Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Govindasamy Bala]

Dear Stephen,

Here too, the attribution would be a big challenge. In this case the
challenge would be because of the presence of large internal variability in
the climate system, particularly on regional scales.
Bala

On Sun, May 3, 2020 at 10:40 PM Stephen Salter  wrote:

> Dear Bala
>
>  . . . .  However countries facing expensive damage from hurricanes and
> typhoons could measure surface temperatures  in surrounding seas and pay to
> have them reduced to more acceptable values.  I understand the 26.5 C is
> nice. Rough calculations appear to give extremely attractive returns on
> investment at least according to my assumptions.  I can send the equations
> to you and anyone else who  would like them and would be grateful for any
> more accurate than my own.
>
> 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)131 662 1180 WWW.homepages.ed.ac.uk/shs,
> YouTube Jamie Taylor Power for Change
>
> On 03/05/2020 16:02, Govindasamy Bala wrote:
>
> Andrew,
>
> In the case of CDR like DAC, one can immediately know much carbon is
> extracted and pricing is easy.  In the case of carbon stocks increase due
> to SRM, attribution of the stock increase to SRM would be almost an
> impossible task in the real world.
>
> Bala
>
> On Wed, Apr 29, 2020 at 9:07 PM Andrew Lockley 
> wrote:
>
>> I would recommend that you consider the numbers on this, before forming a
>> firm view. To order of magnitude, 1t S delivered is $1000 (mileage may
>> vary). If 1Mt a year is roughly enough to offset the RF of global warming,
>> then about 10pc of that is a CO2 effect. That's about 0.1 millionth of
>> global warming per t of S, on an annual basis - according to your figures.
>> Assuming we sustain the intervention for a century, that's $100k for
>> maintenance of that 1t, for a century - again offsetting 0.1 millionth.
>>
>> Offsets go for about $3/t
>> https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/
>>
>> There's about 1Tt of CO2 to offset - ie $3T, using the offset price. 0.1
>> millionths of that is $300k
>>
>> So your $100k costs gives you a $300k return.
>>
>> Not bad, unless (as usual) I've fluffed my 4th grade math.
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 15:44 Govindasamy Bala,  wrote:
>>
>>> With so much uncertainty surrounding this small indirect carbon cycle
>>> effects of SRM, I would not bother about monetizing calculations at
>>> this time.
>>> Bala
>>>
>>> On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley 
>>> wrote:
>>>
 That is indeed correct, but there is no accepted approach to
 financialise temporary radiative forcing. The effect on the carbon cycle
 would give a way to create a business model for SRM operations - as
 described in the papers I've sent.

 Andrew

 On Wed, 29 Apr 2020, 12:32 Govindasamy Bala, 
 wrote:

> Andrew,
> Technically, carbon and radiative forcing are equivalent to each
> other. There are standard formulas to go from carbon to radiative forcing.
> Bala
>
> On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley <
> andrew.lock...@gmail.com> wrote:
>
>> The reason that the CDR aspect is significant is that there is
>> already a way to monetise this, through voluntary carbon offsets. This 
>> was
>> first suggested by Sargoni and I
>> https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market
>>
>> There's no such scheme available to monetise radiative forcing
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 11:43 Govindasamy Bala, 
>> wrote:
>>
>>> Andrew,
>>>
>>> "Are you saying that SRM effect on the carbon cycle still appears to
>>> be the net removal of Atmospheric CO2?"
>>>
>>> Yes, that is what the models say since this first 2008 PNAS paper by
>>> Matthews and Ken on this topic which showed that CO2 levels would be 
>>> lower
>>> in SRM scenarios. This work finds that CO2 is reduced from 900 ppm to 
>>> about
>>> 800 ppm in the atmosphere by 2100 in the A2 scenario. Not a lot as CO2
>>> forcing goes up only  logarithmically with CO2 concentration
>>>
>>> https://www.pnas.org/content/104/24/9949
>>>
>>> There would be of course large uncertainties but I think the
>>> qualitative result would not change across models. I would not go that 
>>> far
>>> to say it is a CDR technique. I would rather say it is a secondary 
>>> benefit
>>> or a co-benefit.
>>>
>>> Bala
>>>
>>> On Wed, Apr 29, 2020 at 1:42 PM Andrew Lockley <
>>> andrew.lock...@gmail.com> wrote:
>>>
 So, to confirm:
 Are you saying that SRM effect on the carbon cycle still appears to
 be the net removal of Atmospheric CO2?

  If so, SRM

Re: [geo] Re: SRM offset standards?

[Russell Seitz]

Many thanks for the link .However, while the paper is convincing in term of 
 theoretical orbital mechanics,  I can't find any treatment of using solar 
sail  attitude alone  to manage torque and acceleration issues, for as the 
authors state, it 
"does not address practicality issues such as the design and deployment of 
the sunshades"

The closest the seem to come to my quetioni :
" in section I in Results and Discussion, the outcome of the geoengineering 
optimizations is an out-of-plane motion of the type z(t) = a sin(t + c) + b. 
Thus, we then know that the sail acceleration in the out-of-plane direction 
must be such that:

(19)

We may also require that the sunshade does not move away from the Sun-Earth 
line, i.e. y = 0, so that the shade is always cast symmetrically over the 
morning and afternoon side of the Earth. Thus,(20)

Precisely because of the two previous constraints, the control history of 
the clock angle δ must then satisfy:(21)

On the other hand, the control history of the cone angle α must also 
satisfy the following expression:(22)

If Eqs 21 

 and 22 

 are 
satisfied, the shape of the motion in the z and y coordinates will be as 
prescribed, and only x(t) remains to be solved."

Which is fine by way of celestial mechanics, but not much use  in terms of 
how to evolve sail to keep a 100 kilometer square rigger on tation in all 
kinds of space weather




On Sunday, May 3, 2020 at 7:11:26 PM UTC-4, Douglas MacMartin wrote:
>
> See 
> https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136648
>
>  
>
> This is straightforward to calculate, and wouldn’t be any more difficult 
> to find than L1.  (That is, solar pressure is well known, so is gravity.)
>
>  
>
>
>

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RE: [geo] Re: SRM offset standards?

[Douglas MacMartin]

See https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136648

This is straightforward to calculate, and wouldn’t be any more difficult to 
find than L1.  (That is, solar pressure is well known, so is gravity.)

