3 ms·
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 analys
by schoper 14y ago
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."
- snowwrestler 14y agoYour 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.
- schoper 14y agoNope, 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.
- snowwrestler 14y agoNo offense, but those are the sorts of things that people say when their own research cannot pass muster for publication. edit: misspelling
- vacri 14y agoYou just claimed not to be a scientist, yet you claim the high ground in knowing how science is conducted?
- snowwrestler 14y agoI 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.
- scarmig 14y agosnowwrestler, 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.
- snowwrestler 14y agoTo 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.