What's a percent or two? Or three? Not much, sometimes. But a lot when we're talking about carbon dioxide emissions that are throwing earth's climate out of whack. And quite a lot when effort is going into ranking emission sources to help prioritize our responses to the climate crisis.
These thoughts are occasioned by a scoop in the Guardian (U.K.) reporting that world shipping -- essentially, freighters and tankers moving goods and raw materials -- accounts for "up to 5% of the global total" of carbon emissions. "CO2 output from shipping [is] twice as much as airlines," shouts the Guardian headline, in light of the 2-3 percent share of emissions associated with air travel.
Goodness, a dozen eco-blogs seemed to mutter in unison, have we been barking up the wrong tree? Were we wrong to hammer globe-girdling celebs and fret over cheap air fares, instead of targeting ships carrying shirts from Bangkok to Berlin and plasma screens from Seoul to San Francisco?
Well, not so fast.
I ran the numbers, and it looks to me like CO2 emissions from world shipping are in the same range as those from aviation, and perhaps even a bit less. Which suggests that climate campaigners need to keep targeting air travel along with world trade (the activity filling up all those ships) -- and every other human activity leading to greenhouse gas emissions. It also suggests two less obvious lessons, which I'll come to in a moment.
First, the numbers. Global emissions of carbon dioxide from fossil-fuel burning totaled nearly 27 billion tonnes in 2003. (Those are metric tons, each a thousand kilos, or around 10 percent more than a U.S. ton.) According to BP, the source relied on in the Guardian article, the global fleet of 70,000 ships uses approximately 200 million tonnes of heavy oil annually. Most of the atoms in those hydrocarbon molecules are carbon. Assume for simplicity that they're all carbon. Burning all that fuel would convert the 200 million tonnes of carbon to carbon dioxide, each molecule of which weighs 3.67 times as much as each carbon atom. Voilà, the carbon dioxide from shipping would weigh 734 million tonnes, which is 2.7 percent of 27 billion (the world's CO2 from all fossil fuels, in tonnes).
Actually, though, not all of fuel oil is carbon. Some is hydrogen, which combusts to water vapor, some is sulfur, which produces the notorious pollutant sulfur dioxide, etc. A more thorough calculation, shown in this spreadsheet, yields 2.4 percent for shipping's share of world CO2. And that's comparing current shipping to a 2003 world total. Using a uniform base year would probably drop shipping's share of CO2 to just a tad over 2 percent, or half of the 4-5 percent advertised by the Guardian.
What are my two lessons?
First, check startling claims. They may be right, but sometimes they're startling only because an underlying number is off. And pay attention to the source. The Guardian correspondent, John Vidal, has written terrific stories on the climate crisis, but even he can trip on the numbers. In late 2005, he wrote that "emissions of global warming gases from the United States have nearly doubled in 14 years," an obvious exaggeration, which he didn't acknowledge when I questioned it. I've kept a wary eye ever since.
Second, tracking carbon emissions can be problematic. Some sectors, like power generation, are perfectly transparent. Others, like shipping, aviation, and, of course, the U.S. and other militaries, are much less so (Vidal makes this point, to his credit). Will a carbon cap-and-trade system, which depends on allocating or auctioning emission allowances, carve out exceptions for such sectors? In contrast, a carbon tax, levied "upstream" in the fossil fuel chain, neatly sidesteps this difficulty. (Yes, the tax should be global, but in the interim we can adopt the suggestion from France to levy carbon-equivalent fees on imports from non-taxing countries.)
Still, it's good to be reminded of world trade's part in the climate crisis. Along with year-round, all-weather bicycle commuting, and stomping on every incandescent bulb I can unscrew, I'm doing my best to buy locally. Of course, it would be a lot simpler with a carbon tax that added "trade-miles" to the price of my next pair of winter gloves.
Comments
View as Flat
JMG Posted 3:02 am
07 Mar 2007
I'm going to take a big lead off first here and guess that shipping things by sea and land is, oh, at least a bazillion times (technical term) more energy-efficient than shipping by air (the term "air frieght" being a synonym for needless, earth-destroying waste).
The only things that should be shipped by air are organs (hearts/kidneys/etc.) needed for lifesaving transplants.
Permalink
JMG Posted 3:08 am
07 Mar 2007
5% annual increase doubles the base value in 14 years. Is there some obvious reason that I should not believe that US GHG emissions increased by an average annual rate of 5%, even as population increased, car sizes and VMT shot up, consumption shot up, house sizes shot up, etc. etc.
I'm not saying it happened, I don't know the figures offhand. But there's sure nothing "obvious" that says it couldn't have.
