long term climate change

Cards (15)

  • 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