"Planet Earth is just a small boat. And if it sinks, we will all sink together," says Secretary General of the United Nations, Ban Ki-moon, at the beginning of Leonardo DiCaprio's new documentary, "Before the Flood."

Those short sentences, almost whispered by Ban, set the tone for the documentary, which in 90 minutes covers almost every aspect of climate change, from the extraction of fuel from oil sands in Alberta, Canada, to the melting ice caps in the Arctic to industrial pollution in Beijing to rural India, where there are as many people without power as there are Americans (more than 300 million). The activist-actor goes to the bottom of the ocean to see coral bleaching, flies above the Indonesian palm oil plantations that have replaced native rain forests that are the lungs (and carbon sinks) of the planet, and takes a hard look at how what we eat affects it all.

The film covers a three-year personal journey that DiCaprio took as a U.N. Messenger of Peace as he traveled the world and interviewed, well, everyone you can think of, from native peoples to climate scientists, politicians, climate activists and islanders, farmers and professors — even Tesla founder Elon Musk.

In its depth and breadth of coverage, it's dazzling — and alarming.

You can watch the documentary, for free, below:

https://www.youtube.com/watch?v=90CkXVF-Q8M


DiCaprio goes back in time, too — to 50 years ago when we decided that cheap fossil fuels were easier to use to produce energy, even though the connection between CO2 and rising global temps was known even then. And in more recent history, it's remarkable to see DiCaprio speaking about global warming in 2000 — and to realize that not much has changed. Indeed, it has gotten worse, as we've careened to more than 400 parts per million of CO2 in the atmosphere from 366 ppm 16 years ago.

In the middle of all this are, of course, the climate-change deniers. As Dr. Michael Mann, an atmospheric scientist at Penn State, who first published the climate change "hockey stick" model linking climate warming to CO2 levels says, "Unfortunately, we are fighting this massive disinformation campaign to confuse the public. These folks know they don't have to win a legitimate scientific debate. They just need to divide the public. And all of that hatred and fear is in fact organized and funded by just a few players."

As if it's not hard enough to make change in general, when it comes to keeping the planet safe and healthy for people to live on, there are companies and governments actively blocking progress on that front.

By the time I reached the end of this crazy-comprehensive, cram-it-all-in 90 minutes, I felt more informed, but I also agreed with DiCaprio when he said, "The truth is, the more I've learned about [climate change], and everything that contributes to the problem, the more I realize I don't know."

Even though I studied climate science toward my degree in geology in college 18 years ago and have written about environmental issues for going on 15 years now, new aspects of the problem were revealed to me in this film.

It's not a pretty picture, but it's important to know where we stand in 2016, and DiCaprio shows is exactly where that is in "Before the Flood."

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.