Because the previous post was so long, and I didn't want this point to be buried among the rest, I dedicated this post to it:
We can be extremely certain that the recent warming we've seen is real, and that it's caused by an increase in the greenhouse effect. The increase in atmospheric CO2 matches the measured increase in the greenhouse effect.
How can we be so certain? It's rather simple: a warming caused by an increased greenhouse effect has a very distinct signature. The greenhouse effect causes an increased opacity of the atmosphere to the infrared radiation emitted by the Earth. This makes it so that there is an increased temperature differential between the surface of the Earth and the upper atmosphere. The increased temperature differential is the cause of the warming: the outgoing radiation temperature is determined by the radiation incoming from the Sun, so if there is a greater difference in temperature between the surface and the upper atmosphere, and the atmosphere itself is relatively opaque to the outgoing radiation, then the temperature of the upper atmosphere is fixed by the Sun.
But if the greenhouse effect increases, this lowers the temperature of the upper atmosphere, which reduces the outgoing radiation, which increases the temperature of the Earth. The temperature of the surface of the Earth will continue to increase until the upper atmosphere warms back up. As long as the temperature of the upper atmosphere remains lowered, the Earth will continue to heat up.
And has this temperature drop in the upper atmosphere been measured?
Indeed it has!
http://www.wunderground.com/education/strato_cooling.asp
I had to put spoiler around the lies that I didn't want to read.