Dear all,
In case you were not aware, the workshop, which was to have been
3-4th September, is now going to be on 15-16th October. Here is
the background and purpose of the workshop...
A group of scientists and engineers (including myself) is deeply
concerned about the potential of methane from thawing permafrost
in the Arctic to cause irreversible, catastrophic and
unsurvivable global warming. Major factors are the
unexpectedly rapid retreat of sea ice [1] and the unexpectedly
large quantities of carbon which might be emitted as methane
[2]. In June 2010 we wrote an open letter to Obama's scientific
adviser, Dr John Holdren, suggesting action was urgently needed
to address the methane issue [3]. Some sea ice experts,
including Professor Peter Wadhams in our group, now reckon the
Arctic Ocean will very likely become seasonably ice free this
decade if there is no action to cool the Arctic.
Recently Peter Wadhams has drawn my attention to work of Natalia
Shakhova with Igor Semiletov on East Siberian Arctic Shelf
(ESAS) - particularly concerning the present large emissions of
methane and the possibility of release of much larger quantities
"at any time". So we have been wondering whether anything can
be done quickly to reduce this methane threat. We have been
discussing possible action, and plan further brainstorming at a
workshop in October in London.
We are hoping this workshop will lead on to a pilot project to
trial the most promising techniques. Here is an extract from
the proposal, concerning management of the methane environment
at the local level (e.g. in ESAS):
[begin quote]
Approaches can be categorised according to
where the intervention action takes place. Where
the methane is from lake or sea bed, the action could be:
- below the
permafrost, where there may already be methane or methane
hydrate;
- in the
permafrost, or to plug gaps in the permafrost where
methane is rising;
- in the bed
of the sea or lake, above the permafrost layer;
- in the water
at the bottom of the sea or lake;
- at the
surface of the sea or lake, and below any ice;
- at the point
of emergence of methane into the atmosphere.
In the case of methane from wetlands, some of
the above actions would be relevant to ponds, commonly forming
above permafrost and emitting most of the wetlands methane. There is also the possibility of pond
drainage as a means to reduce methane emissions.
Returning to the case of lakes and deeper
water, the problem with trying to deal with methane below the
permafrost is that any disturbance is liable to trigger an
eruption of methane through gaps in permafrost known as
taliks. Commercial methods of
extraction of natural gas can be used when there is in
impermeable layer above the gas, but cannot be applied in our
situation because of the danger either from puncture of the
permafrost or from enlarging existing taliks.
In the bed of the sea or lake there may be
aerobic microbes, capable of ‘digesting’ the methane and
converting it into less harmful products. Supply
of oxygen and nutrients to such microbes could be helpful. Microbes may also congregate in a ‘biotic
layer’ at the bottom of the sea or lake. These
could be boosted or encouraged to proliferate.
Methane can dissolve in the water. At atmospheric pressure and freezing
point, 0.04 grams of methane will dissolve in a litre of
water. Therefore one approach could be
to extract the water when it is nearly saturated with methane. A more commercial approach would be to
use a specific methane solvent in a relatively heavy layer,
resting on the seabed (or lake bed). From
time to time the solvent would be extracted, scrubbed to
remove the methane, and replaced. A
major issue could be containing the solvent and making sure
there was no long-term harm to the marine habitat.
A general problem with emissions of soluble
gas from the beds of lakes and shallow seas is that the water
column can become unstable – with the dissolved gases coming
out of solution, leading to a sometime violent upwelling. Because of the low density of the rising
column of bubble-filled water, ships on the surface can sink! Furthermore any turnover of the water
allows warmer surface water to be transported towards the
bottom, which can lead to permafrost melt and enhanced methane
production. Thus any underwater
approach to methane must take into account the stability of
the water column.
However if the methane is already bubbling to
the surface, then one could consider capturing it before it
escapes into the atmosphere. One way
would be to use ice, which will anyway be present in winter. The methane collects under the ice, and
boring through the ice, one could collect the methane that
emerges. The problem would be keeping
an intact layer of ice throughout the year. Therefore
one might consider strengthening the ice to produce ‘pykrete’
[3]. However a more promising
approach would be to have mats, preferably of
methane-absorbing substance (biological or chemical) which
could be harvested to collect the methane. But
care would be needed not to deplete oxygen from water
underneath the mats, since oxygen is required from the
important methane-digesting microbes in any biotic layer that
has formed above the sea or lake bed.
If and when some methane bursts into the
atmosphere, it could be burnt or ‘flared’. In
remote areas, and in open water, this could be problematic. Furthermore, methane only burns in air at
between 5% and 15% concentration by volume. As
it disperses quickly, one would need to torch the methane
within a few seconds of eruption. It
is almost impossible to imagine how this could be done in a
remote location, unless the methane is laser-zapped from a
monitoring satellite!
[end quote]
The pilot project will promote a three-prong
attack, though trials will focus on local action (particular
item 2):
1. cooling the Arctic, regionally or locally, using
SRM geoengineering;
2. management of the methane
environment at the local level (see quoted text above);
3. capture or destruction of methane, already
in the atmosphere.
The capture or destruction of methane in the atmosphere is a
last resort, if other approaches fail. It would also be vital
if there were a sudden large emission of methane with serious
warming potential. Such "air capture"
or destruction could be local or not. The advantage of local
air capture is that efficiency may be improved through having
the methane at higher concentration (as the efficiency is for
CO2 air capture).
The workshop is intended as a brainstorming session to establish
the most promising techniques which might be trialled in the
pilot project. If you have already expressed an interest in
attending the workshop, please confirm that the new date is OK.
If you have not yet expressed an interest, and would like to
attend, let me know.
John Nissen
Chiswick, London W4
[1] Copenhagen Diagnosis, 2009
http://www.ccrc.unsw.edu.au/Copenhagen/Copenhagen_Diagnosis_LOW.pdf
see figure 13 page 30.
[2] Ibid, see page 21 - referring to Shuur et al 2008.
[3]
http://geo-engineering.blogspot.com/2010/06/sea-ice-loss-stuns-scientists.html