Response to comments from Doug MacMartin and Andrew Lockley
“1. Given that theParis agreement commitments don’t actually tell you
what’s going to happentowards even the middle of the century, drawing any line
corresponding to thosecommitments is a guess, but regardless, it seems pretty
remarkable to assertthat no-one will *ever* cut emissions beyond what was
agreed upon inParis – that’s your hypothesis, and doesn’t reflect an
“inaccurate” diagram.”
· Sorry Doug, but you completely miss the point. Under the Paris
Accord, NationallyDetermined Contributions have been made to 2030. These
indicate a cut of <10% in annualemission growth by 2030, from about 60 GTCO2e
under BAU to 56.2 GT (2016report page 9), and still way above the current
level. Including that inthe chart as I suggested would accurately reflect the
marginal impact of current climatepolicy. It does not in any way implythat
emission reduction could not be more than has been already agreed underParis,
as shown with the “aggressive” line on the chart. It might ratchet up, and
economic forcesmight increase the cut to a still marginal 20%, but seeing the
politicalreaction to efforts to make energy more expensive I am not holding my
breathfor more aggressive emission cuts.
“2. Mostlywrong… actually, if net emissions are zero, then once you’ve
paid the price forremoving tropospheric aerosol cooling, the residual committed
warming is mostlybalanced by the residual drawdown of CO2… obviously not going
to be exact, anddepends a lot on whether there are nonlinear tipping points,
but zero emissionsis NOT the same thing as constant-concentration commitment,
so to first orderthe original diagram is more accurate than your amended one.”
· Firstly, the line was not about “net zero emissions” (which
includeCDR) but about emission reduction alone, so your “balancing” argument is
notrelevant to what the graph asserts. Further to that, I would like to see
thesource for your argument about balancing. Recent commentary I have read (eg
from Kevin Lister) says the amplifyingfeedbacks from committed warming, seen in
events such as the melting of thepoles and burning of forests, mean that
aggressive emission reduction alone cannotpossibly cause the planetary
temperature to flatline as you argue here. Given the sensitivity to initial
conditionsseen in the orbital drivers of long term climate, your hypothesis of
balancing byresidual drawdown looks highly unlikely and risky when we leave in
place amassive driver of 700 GT of extra carbon in the air with no CDR.
“3. The version of thisthat John posted has CDR continuing all the way
down towards zero but not belowit, your version goes below zero effects, so I’m
not clear on what your pointis here… Obvoiusly, that’s ultimately a choice
where one stops.”
· No, the choice of where to stop the line on CDR climate effect isfar
from obvious. There is a widespreadfalse assumption in much climate
literature, including from IPCC, that net zeroemissions constitutes a hard
floor. Thisassumption is reflected in how the original diagram shows a
flattening as CDReffect approaches net zero climate effect. Showing CDR effect
extending below zero on the Y axis reflects the needto work out how to remove
enough carbon to get back to 280 ppm, to restoreHolocene planetary stability.
Assuming the X time axis is linear here meansthat CDR objective requires the
line going well below the zero point on the Yeffect axis. The misleading
effect ofthe portrayal in the original diagram is to increase the imagined
benefit of emissionreduction and reduce the potential effect of carbon removal.
“4. Sure… again, that’sa choice, that doesn’t reflect an inaccurate
diagram, simply that the diagramdoesn’t show the full range of possible policy
options.”
· But the problem is that the diagram falsely maximises the effectof
currently promoted policies around decarbonisation while minimising the
potentialof geoengineering. That policy bias is reflectedin this assertion in
the diagram that SRM could not reduce climate effect.
“5. Well, unclear giventhat there are no units or scales on the
qualitative y-axis. ThoughRCP8.5, which is generally what people think of as
BAU, does indeed result inroughly linear increase in temperature over time. Of
course, therelationship between “effects” and temperature aren’t clear.”
· The difference between exponential and linear effects under BAUis
minor, even though an exponential line showing amplified feedback wouldbetter
emphasise the catastrophic risk. Happyto focus on the other lines which appear
to have major politically inspiredmaterial errors.
On Andrew Lockley’s comments, Shepherd’sNapkin Diagram shows a rough sketch
that I would have hoped could have beenmade more accurate over the decade since
it was published. Unfortunately, it looks like the updatedversion of the
Shepherd diagram reflects the ongoing domination of politicsover science within
climate advocacy, so it has not been properly revised toreflect accurate
scientific information.
