Transcript Understanding and Governing the Risks of Solar Radiation Management (SRM) A few basic ideas to start our discussions 2011 January 31 M.

Understanding and Governing the Risks
of Solar Radiation Management (SRM)
A few basic ideas
to start our discussions
2011 January 31
M. Granger Morgan
Department of
Engineering and Public Policy
Carnegie Mellon University
Pittsburgh, PA 15213
tel: 412-268-2672
e-mail: [email protected]
1
Three ways to
change the
climate:
To warm the earth
add CO2 and other
GHGs.
To cool the earth either:
Increase albedo
Remove CO2
and other GHGs OR just a little bit
(this is fast).
(this is slow).
2
There has been a lot of
confusion about nomenclature
Too many things are being termed “geoengineering.”
The result is that people make general statements that
actually only apply to one subset of possible strategies.
The Royal Society has
introduced two terms that help:
SRM or “solar radiation
management”
CDR or “carbon dioxide
removal”
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Three ways to
change the
climate:
To warm the earth
add CO2 and other
GHGs.
To cool the earth either:
Increase albedo
Remove CO2
and other GHGs OR just a little bit
(this is fast).
(this is slow).
CDR
SRM
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Four examples of how the
earth's albedo might be increased:
1. Add small reflecting particles in the stratosphere.
2. Add more clouds in the lower part of the atmosphere.
3. Place various kinds of reflecting objects or diffraction
gratings in space either near the earth or at a stable
location (the L1 point) between the earth and the sun.
4. Change large portions of the planet's land cover from
things that are dark and absorbing, such as trees, to things
that are light and reflecting, such as open snow-cover or
grasses.
The first of these is probably the most feasible
so I will concentrate on just that option.
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Stratospheric aerosols
100
Adding more of the right kind of
fine particles to the stratosphere can
increase the amount of sunlight that
is reflected back into space.
< 70
> 30
Layer of fine ref lecting particles
< 70
There is clear evidence from many large past volcanic eruptions
that this mechanism can cool the planet (Mount Pinatubo
produced global scale cooling of about 0.5°C).
Figure source: NASA and IPCC.
Source: Novim report, 2009, p. 14
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This is not hard to do,
and probably not all
that expensive
David Keith has suggested that it should be
possible to create microscopic reflecting
composite particles that would be selforienting and self-levitating, and thus might
not have to be replaced very frequently.
Figure sources: EADS; NASA; www.carlstumpf.com
A single nation could do these
within its national boundaries7
While there is…
…a great deal of
uncertainty about SRM,
last year in Nature David
Keith, Ted Parson and I
argued that three things
are pretty certain:
In order to get a better estimate of cost…
My colleagues Jay Apt
and David Keith
recently commissioned
a study by Aurora
Flight Systems.
The folks at Aurora
concluded that delivery
by special aircraft is
probably the most costeffective strategy.
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Modest infrastructure
They conclude that
total cost might be just
a few $billion/year
10
Comparing costs
How does the cost of achieving ~80%
reduction in the emissions of CO2 and other
GHGs compare to the cost of SRM (which,
of course, would have no impact on CO2
level but could “eliminate” warming)?
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The cost of GHG abatement
Today, the world is emitting about 50x109 tonnes per year CO2-eq
The IPCC 4th assessment says:
(of which about 30x109 is CO2)
"Modelling studies show that global carbon prices rising to US$2080/tCO2-eq by 2030 are consistent with stabilisation at around 550ppm
CO2-eq by 2100. For the same stabilisation level, induced technological
change may lower these price ranges to US$5-65/tCO2-eq in 2030."
(50x109 tCO2-eq)(5 to 65$/tCO2-eq) = 250 to 3300x109 $/year
The size of the global economy is of the order of $60x1012
0.25 to 3.3x1012 $/year
60x1012 $/year
0.4% to 5.5% of world GDP/year
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The cost of SRM
~ 6 x109 $/year
60x1012 $/year
~ 0. 01% of world GDP/year
BOTTOM LINE: It is probably safe to
assume that the direct monetary cost of
SRM would be >100 times less than the
cost of a full program of GHG abatement.
At this cost, one or several nations that started
experiencing serious climate impacts, might be
tempted to unilaterally engage in SRM.
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That handles “cheap” and “fast”
Now lets consider “imperfect”
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If we change albedo a little…
…to cool the planet, what else might happen?
Possibilities include:
• Impacts will not be uniform. Some places will
change more than others.
• Precipitation patterns will shift (of course, that is
also happening under climate change).
• Continued and growing impacts on the oceans as
they take up more and more CO2.
• Particles in the stratosphere can provide reactive
surfaces that might contribute to the destruction
of the ozone layer.
15
My PhD student Kate Ricke:
Is exploring how uniformly SRM could
offset the effect of rising radiative
forcing. Using climateprediction.net she
has looked at a number of different SRM
scenarios that made uniform
modifications to stratospheric optical depth to
approximately stabilize mean global near-surface air
temperature under SRES A1B.
She finds that the effectiveness of any given amount of
modification to optical depth in returning regional
climates to their baseline state varied from region to
region and varied over time.
