The sun was setting in New York as James Murdoch, looking confident in cream pants and a dark blazer, stepped before 350 guests in a glass-walled concert hall and waxed poetic about his pet TV channel and its dedication to "scientific literacy."

The event on Wednesday night was an advertising showcase for National Geographic, which Mr. Murdoch, 44, has doted on since becoming chief executive of its parent company, 21st Century Fox. As a person who cares deeply about "issues related to the environment, conservation, exploration and education," he told the crowd, "I'm personally grateful for the important work National Geographic does."

Across town at that same moment, his 86-year-old father, Rupert — who once called climate change "alarmist nonsense" — was still dealing with fallout at his most cherished channel, Fox News. Bill O'Reilly, the pugnacious and top-rated talk show host, had been ousted that day after allegations of sexual harassment involving multiple women.