Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development // Elon Musk vs le développement de régénération

[Andrew Lockley]

This has gone a bit CDR, but two quick points:

1) ocean waters down well, so a proportion of the CO2 is now in deep water.
2) if we suck all the CO2 out of the air, much will come out of the surface
ocean to replace it

Andrew

On Thu, 11 Jul 2019, 20:33 Douglas MacMartin,  wrote:

> Just to point out (in response to Kevin, and agreeing with David) that
>
> 1)  We know, for example, that the surface ocean and biosphere have
> already absorbed about 50% of the CO2 that we’ve emitted, so you certainly
> can’t argue that the amount of permanent CO2 sequestration by the rest of
> the climate system is negligible – it’s unquestionably an enormous effect.
>
> 2)  There are a wide range of timescales for both the climate warming
> to a given radiative forcing, and for the uptake of CO2.  For both of
> those, if you vary the input slowly, the output roughly tracks the input.
> So observing that if I put some slowly-varying signal u(t) into a system
> that the output y(t) is roughly proportional doesn’t tell me whether y(t)
> is in equilibrium with u(t) or not.  I could take Kevin’s arguments to *
> *also** assert that the evidence is that there is no significant residual
> committed warming.  (Aside from point #4, which I don’t follow why the
> logarithmic dependence matters; you can always linearize that about the
> current point if you want, and you’ll find a non-zero slope, definitely not
> a zero slope.)
>
>
>
> If we abruptly cease emissions today, then
>
> a)   We lose the cooling from tropospheric aerosols (IPCC SR1.5 put
> that at 0.3C, but I’ve seen estimates as high as 1.2C, it’s uncertain)
>
> b)  The climate warms because the oceans (mainly) aren’t in
> equilibrium with the current forcing from increased CO2 (etc) concentrations
>
> c)   The CO2 concentrations decrease because the oceans (mainly, I
> think) aren’t in equilibrium with the current CO2 concentrations
>
> d)  And, also, if we stop all the rest of the SLCFs (methane, etc),
> then we lose some of the warming from them too, fairly quickly.
>
>
>
> I don’t follow what the evidence is that argues that (b) is so much larger
> than (c) that we can completely ignore (c) in making future predictions.
> Happy to have someone tell me otherwise, but only if they can provide some
> evidence for why IPCC AR5 and SR1.5 got everything so badly wrong…
>
>
>
> And, agree with David that having not conducted the experiment, we don’t
> actually know, that is, regardless of what our best guesses are, we
> shouldn’t be gambling the future of the planet on our best guess, so agree
> 100% with your ultimate policy conclusion anyway.
>
>
>
> (Also, I don’t know what the basis for asserting that we have passed
> tipping points, and will soon pass irreversibilities.  The latter we might
> well have already passed some, I don’t think we really know, and for  the
> former I’ve seen the term tipping point used in so many ways that I no
> longer have any clue what people mean by it.)
>
>
>
> *From:* Hawkins, David 
> *Sent:* Thursday, July 11, 2019 9:37 AM
> *To:* kevin.lister2...@gmail.com
> *Cc:* Douglas MacMartin ; Robert Tulip <
> rtulip2...@yahoo.com.au>; Andrew Lockley ;
> Stephen Salter ; geoengineering <
> geoengineering@googlegroups.com>
> *Subject:* Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative
> development // Elon Musk vs le développement de régénération
>
>
>
> To start, I agree completely with the bottom line that we must do as much
> as possible as fast as possible.
>
> But my understanding of the carbon cycle is that the strength of the land
> and ocean sinks is driven by the cumulative amounts of carbon in the
> atmosphere, not the annual emissions.  Thus, if emissions dropped to zero,
> the current sink strength will decline slowly.  The result would be a
> multi-decadal period during which the land and ocean sink terms would be
> greater than the anthro additions, leading to a gradual decline in
> atmospheric carbon concentrations.
>
> Of course, we have not run this thought experiment in the real world and
> we might be surprised.
>
>
>
> Sent from my iPad
>
>
> On Jul 11, 2019, at 8:16 AM, Kevin Lister 
> wrote:
>
> Hi Doug et al,
>
>
>
> On point 2 below, "*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.*"
>
>
>
> Let me come to John's defence.
>
>
>
> 1. The correlation between cumulative emissions and atmospheric CO2 is
> effectively perfect with r^2=0.999, which is quite extraordinary. This
> strongly  implies that all the CO2 emissions from fossil fuel burning  are
> still in the ecosystem. That obviously doesn't imply that all the CO2 from
> fossil fuel burning is in the atmosphere, but it does reasonably lead to
> the conclusion that all interconnected carbon sinks are filling equally,
> such as the the ocean surface, soils, and the atmosphere. Given that this
> perfect correlation has 

RE: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development // Elon Musk vs le développement de régénération

[Douglas MacMartin]

Just to point out (in response to Kevin, and agreeing with David) that

1)  We know, for example, that the surface ocean and biosphere have already 
absorbed about 50% of the CO2 that we’ve emitted, so you certainly can’t argue 
that the amount of permanent CO2 sequestration by the rest of the climate 
system is negligible – it’s unquestionably an enormous effect.

