
Originally Posted by
RoadToad
You've mis-read the article. This study did NOT use tree rings. The reference to tree rings was a description of previous research that had been done, which did use tree rings, and as a result could only go back 1,500 years. This study used sediment cores, and as a result could go back farther in time. And I'm sorry if you "have no idea how reliable these measurement tools are." Magnesium levels in sea fossils is VERY reliable. Shellfish respond in very predictable ways to changes in temperature.
Not that tree ring data should be dismissed. You're right, "there are a lot of factors that can influence tree ring growth besides temperature." But we do have accurate records of the temperature for about the past 118 years, and it matches up with what is seen in tree rings, so you draw your own conclusions.
"The study tapped 73 sets of climate records, most from ocean sediment cores. Other researchers have inferred temperatures from temperature-sensitive proxies in the cores, such as the levels of magnesium in fossil shells.
Researchers have studied tree-ring data that goes back 1,500 years to estimate temperatures. They've also used individual data sets to try to gauge temperatures over longer periods. But Marcott said previous research hasn't extended global temperatures from proxies beyond the last 2,000 years."
I'm not going to call you cynical. What I will call you is somebody who read the article with a preconceived conclusion in mind.