Well I don't get it. I basically searched for any text files containing the word rocky_desert in Data, and in each of those I copied the entry for rocky_desert and replaced it with Blight. I found that there were two files which required RGB values, and I put in RGB values which I then used in map_climates.

I haven't actally fought a battle in the new climate, I just clicked view settlement to have a look. See if that works for you. How did you get it to appear on the campaign map?

I get the impression that you've got further than this with me. The pink colour is what it ususally throws up when it doesn't recognise a colour in map_climates.tga...