From: geoengineering@googlegroups.com  On 
Behalf Of Russell Seitz
Sent: Sunday, May 3, 2020 3:06 PM
To: geoengineering 
Subject: Re: [geo] Re: SRM offset standards?

" you just need to displace yourself sunward until the forces balance…"

How far  sunward do you calculate that to be, and howfar from Lagrange 1  :

It'cold out there , and there's no valet parking.

On Sunday, May 3, 2020 at 10:36:24 AM UTC-4, Douglas MacMartin wrote:
You don’t need a countervailing force, you just need to displace yourself 
sunward until the forces balance… (though how far depends on areal mass 
density, and displacing too far sunward will require greater area to shade the 
Earth if I recall right).

But even if the propellant requirement is zero, still neither cheap nor 
near-term.

From: geoengi...@googlegroups.com 
> On Behalf Of Russell Seitz
Sent: Saturday, May 2, 2020 10:49 PM
To: geoengineering >
Subject: [geo] Re: SRM offset standards?

If 0.25 m2  per tonne CO2 is correct as presumed  , ~  10 billion m2, or 10,000 
km2 of  relector area would be  required

At 1 micron thickness that translates into 1 cubic meter per  km2. assuming  
for example' sake a  film with a  density  of   1, 5 , like  graphene 
strengthened aluminized one micron mylar, that would mean delivering 15,000 
tonnes to L 1, not counting frame, deployment systems , thrusters and fuel.

As the solar sail force would be on the order of 8 newtons / km2,  a  
countervailing thrust of 80kN, or ~8,000 kg would  be required for station 
keeping.
Even with solar powered ion thrusters, that would entail a  considerable 
propellent mass

As   the ~ 500 kg Deep Space probe consumed oved 100kg of xenon in the course 
of three years of generating  at most 86 millinewtons of thrust a linear 
extrapolation would be on the order of a million times more for so large a 
solar shade--in  which case station keeping at the L1 would requiresending 
up the whole sail system's weight in propellant every few years.

It's hard to see how its proponents  could underbid  earth-based SRM

On Friday, May 1, 2020 at 4:15:00 AM UTC-4, Tim Sippel wrote:
The transition from fossil fuel to renewable energy sources is not happening 
quickly enough, so it seems likely that we will need to supplement with SRM to 
buy time.

Is work being done towards standards to validate and quantify SRM offsets, 
similar to carbon offset standards (VCS, Gold Standard, etc.)?  This could 
reduce the dependency on strained government budgets to support approved SRM 
efforts.

I am also interested in feedback on the following rough calculations.  Sunlight 
energy reaching earth is 1367 W/m^2.  By eyeballing the slope on a graph here 
(https://www.esrl.noaa.gov/gmd/aggi/aggi.html), I have estimated that worldwide 
annual CO2 emissions (~40G tons) is increasing radiative forcing by about 37 
mW/m^2.  From this, I estimate that the incremental radiative forcing of 1 ton 
of CO2 emissions can be canceled out with about 1/4 m^2 of sun shade near the 
Sun-Earth Lagrange 1 equilibrium point.  Using an estimate for the cost of 
deploying a space-based sunshade, I am able to compare the cost/ton equivalent 
of an SRM offset vs cost/ton of a carbon offset.  Does this approach seem valid?

Regards,
Tim Sippel
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Re: [geo] Re: SRM offset standards?

[Russell Seitz]

" you just need to displace yourself sunward until the forces balance…"

How far  sunward do you calculate that to be, and howfar from Lagrange 1  :

It'cold out there , and there's no valet parking.

On Sunday, May 3, 2020 at 10:36:24 AM UTC-4, Douglas MacMartin wrote:
>
> You don’t need a countervailing force, you just need to displace yourself 
> sunward until the forces balance… (though how far depends on areal mass 
> density, and displacing too far sunward will require greater area to shade 
> the Earth if I recall right).
>
>  
>
> But even if the propellant requirement is zero, still neither cheap nor 
> near-term.
>
>  
>
> *From:* geoengi...@googlegroups.com  <
> geoengi...@googlegroups.com > *On Behalf Of *Russell Seitz
> *Sent:* Saturday, May 2, 2020 10:49 PM
> *To:* geoengineering >
> *Subject:* [geo] Re: SRM offset standards?
>
>  
>
> If 0.25 m2  per tonne CO2 is correct as presumed  , ~  10 billion m2, or 
> 10,000 km2 of  relector area would be  required
>
>  
>
> At 1 micron thickness that translates into 1 cubic meter per  km2. 
> assuming  for example' sake a  film with a  density  of   1, 5 , like 
>  graphene strengthened aluminized one micron mylar, that would mean 
> delivering 15,000 tonnes to L 1, not counting frame, deployment systems , 
> thrusters and fuel.
>
>  
>
> As the solar sail force would be on the order of 8 newtons / km2,  a 
>  countervailing thrust of 80kN, or ~8,000 kg would  be required for station 
> keeping. 
>
> Even with solar powered ion thrusters, that would entail a  considerable 
> propellent mass
>
>  
>
> As   the ~ 500 kg Deep Space probe consumed oved 100kg of xenon in the 
> course of three years of generating  at most 86 millinewtons of thrust a 
> linear extrapolation would be on the order of a million times more for so 
> large a solar shade--in  which case station keeping at the L1 would 
> requiresending up the whole sail system's weight in propellant every few 
> years.
>
>  
>
> It's hard to see how its proponents  could underbid  earth-based SRM 
>
> On Friday, May 1, 2020 at 4:15:00 AM UTC-4, Tim Sippel wrote:
>
> The transition from fossil fuel to renewable energy sources is not 
> happening quickly enough, so it seems likely that we will need to 
> supplement with SRM to buy time.
>
>  
>
> Is work being done towards standards to validate and quantify SRM offsets, 
> similar to carbon offset standards (VCS, Gold Standard, etc.)?  This could 
> reduce the dependency on strained government budgets to support approved 
> SRM efforts.
>
>  
>
> I am also interested in feedback on the following rough calculations.  
> Sunlight energy reaching earth is 1367 W/m^2.  By eyeballing the slope on a 
> graph here (https://www.esrl.noaa.gov/gmd/aggi/aggi.html), I have 
> estimated that worldwide annual CO2 emissions (~40G tons) is increasing 
> radiative forcing by about 37 mW/m^2.  From this, I estimate that the 
> incremental radiative forcing of 1 ton of CO2 emissions can be canceled out 
> with about 1/4 m^2 of sun shade near the Sun-Earth Lagrange 1 equilibrium 
> point.  Using an estimate for the cost of deploying a space-based sunshade, 
> I am able to compare the cost/ton equivalent of an SRM offset vs cost/ton 
> of a carbon offset.  Does this approach seem valid?
>
>  
>
> Regards,
>
> Tim Sippel
>
> -- 
> You received this message because you are subscribed to the Google Groups 
> "geoengineering" group.
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to geoengi...@googlegroups.com .
> To view this discussion on the web visit 
> https://groups.google.com/d/msgid/geoengineering/2d993063-8375-45c4-a32e-10b2348ff94a%40googlegroups.com
>  
> 
> .
>

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Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Andrew Lockley]

What is the margin of error?

