Richard J. Behl, PNAS, 108(15), Glacial demise and methane's rise

Proceedings of the National Academy of Sciences, April 12, 2011, Vol. 108, No. 15, pp. 5925-5926; doi: 10.1073/pnas.1101146108

Glacial demise and methane's rise

1. Richard J. Behl*

Department of Geological Sciences, California State University, Long Beach, CA 90840, U.S.A.

1. Department of Geological Sciences, California State University, Long Beach, CA 90840

The historical sciences—geology, archeology, and cosmology—test hypotheses differently than the experimental, laboratory sciences. When the process or event being investigated took place long ago or at a great distance from the investigators, hypotheses are tested by assembling key data that can support or refute the likelihood of the proposed explanation. In this way, we have developed understanding and agreement on many major events in Earth history, such as the Cretaceous–Tertiary extinction or the glacial–interglacial cycles of the Pleistocene epoch. A consilience of findings is required, and in a mechanistic, causative model, timing is of critical importance. If a key factor in the explanation can be shown to have occurred at a time inconsistent with the model—too early or too late—the hypothesis has to be modified or rejected. In PNAS, Reyes and Cooke (1) apply a refined dating approach to assess the timing of deglacial environmental change across the high-latitude circumpolar Arctic and its relation to increases in a major atmospheric greenhouse gas, methane. In their study, these investigators use improved methods for presentation and interpretation of the initiation dates for a very large dataset of Arctic peatland, tundra, and thermokarst sites to demonstrate that their development occurred too late to be the principal cause of impressively abrupt and large methane increases in atmospheric methane abundance at the beginning of the Bølling and the end of the …

*Correspondence e-mail:   behl@csulb.edu

Link to extract:  http://www.pnas.org/content/108/15/5925.extract