The International Maritime Organisation’s plans to warm the world
Ken Caldeira
http://heliophage.wordpress.com/2009/08/20/the-international-maritime-organisations-plans-to-warm-the-world/
(PLEASE NOTE THAT THE ATTACHED PDF'S ARE LOW RES VERSIONS WITH LINKS TO HIGH RES VERSIONS ON PUBLISHER'S WEB SITE.)
The International Maritime Organisation’s plans to warm the world
- Ship tracks in the Bay of Biscay
Yesterday Dan Lack of NOAA gave a talk to the NCAR media fellows about his work on pollution from shipping, and told us something I found pretty flabbergasting. Last year the International Maritime Organisation, as part of a number of measures aimed at air pollution, decided to do something about the sulphur emissions from shipping by reducing the amount of sulphur dioxide permissible from 4.5% today to 0.5% in 2020. This would have great benefits; sulphate pollution, and associated particulate matter, cause significant health problems. According to a new paper in Environmental Science and Technology by Winebrake et al, if in 2012 the world’s shipping complied with this requirement, the associated sulphate pollution would cause 46,000 premature deaths; if that shipping used today’s higher sulphur fuels the death toll would be 87,000.
However, sulphur emissions from shipping have another effect: the sulphate aerosols that form from the gas make the oceans cooler by increasing the cloud cover above them, as the image at the top of this post shows. The effect is large enough that shipping cools the planet through sulphate aerosols much more than it warms the planet through greenhouse gas emissions. In a companion paper in Environmental Science and Technology, this time with modeller Axel Lauer as first author, the same team looks at this effect. Using the same 2012 scenarios they used for the health figures the researchers find that the cooling effect using fuel like today’s, expressed in terms of radiative forcing, is about 0.57 watts per square metre. The cooling effect if everyone uses the new low sulphur fuels is 0.27 W/m². That means a difference of 0.3 W/m² — which is to say that that’s the amount of warming that switching to low-sulphur fuels would produce.
What does a radiative forcing of 0.3 W/m² mean? Here’s a chart from the IPCC showing the radiative forcings associated with all human climate-changing activities as of today. The total (with biggish error bars) is 1.6 W/m², which shows straight off that 0.3 is quite a lot. It is, for example, twice the amount of forcing as is due to N2O, 60% of the forcing due to methane, and the same as the amount due to halocarbons (HFCs). A huge amount of money is currently being spent on the HFC problem.
Put another way (and I calculated these numbers myself, so please check and correct if you have the necessary skills) 0.3 W/m² is the radiative forcing you would expect if you dumped 47.5 billion tonnes of carbon (in the form of carbon dioxide) into the atmosphere, raising the concentration of CO2 from today’s 387 parts per million to 409 parts per million. That’s well over a decade’s worth of carbon emissions and an enormous amount of warming for the IMO to have committed the world to with no-one, as far as I can see, paying very much attention. (The most obvious environmental response to the IMO changes, from the Clean Air Task Force, was to applaud the health effects of the cuts in sulphur while deploring the lack of action on greenhouse gases and not mentioning the cooling issues at all. If you accept Dan Lack’s figure of just 0.06 W/m² for the total warming from shipping, that seems an odd omission.)
Now there are obviously complexities and caveats. This is just one modelling study — but its figures for the amount of cooling due to sulphur fit with those quoted by of others, such as Dan Lack. Taken at face value it would imply both that the total cooling effect of sulphur on clouds was probably greater than the IPCC best guess, and that sulphate from shipping was responsible for a disproportionate amount of it. But the IPCC’s guess has big error bars, and you would indeed expect sulphate from ships to be peculiarly effective — it gets sprayed into places where the clouds are very susceptible to such things. (This is the effect that John Latham’s geoengineering scheme based on cloud brightening seeks to emulate). The papers compare effects for 2012 not 2020, which is when the regulations will call for al fuel to be low sulphur, but does anyone expect less shipping in 2020 than 2012?