On Sun, 3 May 2020, 15:55 Govindasamy Bala,  wrote:

> Andrew,
>
> In the case of CDR like DAC, one can immediately know much carbon is
> extracted and pricing is easy.  In the case of carbon stocks increase due
> to SRM, attribution of the stock increase to SRM would be almost an
> impossible task in the real world.
>
> Bala
>
> On Wed, Apr 29, 2020 at 9:07 PM Andrew Lockley 
> wrote:
>
>> I would recommend that you consider the numbers on this, before forming a
>> firm view. To order of magnitude, 1t S delivered is $1000 (mileage may
>> vary). If 1Mt a year is roughly enough to offset the RF of global warming,
>> then about 10pc of that is a CO2 effect. That's about 0.1 millionth of
>> global warming per t of S, on an annual basis - according to your figures.
>> Assuming we sustain the intervention for a century, that's $100k for
>> maintenance of that 1t, for a century - again offsetting 0.1 millionth.
>>
>> Offsets go for about $3/t
>> https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/
>>
>> There's about 1Tt of CO2 to offset - ie $3T, using the offset price. 0.1
>> millionths of that is $300k
>>
>> So your $100k costs gives you a $300k return.
>>
>> Not bad, unless (as usual) I've fluffed my 4th grade math.
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 15:44 Govindasamy Bala,  wrote:
>>
>>> With so much uncertainty surrounding this small indirect carbon cycle
>>> effects of SRM, I would not bother about monetizing calculations at
>>> this time.
>>> Bala
>>>
>>> On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley 
>>> wrote:
>>>
 That is indeed correct, but there is no accepted approach to
 financialise temporary radiative forcing. The effect on the carbon cycle
 would give a way to create a business model for SRM operations - as
 described in the papers I've sent.

 Andrew

 On Wed, 29 Apr 2020, 12:32 Govindasamy Bala, 
 wrote:

> Andrew,
> Technically, carbon and radiative forcing are equivalent to each
> other. There are standard formulas to go from carbon to radiative forcing.
> Bala
>
> On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley <
> andrew.lock...@gmail.com> wrote:
>
>> The reason that the CDR aspect is significant is that there is
>> already a way to monetise this, through voluntary carbon offsets. This 
>> was
>> first suggested by Sargoni and I
>> https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market
>>
>> There's no such scheme available to monetise radiative forcing
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 11:43 Govindasamy Bala, 
>> wrote:
>>
>>> Andrew,
>>>
>>> "Are you saying that SRM effect on the carbon cycle still appears to
>>> be the net removal of Atmospheric CO2?"
>>>
>>> Yes, that is what the models say since this first 2008 PNAS paper by
>>> Matthews and Ken on this topic which showed that CO2 levels would be 
>>> lower
>>> in SRM scenarios. This work finds that CO2 is reduced from 900 ppm to 
>>> about
>>> 800 ppm in the atmosphere by 2100 in the A2 scenario. Not a lot as CO2
>>> forcing goes up only  logarithmically with CO2 concentration
>>>
>>> https://www.pnas.org/content/104/24/9949
>>>
>>> There would be of course large uncertainties but I think the
>>> qualitative result would not change across models. I would not go that 
>>> far
>>> to say it is a CDR technique. I would rather say it is a secondary 
>>> benefit
>>> or a co-benefit.
>>>
>>> Bala
>>>
>>> On Wed, Apr 29, 2020 at 1:42 PM Andrew Lockley <
>>> andrew.lock...@gmail.com> wrote:
>>>
 So, to confirm:
 Are you saying that SRM effect on the carbon cycle still appears to
 be the net removal of Atmospheric CO2?

  If so, SRM can legitimately be used as a CDR technique. It may
 therefore be eligible for Carbon credits, as per this paper.
 https://journals.sagepub.com/doi/abs/10.1177/1461452916630082

 On Wed, 29 Apr 2020, 08:56 Govindasamy Bala, 
 wrote:

> Andrew,
>
> You are absolutely right that "In situations where plants don't
> remain to decomposition (agro forestry), there will be a loss of NPP"
>
> Stock changes between two time periods are basically the integral
> of the net fluxes between the two time periods. In a warming scenario,
> there is net outward flux (and stocks decline) because the integrated
> respiratory fluxes more than the integrated in flux of NPP. In SRM
> scenario, integrated net flux is positive because the integrated
> respiratory fluxes are smaller than integrated in flux.
>
> Best,
> Bala
>
> On Wed, Apr 29,

Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Stephen Salter]

Dear Bala

 . . . .  However countries facing expensive damage from hurricanes and 
typhoons could measure surface temperatures  in surrounding seas and pay 
to have them reduced to more acceptable values.  I understand the 26.5 C 
is nice. Rough calculations appear to give extremely attractive returns 
on investment at least according to my assumptions.  I can send the 
equations to you and anyone else who  would like them and would be 
grateful for any more accurate than my own.


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)131 662 1180 WWW.homepages.ed.ac.uk/shs, 
YouTube Jamie Taylor Power for Change


On 03/05/2020 16:02, Govindasamy Bala wrote:

Andrew,

In the case of CDR like DAC, one can immediately know much carbon is 
extracted and pricing is easy.  In the case of carbon stocks increase 
due to SRM, attribution of the stock increase to SRM would be almost 
an impossible task in the real world.


Bala

On Wed, Apr 29, 2020 at 9:07 PM Andrew Lockley 
mailto:andrew.lock...@gmail.com>> wrote:


I would recommend that you consider the numbers on this, before
forming a firm view. To order of magnitude, 1t S delivered is
$1000 (mileage may vary). If 1Mt a year is roughly enough to
offset the RF of global warming, then about 10pc of that is a CO2
effect. That's about 0.1 millionth of global warming per t of S,
on an annual basis - according to your figures. Assuming we
sustain the intervention for a century, that's $100k for
maintenance of that 1t, for a century - again offsetting 0.1
millionth.

