Today is 10/10/10, global day of climate action. After the disappointments of Copenhagen – where UN emission targets (‘staying below 2 degrees requires stabilisation at 450 ppm,’ says IPCC 4AR) were not met by great margins – the global climate movement simply went on. There’s not much science news in a massive attempt by consumers to lower their own carbon emissions, there is however in their political claim: 350 ppm.

NASA climate chief James Hansen argues positive feedbacks within the climate system are not properly taken into the IPCC equation. His own risk assessment shows ‘dangerous climate change’ can only be prevented when (a couple of years, perhaps decades of overshoot allowed) CO2 concentrations are stabilised at no more than 350 ppm. That means we actually need to get back, from 390 ppm – and start thinking in terms of negative emissions. Other leading climate experts, like Professor Hans Joachim Schellnhuber of the Potsdam Institute for Climate Impact Research, agree.

The 350.org campaign successfully put a scientific stamp on the global climate movement. Today millions of people word wide, participating in thousands of climate actions in almost two hundred countries, will once again echo its one message: 350 ppm. Cancún, Mexico, December, is their next big stop. Acceptance of the 350 figure in the official UNFCCC texts is the main objective.

© Rolf Schuttenhelm | www.bitsofscience.org