Interstadial is an interesting word. It means a somewhat surprising rapid warm up to a warm period during an Ice Age Glacial period.
Now think about that for just a minute. During a cold glacial time, things rapidly warm up. A lot. And without any nasty old CO2 to blame. This happens so much, so regularly, and so strongly that there is a specific name for it. Interstadial.
One, that happened “recently” in geologic time, is called the Mid-Wisconsin Interstadial. About 30,000 years ago. Things got warm. Just how warm? Well, it’s been hard to say, but most of the time folks figured it to be about as warm as now, or even a bit warmer. A Wag might ask how that can be without the Magic Gas CO2 in the air; but folks not bought into the CO2 Mythology know it’s easy to have natural warming. Nature has done it many many times.
In an article on WUWT, there was a discussion of the Mid-Wisconsin Interstadial. Commenter Frederick Colbourne said:
Scott A. Elias stated in 1999, “A Mid-Wisconsin interstadial warming dating from 43.5–39 ka was rapid and intense. At the peak of the warming event, about 42 ka, TMAX values were only 1–2°C lower than modern.”
That mosses were exposed from this interstadial is not indicative of much. The maximum temperature was not much below the present. Besides, the interstadial lasted only 4,000 years, not long enough for the Arctic coasts to rebound to their present elevation.
But the thrust of the paper in the WUWT article was that mosses were being exposed that had been under ice since that 44,000 years ago time. Which to me says that it was WARMER then as we have only now gotten the ice melted off those mosses and clearly they were not ice covered when they were happily growing to form there in the first place.
An Extraordinary Fondness Of Beetles
Turns out that there are “beetlemometers” that tell you the temperature in the past.
Late Pleistocene of North America
S A Elias, Royal Holloway, University of London, Egham, UK
ã 2013 Elsevier B.V. All rights reserved.
This article is reproduced from the previous edition, volume 1, pp. 222–236, ã 2007, Elsevier B.V.
interstadial, MIS 3, is thought to have lasted from approximately
65–25 ka. Isotopic data from Greenland ice cores and
North Atlantic oceanic cores show multiple, abrupt climate
changes during marine isotope stage 3 (Grootes et al., 1993).
Events within the first half of this interval cannot be dated by
the radiocarbon method, and organic deposits that are stratigraphically
correlated to the mid-Wisconsin interval are poorly
dated in many regions of North America. The analysis of fossil
beetle assemblages has progressed sufficiently in North America
to allow reconstructions of the timing and intensity of MIS 3
climatic change (Elias, 1999).
So climate changes abruptly, rapidly, and all on its own. No CO2 needed. It can, does, and has, rapidly warmed. I’m not going to quote the whole paper at you. Just a couple of cherry picked points about the fact that some places, during some of this time, were warmer than today. At least, per the beetles. Now if it can warm up to warmer than now in some places, all on its own, and without any CO2 from humans, seems to me it could be doing that right now all on its own too.
The clearest indication of the strength of interstadial warming
in eastern North America comes from the series of beetle
faunal assemblages from Titusville, Pennsylvania (Figure 1,
No. 6). The six fossil assemblages were deposited between
approximately 46 and 43 ka. Within this interval, the Titusville
faunas reflect climatic amerlioration, followed by cooling.
The oldest fauna (46.5 ka) indicates cooling of both Tmax and
Tmin to approximately the same level as at the Chaudie`re valley
site (Table 1). At the height of regional warming (ca. 45.7 ka),
Tmax was only 2 C less than modern levels, and Tmin was
approximately 6 C colder than modern. This warm interval
occurred at approximately the same time as the Upper Warren
Interstadial in Britain and the warm sea-surface temperature
interval between Heinrich events 4 and 5 (Elias, 1999). By the
end of the interstadial event (43.2 ka), regional climates had
cooled to even lower levels than previously. Thus, in the space
of approximately 3000 years, regional climates oscillated from
subarctic to boreal and back again.
