Global warming deniers: where is the flaw in this logic?
This is the same logic you use for global warming. You claim that, since global warming (and cooling) have existed for millions of years, it is impossible for humans to make it worse. SO why does your logic make any more sense than the example of forest fires? Why is it possible for humans to make forest fires, if they have existed for millions of years?
If you want to deny the decades of scientific research which has been independently confirmed by hundreds of thousands of scientists on global warming, go ahead. People have been doing the same thing for evolution since it was discovered as well. But don't use a stupid argument like "global warming happened before humans, so humans can't cause it", unless you want to agree that humans can't cause forest fires as well.