How much money has the world wasted because of some tree ring studies?
A Chinese group has looked at all the different kinds of 2,000 year long proxies in the PAGES dataset and found that history looks quite different depending on which proxy you pick. Only the tree rings show the HockeyStick shape that matches the climate models. In other proxies, temperatures have fallen for most of the last 2,000 years, especially in the Southern half of the world. And even after the recent warming, we are not yet back to the temperatures the Romans lived through.

So yet again, we see that that current temperatures are not unusual except according to tree rings, which we know are affected by rising levels of CO2. (The paper does not mention CO2 or carbon or fertilizer).
https://joannenova.com.au/2024/08/paper-finds-the-world-was-cooling-for-most-of-the-last-2000-years-and-started-warming-long-before-big-coal-arrived/?utm_source=rss&utm_medium=rss&utm_campaign=paper-finds-the-world-was-cooling-for-most-of-the-last-2000-years-and-started-warming-long-before-big-coal-arrived

“All the evidence points out that we are still far from a complete understanding of the Common Era temperature variability at hemispheric and global scales,” says Professor Yang.”