3) how to publicize those warnings (about Climate Change) in a way that avoids denial / panic, and that can be channeled into constructive collective action?

ANSWER: "If you care about someone, you just help them, no matter what. Frame your warning in terms of caring, not about abstractions ("collective civilization" was mentioned on ABC but sounds too science fictiony), but about human beings--you and your neighbors" http://ecologywithoutnature.blogspot.com/2012/05/in-dialogue-with-john-protevi.html

IN THESE TIMES 
BY JOEL BLEIFUSS

A power struggle is going on in the movement, between the old vertical type of a Left and a new young Left that isn't so enamored with the old wolf pack mentality.

Last July, Adbusters sent out this invitation addressed to those “ready for a Tahrir moment”: “On Sept. 17, flood into lower Manhattan, set up tents, kitchens, peaceful barricades and occupy Wall Street.” And thus, the Vancouver-based nonprofit magazine published by self-described “culture jammers and creatives working to change the way information flows, the way corporations wield power and the way meaning is produced in our society” sparked a movement.

Estonian-born documentary filmmaker Kalle Lasn co-founded Adbusters in 1989. Lasn, 70-years-young (“old,” as in “old Left,” is an adjective he eschews), draws his inspiration from the Situationists, avant-garde European revolutionaries who believed corporate capitalism perverted the human spirit. The Situationists reached their zenith in 1968 Paris and disbanded in 1972, but their efforts to affirm what it means to be free live on in Adbusters.

In These Times spoke with Lasn in March to see what “the man behind the curtain” had to say for himself and the movement he helped ignite.