“Why are alarmists suddenly and quickly loosing support in public opinion?”
Because the public, in their wisdom, smell a rat, without knowing the details. When you’re told that there’s a new problem whose solution just happens to align perfectly with the post-1960s leftist world-view, it’s not unreasonable to be skeptical. If this is just good science, they ask themselves, how is it that the only possible solution is to turn the nation and the world over to the hands of the people who lost the cold war? This wisdom is intuitive, rather than science-based, but it’s perfectly rational.