For the first time, a group of billionaires from outside the U.S. has agreed to sign the Giving Pledge, a campaign launched by Bill Gates and Warren Buffet to encourage the world's wealthiest to give away at least half of their fortunes to charities of their choosing.

Among the new dozen is Richard Branson, best known as the founder and chairman of Virgin Group. On his personal website yesterday (Feb. 19), the 62-year-old explained why he and his wife Joan decided to sign the pledge.

"‘Stuff’ really is not what brings happiness," he writes. "Family, friends, good health and the satisfaction that comes from making a positive difference are what really matters. Happily our children, who will be our principal heirs, agree with me on this."

According to sources, Branson plans on focusing his philanthropy to support social enterprises focused on environmental initiatives. "Hopefully, the vast majority will realise there are better ways of using wealth than leaving it to future generations," he added.

Since its founding in 2010, the Giving Pledge has signed up 105 families with an estimated collective wealth of more than $500 billion. Mark Zuckerberg, Ted Turner, George Lucas, Michael Bloomberg and Steve Case are just a few of the big names taking part.

“The Giving Pledge brings people together to exchange ideas about how to be as effective as possible and smarter in our giving.” said Gates in a statement. “There are amazing examples of giving happening around the world — and not just among the wealthy — that we can learn from, and I am excited about the conversations and ideas that will happen thanks to this impressive group of international philanthropists. In many cases, their perspectives on giving will be informed by living much closer to the areas of greatest need.”

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Richard Branson signs the Giving Pledge
Billionaire joins more than 100 other wealthy families by vowing to give away half his wealth to charitable causes.