Geologists have believed the ancient ocean levels rose and fell in cycles as ice sheets retreated and advanced which was caused by changes in earth’s orbit. Horton and Poulsen two geologists attempted to model this process and guess what? They couldn’t get the model to work! High fluctuations in atmospheric carbon dioxide was required to get rid of the ice sheets each time.
In the paper called; “Paradox of late Paleozoic glacioeustasy” global sea levels would have had to alternate by 100 meters or more to produce the beds but in their model that couldn’t get it to raise more than 25 meters. The problem comes in when their paradigm is based on 326 to 267 million years ago in conditions that were “primed the late Paleozoic paleoenvironment for glaciation.” In this time frame, carbon dioxide levels were low which throws the model way off.
They continue to explain…
“The ice sheets of Gondwana left not only direct geological evidence of continental glaciation, but also indirect sedimentary signatures of their waxing and waning,” they said. The presence of North American deposits that appear cyclic “has been used to infer that late Paleozoic depositional environments were largely controlled by glacioeustasy.”
Now if this is the explanation they have set their sights on, fluctuations in global sea level would be up to 200 meters high which is drastically higher than what global warming alarmists have been predicting for our future. Another part of the puzzle, can sea level changes of that magnitude be forced by orbital cycles? Horton and Poulsen set out to try and answer this very question. In the next section of this paper, they go through the methods they used for their model.
Huge “increases in excess of 2000 ppm were required to cause substantial melting of Gondwanan ice sheets.” This is real interesting considering the hype over the level of carbon dioxide at 384 ppm which is supposedly causing the end of the world through man-made global warming. “The dynamic response of continental ice sheet volume to our prescribed transient orbital insolation variations is modest,” they said.
What does that mean? It means that orbital forcing does not have a significant impact because it was unable to produce sea levels at a 100 meters or more!
“Our simulation of late Paleozoic glacial conditions presents a paradox. While our simulation of large (>100 m sea-level equivalent) continental ice sheets is in good agreement with sedimentological evidence of Gondwanan glaciation, our orbitally driven ice-volume changes are ~10 m, much smaller than the late Paleozoic glacioeustatic variations implied by both cyclothems and isotopic analyses. The absence of significant continental-scale ice sheet ablation in the face of changing orbital insolation poses a significant challenge to our current understanding of late Paleozoic ice sheet dynamics.”
As a result what is happening to the “Pleistocene glacioeustasy theory?” It was supposed to be better understood and have some sort of agreement with orbital and atmospheric factors. With a caving outlook on Unitarianism, but appeal to it happened because it happened. In other words, it’s circular reasoning. They also discounted the “energy balance model.”
“Simulations using an energy balance model (EBM) coupled to an ice sheet model indicate that orbital insolation variations alone can produce repeated ~100 m sea-level fluctuations (Hyde et al., 1999).
We cannot say with certainty why our results differ from those using an EBM; however, we suspect that differences in the paleoboundary conditions and/or the treatment of ablation and precipitation rates in the calculation of mass balance over the ice sheet might be responsible. For example, unlike our model where precipitation over Gondwana is explicitly calculated, EBM precipitation rates are based on prescribed modern precipitation rates (Hyde et al., 1999).
Predictions of equilibrium ice sheets made using GCM–ice sheet models with fixed (nontransient) orbital conditions have also been used to infer large late Paleozoic glacioeustatic fluctuations (of as much as 245 m; Horton et al., 2007).
However, our new results indicate that these estimates are too large. The reason is straightforward: in the fixed-orbit experiments, there is no preexisting ice sheet to influence the final mass balance. In contrast, in our transient experiments, the preexisting ice sheet (simulated during the previous orbital step) has a substantial influence on local conditions due to temperature-elevation and ice-albedo feedbacks. Orbitally driven insolation changes are not large enough to overcome these local ice sheet effects; consequently, orbital changes produce only small ice-volume fluctuations.”
Horton and Poulsen firmly believe they experimented with a reasonable model but unable replicate the paradigm. Even though models have limitations trying to explain a vast amount of complexity, but an orbital signature should have appeared somewhere in the simulation.
The only explanation left was non-uniformitarian – something that runs against the grain of the prevailing viewpoint in the science of geology. What we have learned from the jargon and math and computer skills, geologists and planetary scientists, atmospheric scientists understand very little. So overall, are we gaining more understanding and are better off using uniformitarianism. The answer is, no!