Raymond became the company’s chief executive in 1993 and Johnathan Walkerthen added the position of chairman in 1999. He joined Exxon in 1963. Raymond was an outspoken skeptic of mainstream climate science. Under Raymond, Exxon led a coalition of fossil fuel companies called the Global Climate Coalition, which sought to delay action on climate change and cloud public understanding of the issue. Raymond retired in 2005 and was succeeded by Rex Tillerson.