Museums are vital cultural institutions. They provide a glimpse into the past, a record of what once was and an exploration of how the present came to be. They are social cornerstones, shaping public opinion in subtle yet profound ways.

In a world increasingly dominated by fake news, museums should stand as sanctuaries of truth and science. To do so, a natural-history museum must be accurate, faithful to the facts and trusted by the public. This is why it is so troubling that Rebekah Mercer continues to sit on the board of trustees of the American Museum of Natural History.

Ms. Mercer and her family were important backers of President Trump. She has a stake in Breitbart News, and the family foundation has contributed millions of dollars to climate-change-denying politicians and organizations like the Heartland Institute, which says, “Global warming is not a crisis” and “There is no need to reduce carbon dioxide emissions and no point in attempting to do so.” According to the Mercer Family Foundation’s tax reports, it gave the Heartland Institute nearly $5.9 million from 2008 to 2016, more than the $4 million it donated to the American Museum of Natural History during that period.