NATIONAL DESK | October 26, 2004, Tuesday THE 2004 CAMPAIGN: THE ENVIRONMENT; NASA Expert Criticizes Bush On Global Warming Policy By ANDREW C. REVKIN (NYT) 914 words Late Edition - Final , Section A , Page 22 , Column 5 ABSTRACT - Dr James E Hansen, NASA climate expert who has briefed Vice Pres Cheney on global warming, will criticize Bush administration policy at University of Iowa lecture, and say that NASA Admr Sean O'Keefe told him last year not to discuss dangerous consequences of rising temperatures; photo; Hansen, director of NASA Goddard Institute, will say administration ignores growing evidence of 'colossal risk' if heat-trapping emissions are not reduced within decade; Hansen to say he will vote for John Kerry, while also criticizing some of Democrat's positions; O'Keefe denies account; Dr Franco Einaudi, also at meeting, says O'Keefe referred to 'delicate issues'; Bush science adviser Dr John H Marburger III denies White House plays down risks of climate change (M)