Sampling Rate

A reader recently asked:

T, from my mechanical engineering world we have strict rules on sampling rates vs. signal frequency rates. Ie you cannot reliably measure a 60hz ac sine wave with a 5hz analog sampling device. The result ends up being strange results that don’t show spikes well and also might not show averages well either. Can you help me understand how 120 year sampling proxies can resolve relatively high frequency temperature spikes?

This objection comes up so often from those who are accustomed to data which are evenly sampled in the time domain, and the misconception is so firmly imprinted on so many people, that it’s worth illustrating how uneven time sampling overcomes such limitations.

Does Fracking Cause Earthquakes?

Mother Jones reports on recent earthquakes in regions not accustomed to much seismic activity, Oklahoma, Arkansas, and Ohio. Much of their story consists of anecdotal evidence, particularly the strongest earthquake in Oklahoma history at magnitude 5.6 in November 2011, which happened along a fault which a Univ. of Oklahoma geophysics professor referred to as “a dead fault that nobody ever worried about.” Since this quake “injured two people, destroyed 14 homes, toppled headstones, closed schools, and was felt in 17 states,” people are starting to worry.

I’m Mad as Hell

This post has nothing to do with climate change, or any aspect of science or mathematics. It’s about politics. It’s about why, even though I think the democratic party in the USA is generally incompetent, I’m still a staunch supporter. Because every now and again I see something that makes me so angry … I feel the need to rant.

I know lots of republicans. Not politicians, not party leaders, just plain old folks with a strongly conservative bent. Some are extreme, claiming membership in the “tea party” and believing that President Obama wasn’t born in the USA. I have strong disagreements with them. But none of them, not one, not a single goddamn person I know, would dare, would even consider, to deny food to a child in school.

Smearing Climate Data

Note: See the update at the end of the post for a test involving 1000 (rather than 100) Monte Carlo simulations.

If a temperature event like we witnessed in the last century — a warming of around 0.9 deg.C in about 100 years — had happened at some other time in the last 11,300 years, would it have left some trace in the recent paleoclimate reconstruction of Marcott et al.?

Too Little Time

Those in denial of global warming and its danger have tried to make a big fuss over what they perceive as a lack of warming recently. How recently depends on just how much they’re willing avoid seeing.

For the Record

Since Anthony Watts has decided to repeat Steve McIntyre’s accusation, I’m posting my response to a previous comment on this blog:

wte9 | April 1, 2013 at 11:40 pm | Reply

“Also for your information, the original version of this post mentioned McIntyre (and linked to his posts) extensively. But prior to posting I decided to remove that, since McIntyre had already fully explored the ‘low road.’”

Can you clarify something: Are you saying you used McIntyre’s ideas, but removed any citations attributing those ideas to him because he was taking the low road? Or are you saying something different? Thanks.

[Response: All I "learned" from McIntyre's "analysis" is that Marcott et al. had re-calibrated proxy ages, that McIntyre blamed the uptick on the re-dating process, and that he was happy to hint at the possibility of deliberate deception on the part of the authors. The references to McIntyre in my original version were to his insulting tone regarding this work, but I finally decided it was better to ignore that and comment on the science. It now seems that on the "dot earth" blog he chose to accuse me of having "shamelessly plagiarized" his ideas on why the exaggerated uptick occurs in the Marcott et al. temperature reconstruction. He's wrong.

I didn't read all his posts about the paper, for two reasons: first, there are so many, and I find them so full of sneering and thinly veiled innuendo that they're sickening; second, there's really very little to be learned from him. In my opinion he's just not interested in understanding the science, he only wants to kill hockey sticks.

I'm hardly ignorant of the effect of station dropout (in this case, proxy dropout) on averaging temperature data, I've known about it since long before Marcott et al. was even published. If Steve McIntyre wants to claim that he identified proxy dropout as the reason for the extreme recent temperature uptick in the Marcott paper before I did, fine. It wouldn't be the first time two different people had the same idea. I congratulate him on his insight. As for his assuming that I got the idea from him and didn't credit him, it's no surprise that he would assume the worst possible motives in others.

My opinion: perhaps if Steve McIntyre had been more careful in explaining himself, more interested in communicating reality than in demeaning the results, and less indulgent of his own sneering, people might refer to him rather than me when mentioning the impact of proxy droupout, and the "dot earth" blog might be referring to his posts rather than mine as "illuminating."

Also my opinion: if Steve McIntyre were really interested in the science rather than just killing hockey sticks, he might have applied the "differencing method" himself and discovered that the uptick is still there (but reduced in size) when the impact of proxy dropout is dealt with, whether one uses the re-calibrated ages or the original published ones.

But that would require him actually to do some science.

Notice that I not only identified (quite independently) the reason for the exaggerated uptick, I also implemented a method to overcome that problem? Notice how I showed the result and compared it to Marcott's reconstructions? Notice how I computed the result using both the re-calibrated and the originally published proxy ages? Notice how I did so for the same latitude bands as Marcott, and compared those too? Notice how I even did an area-weighting of those latitudinal results? Science.

Notice also that I disputed the reality of the exaggerated uptick in the Marcott et al. reconstruction without once even hinting that the authors had manipulated the data for nefarious purposes?

As for the differencing method, I didn't credit the inventor (I don't even know who it is) although I didn't come up with that one independently. Perhaps McIntyre will accuse me of having "shamelessly plagiarized" that as well.]

Easy Question

A question was asked recently:

Sorry, it’s not about Arctic not Antarctic, but the Arctic thread seems to be already closed for commenting. There’s a thing I can’t understand about Arctic sea ice – how come according to NSIDC the maximum sea ice extent in 2013 was the 6th lowest in satellite history while Jaxa is showing it to be higher than the 2000′s (not even 2010′s) average?

http://nsidc.org/arcticseaicenews/

http://www.ijis.iarc.uaf.edu/seaice/extent/Sea_Ice_Extent_L.png

The short answer is: in the JAXA plot, the line labelled “2000′s Average” isn’t the 2000′s average.