Edexcel: Topic 5, Is the climate changing?

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Evidence of climate change

Evidence from personal memory is called anecdotal.  It is often unreliable and can only go back less than 100 years.  We cannot rely on this and need scientific data.  We seem to be in a period of global warming.  This evidence is supported by a range of sources including temperature records, pollen on peat bags and dendrochronology (tree-ring studies)

Temperature records over long periods

Long sequences of temperature records exist for a number of places.  Old data sets are very important in the study of climate change, even if the lack of technology means they are not as accurate as today.

Studying peat bogs

Measures of temperatures taken with a thermometer only take us back around 2-3 centuries.  A way of finding out about the climate back to the last ice age is through studying plant and insect remains preserved in peat (an accumulation of partially decayed organic matter, mainly the remains of dead plants).  When plant material dies it normally decays however in the anaerobic and often acidic conditions of a peat bog, the decay rate is slowed or stopped altogether.

Pollen from the past

Pollen grains are well preserved in peat and can be useful in reconstructing past climates because:

- Plants produce large amounts of pollen and throughout the spring/summer millions of pollen grains fall onto the ground including the surface of peat bogs as 'pollen


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