Re: [geo] RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL WARMING

[Michael MacCracken]

The idea of a shade or mirror, or Fresnel lens at the L1 point goes back 
at least to James Early of the Livermore Lab--see


Early, J. T., 1989: Space-based solar screen to offset the greenhouse 
effect, /Journal of the British Interplanetary Society/ *42*, 567-569.



Mike MacCracken


On 12/12/16 6:04 PM, Douglas MacMartin wrote:

I think if you can get them there, keeping them there is comparatively easy...

(The advantage of it being an equilibrium point is that the effort required to 
keep it there is in principle small.)

Though I think it would be cheaper to massively transform the world's energy 
system in the next few decades than to build something at meaningful scale at 
L1.  (Not a comment on the ease of the former but on the difficulty of the 
latter.)

-Original Message-
From: geoengineering@googlegroups.com [mailto:geoengineering@googlegroups.com] 
On Behalf Of Olivier Boucher
Sent: Monday, December 12, 2016 11:49 AM
To: geoengineering@googlegroups.com
Subject: Re: [geo] RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL 
WARMING


Hello,

it's not the first time that I read such a thing:

The reflectors would be placed near L1 to ensure a stable orbit.

The L1 Lagrange point is *not* stable. They are quasi-periodic orbits around 
it, but it's not clear to me if they are suitable for geoengineering, if they 
are perfectly stable on long timescales needed for geoengineering or if they 
need a bit of controlling.

Regards,
Olivier

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[geo] Stratospheric solar geoengineering without ozone loss

[Andrew Lockley]

http://m.pnas.org/content/early/2016/12/07/1615572113.abstract

Stratospheric solar geoengineering without ozone loss
 Authors

   1. David W. Keith
   
   a ,
   b ,
   1
   
   ,
   2. Debra K. Weisenstein
   

   a ,
   3. John A. Dykema
   
   a ,
   and
   4. Frank N. Keutsch
   

   a ,
   c 

Significance

The combination of emissions cuts and solar geoengineering could reduce
climate risks in ways that cannot be achieved by emissions cuts alone: It
could keep Earth under the 1.5-degree mark agreed at Paris, and it might
stop sea level rise this century. However, this promise comes with many
risks. Injection of sulfuric acid into the stratosphere, for example, would
damage the ozone layer. Injection of calcite (or limestone) particles
rather than sulfuric acid could counter ozone loss by neutralizing acids
resulting from anthropogenic emissions, acids that contribute to the
chemical cycles that destroy stratospheric ozone. Calcite aerosol
geoengineering may cool the planet while simultaneously repairing the ozone
layer.
Abstract

Injecting sulfate aerosol into the stratosphere, the most frequently
analyzed proposal for solar geoengineering, may reduce some climate risks,
but it would also entail new risks, including ozone loss and heating of the
lower tropical stratosphere, which, in turn, would increase water vapor
concentration causing additional ozone loss and surface warming. We propose
a method for stratospheric aerosol climate modification that uses a solid
aerosol composed of alkaline metal salts that will convert hydrogen halides
and nitric and sulfuric acids into stable salts to enable stratospheric
geoengineering while reducing or reversing ozone depletion. Rather than
minimizing reactive effects by reducing surface area using high refractive
index materials, this method tailors the chemical reactivity. Specifically,
we calculate that injection of calcite (CaCO3) aerosol particles might
reduce net radiative forcing while simultaneously increasing column ozone
toward its preanthropogenic baseline. A radiative forcing of −1 W⋅m−2, for
example, might be achieved with a simultaneous 3.8% increase in column
ozone using 2.1 Tg⋅y−1 of 275-nm radius calcite aerosol. Moreover, the
radiative heating of the lower stratosphere would be roughly 10-fold less
than if that same radiative forcing had been produced using sulfate
aerosol. Although solar geoengineering cannot substitute for emissions
cuts, it may supplement them by reducing some of the risks of climate
change. Further research on this and similar methods could lead to
reductions in risks and improved efficacy of solar geoengineering methods.

   - climate change
   

   -
   - geoengineering
   

   - stratospheric ozone
   

   -
   - climate engineering
   

   - atmospheric chemistry
   


Footnotes

   - ↵
   

   1To whom correspondence should be addressed. Email:
   david_ke...@harvard.edu

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[geo] Resistance to Geoengineering: A Timeline

[Andrew Lockley]

http://www.geoengineeringmonitor.org/resistance/

Resistance to Geoengineering: A Timeline

Civil society has been questioning and opposing geoengineering for almost
20 years. What began as a reaction to technocratic hubris rapidly evolved
into worldwide protests against attempts to initiate ocean fertilization
and a consensus of civil society and Global South opposition at
the 2010 People’s Summit in Cochabamba.

