Dr Andy Thorpe, an economist at the University of Portsmouth, explained that a herd of 200 cows burp the annual equivalent amount of methane to the energy produced by a family car being driven 180,000km using 21,400 litres of petrol.

He added that while carbon dioxide (CO2) emissions have increased by 31% during the past 250 years, methane, which has a higher warming potential and a longer lifetime in the atmosphere, has increased by 149% during the same period.

Sources: Breakingnews  - 21 October 2008