Global warming

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Global warming is the term used for the rapid increase in global temperature over the last century

Evidence for global warming:

Temperature records:
Measured using thermometers they give a reliable but shirt term record of global warming change

Dendrochronology (tree rings):
Method to figuring it out how old a tree is. Most trees produce one ring within their trunks every year .The thickness of the rings depends on the climate when the ring was formed the it is, the thicker the rings (because the conditions for growth are better). Scientists can take cores through tree trunks then date each ring by counting them back from when the core was taken. By looking at the thickness of the rings they can see what the climate was like each year

Pollen in peat bogs:
Pollen in peat bigs can be used to show how temperature has changed over thousands of years
Pollen is often preserved in peat bogs which are wetland areas
Peat bogs accumulate in layers so the age if the preserved pollen increases with depth. Scientists can take cores from peat bogs and extract pollen grains from the different aged layers. They can identify the plant species the pollen came from. Only fully grown plant species produce pollen so the samples only show the species that were successful at the time.

Global warming is caused by human activity in enhancing the greenhouse effects. The two main greenhouse effects are carbon dioxide and methane

Carbon dioxide
Carbon dioxide is increasing as more fossil fuels like coal, oil, natural gas and petrol are burnt. Fossil fuels released carbon dioxide into the atmosphere
Carbon dioxide has increased by the destruction of natural sinks such as trees. Trees store the carbon as organic compounds. Carbon dioxide is released her trees a burnt, or when decomposes break down the organic compounds…

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