For 4 billion years there has been atmosphere. And there has been global temperature.
For fewer years there has been CO2 in the atmosphere. For those fewer years, there have been variations of temperatures and CO2 concentrations.
When there is atmospheric CO2, plants fix carbon from atmospheric CO2. Plants die. Plants decay, and return CO2 to the atmosphere.
Continents move, ice ages come and go.
Humans come along. For the last one hundred years humans affect the CO2 concentration of the atmosphere. Present human contribution to CO2 turnover (recycle) is 1/100th of the natural atmospheric CO2 flux.
Today, absent humans, there would be an atmospheric CO2 concentration. And there would be a global temperature trend. And there would be a “CO2 doubling sensitivity”. It would be an “AGW Sensivity” without the “A”. Global warming and atmospheric CO2 concentrations have existed without humans.
So the first question is; have humans changed the the function (temp x time) in the last one hundred years?
Absent humans, what would the ‘doubling sensitivity’ exactly be today? With humans, it is a number that is ‘perhaps’ something slightly different from the prior, non-human extant, number.
If humans have changed the number, is that good or bad?
What is the trend, what is the future? Glaciers will cover Chicago and Seattle, sooner or later.
Is later better than sooner?
Going forward, global temperatures will increase or decrease.