RealClimate has an article up discussing potential tipping points in our climate which, among other things, elaborates further on Jim Hansen’s ‘ten years left’ comment:

The ‘10 year’ horizon is the point by which serious efforts will need to have started to move the trajectory of concentrations away from business-as-usual towards the alternative scenario if the ultimate warming is to stay below ‘dangerous levels’. Is it realistic timescale? That is very difficult to judge. Wrapped up in the ‘10 year’ horizon are considerations of continued emission growth, climate sensitivity, assumptions about future volcanic eruptions and solar activity etc. What is clear is that uncontrolled emissions will very soon put us in range of temperatures that have been unseen since the Eemian/Stage 5e period (about 120,000 years ago) when temperatures may have been a degree or so warmer than now but where sea level was 4 to 6m higher…

Scientific American has a blog post which tackles one of the common global warmign skeptic srguments, namely that the present warming could be a natural uptick. It examines all the different sources of evidence for global warming and explains why the current warming is almost certainly man-made and not a natural uptick. Well worth a read, simply to give you an idea of the depth of evidence. It’s also part of a series of articles dealing with common themes of global warming skepticism, so it’s worth reading the other articles in the series too.