There have been periods of heat and cold so extreme that most life on Earth has been wiped out. This was well before man arrived.
Even in our history - there was a time when one could grow barley in Greenland; this was during the time of the Vikings. You can do so again now, apparently, but still, it's not the first time.
The climate changes no matter what we do. We have to adapt to it. That's all.
Regards, Ivan
I read an article I can't link to here on The Independent Online addition ("Arctic thawed in prehistoric global warming") that core samples of the arctic sea bed showed that the North Pole has in the past been completely ice free and was so warm that it supported tropical marine life. That was 55 million years ago, long before automobiles were burning "fossil" fuels. Funny how that hasn't made the news.
So much ignorance...