Memorandum 150
Submission from Colin Forrest
SUMMARY
- Arctic specialists are warning that rapid
massive release of methane from seabed sediments could occur at
any time.
- This would cause a temperature rise of
at least 6°C, with further rises from additional feedbacks.
Impacts would be more severe and more rapid than those currently
predicted by the IPCC.
- Some geoengineering proposals, particularly
stratospheric injection of sulphate aerosols, and injection of
seawater aerosol in the marine boundary layer, are sufficiently
powerful, and technically feasible within the limited timescale,
to avert this temperature rise.
- These ideas have been discussed and modeled
within the climate community, but are untested, could be less
effective, and could cause significant and possibly adverse effects
on global and regional climate.
- It is an immediate priority that multidisciplinary
scientific and engineering teams, with adequate funding and access
to resources, test and develop these ideas, with a view to being
able to implement full scale deployment within the next two decades.
- Priority should also be given to practical
methods of avoiding the release of methane hydrates from the Arctic
seabed, and of removing excess methane from the atmosphere.
INTRODUCTION AND
OVERVIEW
1.1 Recent measurements of elevated levels of
methane on the shallow, rapidly warming continental shelves of
Russia, where upwards of 540 billion tons of methane are vulnerable
to rapid release, lend support to the worry amongst climate scientists
that rapid release of greenhouse gases (GHGs) from warming and
changing ecosystems could release such overwhelming quantities
of GHGs that reductions in anthropogenic GHGs would make no difference
to global warming. A release of 2%, or 10 billion tons, of this
store would increase GMST by around 6oC, and would trigger further
GHG emissions (from land based permafrost, tropical forest dieback,
ocean outgassing, and increased forest fires in Asian peatlands,
semi arid regions and the boreal forest).
1.2 If there is significant release of methane
from the Arctic seabed, then geoengineering solutions will be
our only option to prevent runaway warming. Unfortunately, earth
science is still in its infancy, and has received less funding
than other branches of science, eg aerospace, armaments or medicine,
which have had more practical use to society (up til now). We
are not starting from a strong baseline, and we might need to
apply planet scale geoengineering within two decades.
1.3 Our ability to model the complex interactions
within the earth/climate system is limited, as the failure of
the IPCC climate models to predict the rapid melting of Arctic
sea ice, underestimation of sea level rise, and rapid rise in
surface temperatures (particularly in the Northern Atlantic/Western
Europe region), has shown.
We need strong cooperation between existing
climate scientists and practical engineers to quickly develop
equipment to test and monitor geoengineering technologies on a
local and regional basis, before large scale implementation.
1.4 There are many ideas and proposals,
so I will concentrate on what I think are the strategically important
ones. I have excluded space based proposals as unlikely to be
technically achievable in the short timeframe, artificial atmospheric
CO2 scrubbing as likely to be too energy intensive and costly,
and increased carbon capture from natural ecosystems (ocean fertilization/biochar/increased
reforestation etc) although valid and achievable, as unlikely
to produce sufficient reductions in atmospheric levels of GHGs
to make a significant difference in the available timescale.
Carbon capture and storage (CCS) from power stations
2.1 This is a mature technology, which will
become mainstream technology when a carbon price of around £26
per ton of carbon (or £95 per ton of carbon dioxide) is imposed
on power generators, and requires mostly existing hydrocarbon
exploration and refining engineering skills. I have included it
partly to emphasize the need for climate engineering research
in addition to rapid reductions in anthropogenic sources of GHGs.
2.2 CCS will be an essential component of
any attempt to control anthropogenic GHG emissions, and a planned
infrastructure of pipelines and transport infrastructure linking
all large and medium sized sources of CO2 (including biomass fired
power stations) to geological storage sites, on a regional and
international scale should be developed.
2.3 A target of capturing the emissions
from all major new and existing power stations within two decades
is technically and economically feasible, requiring only that
the current generation of politicians find the courage to implement
a global price of around £50 per ton of carbon emitted (whether
by taxes or by cap and trade schemes). This would reduce global
GHG emissions by around a third.
