Comments on: Cumulative Emissions and Climate Models

By: Steve Easterbrook

Steve Easterbrook — Fri, 18 May 2012 15:11:32 +0000

Kate,
There was an interesting twitter discussion of your post this week, which I captured here (I’m experimenting with Storify…):
http://www.easterbrook.ca/steve/?p=2891

By: climatesight

climatesight — Thu, 17 May 2012 18:40:47 +0000

Here’s the Zickfeld et al paper too: http://climate.uvic.ca/EMICAR5/PNAS-2009-Zickfeld-16129-34.pdf
I’m pretty sure the full text is already free at PNAS, but it’s hard to tell on the campus network.

By: Andy S

Andy S — Thu, 17 May 2012 18:37:40 +0000

Thanks for an interesting post, Kate. I recently came across this methodology when looking at the climate effect of the exploitation of the Alberta tar sands at Skeptical Science. I’ll insert a link to your post in my article, since your explanation explains the methodology nicely.

http://www.skepticalscience.com/SW12.html

It is fortuitous (computationally, at least) that the effects of the diminishing carbon sinks and the infra-red band saturation roughly cancel out to make the climate response to cumulative emissions linear. (We would be better off in terms of climate effect, though, if the effectiveness of the carbon sinks did not decrease with increasing emissions.) Thinking about cumulative emissions as the key parameter does simplify the metrics for the mitigation response we need to make. It’s a pity that the slopes can’t be better constrained, but I look forward to hearing from you if you make some progress on this.

For those of us without subscriptions, free pdfs of the Matthews et al and the Allen et al papers are available here:

http://www.cccma.ec.gc.ca/papers/ngillett/PDFS/nature08047.pdf

http://www.fraw.org.uk/files/climate/allen_2009.pdf

By: Martin Lack

Martin Lack — Thu, 17 May 2012 13:23:03 +0000

At the risk of seeming like an insufferably smug bar steward, here is what I said on this subject (referring to the work of Dr Myles Allen [2009]) almost 9 months ago:
“The fact that AGW may suffer from issue fatigue, and the fact that I sometimes feel like an old-style street preacher being completely ignored by passers-by, does not change the fact that, on well above the balance of probability, we face an environmental catastrophe if we fail to take significant action within the next 5 years. Furthermore, every year we fail to act, makes taking effective action much, much harder. This is because it is the total (i.e. cumulative) amount of fossilised carbon that we (have and will) put into the atmosphere that will determine the temperature change we will see over the next 50 years or so.”
http://lackofenvironment.wordpress.com/2011/08/19/why-are-we-still-waiting/

See also Wikipedia‘s exhaustively-referenced summary of the 4 Degrees and Beyond International Climate Conference in Oxford in 2009 (at which the work of Allen and many others was first presented).

By: sailrick

sailrick — Thu, 17 May 2012 04:49:56 +0000

Well Kate, you sure do a good job of communicating the sceince. Thanks. I learned something

By: dana1981

dana1981 — Thu, 17 May 2012 02:20:35 +0000

That’s an interesting point about diminishing carbon sinks. It will be interesting to see what values you get for the slope.