ABC Australia reports:
Growth rates of coral can override the climate information held in their skeletons, a study of giant corals has found.
The study, published in Geochemistry Geophysics Geosystems, indicates that scientists need to analyse multiple coral cores to build a picture of past climates…
“People speculate that we can reconstruct past climates from biological archives like tree rings and coral growth bands. But living things grow differently in different years depending on what is happening in the local area.”
“We need to be careful when reconstructing climate based on coral, and need to be able to replicate results from a number of different samples to create an accurate picture of past climate.”
The real question is where do you find a biological record that is affected by temperature and temperature alone. To claim that a tree ring indicates temperature is to claim that it doesn’t indicate hydration, nutrition, predation, pollution, competition… In elementary school I was taught that the first step in designing an experiment was identifying and controlling for variables. I think my fourth grade science project could’ve beaten Professor Mann’s.
no problem, guys like Briffa can just pick out the ones they like and toss the rest… oh wait
Didn’t Mann’s “Hide the decline” prove beyond a reasonable doubt that tree rings do NOT track temperature? Otherwise, there would be no decline in recent temperatures (per tree the rings) to hide.
Indeed. A researcher can crank numbers from almost anything. The first question is and and should always be whether the numbers actually mean anything, then whether they mean anything about the hypothesis being tested. Too many of these proxy methods are accepted with no critical thought or any attempt at validation.
As Jim notes: climate and temperature proxies have value but scientists and interested people need to understand them within their limits. If you’re splitting temps a thousand years ago into tenths based on two trees and their growth rings, you’re claiming a precision far beyond mortal Mann.
A quite sensible point that needs to be applied to all proxy measurement methods.