Robert Tulip
On Thursday, 11 July 2019, 02:24:42 am AEST, Andrew Lockley
<[email protected]> wrote:
To give credit where credit's due, this was originally Shepherds famous napkin
diagram. The srm line has been adjusted somewhat, however. I don't think that
Doug's claims regarding Paris Commitments not conceivably being exceeded is
supported empirically. Swansons law suggests very steep falls in the cost of
energy by mid century, perhaps low single figure percentages of current costs.
It would be implausible if large-scale use of fossil fuels would continue when
renewable energy was one or two orders of magnitude cheaper
On Wed, 10 Jul 2019, 17:12 Douglas MacMartin, <[email protected]> wrote:
Um…
1. Given that the Paris agreement commitments don’t actually tell you
what’s going to happen towards even the middle of the century, drawing any line
corresponding to those commitments is a guess, but regardless, it seems pretty
remarkable to assert that no-one will *ever* cut emissions beyond what was
agreed upon in Paris – that’s your hypothesis, and doesn’t reflect an
“inaccurate” diagram.
2. Mostly wrong… actually, if net emissions are zero, then once you’ve
paid the price for removing tropospheric aerosol cooling, the residual
committed warming is mostly balanced by the residual drawdown of CO2… obviously
not going to be exact, and depends a lot on whether there are nonlinear tipping
points, but zero emissions is NOT the same thing as constant-concentration
commitment, so to first order the original diagram is more accurate than your
amended one.
3. The version of this that John posted has CDR continuing all the way
down towards zero but not below it, your version goes below zero effects, so
I’m not clear on what your point is here… Obvoiusly, that’s ultimately a
choice where one stops.
4. Sure… again, that’s a choice, that doesn’t reflect an inaccurate
diagram, simply that the diagram doesn’t show the full range of possible policy
options.
5. Well, unclear given that there are no units or scales on the
qualitative y-axis. Though RCP8.5, which is generally what people think of as
BAU, does indeed result in roughly linear increase in temperature over time.
Of course, the relationship between “effects” and temperature aren’t clear.
Bottom line, it is completely inaccurate for you to refer to this conceptual
diagram as being inaccurate or containing major errors. It is perfectly
accurate to observe that none of the lines on the diagram are immutable. But
given that there are no units, that’s hardly a criticism…
From: 'Robert Tulip' via geoengineering <[email protected]>
Sent: Wednesday, July 10, 2019 8:21 AM
To: [email protected]; [email protected]
Subject: Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development //
Elon Musk vs le développement de régénération
Further to the needed corrections mentioned by John Gorman, Stephen Salter
correctly points out that this diagram is inaccurate. It actually embeds a
series of major myths in climate politics. I read Benoit Lambert's link but
did not find the chart there.
Here is a revised version of the chart. It shows that every line of the
previous version contains major error with strong potential to mislead decision
makers and the public.
1. Full implementation of current Paris commitments (added) would only have
small marginal effect on Business as usual,
2. Aggressive emission cuts do nothing about committed warming from past
emissions, so do not flatline the climate effect
3. CO2 removal continues below the farcical imaginary floor of zero effect
4. Solar radiation management can produce net negative radiative forcing.
5. The BAU line (not changed here) should show ongoing exponential growth
rather than the shown linear increase.
Robert Tulip
On Wednesday, 10 July 2019, 07:46:59 pm AEST, Stephen Salter
<[email protected]> wrote:
Hi All
Zero emissions do not immediately mean zero temperature rises, especially if we
have passed tipping points.
Stephen
Emeritus Professor of Engineering Design. School of Engineering, University of
Edinburgh, Mayfield Road, Edinburgh EH9 3DW, [email protected], Tel +44
(0)131 650 5704, Cell 07795 203 195,WWW.homepages.ed.ac.uk/shs, YouTube Jamie
Taylor Power for Change
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Index of /shs
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On 10/07/2019 09:35, john gorman wrote:
This diagram from the paper says it all in my opinion, and simply!!
With, of course some variation in angles. Eg SRM could be angled down and I
don’t believe cutting emissions will ever result in zero emissions.
Good realistic paper!
John gorman
From:Benoit Lambert
Sent: 09 July 2019 18:39
To: Carbon Dioxide Removal
Subject: [CDR] blog 28, Elon Musk vs regenerative development // Elon Musk vs
le développement de régénération
blog 28, Elon Musk vs regenerative development // Elon Musk vs le développement
de régénération
https://cologie.wordpress.com/2019/07/09/elon-musk-vs-regenerative-development-elon-musk-vs-le-developpement-de-regeneration-french-below-en-francais-plus-bas/
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