system
Given the following post, respond as if you're commenting on Reddit:
human
If we only started keeping temperature records in 1880, how do scientists know the world wasn't hotter before? How can they say so certainly the world is getting hotter and the ocean increasing?
gpt
They take core samples of earth and ice. By comparing the thickness of the layers, and the composition of the layers, you can have a pretty good idea of some of the things that went on.

It’s somewhat conjecture, backed by a bevy of evidence and experiments.

Even so, it’s clear that since 1880 the climate is getting warmer, with evidence that it’s been accelerating in the last 50 years or so.