• Amazon CEO Jeff Bezos on Tuesday announced the new leader of his $10 billion Earth Fund.
• Andrew Steer, who currently serves as CEO of environmental non-profit the World Resources Institute, will head up the Earth Fund, Bezos said.
• It comes as Bezos is set to step down as CEO of Amazon later this year and is expected to spend more time focusing on projects like the Earth Fund.

Amazon CEO Jeff Bezos on Tuesday named the head of a top environmental think tank as the CEO of his $10 billion Earth Fund.

In an Instagram post, Bezos said Andrew Steer, who currently serves as President and CEO of the World Resources Institute, an environmental non-profit, has agreed to lead the Earth Fund.

"Lauren and I are thrilled to have Andrew aboard and very energized about what lies ahead for the Fund and our partners," Bezos wrote in the post, referring to his girlfriend, Lauren Sanchez. Sanchez has participated in previous meetings with Earth Fund recipients, the Earth Fund said.

The Earth Fund, launched last February, is designed to combat the effects of climate change by issuing grants to scientists, activists and other organizations in their efforts to "preserve and protect the natural world." Last November, Bezos announced the first recipients of the Earth Fund, with groups receiving $791 million worth of grants. Among the recipients were the Nature Conservancy, Natural Resources Defense Council, the World Wildlife Fund and the World Resources Institute.

Bezos actively participated in the interview process and hired Steer, the Earth Fund said. In addition to heading up the World Resources Institute, Steer has deep ties to global groups focused on environmental and economic issues, in addition to previously holding senior posts at the World Bank.

In a series of tweets, Steer said the Earth Fund will invest in scientists, NGOs, activists and the private sector to further development of new technologies, investments, policy change and behavior. One key focus of the Earth Fund, which Bezos hopes to "spend down" between now and 2030, will be around climate change's impacts on "poor and marginalized communities," Steer said.

Steer's appointment comes as Bezos is slated to step down as CEO of Amazon later this year, turning the helm over to AWS CEO Andy Jassy. Bezos is expected to turn more of his attention to projects like the Earth Fund, his Blue Origin space company, The Washington Post and the Amazon Day 1 Fund.