This week Nicholas Stern, the British top climate economist and academic who is probably most known for the Stern Review, endorsed 350 ppm as “a very sensible long-term target.”

350 ppm, as in parts per million, the level scientists have identified as the safe upper limit for CO2 in our atmosphere. We are currently at 390 ppm and, according to the science, we need to get back to 350 ppm as soon as possible to be able avoid runaway climate change.

In an interview with a German newspaper Stern endorsed the 350 ppm target saying he “think it’s a very sensible long-term target.” Bill McKibben, environmental writer and founder of 350.org, writes:

“I think it’s a very sensible long-term target.” He went on to explain: “People have to be aware that is a truly long-term target. We have already passed 350ppm, we are at 390 ppm of Co2 and at 435 ppm of Co2-equivalents right now. It is most important to stop the increase of flows of emissions short term and then start the decline of flows of annual emissions and get them down to levels which will move concentrations of CO2 back down towards 350ppm.

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