Close enough that we have to DO SOMETHING NOW!, but far enough that no one will ever be called to account for being wrong, but not so far away that it's not in our life time and can be ignored. Having lost track of the number of such deadlines for the point of no return that have already passed in my life time let me just say I am a little skeptical.
And you know the Indians, the Chinese, and many others could care less and are going right on growing their populations and carbon production and there is no chance they will do anything but grow for the next 30 years. So if the author is right and we have only that long before we have irrevocably ruined our environment, then the choice for those of us in the industrial world is clear.
Enjoy all the vacations and recreational activities you can now. No seriously, if they are right then we are doomed, so you might as well enjoy it while you can, and they are wrong then you will have the last laugh while they sit around entertaining themselves doing the crossword puzzles, while they suffer without air conditioning.