Someone just asked about whether climate change was man made or natural, and as requested I provided a short summary based on the latest data, which I think everyone should copy and paste for future times when the same question is asked:
There are two single figures here which were used. First the sharp rise in CO2, albeit not from known sources as since discovered by Japan's Ibuki satellite. The jury's still technically out on that one. Secondly, if you didn't check behind it, a slight rise in temperatures for the same 150 year period.
After that it is literally all down to interpretation. Using logical methods rather than scientific (although the two should be the same they are not always) what would we say about the changes, from the temperature to the ice and sea levels, had CO2 not risen:
Temperature rise: 0.8C in 150 years
Sea level rise: 10 inches a century
Global ice level: Stable, although totally unbalanced from north (warmer) to south (colder).
Compare those with historical charts going back thousands of years, and you will see minus the red herring of CO2 figures they look almost flat, and definitely relatively stable. These figures have swung wildly by a few degrees a decade and up to 100 feet of sea level a century after an ice age, while remove the error bars and today's changes almost vanish altogether.
Therefore, like always, people have looked at the birdie and not the sniper pointing his gun or the pot of gold in front of you. The attention has always focused on the definitely unusual but clearly harmless (a 50% rise in 150 years has produced the above figures, and physics says a 100% rise would produce a 1C rise with no positive feedback, their trump card). However, observation and deduction are keystones of physics. We observe an experiment, one here which is well within a primary school science level of understanding, and say "If CO2 adds a degree to the average temperature by doubling without positive feedback, and the experiment is half run and it has added about half a degree, what do you expect the second half to show?"
I'll conclude my presentation here so as not to muddy the water with what are no more than background figures behind the main picture I have given.