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Is the greenhouse theory a fallacy? A paleontological paradox

¹ Department of Geology, Museum of Northern Arizona, Flagstaff, AZ 86001

The first 300 words of the full text of this article appear below.

Over a hundred years ago, Svante Arrhenius (1896), building on earlier work of the French physicist Joseph Fourier, Tyndall (1861), Langley (1884), and others, was the first to model quantitatively the effects of changes in the concentration of atmospheric carbon dioxide on climate (Uppenbrink, 1996; Fleming, 1998). A "greenhouse theory", or "hothouse theory" as it was then called (Arrhenius, 1908), thus was born and has stood the test of time pretty well since its 19^th-century origins, despite falling out of favor for a brief period between 1900 and 1940 (Fleming, 1998). Quaternary ice-core records, now spanning four complete glacial-interglacial cycles (Petit et al., 1997), have provided the strongest support, to date, for the role of greenhouse gasses as primary drivers of global climate change rather than as mere feedback effects (Shackleton, 2000).

A number of recent publications based on paleontological and geochemical proxy data sets, however, have challenged the notion that climate and atmospheric CO₂ have been coupled throughout pre-Quaternary time (Pagani et al., 1999; Pearson and Palmer, 2000; Viezer et al., 2000; Royer et al., 2001). Intervals of extreme global warmth, such as the late Paleocene and early Eocene, appear to be associated with relatively low ambient CO₂ concentrations (Royer et al., 2001), invoking alternative or additional mechanisms, such as altered ocean circulation, for high-latitude warmth during this interval. Similarly, the mid-Miocene climatic optimum ( 17 to 15 Ma), according to some proxy CO₂ records, was not associated with high concentrations of greenhouse gasses (Pagani et al., 1999; Pearson and Palmer, 2000), but rather with concentrations lower than today.

An apparent paradox has emerged—the pre-Quaternary history of CO₂ and climate interaction, which once appeared . . . [Full Text of this Article]