Complex sentence: Of those surveyed, 97% agreed that that global temperatures have risen over the past century and 84% agreed that "human-induced greenhouse warming" is now occurring, only 5% disagreeing that human activity is a significant cause of global warming.
Split into simpler sentences: Of those surveyed, 97% agreed that that global temperatures have risen over the past century. Only 5% disagreed with the idea that human activity is a significant cause of global warming.