Hi Mike,
The 2005 drought in the Amazon is now thought to be due to warming of
the tropical North Atlantic, so not only could John's cloud albedo
enhancement reduce severity of hurricanes, but also reduce risk of
Amazon drought. [1]
If two such droughts were to occur in consecutive years, large areas of
the Amazon would be at risk of burning away altogether - a potentially
disastrous positive feedback on CO2 and on global warming. As usual
the reaction is to demand even more drastic emissions reduction [2],
but clearly there is a risk of droughts in the next decade, during
which emissions reduction would be ineffective. Therefore there is a
strong argument for geoengineering as soon as possible, to reduce this
risk. As an outstanding candidate for geoengineering, cloud albedo
enhancement needs to be developed as a matter of extreme urgency.
Perhaps it could be funded for its hurricane calming capability, even
though the Amazon is more important for us all, not only for the carbon
and water cycles, but also for driving much of the world's weather
system [3].
Cheers,
John
[1] http://news.mongabay.com/2008/0220-marengo_amazon.html
[2] http://news.mongabay.com/2009/0305-amazon.html
"If the earth's carbon
sinks slow or go into reverse, as our results show is possible, carbon
dioxide levels will rise even faster," Phillips, a professor at the
University of Leeds, added. "Deeper cuts in emissions will be required
to stabilize our climate."
[3]
http://www.newscientist.com/article/mg20227024.400-rainforests-may-pump-winds-worldwide.html
----
Mike MacCracken wrote:
Hi John—All good points, and I’ll add
another. SO2 would sort of spread with the winds and have a diffused
influence, whereas your approach would have a much better controlled
distribution of its effects. In that, and this is a point I made at the
NAS meeting, global average temperature is not really likely to be the
most appropriate metric to be using—for example, maintaining
precipitation patterns or even oscillations, or limiting extremes, or
alleviating drought, etc. may be much more significant for people’s
livelihoods, then your controlled effects on clouds in particular areas
might be a much finer and more tunable approach that just generally
releasing SO2 broadly (of course, its regional and temporal release
could be controlled a bit as well—just not as finely). So, indeed,
let’s do the research and figure out how best we can achieve the goals
we set. It is not technique that is what we are after, but results.
Best, Mike
On 6/17/09 10:25 AM, "John Latham" <[email protected]>
wrote:
Hello Mike,
I enjoyed reading your wide-ranging and
authoritative article.
I present below a response to a statement you
made regarding our cloud albedo enhancement scheme, which was: ?I like
the approach, but it works only on some types of clouds and relatively
limited area--SO2 works in more types of clouds over broader area and
also has effect in clear air.?
Your statement is, of course, correct, and
there are clearly significant advantages associated with a scheme which
has a much greater areal coverage, perhaps particularly because the
magnitude of the distortions from existing weather patterns are likely
to be reduced.
However, I think it worth pointing out that
about 25% of the total oceanic surface is covered by clouds suitable
for seeding, and fully coupled atmosphere/ocean GCM computations
indicate that (if various defined scientific and technological issues
are satisfactorily resolved) the cloud albedo technique could produce a
globally averaged negative forcing of at least -4W/m2, which could, in
principle, maintain existing values of polar ice cover and globally
averaged surface temperature for some decades.
Also, vis-a-vis this scheme, some useful
flexibility exists which might prove helpful in reducing adverse
changes from existing patterns to acceptable levels. Our work
demonstrates ? subject to the above-mentioned caveats ? that it is not
necessary to seed all suitable clouds in order to have a very
significant impact in compensating for impacts from CO2 forcing.
Assuming sufficient understanding, it is feasible, in principle, to
modify the selection of regions, time of year, and amount of seeding to
change the geographical and temporal distribution of negative forcing.
In some circumstances, it may also prove possible to obtain beneficial
results from much more limited-area seeding e.g. it may help with coral
reef preservation, hurricane emasculation or restoration or maintenance
of polar ice cover. It may also prove desirable to deploy it in
conjunction with other techniques, such as stratospheric aerosol
geoengineering. One might envisage the latter as contributing the
primary global cooling and the former providing localised and hopefully
quantitatively controlled cooling to optimise or rectify the conditions
obtaining in small and important regions. This idea requires much more
examination.
All Best, John.
*************************************
Quoting Mike MacCracken <[email protected]>:
>
> Hi Alvia--Thanks for comment and making report more accessible.
>
> I would just note that there is no reason one has to think one
would keep
> putting out SO2 emissions from power plants--why mix it with dark
aerosols?
> Emissions could be of pure SO2 (given all the sulfur that has been
> scavenged) and does not have to be done where people are--or in
conditions
> that lead to rainout of large amounts in sensitive areas, etc. And
SO2 does
> not have to be put out continuously or during times of low or no
sunlight.
