Carbon problem 'worse than we thought' - think tank
When it comes to cutting carbon the scale of the problem is even greater than widely believed and humankind has just 40 years to go carbon neutral or face catastrophic consequences, according to a US think tank.
The book also repeats the favoured mantra of the environmental industries - that the challenges posed by climate change also offer opportunities for business and society.
Opinion on what is an acceptable rise in global average temperatures has always been a subject of some contention, but 2 degrees Celsius is the closest thing we have to a standard 'just-about-safe' level where there will be problems, but they will not be insurmountable.
This publication calls that wisdom into question, saying that even a 2 degree increase will bring unacceptable risks to key natural and human systems, including significant loss of species, major reductions in food-production capacity in developing countries, severe water stress for hundreds of millions of people, and significant sea-level rise and coastal flooding.
Temperatures have already gone up by 0.8 degrees and we have close to another degree 'saved up' from past emissions which have yet to impact fully on the climate.
By the Worldwatch Institute's maths, that means we've got until 2050 to go carbon neutral, or face dire consequences.
Cut must not stop there either, it says, claiming we would need to be carbon negative in the second half of the century to restore the balance.
"We're privileged to live at a moment in history when we can still avert a climate catastrophe that would leave the planet hostile to human development and well-being," said Worldwatch vice president for programs Robert Engelman, project co-director for State of the World 2009.
"But there's not much time left. Sealing the deal to save the global climate will require mass public support and worldwide political will to shift to renewable energy, new ways of living, and a human scale that matches the atmosphere's limits."