"There is a strange parallel with what the ancient Maya foresaw": author John Major Jenkins

"The big concern is that we could see famines, wars, and so on triggered by the biological instabilities that would occur as our life-support system crosses the critical threshold towards a planetary-state change," Barnosky said. "The problem with critical transitions is that once you shift to a new state, you can't simply shift into reverse and go back. What's gone is gone for good, because you've moved into a 'new normal.'"

Barnoksy said he's not sure if the trend can be reversed, but to minimize its chances, humans must improve our balance with nature and avoid crossing the threshold of transforming 50 percent of the planet's surface (he calculates that we'll hit that level in 2025, and reach 55 percent by 2045). That would require reducing population growth and per-capita resource use, speeding the transition away from fossil fuels, increasing the efficiency of food production and distribution, better protection and stewardship of natural areas, and "global cooperation to solve a solve global problem."

His conclusion: "Humanity is at a critical crossroads: we have to decide if we want to guide the planet in a sustainable way, or just let things happen."

Perhaps it's not merely a coincidence that our knowledge of the need for a new age is peaking in 2012. "It's not surprising the world is in a crisis as we approach this date," Jenkins said. "I don't know how it works, but there is a strange parallel with what the ancient Maya foresaw."

But the change that we need to make isn't about just buying a Prius, composting our dinner scraps, and contributing to charities. It requires a rethinking of an economic system that requires steady growth and consumption, cheap labor, unlimited natural resources, and the free flow of capital.

"Basically, we are going to have to have a rapid shift in global consciousness," Pinchbeck said. "You would not be able to create a sustainable economy with the current monetary system. It's just not possible."

Yet to even contemplate that fundamental flip first requires a change in our consciousness because, as Pinchbeck said, "We have created a stunted adult population that isn't able to think in terms of collective responsibility."

Brezsny said humanity shouldn't need a galactic alignment or Mayan prophecy to feel the compelling need to take collective action: "I can't think of any bigger wake-up call than to know that we're in the middle of the biggest mass extinction since the dinosaur age."

What comes next is really about how humans use and guide their energies, or as DiMartino said, "We, through our actions and intentions, create the world and take the path that we are creating."

CATASTROPHISM HAS LIMITS

It may be the end of the world as we know it, but sounding that warning may not be the best way to motivate people to action, according to a new book, Catastrophism: The Apocalyptic Politics of Collapse and Rebirth.

Two of the book's authors — Sasha Lilley, a writer and host of KPFA's "Against the Grain," and Eddie Yuen, an Urban Studies instructor at the San Francisco Art Institute — recently spoke about the limits of catastrophism as a catalyst for political change at Green Arcade bookstore.

Christian conservatives have long sounded the apocalyptic belief that Jesus will return any day now. Yet Lilley said those on the left have had a long and intensifying connection to catastrophism — "seen as a great cleansing from which a new society is born" — based mostly around the belief that capitalism is a doomed economic system and the view that global warming and other ecological problems are reaching tipping points.

As committed progressives, Lilley and Yuen share these basic beliefs. "Capitalism is an insane system," Lilley said, while Yuen said climate change and loss of biodiversity really are catastrophes: "We are living in an absolutely catastrophic moment in the history of the planet."