Holy crap on a cracker! This Q&A with Michael Mann at some blog nobody has ever heard of called “Down with Tyranny” leaves me wondering, what is he smoking? I think the self imposed “climate interpreter” title needs some work.

-by Gaius Publius One of my hats is as a climate interpreter to the interested lay person. I have something of a science background and can read the papers “in the original.” Another hat is as an occasional interviewer for Virtually Speaking. This month the two hats merged on the same head, and I got to interview the “Hockey Stick graph” climate scientist, Dr. Michael Mann. – See more at: http://downwithtyranny.blogspot.com/2014/10/michael-mann-on-climate-theres-very.html#sthash.y25kBteI.dpuf

[QUESTION] What level of CO2 is reasonable?

[ANSWER] Most still think that 350 ppm (parts per million) CO2 is what’s needed to keep us at the upper end of Holocene (era of civilized human culture) temperatures. For contrast, the ice ages averaged about 180 ppm CO2 at the bottom, and pre-industrial (pre-1750) concentrations were about 280 ppm CO2. Pre-industrial temperatures were at the bottom of the Holocene (post–ice age) temperature range, so there’s some headroom above that 280 ppm number. How much exactly? No one knows. It looks like we’re headed for a IPCC-“safe” 450 ppm CO2 unless we stop. Not safe, IMO; nor in Dr. Mann’s. For starters, this “450 ppm” measures CO2 only, not other GHGs like methane and nitrous oxide. The effective ppm in “CO2 equivalent” with those other added GHGs is higher if only CO2 is at 450. It’s roughly thought that the original ice sheet formations of 35 million years ago, which gave us modern Antarctic, Greenland and Arctic ice, occurred in a cooling environment that crossed below CO2 concentrations in the range of 550-400 ppm or so. First, that’s a wide range. Second, that’s no indication of what will happen going the other direction, where the warming tipping points are. Hansen writes, correctly IMO, that real climate sensitivity depends on (a) the starting point (i.e., how near we are to tipping points), and (b) the direction (effect of warming of X amount is not necessarily correlated to the effect of cooling of that same amount). Nevertheless, the massive uncertainty, plus the world-historical consequences, gives most of us pause. Me, I think 450 ppm CO2 is ultimately a death sentence for civilized humans. Back to life as hunter-gatherers for our third- or fourth-generation descendants. And if worldwide social chaos takes over before we stop, the process could run to conclusion, which, the old IPCC A1FI scenario says, tops out at +7°C warming.

On Mann:

“First, he’s actually good on the politics, better than most. But second, I wanted to get his thoughts regarding next steps. For me the key, core messages are — Stop Now… Zero Carbon “Budget” … Free Market Solutions Won’t Work. He surprised me in agreeing with the third point, and I hope he carries that message to the public going forward. He was already mainly on board on the first two, but I wanted to hear him say so for the record, since I hadn’t encountered his public comment on this. “

Source: http://downwithtyranny.blogspot.com/2014/10/michael-mann-on-climate-theres-very.html

H/t to Steve Mosher

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