> Balloons holding hoses aloft to a kilometer or so would likely be
all that
> would be needed in a few places--and like a kite, pull the balloon
down when
> a storm comes as it does no good to put out SO2 into a rain storm
(of
> course, choose sites where there are few storms). And I would add
we know a
> good deal about the effects of SO2 in the atmosphere, though
surely not
> enough (like what have been the radiative and meteorological
effects of the
> center of S emissions moving from North Atlantic basin to
southeastern
> Asia--so at lower latitude with more solar effect, but we don't
know
> emissions inventory real well--both amount and altitude of
emissions).
>
> I like the Salter and Latham approach, but it works only on some
types of
> clouds and relatively limited area--SO2 works in more types of
clouds over
> broader area and also has effect in clear air. Of course, SO2 does
have more
> side effects (health, ecosystems, etc.) so I would have to design
the system
> to minimize those (e.g., encouraging sulfate build-up over dark
and remote
> ocean areas for global effect where there are no solar direct
technologies
> being used)--stratospheric aerosols have much lower effects on
health and
> ecosystems, but would have significant effect on direct solar
technologies
> if they are dispersed globally.
>
> As we are learning, there is no such things as a free lunch, so we
need to
> consider the price and quality of all the various lunches
available.
>
> Mike
>
>
>
> On 6/17/09 7:29 AM, "Alvia Gaskill" <[email protected]> wrote:
>
>> Your paper wasn't that easy to find, but find it I did. An
excellent review
>> of most of the major geoengineering proposals and some I
hadn't heard about
>> before. I'm still opposed to allowing SO2 emissions from
power plants to
>> continue, however. I renamed the file for ease of recognition.
>>
>> Summary: Global climate change is occurring at an accelerating
pace, and the
>> global greenhouse gas (GHG) emissions that are forcing climate
change
>> continue to increase. Given the present pace of international
actions, it
>> seems unlikely that atmospheric composition can be stabilized
at a level
>> that will avoid "dangerous anthropogenic interference" with
the climate
>> system, as called for in the UN Framework Convention on
Climate Change.
>> Complicating the situation, as GHG emissions are reduced,
reductions in the
>> offsetting cooling influence of sulfate aerosols will create
an additional
>> warming influence, making an early transition to climate
stabilization
>> difficult. With significant reductions in emissions
(mitigation) likely to
>> take decades, and with the impacts of projected climate
change-even with
>> proactive adaptation-likely to be quite severe over the coming
decades,
>> additional actions to offset global warming and other impacts
have been
>> proposed as important complementary measures. Although a
number of possible
>> geoengineering approaches have been proposed, each has costs
and side
>> effects that must be balanced against the expected benefits of
reduced
>> climate impacts. However, substantial new research is needed
before
>> comparison of the relative benefits and risks of intervening
is possible. A
>> first step in determining whether geoengineering is likely to
be a useful
>> option is the initiation of research on four interventions to
limit the
>> increasing serious impacts: limiting ocean acidification by
increasing the
>> removal of carbon dioxide from the atmosphere and upper ocean;
limiting the
>> increasing intensity of tropical cyclones; limiting the
warming of the
>> Arctic and associated sea level rise; and sustaining or
enhancing the
>> existing sulfate cooling influence. In addition, in depth
consideration is
>> needed regarding the governance structure for an international
>> geoengineering decision-making framework in the event that
geoengineering
>> becomes essential.
>>
>> http://econ.worldbank.org/external/default/main?pagePK=64165259&theSitePK=4693
>>
72&piPK=64165421&menuPK=64166093&entityID=000158349_20090519141020
>>
>> http://www-wds.worldbank.org/external/default/WDSContentServer/IW3P/IB/2009/05
>> /19/000158349_20090519141020/Rendered/PDF/WPS4938.pdf
>>
>> https://blogs.worldbank.org/climatechange/geoengineering-possible-climate-chan
>> ge-insurance-policy
>>
>> Geoengineering: A Possible Climate Change Insurance Policy?
>> By Michael MacCracken
>> Created 06/15/2009 - 18:24
>>
>>
>>
>> Even if all emissions of greenhouse gases and aerosol
precursors ended
>> today, more warming would occur in coming decades than the
0.8°C that has
>> occurred to date, greatly intensifying climate change and its
associated
>> impacts. Already, sea level is rising, sea ice and mountain
glaciers are
>> retreating, the ranges of plant and animal species are
shifting poleward and
>> upward, and the Greenland and Antarctic ice sheets are both
losing mass.
>> Each round of the assessments of the Intergovernmental Panel
on Climate
>> Change has found that change is occurring more rapidly than
previously
>> projected.
>>
>> With coal, petroleum, and natural gas providing over 80% of
the world's
>> energy, greenhouse gas emissions cannot be stopped today, or
next year, or
>> even in a few decades. While international negotiations have
the potential
>> to limit emissions and the ultimate changes in climate to be
experienced by
>> future generations, much greater changes in climate than have
occurred to
>> date are inevitable, and their impacts will continue to
intensify. The
>> changes are so rapid and large that it is becoming much more
likely that
>> critical thresholds will be exceeded, triggering potentially
unstoppable
>> Earth system responses. Most serious would be initiation of
large releases
>> of methane from thawing permafrost or sea level rise of over a
meter per
>> century as deterioration of the major ice sheets accelerates.
