I can remember when the ice age was coming...
So can I. I think it was the mid 70's. Then there was "population explosion" that the world couldn't possibly feed. You also had the alcar scare that almost killed the apple industry. And then you had the ozone depletion that was going to kill every living thing on Earth. Don't forget the original nutrition pyramid that has been changed. Egg yolks will kill you, also. Now they're a good source of protein. I know I'm missing some.
I don't trust scientists any more than I do politicians. They both develop a thesis or problem and then build models/solutions to prove it. Hell, I remember when the Universe would expand forever. Now they say it is on the verge of contracting. The dead String Theory is a good example. The physicists just couldn't work it out on their white boards. Now we have the Dark Matter theory.