Settled Science is one of the few absolutes liberals believe in.
It was once settled science that the earth was flat.
It was once settled science that the earth was the center of the universe.
It was once settled science that bleeding sick people with leeches was an effective medical procedure.
Forty years ago it was settled science that the earth was entering a new ice age.
Settled science is a nonsense concept even when a finding is correct, the discovery asks at least two more important questions. We aren’t anywhere close to a general theory of climate so the “science is settled” is a political statement.
Actually it wasn't. Eratosthenes, born in 276 BC, not only knew that the Earth was a sphere, but through a clever experiment, measured its diameter, getting a value very close to the one we know today.
Moreover, the idea that people once believed the Earth was flat is a 19th Century bit of anti-Catholic bigotry.
For the complete story, see J. B. Russell's book Inventing the Flat Earth. As Russell says, the most interesting question is why we still believe this false legend, when there is ample evidence to the contrary.