DC

An acquaintance is trying to find a book he read some time ago. He thinks it was published in the early 90s and that it was the author's first published novel. It features:

• widespread desertification as a result of climate change
• World War III results from that, as Africa & the Middle East invade Europe
• aliens appear and do inexplicable things (they are seen as lights on the battlefield)
• the story is told from multiple viewpoints.

Does anyone have any idea what novel this might be?