Tree rings tell us there were years where there was more or less rainfall relative to what that tree/forest normally sees - but it does not provide a measurement of how much water/rainfall there was. Different geographical regions experience different norms over time as well.
Same with temperature. We can infer there were hotter years, and colder years within those regions all throughout history. Being able to say the temperature averaged say 30*C was not possible until relatively recently.
It's all observational science, and we can't observe all of the factors unfortunately so we have to infer a great deal.
Same with temperature. We can infer there were hotter years, and colder years within those regions all throughout history. Being able to say the temperature averaged say 30*C was not possible until relatively recently.
It's all observational science, and we can't observe all of the factors unfortunately so we have to infer a great deal.