Stratospheric albedo engineering
3.1 The idea of injecting microscopic particles
into the stratosphere to deflect incoming solar radiation has
been discussed widely, and some very simple modeling has been
done, showing that it could be sufficiently powerful to counteract
some or all of the warming we have created, although it would
likely alter radiation and precipitation patterns on the surface,
and could not be used to target specific regions.
3.2 It must be stressed that our ability
to understand circulation patterns, hydrology, atmospheric chemistry
and radiation balance in the stratosphere is exceedingly limited,
and our ability to predict or model changes due to deliberate
addition of sulphur dioxide or other aerosols is minimal. Here
linkages with aerospace and remote sensing engineers will be crucial,
and ground based testing facilities will need to be improved.
3.3 Diurnal and seasonal variations in each
hemisphere will need to be investigated. Whilst modeling might
provide some initial hypotheses, large scale ground based testing
facilities will provide more substantial results before field
trials in the stratosphere.
3.4 Research is needed regarding the type
of particles most suitable, which parts of the solar spectrum
they will absorb or reflect, and their chemical and physical interactions
in the stratosphere, particularly with water, oxides of nitrogen,
ozone and hydroxyl ions.
3.5 (Hydroxyl ions (OH-) are the primary
atmosphere scrubbers, oxidizing and removing carbon based pollutants.
They are very reactive, short lived ions produced by the action
of sunlight of 310 nm wavelength on water molecules, and they
remove most of the methane which is produced from natural and
human systems. This process is discussed further in the chapter
on methane.
Marine albedo engineering
4.1 The idea of creating sea salt spray
in the lower part of the atmosphere over the oceans (the marine
boundary layer, up to around 500m), to increase the optical thickness
and lifetime of marine stratocumulus cloud has been around for
a while, and has recently become topical. It has recently been
modeled at the Hadley Centre and seems to be powerful enough technique
to offset much of the current anthropogenic warming, reducing
the sea surface temperature, which is the fundamental driving
force of the earth's heat engine. The change in surface albedo
between the dark ocean surface and the enhanced cloud is quite
significant, and the idea has the advantage of being easily targeted
at specific locations (eg endangered coral reefs, tropical cyclone
formation areas, Arctic areas where permafrost is in danger of
melting), has nontoxic byproducts (salt water) and is readily
reversible (the clouds have a lifetime of around a week).
4.2 The process can be easily be seen on
satellite photographs, where the exhausts plumes of commercial
ships, containing particles of black carbon and sulphur dioxide,
leave long trails of artificially created clouds, similar to aviation
contrails, behind them, where weather conditions are suitable.
4.3 Large areas of the world's oceans are
suitable for cloud enhancement, but like all powerful climate
engineering tools, the implementation could alter local climates,
in particular the position of the Intertropical Convergence Zone
(ITCZ) and associated rainfall, or lack of it.
4.4 Unfortunately, the current proponents
Latham and Salter are proposing to disseminate the spray from
of a fleet of unmanned, satellite controlled wind powered boats
propelled by a novel form of sail; the flettner rotor, which creates
three new and unusual technical problems, and reduces the credibility
of the idea.
4.5 However the spray could be produced
from standard ocean going vessels, solving two of the difficulties
at a stroke, and leaving only the engineering problem of producing
large volumes of a very fine aerosol of (filtered) seawater, between
one and ten micrometers in diameter, and disseminating it into
the marine boundary layer. I am no engineer, but I think the right
people, with the right funding, could provide a useable solution
for initial field trials within a year or two.
4.6 From my understanding of the rate of
climate change, and of the possible proposals currently being
discussed, I think that this is the most important single aspect
of geoengineering that needs funded professional research and
development. We can model the process until the cows come home,
but until we start adding salt water aerosol to clouds in the
marine boundary layer, we won't know how much will reach the cloud
base, and what effect it will have.
4.7 Larger particles (or cloud condensation
nuclei, CCN) are known to cause larger raindrops, which rain out
and reduce cloud cover, and there is the possibility that large
numbers of very small CCN will increase the number and surface
area of water droplets, causing rapid evaporation and loss of
cloud cover. CCN may coalesce to form larger drops. The number
of pre-existing CCN, temperature, water vapour content, wind speed,
rates of updraught and entrainment are all important factors and
can only modelled approximately.
