1.So agree with you that if you want to accurately characterize the
Paris agreement on this plot, the line should corresponding to that
should only go to 2030 and then stop. That is, not what you drew.
Also agree that I was wrong in my interpretation of what you meant by
that line; I was misled by the fact that you’d continued the line out
towards the right-hand end of the plot rather than ending it in 2030
like you intended.
2.Agree that there is uncertainty associated with this, and
uncertainty associated with nonlinearity in particular. I generally
go back to Cao and Caldeira 2010,
https://iopscience.iop.org/article/10.1088/1748-9326/5/2/024011/pdf,
simply because Figure 1 has the nicest plot of the effect, but UVic is
admittedly an old model with a lot missing and a questionable carbon
cycle… but there is quite a bit of content on this in IPCC reports
that would be good to digest before ignoring (that is, broadly the
same behaviour is seen in current models, though again, I agree that
there is potentially important physics missing from those models). But
people (well, mostly John Nissen) keep making the argument you’re
making on the assumption that zero emissions = constant
concentrations, which is simply not true.
3.I think we agree that the choice is non-obvious, but I personally
don’t think it is likely that <280ppm is going to be optimal, so I
still don’t think it is particularly disingenuous to draw the line as
it was. (Besides, the axis was climate effects, presumably relative
to some baseline, and if that baseline is preindustrial, then going
below 280ppm is likely to increase climate damages in the opposite
direction… but agree that I don’t know that, and that it would be
wonderful to ever be in a situation where that question matters.)
4.I would never use the word “assertion” with regards to a schematic
figure like that… though as someone who uses (my own version) of this
diagram frequently, I agree with you that when I talk about it I
should be a bit more careful with regards to how I talk about where
the SRM line goes.
(And yes, John’s napkin is the first I know of that diagram, I don’t
know what paper that specific version came from, it looks nearly
identical to the one that I typically use, but with different fonts.
I think I more or less copied the version I use from one that David
Keith was using, so it is hardly surprising that plenty of us have our
own independent but very similar versions.)
*From:*Robert Tulip <[email protected]>
*Sent:* Wednesday, July 10, 2019 9:35 PM
*To:* Douglas MacMartin <[email protected]>; Andrew Lockley
<[email protected]>
*Cc:* Stephen Salter <[email protected]>; geoengineering
<[email protected]>
*Subject:* Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative
development // Elon Musk vs le développement de régénération
Response to comments from Doug MacMartin and Andrew Lockley
“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.”
· Sorry Doug, but you completely miss the point. Under the Paris
Accord, Image removed by sender.Nationally Determined Contributions
<https://unfccc.int/process-and-meetings/the-paris-agreement/nationally-determined-contributions-ndcs>
have been made to 2030. These indicate a cut of <10% in annual
emission growth by 2030, from about 60 GTCO2e under BAU to 56.2 GT
Image removed by sender.(2016 report page 9)
<https://unfccc.int/sites/default/files/resource/docs/2016/cop22/eng/02.pdf>,
and still way above the current level. Including that in the chart as
I suggested would accurately reflect the marginal impact of current
climate policy. It does not in any way imply that emission reduction
could not be more than has been already agreed under Paris, as shown
with the “aggressive” line on the chart. It might ratchet up, and
economic forces might increase the cut to a still marginal 20%, but
seeing the political reaction to efforts to make energy more expensive
I am not holding my breath for more aggressive emission cuts.
“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.”
· Firstly, the line was not about “net zero emissions” (which include
CDR) but about emission reduction alone, so your “balancing” argument
is not relevant to what the graph asserts. Further to that, I would
like to see the source for your argument about balancing. Recent
commentary I have read (eg from Kevin Lister) says the amplifying
feedbacks from committed warming, seen in events such as the melting
of the poles and burning of forests, mean that aggressive emission
reduction alone cannot possibly cause the planetary temperature to
flatline as you argue here. Given the sensitivity to initial
conditions seen in the orbital drivers of long term climate, your
hypothesis of balancing by residual drawdown looks highly unlikely and
risky when we leave in place a massive driver of 700 GT of extra
carbon in the air with no CDR.
“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.”
· No, the choice of where to stop the line on CDR climate effect is
far from obvious. There is a widespread false assumption in much
climate literature, including from IPCC, that net zero emissions
constitutes a hard floor. This assumption is reflected in how the
original diagram shows a flattening as CDR effect approaches net zero
climate effect. Showing CDR effect extending below zero on the Y axis
reflects the need to work out how to remove enough carbon to get back
to 280 ppm, to restore Holocene planetary stability. Assuming the X
time axis is linear here means that CDR objective requires the line
going well below the zero point on the Y effect axis. The misleading
effect of the portrayal in the original diagram is to increase the
imagined benefit of emission reduction and reduce the potential effect
of carbon removal.
“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.”
· But the problem is that the diagram falsely maximises the effect of
currently promoted policies around decarbonisation while minimising
the potential of geoengineering. That policy bias is reflected in
this assertion in the diagram that SRM could not reduce climate effect.
“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.”
· The difference between exponential and linear effects under BAU is
minor, even though an exponential line showing amplified feedback
would better emphasise the catastrophic risk. Happy to focus on the
other lines which appear to have major politically inspired material
errors.
On Andrew Lockley’s comments, Image removed by sender.Shepherd’s
Napkin Diagram
<http://jgshepherd.com/wp-content/uploads/2011/01/Napkin-diagram.pdf>
shows a rough sketch that I would have hoped could have been made more
accurate over the decade since it was published. Unfortunately, it
looks like the updated version of the Shepherd diagram reflects the
ongoing domination of politics over science within climate advocacy,
so it has not been properly revised to reflect 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]
<mailto:[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]
<mailto:[email protected]>>
*Sent:* Wednesday, July 10, 2019 8:21 AM
*To:* [email protected]
<mailto:[email protected]>; [email protected]
<mailto:[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 *Error! Filename not specified.*Image removed by
sender.Benoit Lambert's link
<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/>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
*Error! Filename not specified.*
On Wednesday, 10 July 2019, 07:46:59 pm AEST, Stephen Salter
<[email protected] <mailto:[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,
Scotland [email protected] <mailto:[email protected]>, Tel +44
(0)131 650 5704, Cell 07795 203 195, *Error! Filename not
specified.*Image removed by sender.WWW.homepages.ed.ac.uk/shs
<http://WWW.homepages.ed.ac.uk/shs>, YouTube Jamie Taylor Power
for Change
Image removed by sender.
Index of /shs
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 <mailto:[email protected]>
*Sent: *09 July 2019 18:39
*To: *Carbon Dioxide Removal
<mailto:[email protected]>
*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
*Error! Filename not specified.*Image removed by
sender.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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