Offsets go for about $3/t

https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/

There's about 1Tt of CO2 to offset - ie $3T, using the offset
price. 0.1 millionths of that is $300k

So your $100k costs gives you a $300k return.

Not bad, unless (as usual) I've fluffed my 4th grade math.

Andrew

On Wed, 29 Apr 2020, 15:44 Govindasamy Bala, mailto:bala@gmail.com>> wrote:

With so much uncertainty surrounding this small indirect
carbon cycle effects of SRM, I would not bother about
monetizing calculations at this time.
Bala

On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley
mailto:andrew.lock...@gmail.com>>
wrote:

That is indeed correct, but there is no accepted approach
to financialise temporary radiative forcing. The effect on
the carbon cycle would give a way to create a business
model for SRM operations - as described in the papers I've
sent.

Andrew

On Wed, 29 Apr 2020, 12:32 Govindasamy Bala,
mailto:bala@gmail.com>> wrote:

Andrew,
Technically, carbon and radiative forcing are
equivalent to each other. There are standard
formulas to go from carbon to radiative forcing.
Bala

On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley
mailto:andrew.lock...@gmail.com>> wrote:

The reason that the CDR aspect is significant is
that there is already a way to monetise this,
through voluntary carbon offsets. This was first
suggested by Sargoni and I

https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market


There's no such scheme available to monetise
radiative forcing

Andrew

On Wed, 29 Apr 2020, 11:43 Govindasamy Bala,
mailto:bala@gmail.com>>
wrote:

Andrew,

"Are you saying that SRM effect on the carbon
cycle still appears to be the net removal of
Atmospheric CO2?"

Yes, that is what the models say since this
first 2008 PNAS paper by Matthews and Ken on
this topic which showed that CO2 levels would
be lower in SRM scenarios. This work finds
that CO2 is reduced from 900 ppm to about 800
ppm in the atmosphere by 2100 in the A2
scenario. Not a lot as CO2 forcing goes up
only  logarithmically with CO2 concentration
https://www.pnas.org/content/104/24/9949

There would be of course large uncertainties
but I think the qualitative result would not
change across models. I would not go that far
to say it is a CDR technique. I would ra

Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Govindasamy Bala]

Andrew,

In the case of CDR like DAC, one can immediately know much carbon is
extracted and pricing is easy.  In the case of carbon stocks increase due
to SRM, attribution of the stock increase to SRM would be almost an
impossible task in the real world.

Bala

On Wed, Apr 29, 2020 at 9:07 PM Andrew Lockley 
wrote:

> I would recommend that you consider the numbers on this, before forming a
> firm view. To order of magnitude, 1t S delivered is $1000 (mileage may
> vary). If 1Mt a year is roughly enough to offset the RF of global warming,
> then about 10pc of that is a CO2 effect. That's about 0.1 millionth of
> global warming per t of S, on an annual basis - according to your figures.
> Assuming we sustain the intervention for a century, that's $100k for
> maintenance of that 1t, for a century - again offsetting 0.1 millionth.
>
> Offsets go for about $3/t
> https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/
>
> There's about 1Tt of CO2 to offset - ie $3T, using the offset price. 0.1
> millionths of that is $300k
>
> So your $100k costs gives you a $300k return.
>
> Not bad, unless (as usual) I've fluffed my 4th grade math.
>
> Andrew
>
> On Wed, 29 Apr 2020, 15:44 Govindasamy Bala,  wrote:
>
>> With so much uncertainty surrounding this small indirect carbon cycle
>> effects of SRM, I would not bother about monetizing calculations at
>> this time.
>> Bala
>>
>> On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley 
>> wrote:
>>
>>> That is indeed correct, but there is no accepted approach to
>>> financialise temporary radiative forcing. The effect on the carbon cycle
>>> would give a way to create a business model for SRM operations - as
>>> described in the papers I've sent.
>>>
>>> Andrew
>>>
>>> On Wed, 29 Apr 2020, 12:32 Govindasamy Bala,  wrote:
>>>
 Andrew,
 Technically, carbon and radiative forcing are equivalent to each other.
 There are standard formulas to go from carbon to radiative forcing.
 Bala

 On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley <
 andrew.lock...@gmail.com> wrote:

> The reason that the CDR aspect is significant is that there is already
> a way to monetise this, through voluntary carbon offsets. This was first
> suggested by Sargoni and I
> https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market
>
> There's no such scheme available to monetise radiative forcing
>
> Andrew
>
> On Wed, 29 Apr 2020, 11:43 Govindasamy Bala, 
> wrote:
>
>> Andrew,
>>
>> "Are you saying that SRM effect on the carbon cycle still appears to
>> be the net removal of Atmospheric CO2?"
>>
>> Yes, that is what the models say since this first 2008 PNAS paper by
>> Matthews and Ken on this topic which showed that CO2 levels would be 
>> lower
>> in SRM scenarios. This work finds that CO2 is reduced from 900 ppm to 
>> about
>> 800 ppm in the atmosphere by 2100 in the A2 scenario. Not a lot as CO2
>> forcing goes up only  logarithmically with CO2 concentration
>>
>> https://www.pnas.org/content/104/24/9949
>>
>> There would be of course large uncertainties but I think the
>> qualitative result would not change across models. I would not go that 
>> far
>> to say it is a CDR technique. I would rather say it is a secondary 
>> benefit
>> or a co-benefit.
>>
>> Bala
>>
>> On Wed, Apr 29, 2020 at 1:42 PM Andrew Lockley <
>> andrew.lock...@gmail.com> wrote:
>>
>>> So, to confirm:
>>> Are you saying that SRM effect on the carbon cycle still appears to
>>> be the net removal of Atmospheric CO2?
>>>
>>>  If so, SRM can legitimately be used as a CDR technique. It may
>>> therefore be eligible for Carbon credits, as per this paper.
>>> https://journals.sagepub.com/doi/abs/10.1177/1461452916630082
>>>
>>> On Wed, 29 Apr 2020, 08:56 Govindasamy Bala, 
>>> wrote:
>>>
 Andrew,

 You are absolutely right that "In situations where plants don't
 remain to decomposition (agro forestry), there will be a loss of NPP"

 Stock changes between two time periods are basically the integral
 of the net fluxes between the two time periods. In a warming scenario,
 there is net outward flux (and stocks decline) because the integrated
 respiratory fluxes more than the integrated in flux of NPP. In SRM
 scenario, integrated net flux is positive because the integrated
 respiratory fluxes are smaller than integrated in flux.

