National Geographic’s climate-change documentary Before The Flood, produced by and starring Leonardo DiCaprio, has reached more than 30 million viewers worldwide.

That is the largest sampling for a documentary in the world since 2000, and the largest ever for a National Geographic Film, according to the company.

Before The Flood, directed by the Academy Award-winning documentarian Fisher Stevens (of “The Cove”), presents accounts of the dramatic changes occurring now around the world due to climate change as well as the actions we as individuals and as a society need to take to prevent catastrophic disruption of life on our planet.

DiCaprio steps into the role of science journalist and interviews individuals from every facet of society in both developing and developed nations who provide unique, impassioned and pragmatic views on what must be done today and in the future to transition our economic and political systems into environmentally friendly institutions. Interviews in the film include President Barack Obama, former President Bill Clinton, Secretary of State John Kerry, UN Secretary-General Ban Ki-Moon and Pope Francis as well as top NASA researchers, forest conservationists, scientists, community leaders and climate-change activists.

Yes, Before The Flood is so powerful, because it presents climate change as it a really is: a global threat that links together people separated by class and geography.  The science is clear, the future is not.

You simply need to watch it now.