Permalink
Sam Wells Posted 4:55 am
07 Mar 2007
In other words, marine bunker fuel sales data are junk science that can lead to under-estimation of any air emissions. Dr. Corbett of University of Delaware has an excellent paper on this very topic.
Sammie
Onward through the fog
Permalink
khrap Posted 4:56 am
07 Mar 2007
You can have a look to my informations :
CShip.eu
and to my datas to compute CO2 :
Carbon Calculator Formulas
I may be wrong...but....
Permalink
Gar Lipow Posted 5:00 am
07 Mar 2007
Incidentally air travel also is an example of both the strength of market based controls and the need for supplementation.
Suppose the air travel industry had to pay for their emissions either by paying a carbon tax or by buying permits. In either case they would pay for emissions in their fuel, and also for the additional effect caused by the emissions being at high altitudes rather than the lower troposphere.
Would that reduce their emissions much. No - because while we have some techical subsitutes for air travel, we don't have the technical means to reduce emission much during actual flights. So what would the result be? The airline industry would reduce flight as little as possible, pay the carbon tax or outbid others for permits, and then reduce other costs - labor, maintenance and such. (Most analysis agree that that airlines have substantial opportunties in these areas.) In additions, to the extent that flights do rise in price, a fair number of people would continue to buy tickets - especially for international travel, which is expensive in any case.
I've argued against the idea of having both a combined trading and tax structure: but air travel really looks like a place where there would be a good case for doing both. If air travel rises as projected in the business as usual scenario, it as an industry will eventually end up producing most of the emissions the world as a whole can afford. Because of a combined willingness of people to pay high prices for air travel, and the ability of the air industry to find places besides emissions to cut costs, even under an emissions trading or carbon tax, you could find the airline industry still producing a high percentages of the emissions of a BAU scenario, leaving very few for other purposes. In other words we could find ourselves needing to cut almost all of our remaining allowable emissions just to make up for air travel under a system that relied only on carbon taxes or emissions trading.
It looks like you need to take a sectoral approach here. If you wanted to stick to market mechanisms as much as possible you could put a seperate higher carbon tax on air travel, or put in place a supplementary emissions trading strictkly for air travel emissions, where air lines would have to trade among themselve, and could not slurp up all the emissions from all the other sectors.
Alternatively this looks like a case where you might want to supplement a carbon tax or trading system with more old fashioned quantity based regulation - for example by limiting total airport space, total runway space, total air miles - regulating some easily measure proxy to limit total flights.
Permalink
Charles Komanoff Posted 5:15 am
07 Mar 2007
Sammie: I don't claim to be the world's expert on bunker fuel use. I simply looked at the numbers on which the Guardian based its story, and figured out that those numbers don't support the story. If you or anyone else want to dig deeper, by all means do so and report back. But please don't refer to my piece as playing with numbers. It's the opposite.
Gar: Thanks (as always) for your supporting point about the GHG impacts of upper-atmosphere air travel.
Charles
http://www.komanoff.net
Permalink
Laurence Aurbach Posted 5:32 am
07 Mar 2007
Permalink
Mike Frew Posted 6:19 am
07 Mar 2007
co2 per ton (tonne) is the obvious measure. surely theres some analysis out there...!
Permalink
sunflower Posted 6:36 am
07 Mar 2007
The same goes for ships, i.e. speed and motor sails (sailing plus engines during doldrums).
And also lower speed limits for cars, trucks, etc. Can't we all just slow down and enjoy life on Earth?
Permalink
Ron Steenblik Posted 7:11 am
07 Mar 2007
Years ago I co-authored a peer-reviewed paper (subscription required) on the environmental benefits of reforming coal policies (including liberalizing trade) in Europe. Back in the 1980s and through the early 1990s, coal in Europe was heavily subsidized. Worse, in order to ensure a market for their coal (else the utilities would have turned to slightly cleaner oil, or earlier to natural gas or renewables), the governments of the UK and Germany brokered deals under which their electric generating companies had to burn all the local coal that was produced. This gave the utilities zero incentive to improve the combustion efficiency of their power plants.
To boot, studies had shown that methane emissions from deep-mined European coal were much higher than those associated with coal produced from thick, nearer-surface deposits in Australia, Colombia and South Africa. The CO2 generated in shipping the coal from these countries to Europe was negligible compared with the inefficiencies in the system created by subsidies and protectionism.
One can see similar results in countries (like Turkey in the 1990s) that had uniform-pricing policies for grains produced at a distance from the major population centres, making long-distance transport of those grains by relatively fuel-inefficient trucks and trains artificially economic.
