Science envoy resigns over Trump's Charlottesville comments

— -- One of the State Department’s science envoys has announced his resignation on Twitter, citing President Trump's "attacks on core values of the United States."

Dr. Daniel Kammen, a professor of energy at the University of California, Berkeley, wrote in a long letter that he is resigning because of the president’s "failure to condemn white supremacists and neo-Nazis," calling it "a pattern of behavior that enables sexism and racism and disregards the welfare of all Americans, the global community, and the planet."

Kammen also argued that by pulling out of the Paris climate accord, Trump has "abdicate[d] the leadership opportunities and the job creation benefits" participating in the agreement could have represented.

In his letter, Kammen included an acrostic, in which the first letter of each paragraph spelled out IMPEACH. This is a move similar to the resignation letter from members of the President’s Committee on the Arts and Humanities, who spelled out RESIST.

"Today, Dr. Daniel Kammen made a personal decision to resign. We appreciate his dedicated service to U.S. scientific diplomacy during his appointment working on energy efficiency and renewable energy in Africa as a Science Envoy," a State Department official told ABC News.

Kammen was not the State Department's science envoy, but one of three unpaid scientists and engineers who have been working with the agency on key scientific issues. Science envoys are different than the special envoy roles filled by full-time employees at the State Department, in that they work with the agency to foster cooperation with foreign governments, businesses, universities and others.

Since 2010, 18 science envoys have worked with the State Department and visited 41 countries, according to a State Department official. Their terms last about one year.