You got me curious.  Why are you willing to trust science showing that Earth is 4.5 billion years old, but discount its ability to determine that we are undergoing man-caused climate change?  (I am assuming the second part since your actual comment intimates you believe that scientists are unaware of a time when the Earth previously warmed.  Since I have never heard anyone espouse that theory, my assumption is you are questioning that this warming is caused by mad.)