Many people in Congress, almost all of them Republicans, express doubt about climate science, with some of them promulgating conspiracy theories claiming that researchers have invented the issue to justify greater governmental control over people’s lives. So far, this ideological position has been immune to the rising evidence of harm from human-induced climate change. The Obama administration has been pushing federal agencies, including the Pentagon, to take more aggressive steps. But without action in Congress, experts say these efforts fall far short of what is required. “In the country, certainly in the Congress, it hasn’t really resonated — the billions and perhaps trillions of dollars that we would need to spend if we want to live on the coast like we’re living today,” said David W. Titley, a retired rear admiral who was the chief oceanographer of the Navy, and now heads a climate center at Pennsylvania State University.