Abrupt historic temperature changes
Over at Net Zero Watch David Whitehouse gives an interesting look at some new research on the dreaded melting of European glaciers, in the form of temperature reconstructions over some 2,500 years for the Pyrenees using speleothems
And what we want to draw your attention to, apart from it being real science and neither the authors nor Whitehouse engaging in cherry-picking and (see below) what a “speleothem” even is, is the amount and suddenness of temperature change in the past.
Especially the suddenness.
People often point to the rapid temperature increase in the late 20th century and say well, that’s unprecedented, must be man-made.
But actually these researchers’ charts show not just cycles including the late lamented Medieval Warm Period, and a Roman Warm Period far warmer than today at least on what is now the French-Spanish border, but dramatic surges and drops within the cycles, often over mere decades.
We also have to take a certain degree of satisfaction in the paper being published in something called Climate of the Past.
We keep saying that the right way to test a theory is against real-world data and that history is a splendid companion here because it’s easy to tell a computer to find a correlation between, say, atmospheric CO2 and temperature going forward, but the proof of the programming is in whether they correlated in the past.
Having said so, we then repeat the caveat that, as always when dealing with temperature proxies, you have to be cautious about the degree of precision.
What the authors of the paper in question did was examine oxygen isotopes within speleothems (which, in case you don’t speak geology, are various mineral deposits within underground caverns including stalagmites, stalactites and more, more being flowstone, columns, drapery and straws, since you ask).
The idea, and it is not controversial in principle, is that the ratio of Oxygen 16 to Oxygen 18 in various locations is a clue to the temperature of the oceans at various times. But there’s many a slip twixt the cup and the lip or, in this case, the Atlantic or Mediterranean and a rock dangling from the roof of an underground cave in Navarre.
Still, part of the adventure of science is filling in gaps, and in this case the authors compare their findings with other reconstructions using different proxies and find what looks like a pretty good fit.
We mentioned the lack of cherry-picking. So here’s a finding skeptics might not like:
“The Industrial Era shows an overall warming trend although with marked cycles and partial stabilization during the last two decades (1990–2010).”
And the Medieval Warm Period, or whatever they now want to call it, doesn’t seem to have been warmer than today at least there.
But here’s one the alarmists won’t:
“The Roman Period (especially 0–200 AD), the Medieval Climate Anomaly, and part of the Little Ice Age represent the warmest periods, while the coldest decades occurred during the Dark Ages and most of the Little Ice Age intervals (e.g., 520–550 AD and 1800–1850 AD).”
And
“Solar variability and major volcanic eruptions appear to be the two main drivers of climate in southwestern Europe during the past 2.5 millennia.”
Oh boo! Not the sun!
And here’s the kicker from our point of view:
“Importantly, the LIA cooling or the MCA warming were not continuous or uniform and exhibited high decadal variability.”
So it is normal, even typical, for temperature to fluctuate not just over centuries but even over decades. Which means a rapid warming from, oh, say, 1980 to 2000 doesn’t mean we’re out of the normal and natural.
It’s not the only evidence we have even from the Holocene interglacial.
As we’ve noted repeatedly, the initial and rapid warming at the end of the last glaciation was interrupted by a sudden, violent plunge in temperature into the “Younger Dryas” cold spell and then a sudden, violent increase more recently.
But the further back you go, the less detail the proxies contain especially about short time periods.
So to find that in the chart Whitehouse reproduces even the Roman Period far warmer than today, and everything since, exhibits a pattern of temperatures leaping about, dropping suddenly even in rising periods and shooting up even in falling ones, tells us that to try to draw any lessons at all from a short space of time, a term here meaning a quarter-century, is climate folly.
Again, it’s just one paper, subject to critique, and just one proxy. But as far as it goes, a highly suggestive one that the actual past of the climate does not support what alarmists are saying even about the present, let alone the future.
The city of Ottawa just ended its longest run of days with a high above 16°C in over a century. Must be global warming, right?
Except the days with longer runs since records began in 1872 are 1921, 1908 and in 1st place 1922. And the one we edged out was 1876… even though they measured at the Central Experimental Farm until 1931 then moved to the heat-trap airport.
Unprecedented… or just weather?
Well, for perspective, Ottawa also had our driest September in decades, the 7th since 1872 with less than 25mm of precipitation. Which one of our gardens certainly noticed.
So ‘climate breakdown’ causes drought? (As in, from another source, “The effects of climate change are proving catastrophic to our planet, destroying habitats and natural landscapes with flooding, droughts and other forms of extreme weather.”)
But the year we narrowly beat out was 1908, and the ones we didn’t were in ascending order of dryness 1956, 1941, 1887, 1984, 1948 and in 1st global-warming ravaged… 1897.
See more here climatediscussionnexus
Bold emphasis added
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