2)  There are a wide range of timescales for both the climate warming to a 
given radiative forcing, and for the uptake of CO2.  For both of those, if you 
vary the input slowly, the output roughly tracks the input.  So observing that 
if I put some slowly-varying signal u(t) into a system that the output y(t) is 
roughly proportional doesn’t tell me whether y(t) is in equilibrium with u(t) 
or not.  I could take Kevin’s arguments to *also* assert that the evidence is 
that there is no significant residual committed warming.  (Aside from point #4, 
which I don’t follow why the logarithmic dependence matters; you can always 
linearize that about the current point if you want, and you’ll find a non-zero 
slope, definitely not a zero slope.)

If we abruptly cease emissions today, then

a)   We lose the cooling from tropospheric aerosols (IPCC SR1.5 put that at 
0.3C, but I’ve seen estimates as high as 1.2C, it’s uncertain)

b)  The climate warms because the oceans (mainly) aren’t in equilibrium 
with the current forcing from increased CO2 (etc) concentrations

c)   The CO2 concentrations decrease because the oceans (mainly, I think) 
aren’t in equilibrium with the current CO2 concentrations

d)  And, also, if we stop all the rest of the SLCFs (methane, etc), then we 
lose some of the warming from them too, fairly quickly.

I don’t follow what the evidence is that argues that (b) is so much larger than 
(c) that we can completely ignore (c) in making future predictions.  Happy to 
have someone tell me otherwise, but only if they can provide some evidence for 
why IPCC AR5 and SR1.5 got everything so badly wrong…

And, agree with David that having not conducted the experiment, we don’t 
actually know, that is, regardless of what our best guesses are, we shouldn’t 
be gambling the future of the planet on our best guess, so agree 100% with your 
ultimate policy conclusion anyway.

(Also, I don’t know what the basis for asserting that we have passed tipping 
points, and will soon pass irreversibilities.  The latter we might well have 
already passed some, I don’t think we really know, and for  the former I’ve 
seen the term tipping point used in so many ways that I no longer have any clue 
what people mean by it.)

From: Hawkins, David 
Sent: Thursday, July 11, 2019 9:37 AM
To: kevin.lister2...@gmail.com
Cc: Douglas MacMartin ; Robert Tulip 
; Andrew Lockley ; Stephen 
Salter ; geoengineering 
Subject: Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development // 
Elon Musk vs le développement de régénération

To start, I agree completely with the bottom line that we must do as much as 
possible as fast as possible.
But my understanding of the carbon cycle is that the strength of the land and 
ocean sinks is driven by the cumulative amounts of carbon in the atmosphere, 
not the annual emissions.  Thus, if emissions dropped to zero, the current sink 
strength will decline slowly.  The result would be a multi-decadal period 
during which the land and ocean sink terms would be greater than the anthro 
additions, leading to a gradual decline in atmospheric carbon concentrations.
Of course, we have not run this thought experiment in the real world and we 
might be surprised.

Sent from my iPad

On Jul 11, 2019, at 8:16 AM, Kevin Lister 
mailto:kevin.lister2...@gmail.com>> wrote:
Hi Doug et al,

On point 2 below, "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."

Let me come to John's defence.

1. The correlation between cumulative emissions and atmospheric CO2 is 
effectively perfect with r^2=0.999, which is quite extraordinary. This strongly 
 implies that all the CO2 emissions from fossil fuel burning  are still in the 
ecosystem. That obviously doesn't imply that all the CO2 from fossil fuel 
burning is in the atmosphere, but it does reasonably lead to the conclusion 
that all interconnected carbon sinks are filling equally, such as the the ocean 
surface, soils, and the atmosphere. Given that this perfect correlation has 
been unaffected by the rate of emissions, then it would further imply that the 
rate of permanent sequestration must been extremely slow, and effectively 
negligible compared to fossil fuel emissions.

