Amazon founder Jeff Bezos has said his Bezos Earth Fund will spend $2bn (£1.5bn) restoring landscapes and transforming food systems.
He told the COP26 climate conference in Glasgow that he had grasped nature’s fragility when he travelled into space.
Entrepreneurs including Mr Bezos have been criticised for spending money on trips into space instead of solving problems on Earth.
Amazon has also been criticised by its workers over environmental practices.
Speaking to the COP26 conference, Mr Bezos said: “In too many parts of the world, nature is already flipping from a carbon sink to a carbon source.”
The Bezos Earth Fund plans to spend $10bn fighting climate change overall.
“I was told that seeing the Earth from space changes the lens from which you view the world but I was not prepared for just how much that would be true,” he said.
“Looking back at Earth from up there, the atmosphere seems so thin, the world so finite and so fragile. Now, in this critical year and what we all know is the decisive decade, we must all stand together to protect our world.”
In September, the Bezos Earth Fund pledged $1bn towards conserving nature and indigenous peoples and cultures.
Announcing the follow-up $2bn pledge on Tuesday, Mr Bezos said that two-thirds of Africa’s productive land was degraded but this could be reversed.
“Restoration can improve soil fertility, raise yields and improve food security, make water more reliable, create jobs and boost economic growth, while also sequestering carbon,” he told COP26.
As well as Mr Bezos, Sir Richard Branson and Elon Musk are building up space businesses.
Amazon has also been criticised in the past by its workers over its record on climate change.
Last year, Amazon Employees for Climate Justice called on the online retail giant to achieve zero emissions by 2030, limit its work with fossil fuel companies, and stop funding for politicians and lobbyists who deny the existence of climate change.
In April this year, US labour officials found that Amazon retaliated illegally when it fired two employees who were part of the group.