Friday, August 16, 2013

More problems with climate data

This time it's with tree ring analysis:
A new paper now in open review in the journal Climate of the Past suggests that “modern sample bias “has “seriously compromised” tree-ring temperature reconstructions, producing an “artificial positive signal [e.g. 'hockey stick'] in the final chronology.”

Basically, older trees grow slower, and that mimics the temperature signal paleo researchers like Mann look for. Unless you correct for this issue, you end up with a false temperature signal, like a hockey stick in modern times. Separating a valid temperature signal from the natural growth pattern of the tree becomes a larger challenge with this correction.
Huh.  Pretty hard to see bias as driving that, just a reflection that the universe is a tricky place that we (mostly) poorly understand.  I wonder what sort of biases are in ice core data?  They're obviously highly dependent on precipitation levels as well as temperature.

Dang it.  And I thought that the science was settled.


kotetu said...

Ice cores:
don't forget pressure. I wonder how hard it is to separate out the crushing effects of thousands or millions of tons of ice piled upon itself.

Goober said...

We don't know.

That is essentially the sum of it, and will be for the foreseeable future. By the time we're certain, the changes will have already happened. (Not saying that they will, but if they don't, we'll continue to be unsure for as long as they do not).

Any attempt to "fix" a problem that we don't even know exists will have its own unforeseeable spider's web of consequences, and we have no way of knowing if we're trading the frying pan for the fire.

FOr the life of me, I can't figure out how anyone is attempting to make policy out of this mess in good faith.

Therefore, I can only assume that those trying to make policy out of this mess are not acting in good faith.

As I said over at my place about this time last year - we'll never agree, and we'll never know until (if??) it actually happens, and the only people who are wrong in this debate are the people who are trying to control the lives of others using this as their talking point.