Dear Stephen, Peter,
1. Meeting discussions
Yes, please bring drawings, Stephen. We are meeting at my home, so
it will be a fairly informal affair, to allow maximum brainstorming
and discussion! Anything you can let me have beforehand would be
appreciated, because I want to be able to steer the discussion
sensibly. Also I want to draft a working paper before the meeting,
and then be able to slot in contributions/decisions easily.
Also bring stuff about the cloud brightening. I would also like to
have somebody to discuss stratospheric aerosols, because I think
the geographical distribution of the negative forcing effects is
going to be crucial, especially to cool the ESAS where the methane
seems to be in the most critical state. I'm copying this to Brian
Launder, who worked on the RS report under John Shepherd, and might
have some ideas. Your welcome to the workshop, Brian - 15-16
October - let me know if you're interested.
I'd be very concerned to rely too much on cloud brightening,
because to produce upwards of 1 petawatt cooling, you'd have to
cool the Gulf Stream and North Atlantic currents by a significant
amount - potentially affecting weather in Europe perhaps - opening
up a can of worms!
2. East Siberian Arctic Shelf (ESAS)
This does seem to be the most critical area for the methane, with
50 Gt of the stuff that could be emitted at any time, e.g. as the
result of an earthquake (and this is a real hazard).
Just in case you've not got it, I attach the Shakhova and Semiletov
paper, which describes the situation of the ESAS very graphically.
Indeed, because the whole area was flooded/inundated as the sea
level rose, from its low level at the last glacial maximum (LGM)
about 100-120 metres below current level, you can see what the
seabed looks like! You can also see the approximate sizes of the
places where methane is coming out, etc.
Note that the authors talk about 5 degrees warming in the region
(air temperature presumably), and 3 degrees warming of the water!
It's the warming of the water is particularly dangerous. I don't
know how we can easily cool it. Can we do anything with local
clouds? Could we try brightening the water with clouds of bubbles,
as somebody suggested on the geoengineering list?
BTW, it's amazing that people (who should know better) are still
talking about polar amplification as a doubling of global warming.
It's clear to me that Arctic warming is accelerating relative to
global warming, so the amplification factor is increasing all the
time, and must be well over six by now. So Hadley models that put
16 degrees in the Arctic for 4 degrees global warming are rubbish
(- and anyway they ignore the methane). I think it's basically the
albedo flip that's doing the amplification now - the subject of my
paper to the EGU in April, Stephen. Let's pray that there's not a
methane excursion in the next few years and the sea ice doesn't
retreat faster than PIOMAS trend!
3. Fluxes into Arctic and your comment
Stephen, by "current TO" I assume you mean "turn over". This is
what I was talking about, when I said:
* /Warming is driven by currents from the Atlantic and the albedo
effect/.
The main driver turns out to be the albedo flip effect, which I've
labelled 'F' in my calculations. In order to ascertain the forces
we are up against in geoengineering, I've tried to calculate the
various heat fluxes. 'S' is the extra heat flux from the Atlantic
since pre-industrial times, taking into account that the flow into
the Arctic is balanced by flow coming out, in what is termed AMOC -
the overturning circulation.
I could have added the local greenhouse effect, 'C' to the warming
effect. There is also a cooling effect, 'R', of thermal radiation
from the open water as the sea ice retreats, but these are relative
small fluxes and roughly cancel out.
And there are some other factors, I asked about recently: the extra
water vapour from the open water (positive forcing), the extra
cloud cover (positive forcing) and the extra snow to increase
albedo (negative forcing). I've so far neglected these other
factors. And I've ignored atmospheric heat transfer - water vapour
transport into the Arctic could perhaps be a significant positive
forcing. Otherwise I would expect the total atmospheric heat
transport if anything to diminish, since the Arctic has warmed
relative to the rest of the world.
The rest of this email is copied from a previous email about the
flux calculation. But I may have underestimated the albedo flip
effect, F, when I wrote it.
--
Let significant fluxes (extra since pre-industrial times) be
identified as follows:
S = Gulf Stream warming via North Atlantic Drift heat transport
into Arctic [1];
C = local warming - net effect of gases and aerosols, mainly CO2 at
present;
F = albedo Flip effect, where snow and ice has given way to land
surface and sea;
R = thermal Radiation into space as Arctic surfaces warm [2];
L = Latent heat for melting ice;
W = heat absorbed by land, water and atmosphere, as Arctic warms.
The balance of input flux minus output flux goes into melting the
ice and raising the Arctic temperature.
Thus S + C + F - R = L + W
The geoengineering negative forcing (aka cooling) has to counter S
+ C + F - R.
S is difficult to estimate.But it is observed that the water
entering the Fram Strait from the Atlantic has warmed by about 2
degrees C [3]. I am not sure about the flow volume rate into the
Arctic Ocean, but it could be about 6 Sv [4].Note that the paper
[5] gives 2-3 Sv into Fram Strait and 2-3 Sv through the Barents
Sea Opening (BSO).(1 Sv, or sverdrup, is a million cubic metres of
water per second).This is small compared to the Gulf Stream, at 55 Sv.
The figure of 2 degrees warming, observed in [3], is not throughout
the depth of the water, so cannot be used for calculating the heat
flux.But fortunately there are some figures for the heat transfer
from [5]: about 20 terawatts through the Fram Strait and 50 through
BSO, giving a total of 70 terawatts for a total current of 5 Sv.
