The background of the topic quickly catches the reader up on the development of the conversation thus far. You don't need to take this back to the beginning of time—just the bits that are important to your specific study. That means that you don't have to convince the reader that climate change is a major concern or that technology is advancing rapidly. Your reader already knows that. Instead, describe what previous researchers have been doing with this topic, in a nutshell. 

You've given us an overview of what other people have done with this project; now, we need a sentence or two explaining why you've suddenly butted into the conversation. Don't make the mistake of making promises you can't keep—you can't, for example, solve the global water crisis with a literature review. You can, however, tell me that seawater desalinization technology has evolved rapidly and promises to create a new source of potable water in the near future, so an overview of recent studies is necessary to provide a platform for future research. (In other words, the problem is not the water crisis. The problem is that the research community needs an overview of recent studies, and YOU are just the researcher to do it!)

Once you've established what previous researchers have done, you'll also be able to establish what's left to do. You are arguing that this topic needs a literature review at this point in the scholarly conversation. Why? What can a literature review tell us? That's your research question. (Make sure, though, that it's in the form of a statement!)

Finally, drive home the importance of your project by explaining how your project will contribute to your field. Remember that the "average Joe" generally does not read literature reviews like the one you're proposing. Not only is scholarly research generally too dense for a casual reader, but it is usually locked behind a paywall. Only researchers who have subscriptions to scholarly journals and databases can access those articles - you have this access through the good people at your University Libraries. You can't, therefore, use your literature review to "spread awareness" about an issue or "solve" a major problem like water scarcity or global warming. You can, however, survey recent studies in order to provide a platform for future research.

Next, you'll explain how you plan on answering your research questions. Be specific. We know you'll be looking for "scientific studies" and "peer reviewed journal articles." Tell us more. Which disciplines will your studies come from? Are you looking for studies that ask specific kinds of questions? Are you looking for studies that have a certain kid of research design?