Australia has come up with a way of killing two birds with one stone. Or rather, killing one camel and tackling climate change. The government is considering a scheme that would see \"carbon credits\" awarded for culling the methane-belching ruminants that roam the outback. Imported in the 19th century to help Europeans explore the vast, arid continent, and turned loose in the 1920s, the feral camels are considered a major pest. Now it turns out that they not only compete with native animals for food and water, trample vegetation and damage fences – they also make a hefty contribution to Australia\'s greenhouse gas emissions. Each camel discharges 45kg of methane – equivalent to one tonne of carbon dioxide – every year. With more than million of them in the wild, and their numbers predicted to double every nine years, that represents a lot of climate-changing gas. Under a plan being mulled by the government, the killing of camels would be officially registered as a means of cutting national emissions. People who helped to reduce the camel population would earn carbon credits, which they could then sell to industrial polluters seeking to offset their own emissions. The idea was conceived by an Adelaide-based company, Northwest Carbon, which proposes to shoot camels from helicopters, or round them up and send them to abattoirs to be converted into meat for humans or pets.