2. The immediate upwards rise of atmospheric CO2 at the start of the industrial 
revolution further indicates that the rate of permanent CO2 sequestration is 
very slow. At this time emissions were a fraction of what they are today and 
the ecosystem was in a considerably more healthy 

Re: [geo] Could geoengineering cause a climate war

[Juergen Scheffran]

Following the discussion on climate war last week, some may be 
interested in our article on climate and conflict in today's print 
edition of Nature:


Mach KJ, Kraan CM, Adger WN, Buhaug H, Burke M, Fearon JD, Field CB, 
Hendrix CS, Maystadt JF, O’Loughlin J, Roessler P, Scheffran J, Schultz 
KA, von Uexkull N (2019): Climate as a risk factor for armed conflict; 
/Nature/ 571 (7764): 193–197 (11 July) 
https://www.nature.com/nature/volumes/571/issues/7764


Advance Online Publication: 
https://www.nature.com/articles/s41586-019-1300-6 
Supplementary information: 
https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-019-1300-6/MediaObjects/41586_2019_1300_MOESM1_ESM.pdf




On 03.07.2019 12:59, Andrew Lockley wrote:


https://www.sciencefocus.com/planet-earth/could-geoengineering-cause-a-climate-war/amp/?__twitter_impression=true 



Could geoengineering cause a climate war?
If country leaders manipulate the weather to do their bidding, could 
they create political tensions, or even all-out war?

4 weeks ago
By Clive Hamilton



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Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development // Elon Musk vs le développement de régénération

[Hawkins, David]

To start, I agree completely with the bottom line that we must do as much as 
possible as fast as possible.
But my understanding of the carbon cycle is that the strength of the land and 
ocean sinks is driven by the cumulative amounts of carbon in the atmosphere, 
not the annual emissions.  Thus, if emissions dropped to zero, the current sink 
strength will decline slowly.  The result would be a multi-decadal period 
during which the land and ocean sink terms would be greater than the anthro 
additions, leading to a gradual decline in atmospheric carbon concentrations.
Of course, we have not run this thought experiment in the real world and we 
might be surprised.

Sent from my iPad

On Jul 11, 2019, at 8:16 AM, Kevin Lister 
mailto:kevin.lister2...@gmail.com>> wrote:

Hi Doug et al,

On point 2 below, "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."

Let me come to John's defence.

1. The correlation between cumulative emissions and atmospheric CO2 is 
effectively perfect with r^2=0.999, which is quite extraordinary. This strongly 
 implies that all the CO2 emissions from fossil fuel burning  are still in the 
ecosystem. That obviously doesn't imply that all the CO2 from fossil fuel 
burning is in the atmosphere, but it does reasonably lead to the conclusion 
that all interconnected carbon sinks are filling equally, such as the the ocean 
surface, soils, and the atmosphere. Given that this perfect correlation has 
been unaffected by the rate of emissions, then it would further imply that the 
rate of permanent sequestration must been extremely slow, and effectively 
negligible compared to fossil fuel emissions.

2. The immediate upwards rise of atmospheric CO2 at the start of the industrial 
revolution further indicates that the rate of permanent CO2 sequestration is 
very slow. At this time emissions were a fraction of what they are today and 
the ecosystem was in a considerably more healthy state.

3. The saw tooth profile of the Vostok Ice Core shows the rate of permanent 
carbon sequestration to be slow and averaged over the last 4 inter-glacial 
cycles it is around 6.7E-4ppm/year, which is negligible compared with the rate 
of increase.

4. Even if zero carbon led to CO2 concentration reductions, the cooling effect 
would be too small due to the logarithmic relation between forcing and 
concentration.

So the evidence would support that zero emissions=constant concentrations, at 
least on for any timescale that matters, The  things that matter to determine 
the timescale are the initiation of climate tipping points and points of 
irreversibly, beyond which climate and ecosystem recovery becomes impossible 
even with SRM interventions.  We have certainly past the points of initiation 
of tipping points, and will soon be past the points of irreversibly.

So it seems to me that from a pragmatic risk management perspective, we should 
assume that zero carbon=constant emissions, and plan accordingly, which means 
identifying interventions in the climate system that can lead to cooling and 
CDR, as well as forcing much deeper cuts in anthropocentric emissions.

Kevin



On Thu, Jul 11, 2019 at 11:22 AM Douglas MacMartin 
mailto:dgm...@cornell.edu>> wrote:

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 

Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development // Elon Musk vs le développement de régénération

[Kevin Lister]

Hi Doug et al,

On point 2 below, "*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.*"

Let me come to John's defence.

1. The correlation between cumulative emissions and atmospheric CO2 is
effectively perfect with r^2=0.999, which is quite extraordinary. This
strongly  implies that all the CO2 emissions from fossil fuel burning  are
still in the ecosystem. That obviously doesn't imply that all the CO2 from
fossil fuel burning is in the atmosphere, but it does reasonably lead to
the conclusion that all interconnected carbon sinks are filling equally,
such as the the ocean surface, soils, and the atmosphere. Given that this
perfect correlation has been unaffected by the rate of emissions, then it
would further imply that the rate of permanent sequestration must been
extremely slow, and effectively negligible compared to fossil fuel
emissions.

2. The immediate upwards rise of atmospheric CO2 at the start of the
industrial revolution further indicates that the rate of permanent CO2
sequestration is very slow. At this time emissions were a fraction of what
they are today and the ecosystem was in a considerably more healthy state.

