Causes of Global Climate Change

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Causes of Global Climate Change

Long term climate change can be influenced by either external or internal factors.

An example of an external factor is solar output. This is energy that comes from the sun. This energy changes over time with measurements made in the 1980s showing that total amount of solar energy reaching earth has decreased by 0.1%. Although this is doesn’t seem like much, if it continued over a long period of time, it could influence the global climate.  It is predicted that a 1% change in solar output could make temperatures rise or fall by between 0.5 and 1°C. It has also been suggested that the activity of sunspots on the sun’s surface affects solar output. There is also evidence to suggest that this was the reason for the little ice age.

Another example of an external factor that affects global climate is orbital geometry. Variations in the Earth’s orbit and tilt (called the Milankovitch variations) seem to have a link with climatic change. Colder, glacial periods have occurred when the Earth’s orbit is circular and warmer periods when it is more elliptical. The tilt of the Earth’s axis will also vary over time from 21.5° and 24.5°. The greater the angle of tilt, the hotter the summers are and colder winters are. When the angle of tilt is greater the earth usually experiences warmer periods.

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Another kind of factor is an internal factor.

An example of this is volcanic activity. Volcanic eruptions release large amounts of sulphur dioxide into the atmosphere. These act as a ‘cloak’ and reduce the amount of solar radiation reaching the earth’s surface.  An example of this is the Laki eruption of 1783.  Millions of tonnes of poisonous gas and particles were sprayed out over Iceland over 8 months. Lava erupted from vents in the mountain, killing off vegetation and in turn animals died from starvation - a third of the islands population died from famine. On a global level the ...

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