How much does your morning glass of orange juice contribute to global warming? PepsiCo, which owns the Tropicana brand, decided to try to answer that...it turned out that the biggest single source of emissions was simply growing oranges. Citrus groves use a lot of nitrogen fertilizer, which requires natural gas to make and can turn into a potent greenhouse gas... “The main thing is helping us figure out where the carbon is in the chain,” said Neil Campbell, president of Tropicana North America, a division of PepsiCo... While carbon reduction efforts are generally welcomed by environmentalists, some complain that the marketing claims are backed by fuzzy numbers and dubious assumptions... PepsiCo...[also] will publish carbon-footprint numbers for products including Pepsi, Diet Pepsi and Gatorade. [also refers to Stonyfield Farm, Walkers (part of PepsiCo)]