Tuesday, March 19, 2013

Distinguishing Natural and Man-Made Climate Change

Figure is from here, and shows estimated global temperature from the last glacial maximum to the end of the 21st century (according to a fairly business-as-usual emissions scenario).

8 comments:

yvesT said...

Scary ...

Sam Charles Norton said...

Hi Stuart, you know that I'm a fan of yours so I hope you'll take this in the right 'holy' spirit! I get so very disappointed when you link to stuff like this without engaging with the very specific and detailed criticisms being made of it, especially by Steve McIntyre. You have the intellectual firepower to engage at the proper level with his arguments which to me - as a layman - seem utterly devastating. If you were able to point out ways in which he is being unfair to Marcott you wouldn't just be doing me a service, you'd be helping lots of others. As it stands, the "consensus" on CAGW seems to be sinking faster than the proverbial post-iceberg sea liner!

Sam Charles Norton said...

PS Judith Curry is weighing in on it here: http://judithcurry.com/2013/03/19/playing-hockey-blowing-the-whistle/

Chris Reynolds said...

Stuart,

Thanks for posting.

Sam Charles Norton,

"As it stands, the "consensus" on CAGW seems to be sinking faster than the proverbial post-iceberg sea liner!"

No it isn't. I'll let you know when the consensus in the peer reviewed papers changes.

Mike Aucott said...

Sam,

McIntyre's arguments seem not at all devastating, but rather to be focused on relatively trivial aspects of temperature proxies.

Does McIntyre really think the planet is not warming, and has not dramatically warmed over the same period that CO2, clearly from anthropogenic causes, has dramatically increased?

If CO2, solidly proven to be a greenhouse gas, is not causing this warming, why not? If CO2 is not causing this warming, then what is? Climate change deniers have no good answer to either question.

You can get beyond what you perceive to be a layman's handicap easily by reading some of the excellent books available. One good one is Robert Henson's Rough Guide to Climate Change.

Luke Smith said...

It is a quick change. Can ice-cores or other means of sampling past climate data capture such a change? Do they have that sort of resolution?

stravinsky7 said...

Good question, Luke. Oh and Stu, It looks like the trend line you extracted was on the highly conservative side (either that or it's a problem of resolution). Like the whole left side of that red line is blue.

Sam Charles Norton said...

Thought I'd return to this chart, as Marcott et al have now "clarified": "the twentieth-century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes, and therefore is not the basis of any of our conclusions". Pity that wasn't emphasised when the press release was being prepared...