Microsoft co-founder Bill Gates says that he plans to donate most of his vast fortune to the Bill & Melinda Gates Foundation, and that he will someday cease to be numbered among the world’s wealthiest individuals.

“As I look to the future, my plan is to give all my wealth to the foundation other than what I spend on myself and my family. I do some giving and investing in U.S. health care issues, including Alzheimer’s, outside the foundation. Through Breakthrough Energy, I will continue to invest and give money to address climate change. Overall I expect that the work in these areas will make money, which will also go to the foundation. I will move down and eventually off of the list of the world’s richest people,” Gates wrote in a Wednesday post on his Gates Notes blog website.

Gates announced that he is donating $20 billion to the foundation, which will be ramping up its spending to $9 billion per year by 2026. “To help make this spending increase possible, I am transferring $20 billion to the foundation’s endowment this month,” he wrote.

Gates also noted that Warren Buffett has donated massive sums of wealth to the foundation over the years.

“Although it is named the Bill & Melinda Gates Foundation, basically half of our resources to date have come from Warren Buffett’s gifts,” Gates wrote. “Since 2006, Warren has gifted the foundation $35.7 billion, including his most recent gift of $3.1 billion in June. The actual value of these gifts is about $45 billion if you include the appreciation of the Berkshire Hathaway stock after it was given.”

Last month when the U.S. Supreme Court issued a ruling that struck down Roe v. Wade, Gates decried the decision.

“This is a sad day. Reversing Roe v. Wade is an unjust and unacceptable setback. And it puts women’s lives at risk, especially the most disadvantaged,” he tweeted.

In his post on Wednesday, Gates wrote, “I believe the reversal of abortion rights in the U.S. is a huge setback for gender equality, for women’s health, and for overall human progress. The potential for even further regression is scary. It will put lives at risk for women, people of color, and anyone living on the margins.”