Greg,
Thanks for this addition. My carbon cycle model has a convolution model
for the ocean. This does have a long tail, but it is not as large as in
the papers you cite. So, if these studies are correct, and I do believe
they are, then my results are indeed optimistic.
The main point is that we cannot get back to 350 ppm by mitigation
alone. There are still many who think we can, and my simple sums were
presented as a reality check for those people. As your papers and the
others you cite, and papers cited in these, show, this is not new news.
Tom.
+++++++++++++++++++++++++++++++++++++
On 10/30/2013 4:02 PM, Greg Rau wrote:
Tom,
Your CO2 trajectory would seem overly optimistic unless I'm misreading
Archer's treatment:
http://www.annualreviews.org/eprint/TXVr5xrStR8vCEuTmECx/full/10.1146/annurev.earth.031208.100206
Indeed, we can't get to 350 ppm any time soon with anthro emissions
reduction alone. That's why it's worth considering more proactive
measures, e.g., attached and argued here:
http://www.sciencemag.org/content/340/6140/1522.2.full
not to mention broached in AR5 and elsewhere. A daunting task to be
sure, but trying would seem better than the alternative.
One piece of encouragement - atmospheric CO2 does intra-annually decline
at most latitudes by as much as 16 ppm via natural air capture, and this
uptake is increasing*. So we are not starting with zero CDR - how tough
would it be to safely enhance/accelerate this uptake? Nor as I argue, do
we need to necessarily enhance air capture. We can achieve the same
effect by reducing the leakiness of Nature's carbon storage, the largest
emitter on the planet by far.
*
http://www.sciencemag.org/content/341/6150/1085.full?sid=4adfc7d3-e42f-46e4-9f5b-3507b927672e
Greg
------------------------------------------------------------------------
*From:* Tom Wigley <wig...@ucar.edu>
*To:* geoengineering@googlegroups.com
*Sent:* Wednesday, October 30, 2013 12:19 AM
*Subject:* Re: [geo] TERRA FUTURA 2013: INTERVIEW WITH VANDANA SHIVA
ABOUT GEOENGINEERING | NoGeoingegneria
Dear all,
Dropping CO2 concentrations to 350 ppm in 50 years is impossible
unless we can find a cheap way to suck a whole lot of CO2 out of the
atmosphere.
Some simple calculations are attached.
Tom.
++++++++++++++++++++++++++++++++++++=
On 10/29/2013 2:18 PM, Ronal W. Larson wrote:
> List and Brian:
>
> I just noted a mis-statement. See below.
>
>
> On Oct 29, 2013, at 1:28 PM, Ronal W. Larson
<rongretlar...@comcast.net <mailto:rongretlar...@comcast.net>
> <mailto:rongretlar...@comcast.net
<mailto:rongretlar...@comcast.net>>> wrote:
>
>> Brian (cc list) This to respond to your three inserts in my
>> yesterday’s response to you
>>
>> BC1: */But that's not very good. Warming-induced feedback loops like
>> methane deposits are already very scary. I don't say CO2 levels are
>> irreversible; my point is about warming from all causes, and you
need
>> methods of cooling that are much quicker than 50 years. /*
>>>
>> *[RWL1: Brian’s “that” refers to my just previous statement (see
>> below) that we could drop to 350 ppm in 50 years. Brian is NOT
>> arguing for SRM here, although it may seem so. He is arguing for
>> increased latent heat transfer - an approach that seems questionable
>> at best - given the strong warming potential of increased
atmospheric
>> carbon.*
>
> RWL: The last word was supposed to be “moisture” - NOT “carbon”.
> Apologies. I am too used to following “atmospheric” with “carbon”.
>
> Ron
>
> <snip remainder>
>
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