 Best,
 Bala

 On Wed, Apr 29, 2020 at 12:30 PM Andrew Lockley <
 andrew.lock...@gmail.com> wrote:

> If the incoming flux decreases, the stock will reduce. To counter
> this, the outgoing flux must decrease by as much, or more

Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Govindasamy Bala]

Renaud,

You are not wrong.

The SRM world has two forcings; one from increased CO2 and the other from
sunlight reduction. The sunlight reduction alone offsets the warming from
CO2 and causes a slight reduction in NPP. However, the CO2-fertilization
effect (and the associated very large (??) increase in NPP) is mostly not
offset by the sunlight reduction. The CO2-fertilization effect (and ocean
acidification) are the carbon cycle effects of CO2 increase that are mostly
not offset by SRM.

Hence, relative to the control climate, NPP is larger in the SRM world but
NPP is slightly less relative to the warmer climate. Yes, what you
comparing the SRM world with is extremely important in interpreting these
results. Hope this helps.

Bala

On Sun, May 3, 2020 at 4:11 PM Renaud de RICHTER 
wrote:

> Dear Andrew and Bala,
>
>
> All your discussion you had during this post is very difficult to
> understand.
>
>
> Bala and the other authors of the article cited in the subject found with
> their model that a 2 X CO2 by the end of century will enhance gross primary
> production (GPP) and net primary production (NPP).
>
> See *Table 1*: "*Changes in key climate and carbon variables over land
> for the 2 × CO2 case relative to 1 × CO2 case, and radiation modification
> cases relative to the 2 × CO2 case*".
>
>-  under 2 X CO2 => GPP (+33.1 GTC/yr) and NPP (+7.9 GTC/yr) mainly by
>the fertilizing effect of atmospheric CO2.
>-  meanwhile SRM / SAI will decrease GPP (-14.7 GTC/yr) and NPP (-2.1
>GTC/yr) mainly by cooling effect.
>
> In the abstract it is written "*Relative to the high CO2 state, all these
> approaches reduce gross primary production (GPP) and net primary production
> (NPP).*"
>
>
> So it looks like the opposite to your statement..." *SRM effect on the
> carbon cycle still appears to be the net removal of Atmospheric CO2.*..".
>
>
> Where am I wrong?
>
> Thanks!
>
>
> Bw,
>
> Renaud
>
>
> Le mer. 29 avr. 2020 à 17:37, Andrew Lockley  a
> écrit :
>
>> I would recommend that you consider the numbers on this, before forming a
>> firm view. To order of magnitude, 1t S delivered is $1000 (mileage may
>> vary). If 1Mt a year is roughly enough to offset the RF of global warming,
>> then about 10pc of that is a CO2 effect. That's about 0.1 millionth of
>> global warming per t of S, on an annual basis - according to your figures.
>> Assuming we sustain the intervention for a century, that's $100k for
>> maintenance of that 1t, for a century - again offsetting 0.1 millionth.
>>
>> Offsets go for about $3/t
>> https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/
>>
>> There's about 1Tt of CO2 to offset - ie $3T, using the offset price. 0.1
>> millionths of that is $300k
>>
>> So your $100k costs gives you a $300k return.
>>
>> Not bad, unless (as usual) I've fluffed my 4th grade math.
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 15:44 Govindasamy Bala,  wrote:
>>
>>> With so much uncertainty surrounding this small indirect carbon cycle
>>> effects of SRM, I would not bother about monetizing calculations at
>>> this time.
>>> Bala
>>>
>>> On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley 
>>> wrote:
>>>
 That is indeed correct, but there is no accepted approach to
 financialise temporary radiative forcing. The effect on the carbon cycle
 would give a way to create a business model for SRM operations - as
 described in the papers I've sent.

 Andrew

 On Wed, 29 Apr 2020, 12:32 Govindasamy Bala, 
 wrote:

> Andrew,
> Technically, carbon and radiative forcing are equivalent to each
> other. There are standard formulas to go from carbon to radiative forcing.
> Bala
>
> On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley <
> andrew.lock...@gmail.com> wrote:
>
>> The reason that the CDR aspect is significant is that there is
>> already a way to monetise this, through voluntary carbon offsets. This 
>> was
>> first suggested by Sargoni and I
>> https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market
>>
>> There's no such scheme available to monetise radiative forcing
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 11:43 Govindasamy Bala, 
>> wrote:
>>
>>> Andrew,
>>>
>>> "Are you saying that SRM effect on the carbon cycle still appears to
>>> be the net removal of Atmospheric CO2?"
>>>
>>> Yes, that is what the models say since this first 2008 PNAS paper by
>>> Matthews and Ken on this topic which showed that CO2 levels would be 
>>> lower
>>> in SRM scenarios. This work finds that CO2 is reduced from 900 ppm to 
>>> about
>>> 800 ppm in the atmosphere by 2100 in the A2 scenario. Not a lot as CO2
>>> forcing goes up only  logarithmically with CO2 concentration
>>>
>>> https://www.pnas.org/content/104/24/9949
>>>
>>> There would be 

RE: [geo] Re: SRM offset standards?

[Douglas MacMartin]

You don’t need a countervailing force, you just need to displace yourself 
sunward until the forces balance… (though how far depends on areal mass 
density, and displacing too far sunward will require greater area to shade the 
Earth if I recall right).

But even if the propellant requirement is zero, still neither cheap nor 
near-term.

From: geoengineering@googlegroups.com  On 
Behalf Of Russell Seitz
Sent: Saturday, May 2, 2020 10:49 PM
To: geoengineering 
Subject: [geo] Re: SRM offset standards?

If 0.25 m2  per tonne CO2 is correct as presumed  , ~  10 billion m2, or 10,000 
km2 of  relector area would be  required

At 1 micron thickness that translates into 1 cubic meter per  km2. assuming  
for example' sake a  film with a  density  of   1, 5 , like  graphene 
strengthened aluminized one micron mylar, that would mean delivering 15,000 
tonnes to L 1, not counting frame, deployment systems , thrusters and fuel.

