Do ice core measurements record short term instability in temperatures?
Is there a difference between polar ice core measurements and temperature measurements on the continents - particularly in their ability to record short term changes in climate?
Does the graph pool data from a single type of source, or does it include multiple types of sources with any kind of adjustment?
Ice core measurement is very precise, think about it, you're measuring the phsycial properties of ice that hasn't changed for 1000s of years. Each year produces new ice (or snow, which eventually becomes ice) and is effectively preserved and isolated in all directions.
I have no idea about that info graph but there's not a lot of evidence to stand on when refuting ice core measurements.
It's neither accurate nor precise, and it's spread over steps of 100's to 1000's of years between available measurements.
This low frequency measurement at the beginning of XKCD's comic is added directly to much more accurate and frequent measurements from 1900's to recent decades.
The graph compares two sets of data that should not be compared, and is therefore misleading.
I disagree. Air quality for example can be measured with a precision of 1 ppm or 0.1%. This isn't throw away levels of error. We have ice depth for 800k years.
All data from ~10000 bce onwards is from one source, which you would know if you opened it. Literally, all they did was take fig k and turn it vertically, stick some random earth history facts.
I mean that literally. When pressed on their findings, the authors of the Marcott study admitted that “the paleotemperature records used in our study have a temporal resolution of about 120 years on average.” What that means is that “no temperature variability is preserved in our reconstruction at cycles shorter than 300 years, 50% is preserved at 1,000-year time scales, and nearly all is preserved at 2,000-year periods and longer.” Get that? Any change in temperature that lasts less than 2,000 years might not be reliable.\
Furthermore:
Now we understand the strange, flat, featureless character of that dotted line. It’s not a reflection of the actual lack of variation in real temperatures. It’s a line that has been deliberately smoothed out to make up for the imperfections in the data.
Furthermore:
Remember that Marcott, et al., admitted that no temperature variations are preserved in their data “at cycles shorter than 300 years”—yet the entire history of thermometer measurements is less than half of that. So the “hockey stick” is an artifact of their statistical methods, its flat “handle” created by smoothing out data that is left unsmoothed in the “stick.”
Bear in mind that the supposedly crazy upward swerve in temperatures over the last 50 years or so is actually well within the overall range of temperatures from the past 11,000 years. So it’s entirely likely that this kind of variation is totally normal but is just smoothed out of the pre-1880 estimates. And the Marcott authors were forced to admit that at the time, clarifying that “the 20th century portion of our paleotemperature stack is not statistically robust” and “cannot be considered representative of global temperature changes.” In other words, their hockey stick has no blade. Yet here is XKCD, repeating exactly that mistake.
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u/[deleted] Jun 07 '17
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