2011-06-08 00:09:15Ships, sulphur, and climate
Ari Jokimäki

arijmaki@yahoo...
91.154.111.39

Here's a report written by my friend Esko Pettay with Risto Isomäki - well known Finnish ecological fiction and fact writer. I thought it might be worth advertising a bit. Perhaps we could put this out as a blog post here? Here's an abstract of the report Esko just sent me:

Reducing the ocean-going ships' sulphur emissions would accelerate warming

The International Maritime Organization (IMO) decided, in October 2008, that the maximum allowable sulphur content in the fuel oil used by ocean-going ships should be reduced, by 2020, from the present average of 2.7 per cent to 0.5 per cent. In the more stringent Special Emission Control Areas, or SECAs, the goal is even more ambitious: 0.1 per cent by 2015.  The European Parliament should now decide, whether the IMO treaty will be enforced in the European Union member countries.

It may be a good idea to reduce sulphur emissions in the SECAs, because the more refined fuels would also produce less soot, and soot and sulphur are both harmful for human health. It is, of course, important to ensure that the proposed measures will not shift cargo from ships to trucks. Trucks consume, on average, seven times more diesel oil per kilometre-ton than ships. Above all, trucks do not release their emissions at sea but directly into the middle of dense human habitation.

However, reducing the ocean-going ships' sulphur emissions could be very dangerous.

NASA estimated in 2005 that the Earth is heating up with an efficiency of 0.85 watt for each square meter of the planet's surface, but the most recent estimate is only about 0.5 watt/m2.  At the same time the extra greenhouse gases are heating our home planet by 2.8 watts/m2 and the black soot particles by 0.4 - 0.9 watt/m2.  These figures only make sense if we assume, that the so called bright aerosols, especially sulphur, cool the planet by at least 3 watts/m2. In other words, it seems that sulphur and our other aerosol emissions have this far masked most of the global warming caused by greenhouse gases, soot and man-made cirrus clouds.

The sulphur emissions spread over the oceans by ships are the most important part of our particle parasol and could amount to 40 per cent or more of the aerosols' combined cooling impact. If these sulphur emissions will be eliminated too quickly, global warming will accelerate and much of the impact will concentrate at the North Atlantic. This, in turn, could release huge amounts of methane and carbon dioxide from the Arctic peatlands, terrestrial permafrost, submarine permafrost and offshore methane clathrate fields - and accelerate the melting of the Greenland ice sheet.

It might be advisable to postpone the proposed cuts in the ships' sulphur emissions until we have been able to re-balance the atmospheric greenhouse gas concentrations and the climate.

2011-06-08 01:01:34
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.102.37

The -3 W/m2 aerosol forcing doesn't seem right.  Hansen put aerosols + black carbon (or was it just aerosols?) at -1.6 W/m2 in one of his recent draft papers.  Ramanathan and Carmichael (2008) put BC at +0.9 and aerosols at -2.3 W/m2.  So it seems that -3 W/m2 is a factor of 2 too large.

2011-06-08 02:34:05
Ari Jokimäki

arijmaki@yahoo...
91.154.111.39

I haven't checked the numbers, but they are talking about "so called bright aerosols, especially sulphur", so it's not total aerosol forcing I think, but I'll ask Esko about it.

2011-06-08 07:06:30
Riccardo

riccardoreitano@tiscali...
93.147.82.166

I'd be carefull before asking to not reduce sulphur emissions. We know they have a significant, more direct health impact that we can not dismiss so easily.

2011-06-08 21:50:14
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211

I agree, Riccardo, but here they have decided to reduce sulphur emissions without reductions to CO2 emissions, so the end result might be worse than without sulfur emission reductions. This seems to be a situation where one has to choose between two bad options (well, ok, there would be the third option of reducing both sulphur and CO2 emissions).

Dana, in the full report they discuss the 3 W/m2 issue further.

2011-06-09 01:49:46
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Well in the report they say it's somewhere between 1 and 3.5 W/m2.  Personally I'd be a lot more comfortable saying that than "at least 3 W/m2".

2011-06-10 01:05:57
Ari Jokimäki

arijmaki@yahoo...
91.154.111.39

I think you misunderstood what they are saying. They are looking at how Earth is warming up and suggesting that due to this aerosols must have so large cooling effect. Looking at it now more carefully, I think they are missing some effects such as heat going to ocean.

2011-06-10 18:05:30
Ari Jokimäki

arijmaki@yahoo...
192.100.112.211

There is an agreement with Esko that the abstract needs some re-writing. Esko thanks all the commenters (and of course I do too :) ).

Esko noted that they are not suggesting that sulfur emission reductions should not be done at all, but they are suggesting that emissions should continue in open sea, where he says the health effects are minimal.

2011-06-13 08:32:44
michael sweet

sweetdreamfiji@hotmail...
96.228.135.17

This is the Faustian bargain that Hansen describes.  Eventually the payment will come due no matter what.  What is the advantage of postponing the Faustian payment?  If reducing sulfur emissions enhances the greenhouse effect, perhaps politicians will take action sooner to reduce carbon emissions.  Perhaps the post could discuss the tradeoffs of emitting sulfur versus not emitting.