Global Drying?

I'm not a skeptic about global warming, but I am skeptical of a lot of the specific predictions being made for the specific effects of climate change. I don't think we have anything close to the depth of knowledge to understand how a warming atmosphere will change the particular climate patterns for a given region. In addition, some of the predictions simply don't make sense, and the media tends to present them without any context and in the most alarming possible manner.

Case in point: an article today in the Guardian says that global warming could cause massive forest fires and deforestation (among other things). The Guardian isn't exactly known for its balanced views on climate change, but this article seemed particularly over the top.

Presumably (the article doesn't actually say), the predicted forest fires would be because the burning areas would not only get warmer, but drier too. But from the highest possible level, one would expect that a warmer climate would be, on the whole, wetter, not drier, because warm air holds more water vapor, and warm water evaporates faster.

In fact, one would expect that a warmer climate should be, on the whole, a lot wetter, since both the evaporation rate of water and the water capacity of air go up exponentially as the temperature increases.

Unless I'm missing something, and since I'm not a climate expert, I might be. Feel free to leave me a comment if you know better.

But the media coverage gives me no way to know whether I'm missing some piece of the puzzle, or if regions other than the ones listed will get wetter (the areas predicted to lose forests are "Europe, Canada, Asia, Central America, and Amazonia," which seems to cover about 80% of the land mass of the planet). Furthermore, there's no explanation of why those areas will get drier, and therefore no way for me to understand how reliable the climate model might be.

All I'm left with is the impression that, contrary to what basic physical intuition tells me (that a warmer climate should be wetter), huge swaths of land are predicted to become desert as the climate warms, with no explanation as to the mechanism or the logic. And I know that the models are still very crude, with huge gaps in our understanding of the basic mechanisms.

So you'll pardon me if I'm skeptical about this and similar articles. We'll just have to wait to find out what really happens as the Earth heats up.