Why has the world's climate changed since the last ice age?

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  • Created by: Ellie R
  • Created on: 02-06-13 20:03
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  • WHY HAS THE WORLD'S CLIMATE CHANGED SINCE THE LAST ICE AGE?
    • SOLAR OUTPUT
      • This is energy that comes from the Sun.
      • Measurements made in the 1980s showed that the total amount of solar energy reaching the Earth has decreased by 0.1%,
        • If this continues, global temperatures could start to decrease between 0.5 and 1 degrees Celsius.
      • It is thought that the activity of sunspots on the Sun's surface affects solar output.
      • There was a period of drastically reduced sunspot activity between 1645 and 1715 which might have been one of the causes of the little ice age.
    • VOLCANIC ACTIVITY
      • Volcanic eruptions release large amounts of sulphur dioxide and ash into the atmosphere.
        • These act as a cloak and reduce the amount of solar (radiation) energy reaching the Earth's surface.
      • In 1815, Mount Tambora erupted.
        • The following year was unusually cold over much of the world with Europe having heavy snowfalls and frost throughout the summer; 1816 became known as 'the year without a summer'
    • SURFACE REFLECTION
      • During cooler periods when there is a larger amount of snow and ice on the Earth, global temperature will drop due to the snow and ice reflecting sunlight back to space.
      • As the planet starts to warm up, snow and ice will diminish, and the Earth will continue to get warmer.
    • ORBITAL GEOMETRY
      • The tilt of the Earth's axis varies over time. This variation occurs over a 41,000 year time period.
      • When the angle is greater, the Earth usually experiences warmer periods.
      • The Earth's orbit around the Sun varies from nearly circular to elliptical and back to circular again every 95,000 years.
      • There are many conflicting views on what happens to temperatures as the Earth's orbit's shape changes.
      • Cold, glacial periods seem to have occurred when the Earth's orbit is circular and warmer periods when it is more elliptical.
    • CHANGE IN ATMOSPHERIC GASES
      • There is a clear relationship between the amount of carbon dioxide in the atmosphere and temperature variations.
      • Carbon dioxide is one of the most important gases responsible for the greenhouse effect.
      • The greenhouse effect keeps heat within the Earth's atmosphere by absorbing long wavelength radiation.
      • Without the greenhouse effect the average global temperature of the Earth would be _18 degrees Celsius rather than the present 15 degrees Celsius.
    • TECTONIC ACTIVITY
      • The movement of continents cause by plate tectonics affects the global pattern of atmospheric and ocean circulation
      • And the changing shape of the Earth's surface causes winds and ocean currents to change.

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