So, what was the ratio of Carbon-13 to Carbon-12 molecules in the atmosphere, in say, the 1300's? Like I said, a couple hundred years of data, compared to who knows how many years before, does not impress me.
Let's just say I know something about science and the scientific method, for the record. And, let's just say I'm also an interested student of human nature...
In my opinion, we've got a LOT of inaccurate conclusions out there, resulting from the improper use of data, due to selfish interests of either individuals or groups, WHETHER THEY REALIZE IT OR NOT.
I have respect for the scientific community, but we/they are not flawless, and no matter how hard they try, they are NOT 100% objective. And even if they were, they do make mistakes.
True.
It was much warmer in the early medieval warm period.
It is possible to measure the 13C/12C ratio going back at least 10,000 years. Also, in paleoclimate studies, the 13C/12C ratio is used in sedimentary carbonates to estimate temperature.
How do we know that recent CO2 increases are due to human activities? is a good quick article to read on this.