Doran specializes in polar regions, especially Antarctic climate and ecosystems. Doran was the lead author of a research paper about Antarctic temperatures that was published in the journal Nature in January 2002. Because he and his colleagues found that some parts of Antarctica had cooled between 1964 and 2000, his paper has been frequently cited by opponents of the global warming theory, such as Ann Coulter and Michael Crichton. In an opinion piece in the July 27, 2006 New York Times, Doran characterized this as a "misinterpretation" and stated, "I have never thought such a thing ... I would like to remove my name from the list of scientists who dispute global warming."
Doran also applies his expertise in extreme polar environments to planetary science and has led and been a member of several NASA-funded projects using polar regions as analogs for Mars and icy/ocean worlds. He was nominated by former Apollo astronaut Harrison Schmidt to be a member of the Planetary Protection Subcommittee of the NASA Advisory Council in 2008 and served until 2017. In 2018 he was appointed to represent the U.S. as a member of the Committee on Space Research (COSPAR) Panel on Planetary Protection. In 2022 he was made Vice Chair of the Panel.