4.8 Some understanding of these processes
might be gained from experimental set-ups on land, but fortunately,
there are large areas of empty ocean to experiment on, and results
can easily be verified by remote sensing, once we have developed
suitable machinery for producing a very fine aerosol spray.
4.9 The above comments are a distillation
of my studies over the last few years, a review of the work of
more experienced scientists. The next sections explore what I
think will be the new and important issues, which follow from
the realization that we may have a summertime ice free Arctic
Ocean between 2013 (the projection of the most radical Arctic
expert) to 2030 (the projection of the most conservative Arctic
expert). As most climate scientists work from projections of the
models used in the IPCC Fourth Assessment Report, which envisage
a proportion of summer ice remaining in the Arctic Ocean until
at least 2100, and are not aware of the fast changing reality
of the northern high latitudes, the following comments are likely
to be original, and certainly well in advance of current thinking
by mainstream climate scientists.
Preventing release of methane to the atmosphere
from Arctic regions
5.1 The immediate danger appears to be the
rapid thawing of seabed sediments in the shallow (up to 200m deep)
Russian continental shelves, under the Barents, White, Kara, Laptev,
and East Siberian seas, where the warm waters from the Gulf Stream/North
Atlantic drift are increasingly being driven by the increased
strength of the prevailing westerly winds and the funnelling effect
of the disposition of the continental land masses of Greenland,
Scandinavia and the North Asian continent.
5.2 Stratospheric injections of aerosols
in the northern hemisphere, as discussed above, will reduce the
overall SSTs in the tropical and sub-tropical Atlantic, reduce
the heat brought north by the ocean currents, and reduce the incoming
solar radiation in the Arctic region.
5.3 Increasing marine stratocumulus cloud
cover (also discussed above) in the southern, tropical and northern
Atlantic will also decrease oceanic heat transport into the area,
and in the summer, could reduce direct incoming solar radiation
in the region.
5.4 The Arctic is a special case in that
it receives no solar radiation in winter, and clouds (and air
pollution from North America and Asia) create an insulative layer,
trapping heat. Raining out clouds in the autumn by injecting very
large CCN may allow the Arctic to radiate more heat out to space
in the winter. Seeding clouds for rain is currently is being used
by countries including China, Australia and Thailand.
5.5 The other option is to mine out the
layers of frozen methane in the sediments before they thaw. Methane
hydrates have been successfully mined at the Malik-38 well on
the McKenzie Delta on the northern shores of Alaska, and the hydrocarbon
exploration industry has considerable experience of dealing with
methane hydrates, which can cause drilling problems, blocked pipes,
explosions etc. At present the focus is on commercial exploitation,
but given sufficient financial incentive, it would be technically
possible to prospect for, mine and flare off vulnerable deposits.
Unfortunately the bands of frozen methane are widespread, can
be in thin layers or at low pore densities, and often form a seal
over free gas, which might be released catastrophically if the
structural integrity of the cap is weakened. However the engineering
problems are a continuation of those currently employed in seabed
and Arctic exploration and the hydrates show up well in seismic
surveys and well log analysis.
Removing methane from the atmosphere
6.1 In my personal opinion, even a rapid
deployment of all the above techniques will be insufficient to
prevent a dangerous (for global warming) increase in atmospheric
concentrations of methane, given the wide distribution of methane
in the Arctic, the hostile environment and the vast scale of the
problem (The East Siberian shelf is the largest continental shelf
on this planet).
6.2 This leaves us with the option of removing
or oxidizing the methane once it has reached the atmosphere. Scientists
previously thought that any released methane would dissolve in
seawater and be oxidized by methanotropic bacteria, but recent
air samples over the East Siberian shelf, and observations of
bubbles in the waters of the Gulf of Mexico suggest that significant
amounts will get into the atmosphere.
6.3 Some (possibly 25%) of current atmospheric
methane is consumed by soil bacteria, and it has been suggested
that genetic modification and culture could increase this, indicating
a possible area for research.
