1. The Earth it self has cycles, they are ever going and ever changing. At the moment we are in an inter glacial period and we are moving towards a glacial period. 2. Human activity causes more rapid changes in climate and makes it more unpredictable. The human activity makes the climate warm up faster then it would do so naturally, but on the other hand melting of the ice caps will cause the Golf sea current to stop and bring on us an ice age much quicker.
