Massive glacier collapse

Re:Massive glacier collapse by snowwrestler on Monday February 04, 2013 @01:12PM (#5165855)

> The test in science is whether findings can be replicated using different data and methods. More than two dozen scientific papers, using various statistical methods and combinations of proxy records, have produced reconstructions supporting the broad consensus shown in the original 1998 hockey-stick graph, with variations in how flat the pre-20th century "shaft" appears.[12][13] The 2007 IPCC Fourth Assessment Report cited 14 reconstructions, 10 of which covered 1,000 years or longer, to support its strengthened conclusion that it was likely that Northern Hemisphere temperatures during the 20th century were the highest in at least the past 1,300 years.[14] Ten or more subsequent reconstructions, including Mann et al. 2008, have supported these general conclusions.

http://en.wikipedia.org/wiki/Hockey_stick_controversy

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Re:Massive glacier collapse by schoper on Monday February 04, 2013 @01:31PM (#5165996)

The collected historical temperature data series are messy. You plot them and it looks like noise. A simple average will tell you nothing. The regression analysis that goes on in these reconstructions tends to follow something like this algorithm:

1) Compare your collected data series to each other to determine a "reliability" index for each data series.

2) Construct a series as a weighted average on this reliability index.

3) Iterate, using your new series to calculate the reliability index.

There are substantial issues with the above approach, having to do with sensitivity to particular kinds of signals. For a while, the Climate Audit folks got a lot of mileage over a data set that was put in "upside down" in one of the reconstructions. Rather than claiming "data error," the author defended it based on the idea that the above process would just give it a negative weighting!

Regardless, you should see why the above could easily be susceptible to issues. Further, the disagreement between these reconstructions and what our limited historical sources tell us about the MWP, etc., makes them further suspect.

This is a problem for the global warming model because it means that we don't know what the historical standard deviation for temperature is. So we can't say whether the last 3 decades warming is "within normal deviations" or "unprecedented."

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Re:Massive glacier collapse by snowwrestler on Monday February 04, 2013 @02:17PM (#5166342)

Your critique sounds interesting but I don't know enough to evaluate it--I'm not a scientist myself.

I would just point out that scientific debate occurs through published papers and conference presentations, not programming message boards. I hope that you are publishing in those channels if you feel you have substantive contributions to this kind of research.

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Re:Massive glacier collapse by schoper on Monday February 04, 2013 @02:48PM (#5166599)

Nope, that's not actually how science works. Rather, that is "formally" how science work. Actual practice is far more messy. Personalities matter, personal bureaucratic clout matters.

And happily, informal communication and message boards matter more than you would think!

Also, the published papers reporting these studies are all easily available. I highly advise reading them for yourself.

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Re:Massive glacier collapse by scarmig on Monday February 04, 2013 @03:22PM (#5166830)

snowwrestler, it may vary by field, but my (non-climate) field relied almost entirely on informal communications, presentations, write ups being shared but not published.

I don't have direct experience with climatology, but from what I understand it's somewhat similar: conferences like AGU are really important to climatologists for that reason.

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Re:Massive glacier collapse by snowwrestler on Monday February 04, 2013 @03:57PM (#5167071)

To present (even a poster) at a conference like AGU, you have to submit an abstract and it must be accepted by a committee of other scientists. It's not a paper, but still counts as a form of review and publication.

Edit to acknowledge: obviously a lot of work gets done informally during conferences as well.

But it's in the service of publishable research, is it not? I don't think many scientists are going to say, "I'm changing my research program based on something I read on Hacker News yesterday." There's a bar for serious consideration.

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Re:Massive glacier collapse by snowwrestler on Monday February 04, 2013 @03:15PM (#5166777)

No offense, but those are the sorts of things that people say when their own research cannot pass muster for publication.

edit: misspelling

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Re:Massive glacier collapse by vacri on Monday February 04, 2013 @05:56PM (#5167796)

You just claimed not to be a scientist, yet you claim the high ground in knowing how science is conducted?

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Re:Massive glacier collapse by snowwrestler on Monday February 04, 2013 @08:41PM (#5168505)

I made a jerk comment above.

I stand by the importance of published work in scientific discourse, but I apologize to schoper for taking a personal shot that was not called for.

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