December 15, 2004 | David F. Coppedge

Cretaceous Temperature Estimates Point Out Flaws in Climate Models

Nature1 this week described evidence for high temperatures in the Arctic during the Cretaceous that it termed “astounding.”  Based on work by Jenkins et al. that Arctic waters were 15°C, as warm as modern coastal waters off France and Maryland.

For a region blanketed in darkness for half of the year, the Arctic Ocean was astoundingly warm.  It may have been even warmer earlier in the Cretaceous: proxy evidence indicates that the climate had been slowly cooling for nearly 20 million years.  Although astounding, the new estimate of Arctic seawater temperature is not without precedentFossil evidence of the tropical breadfruit tree Artocarpus dicksoni and of champsosaurs, extinct crocodile-like reptiles, has been found in sediments from the high Canadian Arctic dating to the middle Cretaceous (90-100 million years ago).

Did volcanic eruptions increase the global concentrations of carbon dioxide?  Models show levels 3 to 6 times as high as today’s, but even those do not raise Arctic temperatures that high.  But raising levels higher also produces higher temperatures at mid-latitudes, “temperatures that exceed the estimated values using proxy methods and approach the tolerance level of organisms.”  Christopher Poulson (U of Michigan), author of the news item, uses these findings to point out inadequacies in climate models:

Why do simulations of the Cretaceous climate predict polar temperatures that are too cold and Equator-to-pole temperature gradients that are too large?  The solution to the problem may lurk in the climate models themselves.  Attempts have been made to solve it by incorporating the effects of ocean heat transport, stratospheric clouds, ocean passageways, and vegetation.  The result, however, has been only incremental improvements.  Climate models still do an inadequate job of simulating the extreme warmth of a past greenhouse world – a troubling proposition for predictions of a future greenhouse world.


1Christopher Poulson, “Paleoclimate: A balmy Arctic,” Nature 432, 814 – 815 (16 December 2004); doi:10.1038/432814a.

Yet National Geographic in the September 2004 issue made the case that global warming was absolutely, certainly happening without a doubt, and only the ignorant or politically motivated would deny it.  Is this additional evidence that NG cannot be trusted in its science reporting? (see 10/24/2004 headline).  We all know that aliens cause global warming, anyway (see 12/27/2003 editorial).
    This article points out that models, age estimates and the evolutionary stories that go with them are spotty, inexact and uncertain, to use Poulson’s descriptions of past Cretaceous climate evidence.  How, therefore, can anything they say about the past or future be swallowed so uncritically by science news reporters?  They weren’t there, and they don’t know.
    Finding breadfruit tree fossils and other temperate and tropical plants (08/16/2004) and animals, including dinosaurs (03/29/2004) near both poles tells us something: the world was very different sometime in the past.  How could the poles get warm without the equator being too scalding for life?  It would seem there was a mechanism to moderate the global temperature like a mild greenhouse.  Maybe this will cause a rethink of theories of a pre-Flood global canopy; such models should get a hearing in the light of the failures of evolutionary modeling.  Let’s reconsider all those millions of years while we’re at it.

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Categories: Dinosaurs, Fossils

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