Only Text Quote
Geologists and paleo-climatologists know that in the past the Earth's temperature has been substantially warmer than it is today, and that this warming has occurred under purely natural circumstances. Until we can say precisely how much of the current global warming and greenhouse gas increase is the result of this normal temperature cycle, we will not be able to measure how much human activity has added to this natural trend, nor will we be able to predict whether there will be any lasting negative effects.
