[oops, I tried editing my own response but I seem to have deleted your comment, sorry. Can’t remember exactly what it said but it was an interesting point about inadequate climate records and the Jones et al. (1990) Nature paper on UHI being a bit of a gift to the sceptic/denier side of the argument – AR]
I completely agree that the climate community’s data is not half as good as it could be. That said, I’m amazed that we have as much as we do. Loads of pre-1990s data must be gone because it wasn’t archived properly, people moved on and no-one anticipated how important it would become.
I suppose the other way of looking at this is that it’s brilliant that we have what we do. And it’s all down to some really hard work of people like Jones that these records are available.
There’s a nice series of blog posts on the Protons for Breakfast blog (here, here and here with some background here) that try to simplify one of the issues to do with recovering old data.