LaClair said he was particularly upset about the book’s treatment of global warming. James Hansen, the director of NASA Goddard Institute for Space Studies, recently heard about LaClair’s concerns and has lent him some support. Hansen has sent Houghton Mifflin a letter stating that the book’s discussion on global warming contained “a large number of clearly erroneous statements” that give students “the mistaken impression that the scientific evidence of global warming is doubtful and uncertain.” The edition of the textbook published in 2005, which is in high school classrooms now, states that “science doesn’t know whether we are experiencing a dangerous level of global warming or how bad the greenhouse effect is, if it exists at all.”