2011-01-16 11:43:52Monckton Myth #5: Dangerous Warming
dana1981
Dana Nuccitelli
dana1981@yahoo...
71.140.0.210
I drafted up Monckton Myth #5, which is actually his point #7, but if we stay in order will be our fifth Monckton Myth post.  It discusses the global warming 'danger limit'.
2011-01-16 17:03:36
Ari Jokimäki

arijmaki@yahoo...
91.154.102.166

Looks good to me. I would change this part a bit:

"As discussed above, although the IPCC has not established a specific warming target, there is a strong scientific case to be made for considering 2°C above pre-industrial levels (approximately 1°C above current levels) the 'danger limit' beyond which the risks of significant adverse impacts become too high."

Considering the paper of Jaegers, it seems to me that "strong" is a bit too strong statement here, as there seems to be some controversy scientifically on this limit (although alternative limits seem also to fall quite near it). Maybe just take the word "strong" out?

2011-01-16 18:06:11
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.76.234
The last heading needs another "danger" on the end - ala Robbie the Robot. Looks good.
2011-01-16 21:40:56Is the 2 degree danger limit too high?
James Wight

jameswight@southernphone.com...
112.213.154.212

I notice that your sources are primarily from the 1990s and suspect they may be out of date.

I’ve recently finished reading James Hansen’s book Storms of My Grandchildren (a pretty frightening read). Hansen used to argue for a limit of 1°C above 2000 (= 1.7°C above preindustrial), because that was the global temperature during the Eemian, at the high end of the natural variation during the late Quaternary. It was known at that time that the sea level during the Eemian was higher (we now know up to 9 metres), but such a sea level rise was expected to occur slowly.

Hansen describes how he changed his mind around 2008, partly because of paleoclimate evidence that ice sheets can respond more rapidly than models predict. As you probably know, he now advocates reducing CO2 to 350 ppm to get the Earth back in energy balance. I am currently reading Hansen’s “Target Atmospheric CO2” paper to better understand his argument and I intend to write something about it for SkS.

Also some more useful info to counter Monckton’s claim: The Pliocene was only 2-3°C warmer and sea levels were 25 metres higher. Even the variation during the Quaternary is still quite significant: the 5°C variation referred to is the difference between today and a world with ice sheets in Canada and Europe and sea level 120 metres lower. Talking about past sea levels is a good way to counter the contrarians’ flaky argument that “historically warmth equals prosperity”.

2011-01-17 06:33:44responses
dana1981
Dana Nuccitelli
dana1981@yahoo...
71.140.0.210

Yeah Ari, it's probably fair to take the "strong" out.

Rob, is there another "danger" at the end?  That show was a bit before my time :-)

James - yes, I'm talking about a short-term target, but it's a good point that the long-term target should probably be even lower to avoid the slow-acting feedbacks.  The way I see it is that we try to target 2°C this century, then in the next century or two hopefully we'll have the technology to remove and sequester atmospheric CO2.  I'll add a sub-section on the long-term target referencing Hansen's paper.