Willis Eschenbach submits a fascinating dissection of US temperature claims: even accepting the temperature data as is, with upwards manipulations, all the warming claimed in the past century occurs during winter months at night.
This chart overlays every year back to 1895, with the heavy red line 2009. It is right in the middle, and instead of being "one of the warmest years ever", looks about average.
He then charted monthly temperatures averaged for each decade, and found almost all months were within a very narrow range except the winter months. (You can see the slightly broader range in Nov to Feb in the chart.) He concludes:
My point in all of this is that the temperature changes that we are discussing (a global rise of a bit more than half a degree C in the last century) are trivially small. A half degree change cannot be sensed by the human body. In addition, the changes are generally occurring in the winter, outside of the tropics in the cooler parts of the planet, and at night.