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Climate and Change
The Eruption Theory
Volcanic eruptions can change the earth's climate if they are big enough.
If the ash and sulphur dioxide gas rise high enough they will spread out over the earth's stratosphere.
The blanket of ash and gas will stop some sunlight reaching the earth's surface; instead the sunlight
is reflected off the ash and gas back into space.
This cools the planet and lowers the average temperature.
In 1991 Mount Pinatubo erupted and released 17 million tonnes of gas. This was enough to reduce
global temperatures by 0.5 C for a year.
In general, volcanoes only affect the climate for a few years.
Over 2000 years ago astronomers started recording sunspots. They are black areas on the surface of
Sometimes the sun has lots of these spots, and other times they disappear.
Even though the spots are dark, they tell us that the sun is more active than usual. Lots of spots mean
more solar energy is being fired from the Sun towards earth.
Cooler periods and warmer periods may have been affected by sunspots.
Climate change on a scale of a few hundred years and by 1 2C could not be caused by Volcanoes.
The orbital Theory
Over very long timescales there have been big changes in climate.
Scientists believe that the big change in climate change is from the change of the earth's orbit around
The earth's orbit is sometimes circular, and sometimes more of an ellipse.
The earth's axis tilts, sometimes it is more upright and sometimes more on its side.
The earth's axis wobbles, like a spinning top about to fall over.
These 3 changes alter the amount of light the Earth receives. They also affect where the sunlight falls
on the sun.
On a timescale of thousands of years, the changes would be enough to start and ice age or end one.
These changes are called the Milankovitch Cycles.
The Little Ice Age
During the Little Ice Age cold and rain lashed Europe in the spring and summer of 1315.
Wheat and oats did not ripen and the harvest failed.
The cool wet weather continued in 1316 and 1317.
By 1317 the `Great Famine' had begun. It lasted until 1325.
In some areas 10 -20% of farmers may have died of hunger.
Things did not improve for Europe. Soon after, it was struck by the black plague. This was made
worse by the bad climate and cold weather.
The little ice age caused many problems but people learnt to adapt.
Global warming in the UK
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Human activities are releasing greenhouse gases, which trap more heat released by the Earth at
night and cause the atmosphere to warm.
The UK is a developed country with many industries, which all cause increase in Carbon Dioxide being
Sea Levels will rise increasing coastal flooding and erosion e.g. on the Norfolk coast.
There will be an increased number of storms causing more damage.
An increased number of droughts will take place, causing water shortages.
Many alpine plant species will become extinct.…read more