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).

"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."

"We show that the millennial cooling of annual mean temperatures is likely a global phenomenon."

The paper looked closely at how all the proxies responded to volcano eruptions, and tree rings do seem to be useful. But without acknowledging that trees love carbon dioxide and grow faster with the fertilization effect of extra CO2, it feels like they are dancing around the point. They said tree rings capture the variability of shorter periods (less than 200 years) but that non tree ring proxies were better for variations longer than 200 years. The news that matters the most to mum and dad voters is that they found a significant long term cooling trend, but that information is buried in the text.

And as so many proxies have shown, global warming started back in the late 1600s, long before human emissions of CO2 started.

UPDATE: Look at the non-tree-ring proxy — the warming began in the Southern Hemisphere before 1700AD. See also the 120 proxies of Christiansen and Ldundqvist, and the signal in China. What started that? Climate modelers have no idea. It wasn't cars and coal power. It wasn't man-made CO2. We don't understand the big forces that drive our climate, yet we make you pay for your imaginary sins anyway.