As you're probably aware, the IPCC is releasing it's Synthesis Report in November. However, some of the content has already been leaked. One key point, which is related to this thread, is the following:
The amount of CO2-equivalents in the atmosphere in 2005 exceeded the IPCC expectations for 2017. More specifically, the assumed content was 385 ppm, while new measurements indicate 455 ppm in 2005. (Leaked by Australian climate scientist Tim Flannery on Australian ABC on monday)
If this is true, it means that we're already at the threshold that the EU considers to be the limit of irreversible climate change, meaning it will cause a global temperature increase of more than 2 degrees Celcius by the end of the century.
This would seem to support the findings in the OP, namely that the models are way off. So what to do? If the models were underestimating the outcome this time, what is to say that they can't overestimate next time around?

How can we ever know what to do if the scientific models can't give us accurate estimates?
The climate debate is really all about risk management. What we need to do is determine the appropriate course of action based on qualified evaluation of the possible outcomes of various courses of action, and their respective probabilities. For those of you who haven't seen it yet, I'd recommend you to take a look at these very instructive videos, which are concerned with precisely this:
Video # 1
Video # 2
And before you start bashing the first video, watch the second one.
