With little warning or explanation, the Centers for Disease Control and Prevention recently canceled a major climate change conference that had been scheduled for next month in Atlanta. The Climate and Health Summit, which had been in the works for months, was intended as a chance for public health officials around the country to learn more about the mounting evidence of the risks to human health posed by the changing climate. But CDC officials abruptly canceled the conference before President Trump’s inauguration, sending a terse email on Jan. 9 to those who had been scheduled to speak at the event. The...