In this time, the movement to stop geoengineering has scored several major
victories:

Two geoengineering projects were prevented from continuingSignificant
opposition was raised against three othersInternational moratoria have been
established at the UN Convention on Biodiversity and the London
ConventionReports have consistently anticipated and exposed new
geoengineering techniques as false solutions

A complete timeline follows.

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RE: [geo] RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL WARMING

[Douglas MacMartin]

I think if you can get them there, keeping them there is comparatively easy...

(The advantage of it being an equilibrium point is that the effort required to 
keep it there is in principle small.)

Though I think it would be cheaper to massively transform the world's energy 
system in the next few decades than to build something at meaningful scale at 
L1.  (Not a comment on the ease of the former but on the difficulty of the 
latter.)

-Original Message-
From: geoengineering@googlegroups.com [mailto:geoengineering@googlegroups.com] 
On Behalf Of Olivier Boucher
Sent: Monday, December 12, 2016 11:49 AM
To: geoengineering@googlegroups.com
Subject: Re: [geo] RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL 
WARMING


Hello,

it's not the first time that I read such a thing:
> The reflectors would be placed near L1 to ensure a stable orbit.
The L1 Lagrange point is *not* stable. They are quasi-periodic orbits around 
it, but it's not clear to me if they are suitable for geoengineering, if they 
are perfectly stable on long timescales needed for geoengineering or if they 
need a bit of controlling.

Regards,
Olivier

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Re: [geo] RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL WARMING

[Olivier Boucher]

Hello,

it's not the first time that I read such a thing:

The reflectors would be placed near L1 to ensure a stable orbit.
The L1 Lagrange point is *not* stable. They are quasi-periodic orbits 
around it, but it's not clear to me if they are suitable for 
geoengineering, if they are perfectly stable on long timescales needed 
for geoengineering or if they need a bit of controlling.


Regards,
Olivier

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[geo] RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL WARMING

[Andrew Lockley]

http://www.spaceflightinsider.com/missions/commercial/researchers-investigating-large-sunshades-combat-global-warming/

RESEARCHERS INVESTIGATING LARGE SUNSHADES TO COMBAT GLOBAL WARMING

BART LEAHY
DECEMBER 11TH, 2016

A group of concerned engineers and scientists is investigating a
space-based method to offset global warming. Their concept is called
Heliocentric Earth-Lagrangian Interception of Sunlight (HELIOS), a
flotilla of perhaps many thousands of kilometer-square sun sails that,
once placed at the Sun-Earth Lagrange (SEL1) point, would reduce the
amount of sunlight striking the Earth.

THINKING BIG



HELIOS was born out of a pair of papers presented at the Tennessee
Valley Interstellar Workshop (TVIW) and later in the Journal of the
British Interplanetary Society (JBIS). Those papers focused on
geoengineering, the deliberate large-scale modification of the Earth’s
climate through artificial means. Arguably, human beings have already
been performing accidental geoengineering over the last 200 years by
increasing the amount of carbon dioxide in the atmosphere through
burning fossil fuels.

The paper presenter, Robert G. Kennedy III, proposed building “Dyson
Dots” – a much smaller version of a conceptual swarm of solar
collectors proposed by physicist Freeman Dyson to capture the entire
energy output of a star, now called a “Dyson Sphere”.

These “dots” would consist of multiple reflectors and block an area
approximately 386,000 square miles (over 1,000,000 square kilometers)
in extent, nearly the size of the state of Texas. The reflectors would
be placed near L1 to ensure a stable orbit. At this distance, the Dot
would reduce the amount of sunlight (insolation) the Earth receives by
as much as one-quarter of one percent. Is that enough to make a
difference? Kennedy and the other members of the HELIOS team think so.

image: 
http://www.spaceflightinsider.com/wp-content/uploads/2016/12/L1-Positioning-655x346-1.png

Large sunshades placed at the Sun-Earth Lagrange Point 1 (L1 in this
image) could reduce the amount of sunlight Earth receives by just
enough to offset any effects caused by global warming. Image Credit:
R. Kennedy / Ultimax Group and D. Hughes / www.debbiehughes.com

“This reduction would bring down Earth’s average global temperature by
as much as 2.7 degrees Fahrenheit (1.5 degrees Celsius), approximately
the same change that brought about the “Little Ice Age” (approximately
1550–1850 C.E.).”

The goal is not to produce an ice age. Instead, HELIOS would combat
the anticipated global temperature rise by precisely offsetting it
with artificial cooling.

THE BIG PICTURE



“The initial study assumed the shade just appeared, all in one piece,”
Kennedy explained. “In reality, it will be assembled from smaller
sunshades. Nobody’s going to build a 100-megatonne piece of tinfoil
the size of Texas in one go, especially the first time. An actual
project would be incrementally built, incrementally deployed, incur
[an] incremental expense, and yield incremental benefits.”

