long term climate change

• outline context

  over the last 100 million years earth has been cooling down.

  • Antarctica's ice began forming 34 million years ago
• define quaternary glaciation

  alternating between glacial and interglacial periods over the last 2.6 million years.

  • we are currently in an interglacial period
• define the greenhouse effect

  solar radiation enters the earth's atmosphere and gases trap heat before it reflects into space
• define the continental drift theory

  continents split from one supercontinent called Pangea over the last 200 million years
• define global atmospheric circulation

  different types of environments at different latitudes:

  • Tundra at 90 degrees = cold and dry
  • temperate forests at 60 degrees = cool and humid
  • hot deserts at 30 degrees = hot and dry
  • tropical rainforests at 0 degrees = hot and humid
• define eustatic sea level changes

  changes in volume of water = global effect
• causes of eustatic sea level change

  1. change in mass of glacial ice = water trapped
  2. thermal expansion of water = water heated so more space between molecules
  3. sea floor changes by tectonic processes
• define isostatic sea level changes

  elevation of land relative to sea level = local effect
• causes of isostatic sea level changes

  1. geological or tectonic processes such as uplift of land masses
  2. downward pressure of ice mass lifting and letting land rebound = land uplift = rises above sea level = sea level drops
• define emergent landforms

  influenced by falling sea levels due to cooling climate = previously formed landforms will be inland and away from marine influence.

  • raised beaches, marine terraces, abandoned cliffs = beaches, shore platforms, coastal cliffs that are no longer interacting with wave energy
  • in the UK = most emergent coastlines due to eustatic sea level change because we have no tectonic boundary
• define submergent landforms

  influenced by rising sea levels due to warming climate = sea level is rising faster than land.

  • ria, fjord, shingle beach = landforms
  • the Flandrian Transgression = transition into current interglacial period = creating submergence landforms
• define the Flandrian Transgression

  around 12000 years ago (beginning of Holocene) = large number of glaciers retreated in the last phase of the glacial period = transitioning to interglacial
• outline rias - submergent landforms

  a drowned river valley

  • fluvial processes and rivers cut a channel to the new coastline
  • during the Flandrian Transgression = lower parts of valley is drowned and exposed to marine processes
• outline fjords - submergent landforms

  a drowned glacial valley

  • glaciers have more erosive power = steep cliff-like valley sides and deep water (often over 1000 m)
  • high energy environment = either deepened or infilled by sediment from continued erosion
  • area like New Zealand, glaciers melt and deposits sediment into fjords.
• outline shingle beach - submergent landforms

  rivers and glaciers deposit sediment in nearshore areas