Now we’d expect the NADW from the Arctic to be the same flow as the
flow into the Arctic, and this is given as just under 25 Sv in [6]
(table 4).The Gulf Stream is 55 Sv [4], so it is reasonable that
just under half goes towards the Arctic and returns as NADW.
If 5 Sv is giving 70 terawatts from [5], but we have 25 Sv from
[6], then the total warming, S, could be as much as 350 terawatts.
In the formula S + C + F - R = L + W, I've estimated the parameters
as follows:
S = 70-350 terawatts, from Gulf Stream;
C = 35 terawatts, from current greenhouse warming over Arctic;
F* = 300-1000 terawatts, from the albedo flip when sea ice has gone;
R = 34 terawatts, thermal radiation into space as Arctic warms
(using [2]);
L = 10 terawatts; and
W is derivable from the other parameters.
--
Cheers,
John
[1] http://www.sciencedaily.com/releases/2011/01/110127141659.htm
[2] http://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_law
[3]
http://instaar.colorado.edu/~marchitt/reprints/spielhagenscience11.pdf
<http://instaar.colorado.edu/%7Emarchitt/reprints/spielhagenscience11.pdf>
/These results reveal a rapid warming by ~2°C of uppermost AWin the
FSB in the Arctic Gateway during the past ~120 years, consistent
with the documented sea ice retreat in the Barents Sea (//5//),
terrestrial Paleoclimate reference records (//6//, //19//) (Fig. 3,
C to E), and atmospheric measurements./
[4] http://www3.ncc.edu/faculty/bio/fanellis/biosci119/currents.html
This has excellent maps showing currents.
[5] ftp://ftp.npolar.no/ASOF/library/pdf/Karcher_etal.pdf
[6] http://www.atmos.ucla.edu/~hbrix/papers/brix03jgr.pdf
<http://www.atmos.ucla.edu/%7Ehbrix/papers/brix03jgr.pdf>
[7] From 1975:
http://www.sciencedirect.com/science/article/pii/0012821X76900728
“The rate of Atlantic bottom water formation is estimated at 18
Sverdrups”
---
On 13/09/2011 10:13, Stephen Salter wrote:
John
I think that warming is driven by current TO not from the Arctic.
All the water that goes in must come out but the in flow is warmer
than the out flow.
Do you want me to bring drawings and calculations about a scheme
for methane recovery?
Stephen
Emeritus Professor of Engineering Design
Institute for Energy Systems
School of Engineering
Mayfield Road
University of Edinburgh EH9 3JL
Scotland
Tel +44 131 650 5704
Mobile 07795 203 195
www.see.ed.ac.uk/~shs
On 12/09/2011 23:50, John Nissen wrote:
Dear all,
I need to check figures - especially the 20 W/m-2 figures -
before I send more widely. And I'd like to put petawatts against
the methane, so we have a total petawatt figure for
geoengineering to counter! Anything else missing?
Any other comments? Should I consider 'considerations' at all for
an agenda? Do the figures have to be justified here - or can I do
that in a separate document, with references?
Should I mention that any rise in methane emissions will affect
the carbon budget for CO2 emissions reductions to meet the 2 (or
now 1.5?) degree C global warming target limit?
Cheers,
John
--
Agenda for Arctic methane workshop
Considerations:
* Arctic warming is much faster than global warming, and the
warming is accelerating
* Warming is driven by currents from the Atlantic and the albedo
effect
* The extra heat flux, which is warming the Arctic with respect to
its pre-industrial temperature, is currently of the order of one
petawatt
* September sea ice volume trend is to zero in 2015, by which time
the heat flux could be of the order of two petawatts, ignoring
increased methane emissions
* Around 1600 Gt carbon is held in terrestrial permafrost
* Around 30% of this permafrost could thaw by 2050, producing
mainly methane
* Methane being a potent greenhouse gas, the corresponding global
forcing could rise to over 20 Watts/m², compared to current net
forcing of 1.6 Watts/m²
* Under shallow seas there is around 500 Gt carbon in sub-sea
permafrost, 1000 Gt methane as methane hydrate and 700 Gt
methane as free gas
* Up to 50 Gt of this methane could be released “at any time”
(e.g. by an earthquake), increasing atmospheric concentration by
up to 11 times
* The global forcing from such a pulse could rise to around 20
Watts/m² over the course of a single year and then fall only
slowly
* Such forcing could send global warming over 2 degrees C in a
decade
* Such forcing would also lead to further Arctic methane release
in a positive feedback loop, with the prospect of runaway global
warming, disintegration of Greenland and Antarctic ice sheets
and many metres of sea level rise
The objectives of the workshop are to:
* ascertain the scale of the methane excursion threat and
probability over time;
* ascertain the scale of the local engineering and regional
(geo)engineering required to prevent a significant methane
excursion;
* propose a set of techniques which could meet these requirements;
* propose techniques to capture methane in the event of an
excursion;
* decide on priorities for trials and deployment of key
technologies;
* agree a plan for preparations and pilot trials according to
these priorities;
* agree an outline report to AGU in December.
Agenda:
* Introductions of participants
* Terrestrial and marine methane threats
* Local methane management/engineering ideas
* Regional (geo)engineering – cooling technologies and
capabilities
* Mixed technology strategy to optimise cooling distribution
* Methane air capture
* Preparation of project plans for preparation, trial and timely
deployment
* Agree outline report for presentation at AGU
