The Wyss Foundation and eight other philanthropic organizations pledged Wednesday to give $5 billion by 2030 to protect biodiversity around the planet, the largest-ever private gift for conservation.

Wyss said it would donate $500 million, which comes on top of a $1 billion commitment it made three years ago. Wyss has already invested nearly $676 million of that amount to help local communities, Indigenous peoples and governments safeguard their lands, water and wildlife.

The philanthropic group’s goal is to maintain 30 percent of the planet in its natural state. In May, a United Nations report concluded that a million plant and animal species are on the verge of extinction, a rate of decline that is unparalleled in human history.

“The actions we take from today through 2030 will determine the fate of our natural world,” Hansjörg Wyss, founder and chairman of the Wyss Foundation, said in a statement. “For our grandchildren and their grandchildren to have the same opportunities we’ve had, for them to inherit a functioning planet, we have to rapidly slow the rate at which our economies are destroying nature.”

M. Sanjayan, chief executive of Conservation International, which has received funds from the Moore and Walton foundations, said the wisest approach is to focus on places that are rich in both carbon and species diversity, like forests and peatlands.

“The world is not equal when it comes to carbon or nature,” Sanjayan said. “Some places pulse with carbon. That gives us a fighting chance to get a little ahead of the problem.”

But, he warned, “some places are quite literally irreplaceable if lost, not just because they have such unique life-forms but because if you lose them there’s no way we can get anywhere near the Paris climate targets.”

Moreover, many such areas would not return for 500 to 1,000 years, said Lee Hannah, a senior scientist in climate-change biology for Conservation International.

Cristián Samper, president and CEO of the Wildlife Conservation Society, said in a statement that protecting nearly a third of the planet “is a winning nature-based solution for nature and humanity.”

The group of philanthropic organizations includes the Wyss Foundation, the British Arcadia Fund, Bloomberg Philanthropies, the Gordon and Betty Moore Foundation, Nia Tero, Rainforest Trust, Re:wild and the Rob and Melani Walton Foundation. Also included is the Bezos Earth Fund, which announced its $1 billion share Monday.

Wyss, who started a medical device manufacturing company that he sold for nearly $20 billion, has long been a patron of environmental causes. Gordon Moore, one of the founders of Intel, has been a supporter of Conservation International. Mike Bloomberg’s philanthropy has supported the Sierra Club’s campaign against coal plants, largely in the United States. Nia Tero works with Indigenous peoples. The Waltons are part of the family that founded Walmart.

Bezos owns The Washington Post. His fund said it would focus on the tropical Andes, the tropical Pacific and the Congo Basin.