I read in the Fort Worth Star Telegram the other day that the Earth's air is now the warmest it has been since the year 1600. Since the Earth was at the depths of the little ice age in 1600 that statement certainly makes sense. On the other hand it is meaningless with regards to man's contribution to warming. Check out the chart showing Earth temperature since 900 AD at this site.

http://antigreen.blogspot.com/