As the solar sail force would be on the order of 8 newtons / km2,  a  
countervailing thrust of 80kN, or ~8,000 kg would  be required for station 
keeping.
Even with solar powered ion thrusters, that would entail a  considerable 
propellent mass

As   the ~ 500 kg Deep Space probe consumed oved 100kg of xenon in the course 
of three years of generating  at most 86 millinewtons of thrust a linear 
extrapolation would be on the order of a million times more for so large a 
solar shade--in  which case station keeping at the L1 would requiresending 
up the whole sail system's weight in propellant every few years.

It's hard to see how its proponents  could underbid  earth-based SRM

On Friday, May 1, 2020 at 4:15:00 AM UTC-4, Tim Sippel wrote:
The transition from fossil fuel to renewable energy sources is not happening 
quickly enough, so it seems likely that we will need to supplement with SRM to 
buy time.

Is work being done towards standards to validate and quantify SRM offsets, 
similar to carbon offset standards (VCS, Gold Standard, etc.)?  This could 
reduce the dependency on strained government budgets to support approved SRM 
efforts.

I am also interested in feedback on the following rough calculations.  Sunlight 
energy reaching earth is 1367 W/m^2.  By eyeballing the slope on a graph here 
(https://www.esrl.noaa.gov/gmd/aggi/aggi.html), I have estimated that worldwide 
annual CO2 emissions (~40G tons) is increasing radiative forcing by about 37 
mW/m^2.  From this, I estimate that the incremental radiative forcing of 1 ton 
of CO2 emissions can be canceled out with about 1/4 m^2 of sun shade near the 
Sun-Earth Lagrange 1 equilibrium point.  Using an estimate for the cost of 
deploying a space-based sunshade, I am able to compare the cost/ton equivalent 
of an SRM offset vs cost/ton of a carbon offset.  Does this approach seem valid?

Regards,
Tim Sippel
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Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Renaud de RICHTER]

Yes indeed, but the model used maybe (I hope) took already this factor in
consideration, did it?

Le dim. 3 mai 2020 à 12:46, Andrew Lockley  a
écrit :

> If I understand correctly, SRM reduces decomposition more than NPP -
> presumably because cooler, drier soils are less biologically active.
>
> Andrew
>
> On Sun, 3 May 2020, 11:41 Renaud de RICHTER, 
> wrote:
>
>> Dear Andrew and Bala,
>>
>>
>> All your discussion you had during this post is very difficult to
>> understand.
>>
>>
>> Bala and the other authors of the article cited in the subject found with
>> their model that a 2 X CO2 by the end of century will enhance gross primary
>> production (GPP) and net primary production (NPP).
>>
>> See *Table 1*: "*Changes in key climate and carbon variables over land
>> for the 2 × CO2 case relative to 1 × CO2 case, and radiation modification
>> cases relative to the 2 × CO2 case*".
>>
>>-  under 2 X CO2 => GPP (+33.1 GTC/yr) and NPP (+7.9 GTC/yr) mainly
>>by the fertilizing effect of atmospheric CO2.
>>-  meanwhile SRM / SAI will decrease GPP (-14.7 GTC/yr) and NPP (-2.1
>>GTC/yr) mainly by cooling effect.
>>
>> In the abstract it is written "*Relative to the high CO2 state, all
>> these approaches reduce gross primary production (GPP) and net primary
>> production (NPP).*"
>>
>>
>> So it looks like the opposite to your statement..." *SRM effect on the
>> carbon cycle still appears to be the net removal of Atmospheric CO2.*..".
>>
>>
>> Where am I wrong?
>>
>> Thanks!
>>
>>
>> Bw,
>>
>> Renaud
>>
>>
>> Le mer. 29 avr. 2020 à 17:37, Andrew Lockley 
>> a écrit :
>>
>>> I would recommend that you consider the numbers on this, before forming
>>> a firm view. To order of magnitude, 1t S delivered is $1000 (mileage
>>> may vary). If 1Mt a year is roughly enough to offset the RF of global
>>> warming, then about 10pc of that is a CO2 effect. That's about 0.1
>>> millionth of global warming per t of S, on an annual basis - according to
>>> your figures. Assuming we sustain the intervention for a century, that's
>>> $100k for maintenance of that 1t, for a century - again offsetting 0.1
>>> millionth.
>>>
>>> Offsets go for about $3/t
>>> https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/
>>>
>>> There's about 1Tt of CO2 to offset - ie $3T, using the offset price. 0.1
>>> millionths of that is $300k
>>>
>>> So your $100k costs gives you a $300k return.
>>>
>>> Not bad, unless (as usual) I've fluffed my 4th grade math.
>>>
>>> Andrew
>>>
>>> On Wed, 29 Apr 2020, 15:44 Govindasamy Bala,  wrote:
>>>
 With so much uncertainty surrounding this small indirect carbon cycle
 effects of SRM, I would not bother about monetizing calculations at
 this time.
 Bala

 On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley <
 andrew.lock...@gmail.com> wrote:

> That is indeed correct, but there is no accepted approach to
> financialise temporary radiative forcing. The effect on the carbon cycle
> would give a way to create a business model for SRM operations - as
> described in the papers I've sent.
>
> Andrew
>
> On Wed, 29 Apr 2020, 12:32 Govindasamy Bala, 
> wrote:
>
>> Andrew,
>> Technically, carbon and radiative forcing are equivalent to each
>> other. There are standard formulas to go from carbon to radiative 
>> forcing.
>> Bala
>>
>> On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley <
>> andrew.lock...@gmail.com> wrote:
>>
>>> The reason that the CDR aspect is significant is that there is
>>> already a way to monetise this, through voluntary carbon offsets. This 
>>> was
>>> first suggested by Sargoni and I
>>> https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market
>>>
>>> There's no such scheme available to monetise radiative forcing
>>>
>>> Andrew
>>>
>>> On Wed, 29 Apr 2020, 11:43 Govindasamy Bala, 
>>> wrote:
>>>
 Andrew,

 "Are you saying that SRM effect on the carbon cycle still appears
 to be the net removal of Atmospheric CO2?"

 Yes, that is what the models say since this first 2008 PNAS paper
 by Matthews and Ken on this topic which showed that CO2 levels would be
 lower in SRM scenarios. This work finds that CO2 is reduced from 900 
 ppm to
 about 800 ppm in the atmosphere by 2100 in the A2 scenario. Not a lot 
 as
 CO2 forcing goes up only  logarithmically with CO2 concentration

 https://www.pnas.org/content/104/24/9949

 There would be of course large uncertainties but I think the
 qualitative result would not change across models. I would not go that 
 far
 to say it is a CDR technique. I would rather say it is a secondary 
 benefit
 or a co-benefit.

