Global communications, at least on a basic level, should be very easy to keep up. Building a radio is actually simple as shit, you just have to know how - and that knowledge is widespread enough to survive. Similar considerations apply for many other electronic devices. Modern cryptography, too, can in principle be done by hand or with just a primitive calculator, which means that sensitive information could still be relayed quickly over large distances.
Similarly, vehicles not dependent on fossil fuel - think bicycles, rollerblades - are (relatively) easy to make and use, and give a great advantage over even Napoleonic times. Chemistry on a 19th century level will stick around, too, up to and including primitive antibiotics. Germ theory, too, is something that makes life much easier without requiring advanced materials or long supply chains. Easy steel making, knowledge about alloys, techniques like employing sacrificial anodes for preventing corrosion: All there, all easy-ish even after the collapse. Modern crops will still be around, together with the knowledge of fertilization and soil chemistry - and that's not even considering the fact that you could definitely get farming equipment to run on wood instead of oil products.
It'll take us a while - say, fifty years - to once again send satellites to orbit, or produce computers like our modern ones, or put together fighter jets, rockets, aircraft carriers. But once the radiation dies down and you've gotten used to not being able to contact your friends on the other side of the earth, it'll be relatively fine. Hell, at least in Western Europe there will be a strong desire to rebuild the nations as they were before, due to them being largely defined via language and ethnicity, so larger government structures will assemble quickly, and with them, reliable trade over long distances will resume. Add that to the fact that the European populace is on average much more well-educated than that of the not-First world, and I'd wager you'd have a fair chance of seeing colonialist patterns resume after a few decades as we once again try to suck the oil out from under the Arabs.
Seriously? You used ~100 Mt as realistic yield for nuclear strike?
This kind of post is fairly unconstructive. It doesn't convey whether that's too low or too high, or give any idea of what you think a more reasonable number would be. In fact, the only information it conveys is that you disagree with LW, and that you consider it appropriate to belittle him (although you have not, in fact, provided any explanation as to why you are more correct than he is). It's neither polite nor helpful enough to cover over the rudeness.
Actually it's quite clear that 100 Mt is too much*, and it's also highly improbable that LW doesn't know that, so it's a perfectly reasonable calling-out of laziness or knowing exaggeration on LW's part.
Even if it was not clear that 100 Mt is too much, it's still pretty much self-evident that not all nukes would be of the same size. You really don't have to know all that much about nuclear weapons or nuclear strategy to realize it's a bad map. Not that it's easy to come up with a good one, but he should've at least slapped on a disclaimer 'very rough approximation' or something.
*Especially considering that pretty much all the nuke-owning countries are moving to smaller bombs that are delivered more precisely.
E: Damn ninjas.
