Most people know that global warming is already starting to kill us off, and that it's getting much worse very quickly. Even though they act as if they don't know.
As I've mentioned before on this blog, I think that the word "secrets" is overused today on TV and the Internet and in print, in shows and writings on historical topics. A show with the title "secrets of the Sphinx," for example, may possibly contain some information which was unknown to the producers before work on the episode began, but a graduate student specializing in the early history of Egypt quite likely already knew every fact contained in the show, and besides that would be able to identify every inaccuracy presented by the show as a fact. And those grad students and their colleagues and instructors aren't keeping anything secret: on the contrary, it's the job of historians to spread their historical knowledge to the utmost of their ability.
The state of the Earth's climate is no secret, although if you were to judge strictly from the way people continue to use SUV's, air conditioners, swimming pools and so forth, you might think that it was.
In the 1840's the German Historian Leopold von Ranke wrote:
"Nicht Blindheit ist es, nicht Unwissenheit, was die Menschen und Staaten verdirbt. Nicht lange bleibt ihnen verborgen, wohin die eingeschlagene Bahn sie führen wird. Aber es ist in ihnen ein Trieb, von ihrer Natur begünstigt, von der Gewohnheit verstärkt, dem sie nicht widerstehen, der sie weiter vorwärts reißt, solange sie noch einen Rest von Kraft haben. Göttliche ist der, welcher sich selbst bezwingt. Die meisten sehen ihren Ruin vor Augen, aber sie gehen hinein."
("It isn't blindness or ignorance which ruins people and states. Where the path they're on is leading doesn't remain hidden from them for long. But there is a drive within them, favored by their nature and strengthened by habit, that pulls them forward as long as there is any strength left in them. He who really controls himself is like a god among men. Most people see their ruin before their eyes, but they march right into it.")
Joachim C Fest put that quote by Ranke at the beginning of his biography of Hitler, which has sold millions of copies since its publication in 1973. It's an answer to those Germans who were adults between 1933 and 1945, when the Nazis were in power, and claimed that they didn't notice their friends and neighbors who were Jewish or Leftist or modern artists or gypsies or homosexuals or critics of the regime being attacked by storm troopers in broad daylight or arrested by the Gestapo at night, who claimed that they didn't know that the Nazi regime was headed straight toward disaster. They knew. Of course they knew.
People know that Earth's climate is in very bad shape and getting much worse very quickly, and they know that petrochemical fuels and waste of water and clear-cutting forests are making things worse. It's no secret whatsoever. The only question is how bad things will get before most people act upon what they know.