Env Res Web: Saving Greenland's ice by geoengineering
Dan Whaley
Dec 15, 2009
Saving Greenland's ice by geoengineering
The world's greenhouse-gas emissions show no sign of slowing at
present. In the worst-case scenario this means that melting of the
Greenland ice sheet could pass beyond the point of no return within
150 years, committing us to metres of sea-level rise over the coming
millennia. The eventual complete melting of the Greenland ice sheet
would push global sea level up by around 7 metres. Add to this the
melting of glaciers and the Antarctic ice sheet, plus thermal
expansion of the oceans, and the picture looks even worse.
More than 70% of the world's population lives on coastal plains,
within 9.1 metres of sea level; two thirds of the world's largest
cities are on the coast or estuaries. Just 40 cm of sea-level rise in
the Bay of Bengal would flood 11% of Bangladesh's coastal land,
creating 7 to 10 million climate refugees. Seven metres or more of sea-
level rise is unthinkable.
So what happens if we can't put the brakes on global warming fast
enough to prevent this change? One way of slowing the global
temperature rise and the accompanying melting of the Greenland ice
sheet might be to deflect some of the Sun's rays away from Earth.
With this in mind Peter Irvine, from the University of Bristol, UK,
and his colleagues calculated how much solar-radiation management
would be required to prevent the Greenland ice sheet from melting.
Current estimates suggest that it would be impossible to prevent the
Greenland ice sheet from melting completely if atmospheric carbon
dioxide is allowed to climb to four times pre-industrial levels (1120
ppmv) and remain around or above this concentration. With "business as
usual" emissions we are predicted to reach this particular tipping
point by 2150, jamming the Greenland ice sheet into melt mode and
leading to complete melting within a few thousand years at most.
Using a global-climate model coupled with an ice-sheet model, Irvine
and colleagues assessed the impact of varying levels of solar-
radiation management on a world with carbon dioxide levels four times
those of pre-industrial times.
To bring the average global temperature down to pre-industrial levels
in this scenario they found the amount of sunlight reaching the top of
the atmosphere had to be reduced by 4.2%. "To achieve this reduction
in sunlight you would need to inject millions of tonnes of sulphur
into the stratosphere per year," Irvine told environmentalresearchweb.
However, the modified climate would have some important differences to
the pre-industrial one. The extra carbon dioxide in the atmosphere
would have an insulating effect at the poles, making them a little
warmer than in pre-industrial times. Meanwhile, the tropics would
become a little cooler because of the reduction in direct sunlight.
Because of regional effects for Greenland, including increased
precipitation as a result of the geoengineering, the researchers
estimate that a 2.5% reduction in sunlight – 60% of the amount
required to obtain pre-industrial temperatures – would be sufficient
to prevent the Greenland ice sheet from melting in a four times pre-
industrial carbon dioxide world. This would equate to 60% of the
sulphur required in the stratosphere for full geoengineering.
Alternatively the same effect could be achieved by placing a bank of
satellites between the Earth and the Sun, to act like a giant
sunshade. But the model doesn't include the Antarctic ice sheet,
glaciers or thermal expansion of the ocean, so it is still unclear
what impact solar-radiation management would have on these potential
causes of sea-level rise.
Nonetheless, the new study, which is published in Environmental
Research Letters, indicates that the degree of solar geoengineering
required to mitigate the worst effects of global warming, such as sea-
level rise, need not be as extensive as previously assumed.
But solar geoengineering can't prevent all of the unwelcome impacts
that come with increased atmospheric carbon dioxide. Ocean acidity
would continue to rise, destroying corals and making life exceedingly
difficult for shelled organisms. And some parts of the world might get
a raw deal out of a geoengineered climate. "A solar-radiation
management-geoengineered world would be drier on average and the
climate would differ from its natural (pre-industrial) state," said
Irvine. In addition, we could come to rely on solar geoengineering,
leaving us vulnerable to attacks on the solar shield; something akin
to the threat of nuclear war.
Irvine and his colleagues stress that reducing carbon dioxide
emissions now is likely to be an easier and cheaper option. "If we
spend less on carbon dioxide cuts now, then we may rely more heavily
on solar-radiation management in future," said Irvine. "If we spend
more on cuts now then we will not have to rely so heavily or at all on
solar-radiation management."
Will the world's governments decide to rely on the solar
geoengineering "sticking plaster" or are they going to "swallow the
medicine now", drastically cutting emissions and curing the problem?
Either way, the decision will have to be made within the next decade
or so.
About the author
Kate Ravilious is a contributing editor to environmentalresearchweb.
Veli Albert Kallio
Date: Wed, 16 Dec 2009 10:43:43 -0800
Subject: [geo] Env Res Web: Saving Greenland's ice by geoengineering
From: dan.w...@gmail.com
To: geoengi...@googlegroups.com
Dec 15, 2009
Saving Greenland's ice by geoengineering
1) First of all, where we stand now?
October 2009 the concentration of CO2 was 384.38 p.p.m. Table data source: Dr. Pieter Tans, NOAA/ESRL
2) Second, allowing CO2 to raise 1,120 p.p.m.v. or four times our current use of athmosphere as a carbon sink?