>>>

Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Andrew Lockley]

If I understand correctly, SRM reduces decomposition more than NPP -
presumably because cooler, drier soils are less biologically active.

Andrew

On Sun, 3 May 2020, 11:41 Renaud de RICHTER, 
wrote:

> Dear Andrew and Bala,
>
>
> All your discussion you had during this post is very difficult to
> understand.
>
>
> Bala and the other authors of the article cited in the subject found with
> their model that a 2 X CO2 by the end of century will enhance gross primary
> production (GPP) and net primary production (NPP).
>
> See *Table 1*: "*Changes in key climate and carbon variables over land
> for the 2 × CO2 case relative to 1 × CO2 case, and radiation modification
> cases relative to the 2 × CO2 case*".
>
>-  under 2 X CO2 => GPP (+33.1 GTC/yr) and NPP (+7.9 GTC/yr) mainly by
>the fertilizing effect of atmospheric CO2.
>-  meanwhile SRM / SAI will decrease GPP (-14.7 GTC/yr) and NPP (-2.1
>GTC/yr) mainly by cooling effect.
>
> In the abstract it is written "*Relative to the high CO2 state, all these
> approaches reduce gross primary production (GPP) and net primary production
> (NPP).*"
>
>
> So it looks like the opposite to your statement..." *SRM effect on the
> carbon cycle still appears to be the net removal of Atmospheric CO2.*..".
>
>
> Where am I wrong?
>
> Thanks!
>
>
> Bw,
>
> Renaud
>
>
> Le mer. 29 avr. 2020 à 17:37, Andrew Lockley  a
> écrit :
>
>> I would recommend that you consider the numbers on this, before forming a
>> firm view. To order of magnitude, 1t S delivered is $1000 (mileage may
>> vary). If 1Mt a year is roughly enough to offset the RF of global warming,
>> then about 10pc of that is a CO2 effect. That's about 0.1 millionth of
>> global warming per t of S, on an annual basis - according to your figures.
>> Assuming we sustain the intervention for a century, that's $100k for
>> maintenance of that 1t, for a century - again offsetting 0.1 millionth.
>>
>> Offsets go for about $3/t
>> https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/
>>
>> There's about 1Tt of CO2 to offset - ie $3T, using the offset price. 0.1
>> millionths of that is $300k
>>
>> So your $100k costs gives you a $300k return.
>>
>> Not bad, unless (as usual) I've fluffed my 4th grade math.
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 15:44 Govindasamy Bala,  wrote:
>>
>>> With so much uncertainty surrounding this small indirect carbon cycle
>>> effects of SRM, I would not bother about monetizing calculations at
>>> this time.
>>> Bala
>>>
>>> On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley 
>>> wrote:
>>>
 That is indeed correct, but there is no accepted approach to
 financialise temporary radiative forcing. The effect on the carbon cycle
 would give a way to create a business model for SRM operations - as
 described in the papers I've sent.

 Andrew

 On Wed, 29 Apr 2020, 12:32 Govindasamy Bala, 
 wrote:

> Andrew,
> Technically, carbon and radiative forcing are equivalent to each
> other. There are standard formulas to go from carbon to radiative forcing.
> Bala
>
> On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley <
> andrew.lock...@gmail.com> wrote:
>
>> The reason that the CDR aspect is significant is that there is
>> already a way to monetise this, through voluntary carbon offsets. This 
>> was
>> first suggested by Sargoni and I
>> https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market
>>
>> There's no such scheme available to monetise radiative forcing
>>
>> Andrew
>>
>> On Wed, 29 Apr 2020, 11:43 Govindasamy Bala, 
>> wrote:
>>
>>> Andrew,
>>>
>>> "Are you saying that SRM effect on the carbon cycle still appears to
>>> be the net removal of Atmospheric CO2?"
>>>
>>> Yes, that is what the models say since this first 2008 PNAS paper by
>>> Matthews and Ken on this topic which showed that CO2 levels would be 
>>> lower
>>> in SRM scenarios. This work finds that CO2 is reduced from 900 ppm to 
>>> about
>>> 800 ppm in the atmosphere by 2100 in the A2 scenario. Not a lot as CO2
>>> forcing goes up only  logarithmically with CO2 concentration
>>>
>>> https://www.pnas.org/content/104/24/9949
>>>
>>> There would be of course large uncertainties but I think the
>>> qualitative result would not change across models. I would not go that 
>>> far
>>> to say it is a CDR technique. I would rather say it is a secondary 
>>> benefit
>>> or a co-benefit.
>>>
>>> Bala
>>>
>>> On Wed, Apr 29, 2020 at 1:42 PM Andrew Lockley <
>>> andrew.lock...@gmail.com> wrote:
>>>
 So, to confirm:
 Are you saying that SRM effect on the carbon cycle still appears to
 be the net removal of Atmospheric CO2?

  If so, SRM can legitimately be used as a 

Re: [geo] A Model‐Based Investigation of Terrestrial Plant Carbon Uptake Response to Four Radiation Modification Approaches - Duan - 2020 - Journal of Geophysical Research: Atmospheres - Wiley Online

[Renaud de RICHTER]

Dear Andrew and Bala,


All your discussion you had during this post is very difficult to
understand.


Bala and the other authors of the article cited in the subject found with
their model that a 2 X CO2 by the end of century will enhance gross primary
production (GPP) and net primary production (NPP).

See *Table 1*: "*Changes in key climate and carbon variables over land for
the 2 × CO2 case relative to 1 × CO2 case, and radiation modification cases
relative to the 2 × CO2 case*".

   -  under 2 X CO2 => GPP (+33.1 GTC/yr) and NPP (+7.9 GTC/yr) mainly by
   the fertilizing effect of atmospheric CO2.
   -  meanwhile SRM / SAI will decrease GPP (-14.7 GTC/yr) and NPP (-2.1
   GTC/yr) mainly by cooling effect.

In the abstract it is written "*Relative to the high CO2 state, all these
approaches reduce gross primary production (GPP) and net primary production
(NPP).*"


So it looks like the opposite to your statement..." *SRM effect on the
carbon cycle still appears to be the net removal of Atmospheric CO2.*..".


Where am I wrong?

Thanks!


