Research it thoroughly. People aren't necessarily looking for something that will happen, but if you can write a scary plot about something that might happen, you will pique their interest. Talk withpeople who are knowledgeable about science. Often you'll find several interesting ideas worthy of pursuit. Even though I am a scientist myself, when I feel out of my depth I go ask the experts.
Many scientists are very approachable and can supply useful background information.
Some might be willing to read critical sections if they can get an acknowledgment in the book. The subject of your book should excite you personally. Don't write about something that won't hold your attention 24 hours a day. Pick something you can dream about, talk about, fantasize about. That should be your mantra.