UN climate panel calls for urgent action as risks increase

Could someone please explain to me how the IPCC can be calling for urgent action when their models are looking increasingly busted?

http://judithcurry.com/2014/03/04/causes-and-implications-of...

I can see three main possibilities:

- their models aren't busted (Judith Curry is wrong, as are those whom she cites)

- their models are busted, and that increases the risk (i.e. risk increases as a result of forecasting being essentially impossible)

- their models are busted, and they're doubling down on a bad bet for political reasons

This story is being discussed here:

https://news.ycombinator.com/item?id=7499072 (22 points, 28 comments)