Bw,

Renaud


Le mer. 29 avr. 2020 à 17:37, Andrew Lockley  a
écrit :

> I would recommend that you consider the numbers on this, before forming a
> firm view. To order of magnitude, 1t S delivered is $1000 (mileage may
> vary). If 1Mt a year is roughly enough to offset the RF of global warming,
> then about 10pc of that is a CO2 effect. That's about 0.1 millionth of
> global warming per t of S, on an annual basis - according to your figures.
> Assuming we sustain the intervention for a century, that's $100k for
> maintenance of that 1t, for a century - again offsetting 0.1 millionth.
>
> Offsets go for about $3/t
> https://www.energysage.com/other-clean-options/carbon-offsets/costs-and-benefits-carbon-offsets/
>
> There's about 1Tt of CO2 to offset - ie $3T, using the offset price. 0.1
> millionths of that is $300k
>
> So your $100k costs gives you a $300k return.
>
> Not bad, unless (as usual) I've fluffed my 4th grade math.
>
> Andrew
>
> On Wed, 29 Apr 2020, 15:44 Govindasamy Bala,  wrote:
>
>> With so much uncertainty surrounding this small indirect carbon cycle
>> effects of SRM, I would not bother about monetizing calculations at
>> this time.
>> Bala
>>
>> On Wed, Apr 29, 2020 at 5:49 PM Andrew Lockley 
>> wrote:
>>
>>> That is indeed correct, but there is no accepted approach to
>>> financialise temporary radiative forcing. The effect on the carbon cycle
>>> would give a way to create a business model for SRM operations - as
>>> described in the papers I've sent.
>>>
>>> Andrew
>>>
>>> On Wed, 29 Apr 2020, 12:32 Govindasamy Bala,  wrote:
>>>
 Andrew,
 Technically, carbon and radiative forcing are equivalent to each other.
 There are standard formulas to go from carbon to radiative forcing.
 Bala

 On Wed, Apr 29, 2020 at 4:45 PM Andrew Lockley <
 andrew.lock...@gmail.com> wrote:

> The reason that the CDR aspect is significant is that there is already
> a way to monetise this, through voluntary carbon offsets. This was first
> suggested by Sargoni and I
> https://www.researchgate.net/publication/284534197_Environment_Policy_Solar_Radiation_Management_and_the_voluntary_carbon_market
>
> There's no such scheme available to monetise radiative forcing
>
> Andrew
>
> On Wed, 29 Apr 2020, 11:43 Govindasamy Bala, 
> wrote:
>
>> Andrew,
>>
>> "Are you saying that SRM effect on the carbon cycle still appears to
>> be the net removal of Atmospheric CO2?"
>>
>> Yes, that is what the models say since this first 2008 PNAS paper by
>> Matthews and Ken on this topic which showed that CO2 levels would be 
>> lower
>> in SRM scenarios. This work finds that CO2 is reduced from 900 ppm to 
>> about
>> 800 ppm in the atmosphere by 2100 in the A2 scenario. Not a lot as CO2
>> forcing goes up only  logarithmically with CO2 concentration
>>
>> https://www.pnas.org/content/104/24/9949
>>
>> There would be of course large uncertainties but I think the
>> qualitative result would not change across models. I would not go that 
>> far
>> to say it is a CDR technique. I would rather say it is a secondary 
>> benefit
>> or a co-benefit.
>>
>> Bala
>>
>> On Wed, Apr 29, 2020 at 1:42 PM Andrew Lockley <
>> andrew.lock...@gmail.com> wrote:
>>
>>> So, to confirm:
>>> Are you saying that SRM effect on the carbon cycle still appears to
>>> be the net removal of Atmospheric CO2?
>>>
>>>  If so, SRM can legitimately be used as a CDR technique. It may
>>> therefore be eligible for Carbon credits, as per this paper.
>>> https://journals.sagepub.com/doi/abs/10.1177/1461452916630082
>>>
>>> On Wed, 29 Apr 2020, 08:56 Govindasamy Bala, 
>>> wrote:
>>>
 Andrew,

 You are absolutely right that "In situations where plants don't
 remain to decompo

[geo] Re: SRM offset standards?

[Russell Seitz]

If 0.25 m2  per tonne CO2 is correct as presumed  , ~  10 billion m2, or 
10,000 km2 of  relector area would be  required

At 1 micron thickness that translates into 1 cubic meter per  km2. assuming 
 for example' sake a  film with a  density  of   1, 5 , like  graphene 
strengthened aluminized one micron mylar, that would mean delivering 15,000 
tonnes to L 1, not counting frame, deployment systems , thrusters and fuel.

As the solar sail force would be on the order of 8 newtons / km2,  a 
 countervailing thrust of 80kN, or ~8,000 kg would  be required for station 
keeping. 
Even with solar powered ion thrusters, that would entail a  considerable 
propellent mass

As   the ~ 500 kg Deep Space probe consumed oved 100kg of xenon in the 
course of three years of generating  at most 86 millinewtons of thrust a 
linear extrapolation would be on the order of a million times more for so 
large a solar shade--in  which case station keeping at the L1 would 
requiresending up the whole sail system's weight in propellant every few 
years.

It's hard to see how its proponents  could underbid  earth-based SRM 

On Friday, May 1, 2020 at 4:15:00 AM UTC-4, Tim Sippel wrote:
>
> The transition from fossil fuel to renewable energy sources is not 
> happening quickly enough, so it seems likely that we will need to 
> supplement with SRM to buy time.
>
> Is work being done towards standards to validate and quantify SRM offsets, 
> similar to carbon offset standards (VCS, Gold Standard, etc.)?  This could 
> reduce the dependency on strained government budgets to support approved 
> SRM efforts.
>
> I am also interested in feedback on the following rough calculations.  
> Sunlight energy reaching earth is 1367 W/m^2.  By eyeballing the slope on a 
> graph here (https://www.esrl.noaa.gov/gmd/aggi/aggi.html), I have 
> estimated that worldwide annual CO2 emissions (~40G tons) is increasing 
> radiative forcing by about 37 mW/m^2.  From this, I estimate that the 
> incremental radiative forcing of 1 ton of CO2 emissions can be canceled out 
> with about 1/4 m^2 of sun shade near the Sun-Earth Lagrange 1 equilibrium 
> point.  Using an estimate for the cost of deploying a space-based sunshade, 
> I am able to compare the cost/ton equivalent of an SRM offset vs cost/ton 
> of a carbon offset.  Does this approach seem valid?
>
> Regards,
> Tim Sippel
>

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