Could this bird really have a worse carbon footprint than a patio heater?

Pink-footed geese . . . their numbers, and the amount of carbon they release, are on the increase.

Photograph: Alamy

The Guardian, Wednesday 20 January 2010

The pink-footed goose is an increasingly common sight on the waterways and fields of Britain. Smaller than a mute swan but larger than a mallard, the geese can currently be spotted all over estuaries such as the Wash and Solway, where they will stay until April, when they head for their Arctic breeding grounds.

The RSPB notes that the pink-footed goose is pinkish-grey with a dark head and neck, a pink bill and, not surprisingly, pink feet and legs. It likes to eat grain and potatoes. What was less well known about the pink-footed goose, until now, is that each bird is responsible for more than 100 kg of ­carbon-dioxide emissions each year. The pink-footed goose: the bird with a carbon footprint four times larger than a patio heater.

Unlike cows and sheep, the geese do not fart and burp out their sizable contribution to ­global warming. Rather, they free the carbon from the ground when they grub around in the Arctic soil for food.

"The geese arrive in the Arctic in April and May, before the vegetation has had a chance to grow," says James Speed, a scientist with both the University of Aberdeen and the University Centre in the remote Norwegian archipelago of Svalbard, halfway to the North Pole. "So to get something to eat they dig down into the soil with their bills to get at the bits of plants that are still buried."

The foraging geese leave the landscape in a mess, its mossy coating pulled up and scattered to the wind. And as the hungry birds move on, they leave a ­minor ­environmental ­crisis in their wake. Stripped of its protective layer of moss, the exposed ­Arctic soil warms and decomposes, and is washed away by wind and water. Once freed from its secure store, goose by goose, the liberated carbon can be converted to carbon dioxide by bacteria.

A new analysis by Speed and his colleagues, published in the journal Polar Biology, calculates that each goose grubs up some 37 kg of Arctic carbon each year. That's the equivalent of 136kg of carbon-dioxide emissions per bird, compared with a measly 35kg of CO2 produced by the average patio heater.

Ironically, the number of pink-footed geese, and the amount of carbon they release, is on the increase due to conservation measures in Britain and northern Europe. Changes in farming styles and reduced shooting have also contributed to a three-fold rise in the Svalbard population since the 1960s.

Not that people concerned about global warming should reach for their shotguns. "The carbon produced by the birds is minuscule in terms of the global carbon picture," Speed says. "We're not saying that there should be controls on their numbers or anything like that."