Watch the News together, discuss the economy and the numerous of people who are without jobs and unable to find adequate employment. Explain to your 16 year old, that without proper education, their chances of finding suitable employment is slim.
Discuss what their interests are and what do they think they would like to do, simple questions, like someday would they like to have a car, home, a family? Do they want their own independence and be self sufficient? Discuss, how this will happen without employment.
Show them examples of available jobs without an education and show them examples of available opportunities with education. Discuss how much these jobs pay. Ask which would they like to do?
Also, you could do online job searches that will give some ideas of what is available and a pay scale. I've included a couple of links to these sites.
I must respectfully disagree, and only slightly, with some of these answers. Yes, education does traditionally lead to higher-paying jobs. But, if you'll excuse the corny phrase, money doesn't buy happiness. Instead of giving your son a "ghost of Christmas future" warning that he'll be poor -- there are plenty of people that hold down typically "working class" jobs that are perfectly happy -- show him that getting an education, whether it's an Ivy League college or a trade school, will give him more options when choosing a career. For instance, my former roommate from college graduated with a traditional degree, but after she left, decided she wanted to go into cosmetology! Going to college will open up many more doors for your son. Which one he decides to open, be it CEO or auto mechanic, is entirely up to him.