First 243 words of the document:
Geography global issues climatic hazards revision
Causes of climate change: manmade or natural?
Natural as evidence from Vikings who settled in Greenland as they were able to
grow crops, whereas now it is a lot less habitable. Also during this time the
population of Britain grew and harvests were good during the medieval warm
period. Therefore warmer temperatures should be expected.
However, evidence from natural indicators of temperatures such as trees and
coral reefs, showed that the medieval warm period didn't exist and that recent
warming was manmade. Other evidence has supported this concluding the warming
today is unusual.
Another natural cause of climate change is changes in the sun's level of activity
which is indicated by the number of sun spots that are visible on the sun's surface.
Sunspots occur when the activity of the sun is greatest and in the 1800's there
was a period of 50 years where no sunspots were visible, which is also when the
mini ice age occurred, when temperatures were lower than average. This shows a
link between the sun's activity may not be due to CO2 levels.
However, recently the sun's activity has fallen but temperatures continue to rise,
suggesting the rising temperatures are caused by something else which is likely to
be caused by human activity, increasing carbon dioxide levels.