So is this a matter of balancing 40,000 lives a year against a decade of global warming? Not necessarily. There is another sulphate reduction option: burn low-sulphur fuels when close to land, and ordinary fuels when far off. There are already some areas where ships have to use low sulphur fuels, and they could be extended to all the places where the sulphate is likely to do its greatest harm. In further scenarios the authors of the two papers looked at a world of 2012 in which ships’ sulphur was reduced to 0.5% or even 0.1% when within 200 nautical miles of land, but left unchanged in mid voyage. In terms of fatalities the 0.1% in coastal waters is slightly better than 0.5% all over the place (44,000 deaths), 0.5% in coastal waters is slightly worse. In terms of cooling these two options are lower than business as usual but higher than a global reduction to 0.5% — their forcing is 0.45-0.48 W/m².
Low-sulphur fuels in coastal areas could lessen the warming associated with a global sulphur reduction and still save as many lives — or more. They would impose other costs, though. Getting sulphur out of fuel costs money, and this might make getting down from 0.5% to 0.1% an issue. Ships would have to carry two different types of fuel, which is also problematic, though not impossible. And going low-sulphur still deprives the world of a lot of cooling, even if the regulations only apply in coastal waters. That’s largely because most shipping is coastal. (This suggests that forcing ships to take longer, less coastal routes — to put out straight to sea where possible, and spend more time further from land — might be an option. Again it has costs.)
Beyond preferring coastal controls to global controls I have no real policy case to make here. I’m aware that there is in general a trade off between air quality reasons for reducing sulphates and the possibility that their cooling effects can be climatically helpful. But the fact that this measure involves reducing sulphur emissions in places where they do no harm (the mid oceans) and where their cooling effects are greatly enhanced (by the presence of low clouds they can brighten) makes the question particularly pointed. I have no way to balance the advantages of reduced global warming against the advantages of decreased mortality. I don’t know who has. But I do think that it’s kind of extraordinary a regulatory change with this much effect on global warming could be made with so little apparent fuss.
And I also think this all makes the case for experiments with Latham-type techniques that brighten clouds to cool the seas even stronger than it already is. If, for good reason, we are actively reducing the amount of cooling provided by shipping, surely we should at least look at possible ways of putting it back?
Citations
“Mitigating the Health Impacts of Pollution from Oceangoing
Shipping: An Assessment of Low-Sulfur Fuel Mandates”, Winebrake, J. J. et al, Environ. Sci. Technol., 2009, 43 (13), pp 4776–4782
DOI: 10.1021/es803224q
“Assessment of Near-Future Policy Instruments for Oceangoing
Shipping: Impact on Atmospheric Aerosol Burdens and the Earth’s
Radiation Budget” Lauer, Axel et al, Environ. Sci. Technol., 2009, 43 (13), pp 5592–5598
DOI: 10.1021/es900922h
___________________________________________________
Ken Caldeira
Carnegie Institution Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
kcal...@ciw.edu; kcal...@stanford.edu
http://dge.stanford.edu/DGE/CIWDGE/labs/caldeiralab
+1 650 704 7212; fax: +1 650 462 5968
Veli Albert Kallio
Date: Thu, 20 Aug 2009 07:34:39 -0700
Subject: [clim] The International Maritime Organisation’s plans to warm the world
From: kcal...@stanford.edu
To: geoengi...@googlegroups.com; climatein...@googlegroups.com
Alvia Gaskill
John Nissen
Hi Ken,
This is a golden opportunity to publicise that the reduction of sulphur aerosols in the troposphere, which would warm the world, can be counterbalanced by a relatively smaller quantity of sulphur aerosols in the troposphere, while overall reducing acid rain and harmful "pollution" effects (on health, etc.).
Lets put this in context. (This is based on a not proven but scientifically plausible hypothesis by Ruddiman [1], rapidly gaining acceptance [2].)
Over the past 8000 years or more, mankind has been walking a tightrope by geoengineering the environment to keep temperature and sea-level constant, thus allowing both the emergence of civilisations and the growth of population to billions. Otherwise we would now be descending into a glacial period - as another Ice Age is due because of Milankovitch cycle [3]. Forests have been cleared to allow CO2 levels to rise, and rice has been planted to allow methane levels to rise. The resulting climate forcing from these has almost exactly balanced other forcings. This has been entirely inadvertant - and it is by pure chance that we have maintained near constant global temperature and sea level. (Note that the sea level has oscillated by around 120 metres over the Ice Ages. We have been very near the top of the range of both temperature and sea level for the past 8000 years.)
