If climate science is so settled, why are we told that the alleged global warming signal emerged from the noise in the late 1800s, or maybe it emerged in the 1980s?

Global warming study suggests human causes dating back to 1800s - Science

A long-term global cooling trend ended in the late 19th century, a reversal in temperature that cannot be explained by natural variability alone, according to a new study.

Settled science

[1989: Stephen Schneider wrote, "I strongly suspect that by the year 2000 increasing numbers of people will point to the 1980s as the time the global warming signal emerged from the natural background of climatic noise"]