For the December holidays my girlfriend and I decided to hire a car to get around. Over the course of the two weeks we drove 984 km, visiting the winelands, and spending a lot of time on the beach and in the forests around the peninsula.

When we recieved the bill for our hire car last night, I was bowled-over to see that our little Kia Piccanto had coughed out the equivalent of 146 kg of CO2! Apparently the car emits around 149g per kilometre, and since we did almost a 1000km, it works to 146 Kgs: that's almost double how much I weigh.

The surprising thing is that at 149g of CO2/KM, the car we were driving had a pretty light carbon footprint compared to other cars. A BMW 5 series, for example, emits 166g/Km, while a Land Rover Discovery emits 244g/Km! If you'd like to know how your car fares, you can do so here.

Worldwide, transport is a huge contributor to climate change, and road transport makes up the largest portion of that contribution. Transport -- including personal, public, and the transportion of goods -- uses up a huge amount of energy and most of the world's petroleum. Transport is the fastest growing emissions sector.

By far the most common way of offsetting carbon emissions seems to be by planting trees. A mature tree is expected to absorb around 21Kgs of carbon a year, or roughly one tonne of CO2 over its first 50 years. That's bad news: it would take 7 fully-grown trees a year to absorb my two-weeks worth of carbon emissions.

So I'm not quite sure where that leaves us. The bottom line is that we need transport in our lives, but at the same time it's impractical, and perhaps even impossible, to offset all of our carbon emissions. In the end the only real way of offsetting emissions is by limiting the amount that we emit in the first place.

Now as individuals we can go some way in controlling these by taking public transport, cycling or walking short distances instead of using the car, and setting up car pools. But I think policy makers, government and car manufacturers also have a responisbility to see that more environmentally friendly cars are made. For although we can each control our carbon emissions to some extent, and we are definitly responsible for those, our choices are also constrained by what cars are available on the market.

But for now its time to roll up my sleeves I guess -- and be more conscious of the amount of carbon I'm putting out there next time I get behind the wheel.