Green Travel: Ship or Plane?

I will be moving back to the United States at the end of this month after spending five years in Spain. Ever since i arrived in Spain i have had the wish to take a long boat ride so i have decided to travel back to America on a freighter boat. I have booked a passage on the freighter Ibn Sina which sails from New York through the Mediterranean and the Middle East to India and which stops in Valencia, Spain before returning to New York. It will be an 11-day voyage, non-stop, leaving “on or about” April 21st.

The decision to travel by boat was influenced by several factors. It will allow me to transport all my books and other stuff to the US without having to pay an extra shipping cost; it will be a long and slow journey during which i can reflect on my time in Spain and enjoy a more gentle transition into my new life instead of having a plane zip me from one world to another; and it will help me get to know a part of our world (the ocean) in a way that i have never experienced it before. However, the reason that initially inspired me to inquire about boat travel was the desire to find a means of getting from Europe to America in a way that is more environmentally-friendly than flying. I have been hearing more and more about how damaging for the environment commercial airlines can be so i wanted to find an alternative… but now that i have done some research i am not sure if i made the correct ecological decision.

I naturally assumed that travel by ship is better for the environment than travel by aircraft (mostly because i thought it must take more energy to sustain a plane’s altitude against the force of gravity than to propel a boat along the water) but as some of my friends have pointed out, this is not necessarily a correct assumption. Freighter boats require a lot of energy and are responsible for a substantial amount of the world’s CO2 emissions. Indeed, a recent article in the Guardian opened with the line: "Carbon dioxide emissions from shipping are double those of aviation and increasing at an alarming rate..."

So i did some research on the internet to find some comparisons between boat-travel and plane-travel and try to determine which is less harmful to the environment. And the main conclusion that i came to is that nobody really knows which is better or worse. There have been some studies done on the environmental effects of the aviation industry (for example, see the thorough report, The Plane Truth: Aviation and the Environment) and there are some statistics on the CO2 emissions of the shipping industry but there is very little reliable information that compares the environmental effects of the two modes of transport.

The best sources i could find were the Guardian article, a response to that article on treehugger.com, and an article on planetark.com. But even these articles provide insignificant comparative data; their benefit lies in their attempt to explore an issue and raise awareness in the face of a dearth of facts and figures. Indeed, i found the comments to these articles more illuminating than the articles themselves because they demonstrate how little we know and how the available information can be interpreted in a number of different ways.

Having read a number of articles and opinions on the issue, my general understanding of the situation is: 1) that little attention has been given to the environmental effects of shipping partly because, like the aviation industry, it is not regulated by the Kyoto protocol and because it is difficult to assign responsibility for international transportation to individual countries; 2) that the shipping industry, overall, is responsible for more environmental pollution than the aviation industry (about twice as much) but that this is due to the fact that the shipping industry transports much more of the world’s goods (90%) than the aviation industry; 3) that if we were to transport everything by plane the financial and environmental cost would be exorbitant and therefore that the ecological footprint of flying is more costly than shipping; 4) and that ships and planes produce a different type of pollution due to the fact that "modern jets emit substantial quantities of nitrogen oxides [in addition to carbon dioxide] because they operate at very high temperatures and high pressures" and because planes release most of their emissions in a different layer of the atmosphere than vehicles close to the surface of the earth. (This complicates the attempt to conduct a comparative study of the two industries.)

There is a lot that we don’t know about the specific details of global warming and the effects of our actions on the environment and, until we have more of a consensus, each of us has to make decisions based on our own understanding. Often this will mean that our actions are determined more by our beliefs than any factual data. But the scarcity of reliable information does not absolve us from taking responsibility for our world. We need to make personal changes if we want to improve the conditions of our world – even if those changes turn out to be misguided or misinformed.

So i am going to take a boat to America and i hope this is better for the environment than flying. But, to be honest, i don’t really know if it is.