Joseph, thanks for your very informative article, with whose final conclusion I'd generally concur.

Three questions arise that I'm hoping you can resolve.

1st, given that we have a small and declining capacity to forecast any year's CO2-equiv output of the diverse accelerating P-feedback loops
(due to intensifying destabilization of the climate)
and given that we'll have a limited capacity even under a global climate treaty to adjust anthro-GHG outputs annually to offset those unexpected P-feedback effects over and above the agreed treaty control-rates,

how exactly is stabilization anything more than a rhetorical goal ?

That we might one day recover sufficient airborne GHGs to restore a pre-industrial climate and thus restore a natural stabilization,
I don't dispute,
but I've yet to see a rational plan for doing so at any level where P-feedbacks are active.

Which raises the 2nd question - The earliest active P-feedback was AFAIK that of the microbial response to raised CO2,
causing an exponentially rising decay of peat bogs globally,
resulting in the troubling DOC count for watercourses.
That DOC count was first recorded in the early '60s, when CO2 was around 320ppmv.
The concentration at which this P-feedback actually began is not known.
So the 2nd question is, why 350 ppmv rather than 320 ppmv ?

The simplest target, which I suggest will also attract the best cultural take-up, is to aim to recover sufficient carbon to restore the pre-industrial concentration just as soon as that is feasible.

A 3rd question is this :- can you explain why, if as you say the P-feedbacks will unavoidably deliver another 0.6dC of GW in coming decades,
short of our somehow cutting airborne CO2 to 350ppmv by the date that they've done so,
what phenomenon is then expected to close down those P-feedbacks from making further contributions after that date ?

Is not the reality that the P-feedbacks will only decellerate (after a time lag) in response to a sufficiently large cut of airborne GHG concentrations below their present level ?

Regards,

Billhook

Dear Billhook,

> So the 2nd question is, why 350 ppmv rather than
> 320 ppmv ?

Very good question.  As far as I can see there is no scientific reason.  If the tipping point for the Arctic lies somewhere between 300 - 320 ppm, and if we can't have a safe climate without the Arctic sea ice in summer (which I believe is the case - see: report Climate Code Red online at climatecodered.net ) then it seems to me that the precautionary principle says that we should err on the side of 300 ppm till science can tell us that the real (safe) upper limit is 320 ppm.

> P-feedback.......

Can you please explain what you mean by P-feedback .  I'm moderately well educated in this stuff and P-feedback is not a term I've come across before.

Cheers,  Philip

Joseph,  I appreciated your article in Salon.com and enjoyed this commentary on Hansen's new paper, but when I finished reading your comments I found myself laughing and it took me a bit to understand my own response.

You're desperate. (We all are, but unfortunately most of the world doesn't realize that yet.)  So you are desperately shouting No! NO! NOOOO!!! 2+ 2 equals 5.5 possibly 5 but it can't equal 4!!!!  We don't have enough political will for 2 + 2 to equal 4!!!!

You hoping that Science (assuming Hansen's new 350ppm figure is correct science) will bow to the foibles of Human Nature and admit that the Laws of Nature are wrong so that Humanity will have the time to save itself from itself.  HA!!!!  

And your right!!  At least I agree it will be virtually impossible to muster the political will and world consciousness necessary to keep from reaching 450ppm C02 let alone 350ppm!  350ppm is truly an insane target, even if it is accurate...  Unfortunately, no matter how we kick and scream or pray, 2 + 2 will always equal 4.

Bill McKibben in converstion with Michael Krasny on Forum (KQED) said really, it's all a Hail Mary pass from this point on.  But, besides our ameobic like understanding of the world, (despite the fact that we're so proud that we are the brightest bulb on the planet), we have this other enduring quality of not giving up.  I have never seen a football game when the losing team had a chance to win and didn't in the closing seconds of the game throw up a Hail Mary pass..  So we will throw up our Hail Mary efforts to stave off the catastrophic affects of Global Warming, but our chances are I'm afraid many thousands of times worse that than losing foot ball team's chance to win.  Think SuperLotto or MegaLotto!! But hey Joe, I still buy an occasional ticket.  So.. Let's give it a try anyway.

Best to you and all of us,  wayne roth