If CO2 emissions are allowed to raise to 1,120 p.p.m., we are already suffocating ourselves with the carbon dioxide poisoning, just please refer to the Workplace Health and Safety Authority table about safe CO2 in the workplace air. The windows are always opened for the breaks to allow the fresh air in to prevent the classroom air becoming putrified at 1,000 p.p.m. The workplace authorities define this phenomenon as follows: "1000 ppm 0.1% Prolonged exposure can affect powers of concentration."
Can we imagine a world where we need air conditioning to pour out excess CO2 from our living space to outdoor carbon sink. This defies any intelligence and has not been adequately recognised by the meteorologists who have become too segregated in their study from a real world.
Or may be, we need to re-write the whole story of evolution, perhaps the early stages were so slow, as the air was so putrified by CO2 that the whole globe, like the Neanderthals were just like an army of "walking zombies due to carbon dioxide poisoning" at 1,000 p.p.m. and above.
I think these meteorologists should be locked up in their own study to sniff their own CO2 long enough that they loose their powers of concentrations to do these crazy propositions. I think they should sue the workplace health and education authorities' instructions for classroom ventilations that are there to prevent the kids getting their heads filled 1000 ppm CO2 poisoning "to lose powers of concentration".
http://www.analox.net/site/content_HOSP_co2_dangers.php
The Dangers of Carbon Dioxide
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3) Physiological constraints to humans, indoor and sporting activities, and other biological organisms
It also sounds plausible that of 2,500,000 biological organisms many might be far more sensitive to CO2 than "our powers of concentration" at 1,000 p.p.m. There are many fish for whom tap water is toxic due to its chlorine content and they die immediately. On marine organisms, the exoskeleton building organisms like corals ocean acidification by carbonic acid is problematic already now. Let alone 1,000 p.p.m. birds or reptiles might find it impossible to breath anymore. How about the poor or even schools who would not have air purification system to pour CO2 outside from room air and would start to accummulate CO2 from 1,000 p.p.m. to 2,000 p.p.m. or more indoors instead. All the sporting events, churches, rock concerts etc densely-packed gatherings would rise much higher CO2 were it to start from above the safe 1,000 p.p.m.
Therefore, we can conclude this topic whoever presented it (and where-ever) as a no-goer and ready for the next Iq Nobels' nominations for its stupidity. I think my nomination of this will sink very well in the judges. This sounds an excellent candidate for that dubious Iq honour.
Sometimes not so impressed of ideas what the climate researchers and meteorologists can come up with.
(Not to mean that Dan should be reprimanded particularly over this non-intelligent time-wasteage.)
Regards,
Albert
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p.j.irvine
Our research was not proposing that getting to 1120 ppmv and then
geoengineering is a good idea, it is likely a very bad idea and we
should do what we can to avoid it. The point about mild CO2 poisoning
is one I wasn't aware of and is something we certainly want to avoid!
The article is published online here: http://stacks.iop.org/1748-9326/4/045109
Our focus was on the level of geoengineering required to prevent the
melting of the Greenland ice sheet in an extreme climate. Our main
observation was that solar geoengineering does not need to be
implemented fully (i.e. returning global average temperatures to pre-
industrial) to prevent this.
regards,
Pete Irvine
On Dec 16, 9:34 pm, Veli Albert Kallio <albert_kal...@hotmail.com>
wrote:
> Please note that Dan's proposition cited below is fundamentally flawed and I like to draw attention to the reasons why:
>
> Date: Wed, 16 Dec 2009 10:43:43 -0800
> Subject: [geo] Env Res Web: Saving Greenland's ice by geoengineering
> From: dan.wha...@gmail.com
> ...
>
> read more »
p.j.irvine
Andrew Lockley emailed me these questions:
1. Please can you clarify if your envisaged geoengineering would be
enough to keep the permafrost frozen?
2. Further, can you clarify whether or not you've taken into account
ice dynamics in the altitude reduction leading up to your
geoengineering date?
We ran equilibrium runs for our climate and ice sheet modelling so the
simulations aren't realistic 'scenarios' they explore the long term
viability of the ice sheet in a geoengineered climate. In answer to
the first question the simple answer is I don't know, the data are
still around so I could find out but HadCM3 does have a fairly large
cold bias at the poles and so i don't know whether it would be
appropriate for this kind of analysis. This cold bias is not an issue
for the ice sheet modelling as we used an anomaly method for the
driving climatology. Saying that, we observed that even if the global
average temperature is returned to the pre-industrial value with
1120ppmv of CO2 in the atmosphere there is still a warming of the
poles so permafrost could still be in danger.
For the second question, we used equilibrium runs so it is not a
'scenario' and so would not cover modern melting to then determine
future melting. The current generation of ice sheet models (including
ours) does not include a realistic representation of ice sheet fast-
flow dynamics. approximately 50% of the current melting of the
greenland ice sheet is due to these fast flow losses. Our study gives
an estimate of the long-term viability of the greenland ice sheet, to
investigate the effect of geoengineering on the fast-flow dynamics
will require a next generation ice sheet model.
Ken Caldeira
Peter J Irvine1,3, Daniel J Lunt1,2, Emma J Stone1 and Andy Ridgwell1
The fate of the Greenland Ice Sheet in a geoengineered, high CO2 world
Environ. Res. Lett. 4 (2009) 045109 (8pp) doi:10.1088/1748-9326/4/4/045109
___________________________________________________
Ken Caldeira
Carnegie Institution Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
kcal...@carnegie.stanford.edu
http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab
+1 650 704 7212; fax: +1 650 462 5968
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