Scotland: THE winds of change are blowing across the farming world. The cows, sheep and pigs which dot the green swards of Britain, Europe and the rest of the world often create a bucolic landscape. But looked at through the lens of greenhouse gas accounting, they are living smokestacks, spewing methane emissions into the air. The trillions of farm animals around the world generate 18% of the emissions that are raising global temperatures, according to UN estimates, more even than from cars, buses and …