Warming Being Underestimated?

Some analysis of climate models undertaken last year indicates that it is quite possible that we are underestimating the rate of forcing which would mean that 4degC warming is a distinct possibility. This work was based on looking at the models that best fit real-world data and then using them to project forward. I won't go into detail - it's worth taking some time to read the original paper - but there's certainly no room for complacency.