As the spokesperson for Viva (Vegetarians International Voice for Animals) Paul McCartney’s estranged wife Heather Mills helped launching a new environmental campaign on Monday aiming to convince people they can reduce global warming by reducing the amount of meat, dairy and other animal products they eat.

"There are fields and fields of grain just miles from starving children in Africa, being shipped to Europe to feed our livestock," she said, unveiling billboards for the campaign at the Hyde Park corner site.

Mills, who is featured on two large billboards and a series of ads which promote the reduced consumption of dairy and livestock, said she turned vegan when an African woman at Live 8 asked her "Why don’t people stop drinking cows’ milk lattes?"

The 39-year-old former model turned activist launched the pro-vegan campaign insisting that the milk of rats, cats, and dogs would be more eco-friendly.

"Why do we not drink rats' milk, cats' milk or dogs' milk?" she asked.

"When (Viva) told me it was 18%, that's more than all global transport, I was in shock. Aeroplanes only bring 3%, while they are being picked on with taxes."

Explaining that she doesn’t want to sound unreasonable, she called on people to "cut down on one or two meat and dairy and fish dishes a week."

"It's mad that we are having cow's milk. Even cows don't drink it after one year but we continue forever."

She added: "As individuals, and hopefully within your family, you can reduce global warming rather than rely on governments who talk and talk but do very little about it."

This is Mills’ biggest campaign since she split from McCartney, and about 100 billboards are set to be erected around the country as part of it.

"The startling truth is that animals farmed for meat and dairy are now one of the greatest threats to the planet. The United Nations last year issued a shocking report on the environmental damage being done by livestock," the Daily Mail quoted Mills, as saying.

Before arriving at the paparazzi-crowded event, Mills stormed out of an interview with LBC’s Nick Ferrari when the DJ quizzed her about her recent TV rants and what had happened between her and former legal team Mischon de Reya, whom she parted ways with recently.