Just to play devil's advocate, and I do agree with the climate research, the primary mechanism for global temperature is heat. There is one thing that I think

Just to play devil's advocate, and I do agree with the climate research, the primary mechanism for global temperature is heat. There is one thing that I think could muddy the waters of historic variability: the history of geologic trends in correlation to expended heat versus CO2 emission. I think it does the challenges of climate science a disservice to use CO2 concentration as a simplified blank check. Before the industrial revolution the largest non-cyclical emission of CO2 was geological events. That is primarily volcanic eruptions, but not limited to that. Large geologic events expend a large amount of CO2 and heat in different ratios. For example an earthquake will expend more heat than CO2, especially compared to a volcano, and an underwater volcano will expend less CO2 into the atmosphere than a surface volcano. This is more complicated than it sounds because CO2 emission into the atmosphere isn't uniform due to sequestration factors by geography and chemical reactions from ocean chemistry. This is also complicated in that greater than 2/3s of the planet surface are oceans and water is the fastest and most efficient natural conductor of heat. I believe the current climate science indicates that mean ocean temperature is rising faster than mean atmospheric temperature, which could be due to a combination of various considerations. This by no means suggests that human activity isn't responsible for temperature rise in part or whole, but it could mean there are additional natural factors that human activity is exacerbating beyond CO2 concentration.