That's because the acclaimed environmentalist has deeply studied the variety of environmental and geopolitical tipping points we are fast approaching, and found that we're headed for a seriously dark dystopia if we don't turn civilization as we know it around, and fast. A catastrophic confluence of food and water shortages, overpopulation and pollution, collapsed governments and communities and more natural disasters than Roland Emmerich can dream up await us on the other side of Plan A, which Brown calls "business of usual."
We have to fully understand the depth of our collective predicament if we're going to work together to address it. There are, of course, a lot of people whose paychecks depend on not understanding it, but my grandchildren's paychecks depend on figuratively knocking those people upside the head. See if you can get one of them to watch the film with you. One step at a time.