In the long term, learning to build megastructures like the Dyson Dot
would advance the progress of solar-sail propulsion. Solar sails are
one possible method of transport within the solar system and to other
stars.

“Also, we’re certain the sunshades would have to be manufactured in
space, with off-world resources,” Kennedy said.

HELIOS could spur the in-space economy, as it will require access to
in situ magnesium – which is three times more common off Earth than
aluminum – as well as silicon, carbon, and iron. In addition to
resources, of course, the array requires advanced, industrial-scale
in-space manufacturing capabilities.

Lastly, a Dyson Dot could act like a conventional household or
satellite solar panel, converting solar radiation into electricity.
The solar energy collected from the Dyson Dot network could be
transmitted to Earth through space via a series of relays, supplying
over 10,000 gigawatts per year – Earth’s entire electric power demand.

Before that, HELIOS, the first-generation sunshield without the power
generation capability, has to help address the global warming problem.

HELIOS’ NEXT STEPS



Obviously, a project as ambitious as HELIOS will be difficult and
expensive, so the group’s initial priority will be financing. This
means attracting the interest of venture capitalists or angel
investors as well as getting their ideas into the public consciousness
(full disclosure: the author of this article is the HELIOS team’s
outreach consultant).

Technically, the initial steps for developing HELIOS will include
defining the system architecture, defining its physical
characteristics, and determining its actual environmental performance.
The team will also need to do a due-diligence review on the system.
For example, they must determine the Technology Readiness Level (TRL)
of the major system components and develop 

[geo] NASA's role in gauging environmental change

[Andrew Revkin]

This seems highly relevant to GEO-ENG discussion because it explores
arguments that NASA is not the right agency to do Earth science.

I couldn't fit it in, but studies of Mount Pinatubo cooling were largely
NASA and important in refining climate models (and relevant here).

https://www.propublica.org/article/will-trump-scrap-nasas-climate-research-mission

Here's an excerpt:

Trump’s most visible advisor on space policy has been Bob Walker, a
former House
Science committee chairman
who
is now a space-policy lobbyist pressing
to move “Earth-centric
”
and “heavily politicized
”
climate science out of NASA altogether. And Christopher Shank, who was
chosen by Trump to lead the transition at NASA, is a seasoned strategist
who has expressed strong skepticism
 about
the severity of global warming.

Should Trump come to take a dim view of NASA’s research on climate change,
he’s likely to have no shortage of support in Congress. The last few years
have seen intensifying moves against the Obama administration’s investments
in climate science in hearings led by the Texas Republicans Sen. Ted Cruz
 and
Rep. Lamar S. Smith, whose views on NASA and climate parallel those of
Walker — built around the notion that NASA needs to focus on outer space,
not back on Earth.

As Smith put it in 2015, “There are 13 other agencies involved in climate
change research, but only one that is responsible for space exploration."

NASA’s Earth Science division, if less well known to the public, has
regularly seen its budget fluctuate with turnover in the White House. Under
Ronald Reagan, there were substantial investments
 in
what was then called the Earth Observing System. George H.W. Bush, building
on a 1987 report by astronaut Sally Ride, funded a program that came to be
known as the “Mission to Planet Earth
.”

George W. Bush reversed course, and reduced resources
 for the program
(his administration was eventually exposed for trying to suppress NASA
research on global warming
).
Most recently, though, the division’s budget was greatly restored by Barack
Obama. A core argument of Walker and congressional critics of NASA earth
science, that budgets have ballooned and reduced resources for other NASA
science programs, has no basis, said Arthur Charo, who has tracked NASA
science budgets for the Standing Committee on Earth Science and
Applications from Space  of
the nongovernmental National Academy of Sciences.

He said a careful look at programs, adjusting for inflation, shows no
evidence of such a pattern. “There is a mythology that Earth Science has
undergone dramatic growth and that this growth has occurred at the expense
of other divisions in the Science Mission Directorate,” he said. “Both
assertions are false.”

An important chart of relative spending on Earth/Space science came in too
late to get in the story but makes some points that appear to contradict
Bob Walker's assertions, bolstering Arthur Charo's point in the piece. It's
here:

https://twitter.com/Revkin/status/808300867980066817


-- 
*ANDREW C. REVKIN,* *ProPublica Senior Reporter
 (*climate and
related issues) | Read my 2,810 Dot Earth posts
, my essay making sense of the
#Anthropocene , my reflection on 30 years
of climate learning .

*Mobile: 914-441-5556, Twitter: @revkin
, Facebook
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Andrew Revkin
[image: https://]about.me/revkin


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