I can see why this became so popular. The biggest strength, I think, is the protagonist. Sixteen year old Miranda is very human, by which I mean she experiences the apocalypse as many of us would: with quite a lot of resentment and whinging. She has many good qualities too, of course, but let's not pretend that a slow, freezing death, trapped in close quarters with family (with anyone) is something to be experienced with pie-eyed optimism. The constant focus on food, too, is realistic, as is the struggles of everyday life: how to do laundry in winter with no running water and no electricity, for instance.

I complain quite a lot, when it comes to post-apocalyptic stories, about how they tend to focus on over-the-top conflicts and - far too depressingly often - sexual assault. I'm pleased to say there's none of that here. The setting, and the conflicts, are entirely domestic and entirely small-scale. They're absolutely relatable, and if the really grim tone of the book is undercut by the sudden happy-ish ending I'm still pleased to see the main character live. 

I find the mechanism of apocalypse here generally unconvincing, but handwavium on the science. That litany of natural disaster becomes almost comical at one point - how much more could go wrong? - but the realism of the characters makes up for it somewhat.