3. The saw tooth profile of the Vostok Ice Core shows the rate of permanent
carbon sequestration to be slow and averaged over the last 4 inter-glacial
cycles it is around 6.7E-4ppm/year, which is negligible compared with the
rate of increase.

4. Even if zero carbon led to CO2 concentration reductions, the cooling
effect would be too small due to the logarithmic relation between forcing
and concentration.


So the evidence would support that zero emissions=constant concentrations,
at least on for any timescale that matters, The  things that matter to
determine the timescale are the initiation of climate tipping points and
points of irreversibly, beyond which climate and ecosystem recovery becomes
impossible even with SRM interventions.  We have certainly past the points
of initiation of tipping points, and will soon be past the points of
irreversibly.

So it seems to me that from a pragmatic risk management perspective, we
should assume that zero carbon=constant emissions, and plan accordingly,
which means identifying interventions in the climate system that can lead
to cooling and CDR, as well as forcing much deeper cuts in anthropocentric
emissions.

Kevin



On Thu, Jul 11, 2019 at 11:22 AM Douglas MacMartin 
wrote:

> 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 

[geo] Solar Radiation Management for Great Barrier Reef

['Robert Tulip' via geoengineering]

The Australian Government is investing AUD $1.6 million in SRM work this year.
https://www.barrierreef.org/uploads/RTP_Annual%20Work%20Plan%202019-2020_FINAL.pdf

"Activity: Solar radiationmanagement: 
Description: RRAP [Great Barrier Reef Restoration and Adaptation Program] model 
predictions indicate that keeping existing corals alive at a largescale would 
have the biggest impact of all considered interventions. Theconcept of creating 
shade through clouds, mist, fog, or surface films assumesthat decreased solar 
radiation protects corals from bleaching. Ecological andphysiological factors 
will be investigated through the foundational knowledgeactivity. Proof of 
concepts and assessment of the impact of manipulating solarradiation at scale 
will underpin risk and environmental impact assessments tobe considered under 
the regulation and policy activity. 
Deliverables: Proof of concept including environmental impact and 
regulatoryassessment. 
Budget:  $1.6m"

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Re: [geo] Intergovernmental conferences

[Andrew Lockley]

I'd start by looking at the history, notably the US / Saudi spiking of the
recent SRM resolution

On Thu, 11 Jul 2019, 12:34 Gideon Futerman,  wrote:

> Thoughts on which intergovernmental conference it may be best for a
> government to bring up SRM research and governance and CDR research,
> governance, cooperation and incentivisation. I am looking to put together a
> letter to Claire Perry (UK minister for energy and clean growth) so I was
> just wondering. Would COP this year be appropriate, or should this wait
> until UNEA 5 for example?
>
> --
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> "geoengineering" group.
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> Visit this group at https://groups.google.com/group/geoengineering.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/geoengineering/63bb10b6-5474-4d95-a767-f1d96706dd8e%40googlegroups.com
> 
> .
> For more options, visit https://groups.google.com/d/optout.
>

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[geo] Intergovernmental conferences

[Gideon Futerman]

Thoughts on which intergovernmental conference it may be best for a 
government to bring up SRM research and governance and CDR research, 
governance, cooperation and incentivisation. I am looking to put together a 
letter to Claire Perry (UK minister for energy and clean growth) so I was 
just wondering. Would COP this year be appropriate, or should this wait 
until UNEA 5 for example?

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Re: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development // Elon Musk vs le développement de régénération

[Stephen Salter]

Hi All

Some of my very best friends are vegetables and they really need CO2 
especially if we have to grow more of them.


Suppose that we could put temperature patterns, ice cover and sea level 
back to pre-industrial but leave cabbage-friendly amounts of CO2 just 
below the shell-fish point?  Does anyone have a number?


Stephen

Emeritus Professor of Engineering Design. School of Engineering, 
University of Edinburgh, Mayfield Road, Edinburgh EH9 3DW, Scotland 
s.sal...@ed.ac.uk, Tel +44 (0)131 650 5704, Cell 07795 203 195, 
WWW.homepages.ed.ac.uk/shs, YouTube Jamie Taylor Power for Change


On 11/07/2019 11:22, Douglas MacMartin wrote:


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 
*Sent:* Wednesday, July 10, 2019 9:35 PM
*To:* Douglas MacMartin ; Andrew Lockley 

*Cc:* Stephen Salter ; geoengineering 

*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 
 
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) 
, 
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 

RE: [geo] RE: [CDR] blog 28, Elon Musk vs regenerative development // Elon Musk vs le développement de régénération

[Douglas MacMartin]

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 
Sent: Wednesday, July 10, 2019 9:35 PM
To: Douglas MacMartin ; Andrew Lockley 

Cc: Stephen Salter ; geoengineering 

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
 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), 
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