Complex sentence: An abrupt climate change takes place when the climate system is forced from one state into another in a period of time faster than the expected rate of change from the outer forcing Committee on Abrupt Climate Change, National Research Council.
Split into simpler sentences: An abrupt climate change takes place when the climate system is forced from one state into another in a period of time faster than the expected rate of change from the outer forcing. ^ Committee on Abrupt Climate Change, National Research Council.