To James Hansen (and his fellow 350 ppm-ers):
You make a compelling case we must ultimately return atmospheric concentrations of carbon dioxide to 350 parts per million to avoid catastrophic climate impacts (see “Stabilize at 350 ppm or risk ice-free planet, warn NASA, Yale, Sheffield, Versailles, Boston et al“).
But you have made an uncompelling case about how President-elect Obama should go about achieving 350 ppm in your new draft essay Tell Barack Obama the Truth — The Whole Truth and in previous essays (see here). You are, for instance, overly dismissive of cap-and-trade and overly enamored of a carbon tax, when, in fact, neither holds any prospect whatsoever of achieving your goal. Your discussion of as-yet non-commercial 4th generation nuclear technologies is equally off the point, as we’ll see.
If the truth is that we must have a target of 350 ppm, then you must be equally truthful in insisting on national and international policies that could achieve that goal. So far, you haven’t. Nobody has.
I have yet to seen anybody lay out just what is required to achieve 350 ppm from an energy technology and policy perspective, so let me do so here using the incredibly demanding carbon targets from your paper:
[Note: Sadly the ship has sailed on your blue line. We hit global carbon emissions from fossil fuels of 8.5 billion metric tons (GtC) in 2007, according to the Global Carbon Project (see here).]
Absent such specificity, everything else is pure handwaving. The simplest tool for explaining the scale of the solution is the much misunderstood “stabilization wedges” approach of Princecton’s Socolow and Pacala (technical paper here, less technical one here, my discussion of its analytical problems here). Used properly, it is almost as good as an expensive economic and energy model (see “IEA report, Part 2: Climate Progress has the 450-ppm solution about right“).
Wedges are strategies that reduce emissions steadily until they achieve a 1 GtC/year saving — in 50 years in Princeton’s original framework, but for those in a hurry like all of us now are, it must be less.
The bad news about 350 ppm is that you need some 18 standard (50-year) wedges from 2010 to 2060, if I’m reading your paper right — plus a whole lot more after that — just to be on a path to get back to 350 ppm in 2150. The really bad news is that, to achieve your frontloaded reductions from shutting down all traditional coal plants in the next two decades, you need eight of those wedges by 2030.
Why is this bad news? Three reason:
- An individual wedge is a staggering amount of carbon-free energy
- There isn’t political support to do even a single 20-year wedge today.
- Doing eight such accelerated wedges simultaneously is far beyond the capability of the market on its own no matter how high a carbon tax you impose.
Here is one possible list of all the (20-year) wedges the world must achieve simultaneously starting almost immediately: