Ships aren't bad for the climate

There's a story that's been gaining currency in the media of late, that the shipping industry has been getting off lightly when it comes to being harangued about its carbon emissions.

I'm not sure where the story came from - the cynic in me suspects it was originally dreamt up by a PR working for the aviation industry - but it's a woeful example of journalists accepting what their told and failing to understand basic physics or statistics.

The figures that caught my eye recently said 90% of the world's freight is carried by ships and the sector's emissions are 'twice that of aviation'.

To anyone with a basic understanding of maths, those stats look, well, pretty good actually.

Let's assume for a minute that aviation takes up half of that remaining ten per cent (it doesn't - far more stuff is carried by road and train), that means that air freight account for 5% of the global total.

But it still manages to emit half the CO2 of the shipping sector, which is carrying almost 20 times as much.

By my back-of-a-beermat maths, that suggests that flying goods from A to B leads to almost ten times the carbon emissions as sending them by sea.

This explains why environmentalists are not fond of planes.

For those who prefer physics to maths, think about the amount of energy it takes to push a model boat across a pond versus the amount it takes to hurl the equivalent model aeroplane the same distance.

Do the same experiment with a model car too, if you like, and you'll see that boats are a pretty sensible way of moving heavy loads.

Shipping is guilty of a multitude of environmental sins, for sure - transferring invasive species from one end of the world to the other in ballast water, all manner of spills and causing a horrendous waste management headache when vessels come to the end of their working lives to name but a few.

But when push comes to shove, moving stuff by sea is a pretty energy efficient way of doing things - which means fairly low carbon emissions.

There's always going to be room for cleaner, more efficient engines in all modes of transport, of course, but the bottom line is that for as long as we feel the need to transport goods all over the world, ships are going to be the best bet for the environment.Tim Door

Topics: Energy efficiency & low-carbon
Tags: aviation | CO2 | low carbon | shipping | transport | waste management | water
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