The resources
>> required to deal with the consequences if this occurs would be
enormous.
>>
>> While limiting emissions through mitigation is essential and
can help slow
>> climate change, the problem is that just reducing emissions
will only very
>> slowly limit climate change over the next few decades. And
while adaptation
>> is also essential, there are many consequences of climate
change for which
>> no practical adaptive response exists-societies will have to
suffer,
>> migrate, or find new ways to provide the lost services. With
international
>> negotiations moving slowly, the situation continues to become
more and more
>> problematic.
>>
>> The urgency of the situation has resurrected consideration
about whether it
>> might be appropriate to not just limit what we are doing to
the climate,
>> but, in addition, to attempt to deliberately manipulate the
climate and/or
>> atmospheric composition in a way that would counteract the
changes being
>> induced by the energy-related emissions of carbon dioxide and
other
>> greenhouse gases. This category of effort has been dubbed
geoengineering,
>> although it might better be termed georestoring of the
climate, because the
>> intent would be to moderate climate change and its impacts.
>>
>> For example, nations might choose to try to emulate the
cooling influence of
>> major volcanic eruptions by, on a continuing basis, augmenting
the amount of
>> particulate matter in the stratosphere. Injecting sulfate
aerosols globally
>> or at the right latitudes could be done in a way that would
reflect an
>> amount of solar radiation equal to the increased trapping of
energy by the
>> greenhouse gases. Although this could limit global warming,
thus reducing
>> impacts like the loss of sea ice and slow the increase in sea
level, there
>> would be several side effects, including whitening of the sky,
perhaps
>> altering the course of storm systems, and reducing the
efficiency of many
>> types of solar energy systems. While this might seem an
acceptable tradeoff
>> today, it is worth noting that future generations would have
to continue
>> these injections for centuries, or the warming that was being
offset would
>> reappear relatively rapidly. The report, Beyond Mitigation:
Potential
>> Options for Counter-Balancing the Climatic and Environmental
Consequences of
>> the Rising Concentrations of Greenhouse Gases, just published
provides an
>> overview of the range of proposals that have been made over
the past few
>> decades.
>>
>> In addition to limiting global change through mitigation, a
conceivable
>> complementary approach could be to augment the international
approach could
>> be augmented with specially designed efforts to limit the
intensity of
>> specific, particularly severe impacts. In my view, four
possible actions
>> deserve intense analysis because the potential losses appear
to be far
>> larger than the likely cost of implementation:
>>
>> 1.. Limiting the solar radiation that reaches the Arctic and
Antarctic in
>> order to restore conditions needed by the region's species and
to limit sea
>> level rise from the melting of the Greenland and West
Antarctic Ice Sheets.
>> 2.. Enhancing uptake of carbon by the ocean, storing it in
the deep ocean
>> in order to moderate ocean acidification and limit damage to
the marine food
>> web. Alternatively, ocean acidification might be limited in
specific areas
>> such as the Great Barrier Reef by adding a buffering compound
to ocean
>> waters.
>> 3.. Limiting the warming of the ocean in the regions that
contribute to
>> intensification of tropical cyclones (i.e., hurricanes,
typhoons, etc.).
>> 4.. Actively managing the global emissions of sulfur dioxide
in order to
>> maintain, or even enhance, the global cooling influence of
tropospheric
>> aerosols.
>> Each of these actions, and there may be others worthy of
consideration,
>> would focus on intervening to moderate a specific impact.
There are viable
>> technological approaches for each of these activities, and
they would be
>> readily reversible if unexpected, adverse consequences arose.
What is needed
>> now is an aggressive research and development effort that
determines the
>> optimum approach, carries out small scale tests, investigates
and compares
>> unintended side effects with the impacts of greenhouse gases
that are
>> alleviated, and puts forth a near-term plan for active
consideration at an
>> appropriate regional or global forum.
>>
>> None of these actions would be a substitute for aggressive
global mitigation
>> of emissions or alleviate all of the adverse consequences.
However, they
>> could more evenly spread the burden of global warming and
potentially slow
>> the onset of at least some of the irreversible consequences.
In this way,
>> geoengineering could buy a small amount of time for global
mitigation to be
>> negotiated and take hold. Undertaking research on these impact
interventions
>> seems important and timely.
>>
>>
>>
>> ----- Original Message -----
>> From: "Mike MacCracken" <[email protected]>
>> To: "Geoengineering" <[email protected]>
>> Sent: Wednesday, June 17, 2009 12:31 AM
>> Subject: [geo] World Bank posting
>>
>>
>>>
>>> You might be interested in the World Bank posting at
>>> https://blogs.worldbank.org/climatechange/
>>>
>>> It is an intro and pointer to a background report that
reviews many of the
>>> possibilities for geoengineering prepared in support of
the major World
>>> Bank
>>> report to be issued on Sustainability and Climate Change.
>>>
>>> Best, Mike MacCracken
>>>
>>>
>>>
>>> >>
>
>
>
> >
>
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