More “nothing to see here” for the climate hysteria crowd. One long-standing uncertainty has been the extent to which warmer temperatures lead to more CO2 in the air, or more CO2 in the atmosphere leads to higher temperatures, and vice versa. The two are clearly correlated, but longer-term climate records, like ice cores from Antarctica cannot be resolved with enough precision to really say which appears to lead, which might show causation, or just some correlation through another factor.
These authors suggest that a meta-analysis of a number of studies on the CO2/temperature relationship demonstrates that between the year zero AD and 1850, CO2 lagged temperature by about 150 years. If there were some causation between the two, this would indicate that whatever the process involved, it takes about 150 years to result in the change. The authors also looked at the total amount of energy the sun was delivering to the Earth to determine a possible relationship with temperature changes, which seems very obvious to me as the leading cause of any temperature changes. (SCE Article)
What remains unresolved is that humans likely have contributed a fair amount of additional CO2 to the atmosphere in the last 200 years, as industrialization ramped up. That means that the relationship the authors posit could be different in the period after their study ended. What kinds of change did those recent CO2 additions cause? They weren’t unusual in the longer-term record of the Earth, so maybe they have no different effects. Does the CO2 get taken out of the air by natural processes, and if so, how quickly (the answer is yes, but the carbon cylce is also complex)? It clearly doesn’t stay, looking at the pre-industrial record. And of course, I don’t believe there is any significant evidence that the net effect of more CO2 is warming in the complex climate system, it appears to also have cooling effects.
