Now You Sea Me...

After getting all historical for the last couple of weeks, I thought it might be about time switch attention to the impact travel is having on the environment in the present day.  

With much of the current day work focussing on the impact of flying and driving, sea transportation seems to have been forgotten. In 2003 Endresen et. al, highlighted the environmental impact of marine travel, estimating that the 106,000 ocean going ships used over 200 million tonnes of fuel each year.

The estimates were calculated through the use of an extensive model that took into account factors such as the engine type and power output, the load of the ship, and the speed at which it would travel.

It was not the first time a fuel usage estimate has been calculated, and was in fact a response to the work of Corbett et. al (1999) who suggested the international fleet only used 147 million tonnes. While this study went onto show Nitrogen and Dimethlysulphate emissions from ships account for 14% and 20% of the global emissions respectively, the lower estimate of fuel usage is perhaps a result of a less extensive model that investigated fewer variables.  

While these two studies disagree on the exact level of fuel used through global sea transportation, and the emissions it is responsible for, they both conclude emissions are larger than they were previously considered to be. Although both are quick to mention the continuing uncertainty surrounding the impact variables, it is of vital importance to recognise the contribution of sea transportation to the global environment and not to just focus on the effects of air and road travel.