Gavin A. Schmidt, a climate scientist who works with Dr. Hansen and manages a popular blog on climate science, realclimate.org, said those promoting 350 or debating the number might be missing the point.
“The situation is analogous to people trying to embark on a cross-country road trip to California but they’ve started off heading to Maine instead,” Dr. Schmidt said. “But instead of working out ways to turn around, they have decided to argue about where they are going to park when they get to L.A.”
“If you ask a scientist how much more CO2 do you think we should add to the atmosphere, the answer is going to be none.”
I’ve been told that some readers may have misinterpreted the quote as a criticism of the 350.org campaign itself. This was not the intent and in fact my metaphor wouldn’t have made sense in that context at all. Instead, it was a criticism of people who are expending effort arguing about whether 350 is precisely the right number for a long term target, or whether it should be somewhat higher or lower. Since we aren’t currently headed anywhere near 350 ppmv (in fact we are at 388 ppmv CO2 and increasing by about 2 ppmv/yr), we need to urgently think of ways the situation can turn around. Tapping into the creativity and enthusiasm shown by the 350.org campaigners will certainly be part of that process.
We discussed some of the thinking behind this ‘Target CO2‘ when Jim Hansen and colleagues’ paper first came out, where I think we made it clear that picking a specific CO2 target to avoid ‘dangerous’ climate change is an inexact science at best. The comments by Robert Brulle and Ray Pierrehumbert at DotEarth and James Hrynyshyn also highlight some of that complexity. And I think the suggestions by ‘Paulina‘ for how a tweaked article might have been clearer are very apropos.
However, as the final line in my NYT quote should make clear, personally I think the scientific case not increasing CO2 any further is very strong. Since the planet has not caught up with current levels of concentrations
emissions (and thus will continue to change), picking an ultimate target that is less than today’s level is therefore wise. Of course, how we get there is much trickier than knowing where it is we should be going, but having a map of the destination is useful. As we discussed in the ‘trillionth ton‘ posting a couple of months back, how we get there also makes a difference.
In my original email to Andy Revkin, I had actually appended a line:
If you ask a scientist how much more CO2 do you think we should add to the atmosphere, the answer is going to be none.
All the rest is economics.
(and technology, and sociology, and psychology and politics etc.) but the point is that working out how we get there from here is the real challenge and the more people who are aware and involved in developing those solutions the better.