The scientific evidence is that we caused it – this is now almost overwhelming evidence. I can accept though that maybe some of the warming could be associated with warming cycles, but we are definately making it worse.
While the Earth has always gone through periodic warming and cooling, the speed of those cycles has involved at least 10’s of thousands if not 100’s of thousands of year. Global warming is happening over a period of 100 years and the ecosystems simply cannot respond fast enough to cope. No – this is definitely mankind’s doing and it is up to mankind – us, all of us – to do something about it.