6.4 Most atmospheric methane (possibly 75%)
is oxidized by the hydroxyl ion, or OH radical, and this is the
key determinant of atmospheric concentrations. After a substantial
rise in atmospheric levels of methane from pre-industrial levels,
in the last few years, methane levels have been steady, indicating
a rise in the OH atmospheric sink, compensating for increased
anthropogenic emissions. OH radicals are produced by sunlight
on water molecules in the air, and the proposed explanation was
that a warmer atmosphere could hold more water vapour, and hence
allow more OH production. Unfortunately levels of methane in the
atmosphere started rising again in 2007, and we don't know enough
about the sinks and sources to know why.
6.5 OH radicals also oxidize carbon monoxide
(40%), organic compounds eg isoprene from forests and dimethyl
sulphate from plankton (30%), as well as methane (15%), and ozone
(O3), hydrogen (H2)and hydroperoxy radicals (HO2).
6.6 It would seem easier to attempt to produce
more OH radicals, rather than reduce atmospheric concentrations
of the other chemical species which compete with methane, as we
seem remarkable unable to reduce the amount of gases we produce
from our activities. Also, several geoengineering solutions such
as reforestation and ocean fertilization would also increase the
amount of airborne carbon compounds as byproducts of increased
biological activity.
6.7 The necessary ingredients would be water
vapour and the high energy part of the solar spectrum (310nm).
OH radicals are very reactive and have a lifetime of less than
a second, so would need to be produced within air masses with
high concentrations of methane.
6.8 As the oxidation of methane proceeds
at a rate 100 to 1000 times slower than that of the other organic
compounds mentioned above, research into a catalyst which speeded
up the rate of oxidation of methane could also prove productive.
6.9 It is also worth pointing out that,
even if the threat of catastrophic releae of methane from the
Arctic is averted, research into the removal of methane from the
atmosphere would be worth pursuing, as it would reduce global
warming, and could have financial benefits within a GHG trading
scheme.
CONCLUSIONS AND
ANSWERS TO
TERMS OF
REFERENCE
7.1 At present engineers have minimal input
into geoengineering research (with the notable exception of Professor
Steven Salter.) Most work is done by established climate scientists
and advanced students on an ad hoc basis. I know of no
structured research or training, apart from one Ph D student at
East Angia University, and funding is negligible. Many policymakers,
and the established scientists working in quasi-political positions
(IPCC, Defra and international counterparts), are unaware, or
have insufficient evidence to act, regarding the possibility of
global warming becoming uncontrollable, and the status of geoengineering
was laughable, until the upsurge in media interest in 2008.
7.2 If geoengineering is to be successful,
engineers with various specialized skills must form an integral
and essential part of multi disciplinary scientific teams, including
earth scientists, modellers, atmospheric physicists and chemists,
geologists, oceanographers, meteorologists, biologists, remote
sensing specialists, and others.
7.3 Engineers should be involved in the
initial design of projects, providing limits to what is practicable
or possible, and working on the building, calibrating, running,
maintaining, monitoring and improving on the experimental testing
of laboratory, field, regional, and full scale implementation
of the above proposals. Engineers are also likely to be the best
trained personnel to deal with project management, including cost
estimates and budgeting, whereas generalist earth/climate scientists
are likely to be best placed to advise of environmental costs
and benefits, and the risks of non-action.
7.4 Key areas will include; aerospace, remote
sensing, aerosol and nanoparticle production, marine engineering,
geological exploration and drilling, and general design of materials
and structures. Work in the harsh Arctic environment, and remote
oceanic regions, will likely be needed.
7.5 Again I must stress that we still know
little about the climate system, climate modelling is very complex,
with considerable uncertainty over many basic parameters (including
the influence of clouds and aerosols) and still omits many key
processes (ice sheet dynamics, for example) and the safest and
fastest way to develop effective geoengineering solutions is to
provide practical field trials, scaled up as soon as practicable.
Engineers will play a key part in these experiments, but we do
not have the time to train up a new generation of personnel to
take this forward. We must use the existing skills base.
7.6 Unfortunately, we are in the crisis
management phase of geoengineering, which must be successful before
a future generation of scientists and engineers can be trained
up for the responsibility of ongoing management of the global
climate.
September 2008
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