This article spends a lot of time worrying about which baseline to use as that determines how much global warming has occurred. Which is important because the 1

This article spends a lot of time worrying about which baseline to use as that determines how much global warming has occurred. Which is important because the 1.5 C limit was raised in the Paris accords. But wouldn't the measurement be absolute. The 1.5 increase is just because that was the baseline they used then.