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Climate Emergency Tour: Interglacial Edition

We found the climate emergency. We weren’t having any luck rummaging through the current interglacial era, namely the 10,000 years and counting since the great ice sheets last retreated. So we decided to look a little further back and see if there might have been a climate crisis in previous interglacial periods. By the alarmist's reasoning the previous four interglacials had to have been non-stop emergencies, since they averaged 1-3 degrees warmer than the current one.

Which means tipping points, runaway greenhouse effects, mass extinctions and general disaster, right?

The graph above comes courtesy of Professor Ole Humlum's helpful website climate4you.com. It shows the average temperatures relative to the present (the dotted line) as inferred from an ice core drilled deep into the Antarctic ice cap going back 450,000 years BP (Before Present). And in it we can make out many interesting details of our planet's climate history.

Most of the past half million years was an ice age in the popular sense, with glaciers covering much of the northern and southern hemisphere continents. (The technical definition is any period with significant polar ice, so the entire 2.7 million year Pleistocene Epoch is an “ice age” including our current Holocene “interglacial” which is not an Epoch but a mere Age.) The little red islands on Humlum’s graph represent short 10-20,000 year respites of warmth when the ice melted back and, um, life flourished. And as you can see, over the past half-million years when warming does happen it is both sudden and brief, and ends as suddenly as it began. And the periods of glaciation get, on average, 6 to 8 degrees C colder than the present before they're over, which means that if another one starts, even the high end of climate model predictions for the effects of doubling CO2 in the atmosphere (about 4.5 degrees C) wouldn't spare us and many other species an icy death.

Another peculiar feature of this graph is that the current interglacial is surprisingly cool compared to previous ones, just as the temperature in successive glaciations seems to be trending downward. Which doesn’t just suggest that the planet is on a long and frankly ominous cooling trend. It means that each of the past four interglacials saw temperatures at or above the level the alarmists claim would constitute a crisis if we returned to them. But if so, the 10-20,000 year warm intervals in those earlier interglacials ought to have been times of perpetual climate crisis for the whole Earth. Certainly the polar bears and coral reefs should have vanished.

At least, they should have if you accept the alarmists' definition and assumptions. We think the brief warming wasn't the crisis. It was a short respite between long stretches of climate crisis, the cold periods in which life retreated, plants died, vast regions became deserts and the planet approached the genuinely uninhabitable condition it will reach if CO2 falls below 150 ppm or temperature drops much more than 10 degrees below its present level.

3 comments on “Climate Emergency Tour: Interglacial Edition”

  1. The difference between the peak temperature on this graph, and the low temperature on this graph, is about 12 degrees C. Meanwhile, over the past 450,000 years, atmospheric CO2 levels have fluctuated from about 230 ppm to 350 ppm. - as Al Gore famously mislead everyone, more or less in lock-step with the temperatures in this graph. (Actually, when you look closely, CO2 concentrations lag temperature by about 800 years. But set that problem aside for the time being.) Now, if CO2 is the control knob of global temperature, it follows from the above figures that temperature rises and falls 1 degree C for every 10 ppm rise or fall in CO2, within this range. But we are now at 410 ppm CO2 in the atmosphere, which is 70 ppm higher that the highest historical peak in this range. So we should be about 7 degrees C warmer than the hottest peak on this graph, if the relation between CO2 and temperature conjectured by global warming theory is correct. Instead, we are about 3 degrees C cooler than the hottest peak on this graph. That means we are 10 degrees C cooler than the theory suggests. Of course, that's a good reason to double down on the scaremongering; it's not a good reason to reject the theory.

  2. Dear Thylacine,
    Please write me. Alan Stewart landscapejaspers@gmail.com
    Finally, finally someone else noticing the ratio of CO2/temps WHICH COMPLETELY DESTROY THE ALARMIST B.S.
    The time lag is irrelevant. The ratio is the only thing of importance. 7 degrees is interesting as the Scotese-Berner graphs show max temps over the last 600 million years at ~22 about 7 above our present estimated 14.5C

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