So in 3000 years, it can be all over the place.
In the earlier MIS 5e period (roughly, the last interglacial period), it was warmer:
This evidence comes from several sites
on the Noatak River in northwestern Alaska (Figure 4,
Nos. 4–6) and the Nuyakuk site in southwestern Alaska
(Figure 4, No. 7). Full interglacial warming peaked at
levels that varied from region to region. In southwestern
Alaska, the height of MIS 5e amelioration was as much as
3.5 C warmer than modern at the Nuyakuk site. At the
NK-37 site in northwestern Alaska, Tmax climbed to as
much as 4.5 C above modern levels. Further east, summer
temperatures were probably closer to modern levels. The
best constrained estimate of average winter temperatures
during MIS 5e comes from Chi’Jee’s Bluff. This estimate
suggests that Tmin was approximately 4–7 C warmer than
Still, the world came through it OK…
But was it ever warmer after that last interglacial? Closer to modern times, but during the last glacial?
The strongest indication of interstadial warming
comes from the Titaluk River fauna dated 33.6 ka. This fauna
yielded a Tmax estimate 0.5–2 C warmer than modern. The
other faunas discussed previously yielded Tmax estimates that
were 0.5–2 C cooler than modern. Interestingly, a fauna dated
31.5 ka from Mayo Village, Yukon (Figure 4, No. 18), indicates
that regional Tmax had fallen to 5–6 C colder than modern
levels. Likewise, a fauna dated 35.2 ka from Eva Creek, interior
Alaska (Figure 4,No. 8), indicatedTmax levels 7–8 C colder than
modern. Thus, within the space of 2,000 years, temperatures
appear to have oscillated dramatically in eastern Beringia.
So about 33.6 thousand years ago. Smack in the middle of the glaciation. It gets 1/2 C to 2 C warmer than now in Titaluk River basin. Then turns around and plunges up to 7-8 C. All in about 2000 years. Kind of like the Roman Optimum to the Little Ice Age and back to the Modern Optimum. Only more so…
Now just how can some folks ignore that? In geologic terms, 30kya “nearly now”. There is just no foundation at all for saying that temperatures ought to be stable, nor that any changes are caused by people. The temperature changes on this planet. All by itself and whenever it wants to.
Further, it has been warmer than now; fairly recently. Polar life survived. The Bears were fine, as were the penguins.
It’s an interesting paper. There are many more like it. Searching on Mid-Wisconsin Interstadial is interesting; as is a search on Marine Isotope Stage 3 and similar.
Yes, many of the 24 or so interstadials in the recent glacial were D.O. events. That just makes the point even stronger. There is something, natural, driving those periodic warm then cold wobbles. It is not people doing it.
A stadial is a period of lower temperatures during an interglacial (warm period) separating the glacial periods of an ice age. Such periods are of insufficient duration or intensity to be considered glacial periods. Notable stadials include the Older Dryas and Younger Dryas stadials and the Little Ice Age.
An interstadial is a warm period during a glacial period of an ice age that is of insufficient duration or intensity to be considered an interglacial.
Generally, interstadials endure for less than ten thousand years and interglacials for more than ten thousand. The Eemian Stage, which lasted from about 130,000 to 114,000 years ago, was the last interglacial prior to the present Holocene epoch. The Bølling Oscillation and the Allerød Oscillation, where they are not clearly distinguished in the stratigraphy, are taken together to form the Bølling/Allerød interstadial, and dated from about 14,700 to 12,700 years before the present.
Greenland ice cores show 24 interstadials during the one hundred thousand years of the Wisconsin glaciation. Referred to as the Dansgaard-Oeschger events, they have been extensively studied, and in their northern European contexts are sometimes named after towns, such as the Brorup, the Odderade, the Oerel, the Glinde, the Hengelo, the Denekamp, etc.
So who’s to say this isn’t just another D.O. / Bond Event wobble? I can say they have not stopped happening.