350 Parts Per Million

I have very little hope that we will turn this mammoth around.
But that does not mean that I think giving up is an option.

"The evidence indicates we've aimed too high -- that the safe upper limit for atmospheric CO2is no more than 350 ppm," he said after his presentation. Hansen has reams of paleo-climatic data to support his statements (as do other scientists who presented papers at the American Geophysical Union conference in San Francisco this month).*

We are already at 383 ppm CO2.*

We can still fix this. But then we need to get busy.

* source