The American Museum of Natural History has long been on the front lines of the climate change discussion, as its scientists study the potential damage and its educators try to alert new generations to the dangers of global warming.

The depth of that mission is evident in the numerous exhibitions at this Manhattan museum, like the film “Wonders of the Arctic,” which is on view through March 2. “The polar bear has always been the symbol of the Arctic,” the narrator intones. “Now it’s become the face of climate change and the threat it poses.”

But one of the museum’s leaders, a trustee who is also an important donor to the institution, Rebekah Mercer, has been using her family’s millions to fund organizations that question climate change, a cornerstone of the conservative agenda she is advancing as an influential member of President-elect Donald J. Trump’s transition team.

In recent years the Mercer Family Foundation — which Ms. Mercer operates with her father, the New York investor Robert Mercer — has given nearly $8 million to organizations including the Heartland Institute in Illinois, a group that rejects the scientific consensus on climate change. She is also on the board of the Heritage Foundation, a conservative think tank that is skeptical of whether human behavior causes climate change.