I would not jump too quickly to that conclusion. Check out the climate data for the US at this location. Look at about 50 locations focusing on small towns if you can. Jot down the direction of the trend line. I think you will be surprised.
http://www.co2science.org/scripts/CO2ScienceB2C/data/ushcn/ushcn.jsp
Once you have done that go to Steve McIntyre's site
www.climateaudit.org
and explore the Siberian influence on Global Warming. I think you will find the whole exercise worthwhile.
To balance the skeptics out you can visit
www.realclimate.org
These tend to be sites where they discuss data in non-hyperbolic ways.
Good luck.
Thanks for the links. I looked at some charts the other day that show we're coming out of a Little Ice Age. To me, that must mean we're warming up...and not by our own hand, either.
I went to your recommended site and checked out State College PA. Clearly a warming trend, especially in the 1950's, with a decline in the 60's-80's, and another increase since then, especially steep in 2000. Curious about that pattern, I used Google Earth to find the location of the reporting station. Looks like Old Main at Penn State. So the temperature was low when it was out in a field with no buildings around it, went up in the 50's as they built buildings around it, declined as the newly planted trees grew to shade it, then went up steeply when they did a lot of construction around it - rebuilding the road out front with a huge pedestrian plaza, updated the underground steam heat system, cutting out diseased trees. Yep, lots of Global Warming going on there. Thanks for the link!