Walking to the shops does to cause global warming than driving – this is the extraordinary claim of a leading environmentalist.

According to Chris Goodall, food production is now so energy-intensive that more carbon is emitted producing food with enough calories for a person to talk to the shops than a car would emit over the same distance. So, does this mean climate change could be avoided if people didn’t exercise and spent their days curled up on their sofas as couch potatoes?

Chris Goodall calculated the carbon dioxide emitted from particular activities. According to his figures (based on the UK Government’s official fuel emission figures), a standard UK car emits around 2lb (0.9 kg) of carbon dioxide over 3 miles (4.8 km). Walking the same distance uses roughly 180 calories. This equates to around 100g of beef, and this quantity of beef produces around 3.6 kg of carbon emissions – that’s four times more emissions than driving.

If he’s right, it wouldn’t be the first time that so-called environmentally friendly options actually turn out to be worse than their ‘polluting’ alternatives. Catching a diesel train is actually twice as polluting as driving the same distance; Paper bags may actually be worse for the environment thanks to the extra energy required in the manufacture and transport of them.

In last month’s New Scientist, figures stated that 1 kg of meat produces around 36 kg in global warming gases. These figures were based on Japanese methods of beef production, and figures are estimated to be roughly the same the world over for standard beef production. Converse to popular belief, organic beef is actually more damaging to the environment than non-organic beef as the cows emit more methane.

Of course, humans eat a varied diet, but the overall results remain the same no matter what the food substance. A glass of milk (420 ml in size) would be needed to complete the 3 mile walk. Dairy farming emits around 1.2 kg of carbon dioxide to produce this amount of milk – again, higher emissions than the equivalent journey in a car.

In the developed world, we have a market for ready-made goods and processed foods. These are incredibly bad for the environment, not least because huge amounts of energy are required to store the food in fridges and freezers. Developed nations also tend to be guilty of having high food miles – the more miles the food does, the more polluting it is.

In fact, the food industry in developed nations is estimated to produce around a sixth of the total carbon emissions. It may even be the case that cows produce more greenhouse gases than aircraft, although that doesn’t mean it’s OK to fly or drive everywhere – particularly given the health implications of the lack of exercise and the pollutants emitted by cars and aircraft and the emissions from tasks such as maintaining the roads and creating the metal for the cars. Simply reducing or eliminating these food products with high emissions from our diet won’t solve the problem either – more needs to be done to understand the greenhouse gas emissions from food production and steps must be taken to reduce them.

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