Chicken Littles at Earth Day: Yeah, mass starvation was a very hot button topic back then. I remember whole books being devoted to the problem. Of course, you have to recognize the caveats people were putting into their dire warnings: "If things don't change..." or "At current levels of...". Obviously, a lot has been done since 1970 to make those warnings so much empty verbage - of course, I suppose you could say that shows the warnings were successful in their impact.
What is much more interesting and persuasive is to show a change over a period of time, or a trend, or perhaps a reversal of trends. There is a lot of back-and-forth right now about whether things are getting better, worse or they really haven't changed at all - it's just the perspective. Some say bio-diversity in the ocean is down 90% over past few decades. Some would say that's just how oceans work, or that the data-collection was bad. Either way, I think we need to acknowledge that there's a lot of things we don't understand. There's also a lot of rhetoric that gets in our way of seeing what the real problems are.
In fact, some would say the most pressing problem the world faces is the one we see every single day on our way to work, on the news, or even in our neighborhoods, yet there are few catchy slogans for it, or celebrities willing to lend their name to the issue. In fact, this issue actually inhibits the fashionable causes, even though its solution would probably, as a mere side efffect, take care of most of the ones Sting sings about. But, it's only poor people, so let's just pet some cute dolphins, shall we?