The amount of convolution in the answers is overwhelming. Some of the people say that global trends can't be extrapolated from 10 years of temperatures over the last 150 years, a time when we were emerging from the little ice age. Then they say it can be extrapolated from the last 150 years over the last 3,000 years or even the last 4.5 billion years. In the 1970's, there was a lot of concern about a new ice age. You can see the temperature was declining since the 1930's until about the mid 70's. The news magazines and the news programs were full of stories about the next ice age. I know, I was there. It was presented as an inevitability, possibly the end of mankind, not something we had to try to stop, but maybe something to prepare for because we couldn't stop it if we wanted to. In this new age of narcissism, the Earth is perfect from the moment I was born and I must preserve this moment in time for the future of the human race because Man is now more powerful than any force on the planet and only I can change the future! Truth is, you and I are only Dust in the Wind.