These days everyone is worried about the size of their carbon footprint. In order to reduce global warming we need to make our carbon footprints smaller. But how much CO2are we responsible for? A new book by Mike Berners Lee, an expert, might be able to help. The carbon footprint looks at the different things we do and buy, and calculates the amount of CO2all of the following created: the ingredients, the electricity, the equipment, the travel and commuting of the beer, and the packaging. It's amazing how many different things need to be included in each calculation. And it's frightening how much carbon dioxide everything produces. This can help us decide which beer to drink. From Berners Lee's calculations, it's clear that a pint (568ml) of locally _ beer has a smaller carbon footprint than a bottle of imported beer. This is because the imported beer has been transported from far away, and it uses more packaging. The local beer only produces 300g of CO2, but the imported beer produces 900g! So, one pint of local beer is better for the environment. Berners Lee has even calculated the carbon footprint of cycling to work. Nothing is more environmentally friendly than riding a bike, surely? Well, it depends on what you've had to eat before. To ride a bike we need energy and for energy we need food. So if we eat a banana and then ride a kilometer, our footprint is 65g of CO2. However, if we eat bacon before the ride, it's 200g. In fact, bananas are good because they don't need packaging, they can be transported by boat and they grow in natural sunlight. So, does this mean that cycling is bad for the environment? Absolutely not, for a start, if you cycle, you don't use your car, and the fewer cars on the road, the fewer traffic jams. And cars in traffic jams produce three times more CO2than cars traveling at speed. Cycling also makes you healthy and less likely to go to hospital. So maybe it's time for us all to start making some changes. Pass me a banana and a pint of local beer, please. What's the main purpose of writing this passage?
To tell the differences among bikes, beer and bananas. To call on us to take action to make carbon footprint smaller. To introduce what CO 2 really is in our life. To remind us to start healthy eating habits.