New York CNN  —  OpenAI CEO Sam Altman and his husband have become the newest billionaires to sign the Giving Pledge, a charity that encourages the ultra-rich to donate their wealth to philanthropic causes. In their letter, released Tuesday, Altman and husband Oliver Mulherin credited “the hard work, brilliance, generosity, and dedication to improve the world of many people that built the scaffolding of society that let us get here.” “There is nothing we can do except feel immense gratitude and commit to pay it forward, and do what we can to build the scaffolding up a little higher,” the pair added. Bloomberg reports that Altman is worth at least $2 billion, with much of his wealth drawn from startup investments, including a sizable investment in Reddit. He doesn’t have a stake in OpenAI, the tech company that’s at the forefront of artificial intelligence. The Giving Pledge was started in 2010 by billionaires Warren Buffett and the formerly married couple, Bill and Melinda French Gates, to get the world’s wealthiest to commit to donating at least half of their fortunes to charities and philanthropic causes either during their lifetimes or in their wills. The pledge isn’t a legally binding contract, but more of a moral commitment. The campaign’s intention is to “inspire conversations, discussions, and action, not just about how much [to give] but also for what purposes and to what end,” according to the website. There are currently more than 245 couples and individuals from 30 countries that have signed on. Earlier Tuesday, French Gates, who is one of the world’s wealthiest and most prominent philanthropists, announced that she was donating $1 billion through 2026 to advance women’s rights around the world through her organization, Pivotal Ventures. She recently resigned from the Bill & Melinda Gates Foundation earlier this month following her divorce from Bill. As part of her divorce agreement, she received $12.5 billion from the Gates Foundation for her work upon her resignation.