The Australian Greens' policy to put Australia on a trajectory towards zero net emissions was backed up overnight by the release of a report calling for global greenhouse emissions to fall below zero after 2050.

The highly respected World Watch Institute State of the Planet report, with a foreword by IPCC Chair Rajendra Pachauri, sets out a clear scientific case for cutting global emissions as fast as is technically feasible in order to prevent global catastrophe.

"We know that our current path is the road to climate catastrophe. The only responsible thing to do is to immediately start building a new zero emissions economy or better," Australian Greens Deputy Leader and Climate Change Spokesperson, Senator Christine Milne, said.

"The Greens' existing goal of a net zero emissions Australia as soon as feasible, dismissed by Penny Wong a month ago, is now being seen by credible scientific voices as conservative.

"Far from being able to see carbon levels go as high as 550 parts per million, as the Rudd Government thinks is reasonable, it is absolutely clear that we will soon be forced to suck carbon out of the atmosphere if we are to pass on a safe climate to those who come after us.

"The emissions trading scheme that the Government is planning must put Australia on a trajectory towards zero emissions as we begin the massive economic and societal transition to the negative emissions that will be necessary in the latter part of this century.

"The emissions trading scheme must have targets that will give the planet a fighting chance of avoiding catastrophe, and must be designed in order to change the way we produce and use energy, instead of doing everything possible to protect the status quo."

The report's co-author, World Watch Institute director, Chris Flavin, called this morning for an end to incrementalism. He said we must stop building new coal plants and immediately begin the process of replacing existing plants with proven zero emissions alternatives such as solar, wind and energy efficiency, as well as switching to electric transport, stopping logging and changing agricultural practices to lock carbon in our soils.

Minister Wong told ABC AM's Lyndal Curtis on December 16:

"The Greens want carbon neutrality, that is, no net emissions by 2050, at the latest. Which is, frankly, I'm not sure how they propose to get there - to be carbon neutral by 2050. So obviously if we're going to have a discussion with them we'd need to understand how on earth Bob Brown proposes to get there."

"Minister Wong could do worse than to read this report and then come and talk to us about how we can make Australia part of the real climate solution," Senator Milne concluded.

State of the World 2009 can be downloaded from http://www.worldwatch.org/node/5984