead zones are the result of eutrophication and the subsequent bacterial activity that follows creating a anoxic environment which kills O2 breathing aquatic organisms.
higher global temperatures will result in greater spring run off and sea temperatures, this will allow greater plumes of eutrophication and bacterial decay, dead zones may become more common.
This may be further enhanced by changes to global circulation and increased coastal up-wellings.
What are the effects of increased co2 levels?
increased sea temperature - coral bleaching
acidification - reducing the ability of calcareous organisms to create and maintain their shells and skeletons.
What did the UN climate summit Copenhagen 2009 decide?
global warming must be limited to an increase of 2 degrees,
provide 30bn a year for poor countries to adapt to climate change and 100bn by 2020
