President Barack Obama with Interior Secretary, Sally Jewell on Feb. 06 2013.

Scientists must confront climate change deniers and speak up if U.S. President-elect Donald Trump tries to sideline climate research, Interior Secretary Sally Jewell is due to say on Wednesday.

"If you see science being ignored or compromised, speak up," Jewell will tell a meeting of earth and space scientists in San Francisco, according to a draft of the speech seen by Reuters.