To some extent the balance has been maintained over the the past century by sulphur emissions, in a process sometimes called "global dimming" [4]. According to some scientists, up to 3/4 of global warming has been masked. The effect of removal of sulphur emissions may have caused the acceleration in global warming, visible in the records of glacier ice mass loss since late 80's [5] (allowing for Pinatubo cooling in early 90s [6]).
Thus it is entirely sensible to mimic Pinatubo and put some sulphate aerosol in the stratosphere - enough to counter the effect of removing aerosols from the troposphere. If that works without exceptional side-effects, we would have the experience to try and produce some net cooling of the globe by putting up more aerosol in the stratosphere.
Would you be able to put this case to the International Maritime Organisation and regulatory authorities?
Cheers from Chiswick,
John
[1] http://en.wikipedia.org/wiki/William_Ruddiman
[2] http://ecotope.org/blogs/post/Pushing-back-the-Anthropocene-at-the-AGU.aspx
[3] http://en.wikipedia.org/wiki/Milankovitch_cycles
An often-cited 1980 study by Imbrie and Imbrie determined that, "Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend which began some 6,000 years ago will continue for the next 23,000 years."[9]
[4] http://en.wikipedia.org/wiki/Global_dimming
[5] http://www.geo.uzh.ch/wgms/mbb/mbb10/sum07.html
[6] http://geography.about.com/od/globalproblemsandissues/a/pinatubo.htm
David Keith
A few comments.
- Am CCing my colleague Jim Corbett, who wrote a bunch of the important papers on emissions from shipping, is an author of the latest paper mentioned her, and as worked with the IMO on this. Jim: any discussion on this tradeoff at IMO?
- Some ships already dual fuel (bunkers and natural gas), where the NG is burned in and near port to comply with local air quality.
- Numbers only work against bifurcated system if no policy to preserve or promote sulfur emissions in open ocean.
- Work needed to estimate the ratio of climate forcing to heath impacts of S emissions as a function of the location of the emissions, this would allow where it make most sense to promote or restrict emissions. I will pitch this to atmo chemists at their Gordon Research conference this evening.
- We don’t just want to leave ship emissions as they are because we will need manage NOx even if we want S emissions. Both are big from ships. See Jim’s paper: J. J. Corbett and P. S. Fischbeck, "Emissions from Ships," Science, vol. 278, no. 31 October 1997, pp. 823-824.
- The idea that we can use the S for geo is likely irrelevant. There is ample S as H2S in sour gas either produced and re-injected or made into elemental S using Claus process. (There are many megaton-scale blocks of elemental S from this process in Alberta where I live, stunning yellow patches on the landscape.)
-David
From:
geoengi...@googlegroups.com [mailto:geoengi...@googlegroups.com] On Behalf Of Alvia Gaskill
Sent: August 20, 2009 1:07 PM
To: kcal...@stanford.edu;
geoengineering; Climate Intervention
Subject: [geo] Re: The
International Maritime Organisation’s plans to warm the world
John Nissen
Dear David,
The whole climate system is out of kilter with the colossal pulse of anthropogenic CO2, you described so aptly in your lecture to the RGS in London. We need to do everything we can to counter this. It seems criminal to take sulphur out of the troposphere when it has a negative forcing. The least we can do is to balance the effect of taking sulphur out of the troposphere by putting sulphur into stratosphere. There is plenty of sulphur to do this with.
So my argument is that, with every regulation to remove "polluting" sulphur from the troposphere, there should be an obligation to restore its cooling effect by some other means - and stratospheric sulphate aerosol is the most obvious means.
Cheers,
John
---
Andrew Lockley
Stephen Salter
We will certainly use existing ships for early experiments but they carry fuel food and water to go from A to B rather ansd so cannot be on station in mid ocean all the time. The best places for spraying tend to be far from existing shipping routes, partly because it is more effective to use clean air. If HTML works the slide below shows how much sulphur the ships produce.
You can get the full Lauer paper 'Global model simulations of the impact of ocean-going ships on aerosols, clouds, and the radiation budget' from http://www.atmos-chem-phys.net/7/5061/2007/acp-7-5061-2007.html
Stephen
Andrew Lockley
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.