Fox, while one of the assumptions in the linked paper is IMO fanciful (that is would be "easy" for India to head north and take on Pakistan with conventional forces, thus evoking a nuclear response from Pakistan) the follow on "what if Pakistan or India uses nukes and the other responds" analysis
is pretty grim reading.
How does that apply to the UK's nuclear posture? Sad thing is that even if the traditional nuclear exchange that we all worried about in the Cold War never happens, the impact of even a local nuclear exchange that isn't aimed at the old school MAD, Eurocentric model, is still going to screw the whole globe.
The failures of the NPT, or maybe I should say its current status of decay, is indeed a grim prospect for the whole of civilization.
That overarching worry doubtless informs President Obama's current attempts at a deal with Iran. What I wonder at is why old Vlad isn't walking in lock step with us, and the leadership in China. I would think that the Chinese would be very concerned with nuclear proliferation. It would have a marked impact on them.
If you look at the linked analysis, the devastation to Asian, in general, and Chinese agricultural output is macabre should local powers in the South Asian and Asian sphere start lobbing buckets of sunshine at one another.