Long term Causes of Climate change

This is a short essay to outline the long term causes of climate change.

AS level Geography from the WJEC syllabus.

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  • Created on: 04-05-11 21:28
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Explain the Long Term Patterns of Climate Change
Climate change occurs due to short-term and long-term causes. In the last
1000 years the temperature of the Earth has generally increased. In the 1900s
the temperature was -0.1 degrees lower than in the 19th century, this could
have been caused by the eruption of Krakatoa. From here onwards the
temperature has continued to rise to almost a 0.4 degree increase from the
end of the 19th century, which could be due to an increase in solar activity and
a warming of the oceans. In 1940 the temperature experienced a massive drop
down to 0.2 degrees warmer than in the 19th century. This is thought to have
been because of the increase of aerosols in the atmosphere due to the
increase in industry after the First World War. The aerosols repel the Sun's
radiations once they have got to the atmosphere, away from the Earth,
causing a drop in temperatures. However, from 1960, this drop carries on rising
again which could partly be due to the increase in emissions of green house
gases in countries such as China and India, even though Europe and the US
have started to decrease their emissions, reaching 0.8 degree increase from
the 19th century in 2000. The short-term causes can be things such as human
activity, like the industrial revolution, or more naturally occurring factors such
as the El Nino and La Nina cycles, as well as volcano eruptions. However, you
could argue that volcanoes are a long-term cause, as they can often affect
many years, especially if there is a prolonged time of volcanic activity which
may cause a temperature fall for a longer period. The Sun's activity is also a
massive long-term factor linking to climate change. The amount of energy
emitted by the sun varies as a result of sunspots. These are caused by intense
magnetic storms, blasting more solar radiation towards the Earth. The last
main long-term factor showing a pattern in climate change is the Milankovitch
Cycles. This cycle is made up of three parts; the eccentricity, obliquity and
procession of the Earth.
Climate change is not an unusual occurrence. The climate can easily be
affected in the short term by factors such as volcanic activity. When a volcano
erupts, the sulfur dioxide from the volcano forms small sulfuric acid aerosols
high in the atmosphere. These aerosols absorb as well as scatter solar energy
back into space. This means there is less of the Sun's radiation getting into the
Earth surface so there is a period of cooling. The period of cooling can be for
as long as a couple of years because the clouds stay in the atmosphere for a
fairly long time. An example of volcanic activity effecting climate change would
be in 1963, when Mount Agung erupted. The temperature in 1963 was at around
0.2 degrees warmer than in the 19th century, however, after the eruption it went
down to 0.1 degree warmer than in the 19th century. It then took slightly less
than 20 years for the temperature to get to the original temperature before the
eruption. Another example would be to look at the Tambora eruption in
Indonesia in 1815, which gave off 200 million tons of sulfur dioxide. This
lowered the temperature in 1816 from 0.4 degrees to -0.7 degrees. This shows
how much the sulfur dioxide can effect climate change and the amount of
radiation getting into the Earth's atmosphere. The period of warming the the
10th - 14th century, the Medieval Warm Period (MWP), and the cooler period in

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Little Ice Age (LIA), could be because of
the abnormal volcanic activity at the time.
There have been many long periods of going in and out of glacials and
interglacials over time. For example, the MWP, which caused warming
throughout Europe. In this period there were prolonged summers because the
summer climate was around 1 - 1.4 degrees warmer than today. The winter
climate was as high as 6 degrees, almost 2 degrees warmer than today.…read more

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The procession of the Earth tell us how much
the Earth is "wobbling". This can change every 23,000 years. When these three
parts are all lined in a certain way, they can trigger periods of cooling or
warming of the Earth, such as the MWP and the LIA. Many people say that
during the MWP, the Earth was lined up against the Sun in a fashion that
caused a more intense warming than usual.…read more


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