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Kate finds that
“Optimal” SRM varies regionally
“Optimum” by region in 2020s
“Optimum” by region in 2070s
More
Geoengineering
Less
Geoengineering
Approximate Global-Mean SAT (°C)
Source: Ricke, Morgan and Allen, Nature Geoscience, 2010
Imperfect compensation
and regional disparities
Source: Ricke, Morgan and Allen, Nature Geoscience, 2010
18
In a new round of studies…
Kate is doing “perturbed physics” runs to see if any
of the range of values of key model parameters that
are consistent with past climate can result in
dramatically different outcomes.
So far, it looks like the general finding that responses
will likely be different in different parts of the world,
and that they may diverge over time, remains true.
19
Acification of the oceans
I hardly need to note for this audience that much of
the CO2 we put into the atmosphere ultimately ends
up in the oceans.
Today the oceans are 30% more acidic
than before the industrial revolution.
20
Source: Doney et al., Annual Reviews of Marine Science, 2009
During this workshop…
…I look forward to learning whether there is agreement
that this means the demise of most coral reefs and the
ecosystems they support.
450-500ppm +2°C >500ppm >3°C
Source: O. Hoegh-Guldberg et al., "Coral
reefs under rapid climate change and ocean
acidification," Science, 318, pp. 1737-1742,
December 14, 2007.
375ppm +1°C
21
Shell dissolution (e.g. pteropod or "sea butterfly")
A key food source for juvenile pink
salmon and other small fish.
22
Source: Orr et al., Nature, 2005; Wikipedia; www.ims.uaf.edu
Serious studies of acidification
have hardly begun
Source: Doney et al., Annual Reviews of Marine Science, 2009
23
And as Ken will no doubt point out…
…the longer one does
SRM by injecting fine
particles in the
stratosphere, the greater
the risk of rapid change
if one suddenly stops.
Such changes could
devastate many
terrestrial ecosystems.
Source: Matthews and Caldeira, PNAS, 2007.
24
Given all the uncertainties…
…shouldn't we just create a global taboo against
geoengineering as we have for CBW?
Two reasons to say no:
1. If in a few decades we have major
climate surprise (e.g., lose half the ice
in Greenland so sea level goes up
>3m), we may have a billion people
at risk and need to take collective
protective action.
2. We may need a bit of geoengineering in
combination with abatement to “get the world
over the hump” while we reduce GHG levels.
Figure source: www.globalwarmingart.com
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The CFR workshop…
Because the diplomatic community was
almost completely unaware of SRM, in
2008 we organized a workshop at the
Council on Foreign Relations in
Washington, DC.
The workshop led to a paper that appeared in the 2009 March/April
issue of Foreign Affairs.
Participants in the 2008 workshop
were all from North America.
To extend the conversation to a more
international group, we ran a second
workshop in April 2009 in Lisbon,
Portugal.
Source: Council on Foreign Relations
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The Lisbon Workshop…
…was hosted by the Ministry of Science,
Technology and Higher Education of
the Government of Portugal. The two-day
workshop was held at the facilities of the
Gulbenkian Foundation.
Co-sponsors included: IRGC, CMU-CDMC, U Calgary. Participants
came from N. America, EU, China, Russia, and India.
Sources:
Gulbenkian & Qian Yi
27 4
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The Lisbon Workshop
has been followed by…
Sep. 2009: The
governance section
of the Royal
Society’s report on
Geoengineering
March 2010: The
discussion of
risk governance at
the Asilomar
conference on
geoengineering
Ongoing: Adoption of
the “allowed zone”
concept by the NCEP in
its advice to the US Gvt.
Jan 2010
June 2009:
Contributions
by several
IRGC-linked
experts at the
US NRC
workshop on
geoengineering
Jan 2011
March 2010:
Testimony to a joint
session of the US
House Science
Committee and the
Science Committee
of the UK
Parliament
March 2010: Evening
briefing to CFR
Ongoing: IRGC’s cosponsorship of the Royal
Society’s follow-on project
on global risk governance
August 2010: First multiuniversity summer study
program for graduate
students on geoengineering
held at Heidelberg. Second
will be summer 2011 in
Calgary
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Returning now to
the issue of
research…
Global norms versus global regulations
There are some already calling for formal global
regulation of any SRM-related research.
At this early stage, that would be a recipe to make
sure that no research gets done.
I think the proper way forward in the early stages is
for the international research community to agree on
some norms about what constitutes modest research
that will have no significant impact and thus should
be allowed, subject only to national rules. Any such
work should be open and transparent, and all results
should be made public.
30
Defining an allowed zone
Source: Morgan and Ricke, IRGC, 2010
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Research time line
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Unilateral deployment
Collective deployment
For more…
…on the policy and
risk governance
issues in SRM go to
“publications” at:
www.IRGC.org
www.irgc.org/IMG/pdf/SRM_Opinion_Piece_web.pdf
Thanks
Portions of this work have been supported by the Climate
Decision Making Center funded by the US National Science
Foundation (SES-0345798), by an NSF Graduate Fellowship
to Kate Ricke, and by the International Risk Governance
Council (IRGC). The views are those of the speaker.
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