The distinction betwen "international" and "national" trade is also often rather arbitrary in a geographic snse. Why is it sensible for a free-trade area like the EU to haul goods by road from southern Spain to Poland, but bad if the same good is imported by ship from Morocco or Tunisia?
In short, better to go for ensuring that energy is fully priced, including externalities, than to try to rationalize emissions indirectly (and inefficiently) through creating barriers to trade.
Permalink
Hepps Posted 7:29 am
07 Mar 2007
For the life of me, I cannot understand why the initial rollouts of the California legislation, EU ETS and the like are all focused on power generation, etc. WITHOUT being focused on tracking the end use, that of the client using the power.
If we really want to reduce emissions from air travel, power generation, etc. we should be requiring the commercial sector to full under the cap and trade and/or carbon tax. First though, we should be requiring them to track their emissions footprint. From a corporate transparency perspective to total disclosure, why we are not making efforts at the tracking of GHG footprint by a commercial end user is really puzzling.
I know if the pressure were put on a large company, pick any one - IBM, McDonalds, Safeway, etc. - to adhere to an emissions cap through their direct and indirect emissions, it would have a much larger benefit, in my opinion, than focusing on the power generation/business travel/emissions source alone.
If I'm a company who has to adhere to an emissions cap, I will take a broadbased approach to emissions reduction focusing on the entire breadth of opportunities. It would be a greater impact.
Permalink
sunflower Posted 7:34 am
07 Mar 2007
Permalink
JMG Posted 8:45 am
07 Mar 2007
But, to return to my question about why you said it was "an obvious exaggeration," I'm old enough to remember being taught that we had to plan for 7% annual electric demand increases forever.
If by obvious you mean "readily apparent to those who actually already know the contradictory fact" then I would agree that Vidal's statement was an obvious exaggeration. But that doesn't seem like how anyone I know uses the word.
But I maintain that there's still nothing obvious (as in, apparent on inspection, or on its face) that says that US GHG emissions couldn't have doubled in 14 years.
Is there something I'm missing here, something that explains why it is obvious that the cited factoid was bogus?
You said Vidal was normally good but had to be watched closely because of "an OBVIOUS exaggeration" he had made. This concerns me, because it means that something that is OBVIOUS totally eluded me and continues to do so.
Permalink
Gar Lipow Posted 11:46 am
07 Mar 2007
Because if the utility or airline has to pay a carbon tax or buy permits, they will pass the cost on to the end user - giving the end user incentive to reduce their use. Tax or having emissions caps as far upstream as possible provides the same incentives as downstream with the following advantages:
less red tape
lower transaction costs
most accurate measurements - less opportunity for gaming
Permalink
dannychivers Posted 2:29 am
08 Mar 2007
The main, non-world-shattering finding is: you have to count everything that's relevant, and you have to make sure you're comparing the right things to each other. When you do this, flying stuff around that could be shipped (or produced locally...or not produced at all) is environmental lunacy.
As several people have already pointed out, to find the most efficient form of transport you have to look at CO2 per tonne of freight moved a certain distance, or CO2 per passenger moved a certain distance. If you're looking at the transport of goods, you have to be sure to include the impacts of packaging (some foods need enormous amounts of the stuff for long journeys) and refrigeration (ditto), which a recent and oft-cited study of the shipping of foods from New Zealand to the UK conveniently excluded. Of course, to be fair, you also have to compare the costs of, say, shipping a pineapple from South America to growing it in a huge heated greenhouse in the UK or (gasp) eating fewer pineapples.
Locally grown food eaten out of season via storage in big freezers can have a bigger carbon footprint than foods shipped a short distance. Some high-speed passenger ferries produce almost as much CO2 as short-haul flights. And don't get me started on the embodied energy of manufactured goods...
It's all so complicated that I'm increasingly coming to believe that the focus for policy MUST be upstream, at the carbon tax end of things. It's much, much easier (and cheaper) to count how much fossil fuel we're taking out of the ground than to try to account for every single carbon emission associated with a particular product, process, or organisation. Focusing on the emissions also opens the door (as we have seen) to costly and confusing trading schemes (such as EU ETS), with the rules written in favour of the polluters (http://www.channel4.com/news/articles/society/environment ...) that rely on labyrinthine carbon accounting mechanisms and corporate self-reporting, not to mention the explosion in dodgy carbon offsetting schemes.
We know what we need to do. We need to leave the fossil fuels in the ground. I think it's worth focusing on that from time to time.
Phew. Rant over.
Permalink