May 2008 GEOLOGY media highlights

Combustion of fossil organic matter at the Cretaceous-Paleogene (K-P) boundary
Mark C. Harvey et al., 5/26 Picton Street, Ponsonby, Auckland, New Zealand. Pages 355-358.

Harvey et al. have discovered curious, tiny smoke particles in sediments deposited during the dinosaur extinction event. Close examination of the distinctive particles revealed a striking resemblance to smoke from industrial burning of coal and oil. Because this type of smoke cannot be produced by forest fires, the likely explanation is that the Cretaceous-Paleogene meteorite struck and ignited an oil field. In fact, one of Earth's largest known oil fields lies next to the meteorite crater in the Gulf of Mexico. The meteorite impact would have released enough heat to burn vast quantities of oil, injecting massive amounts of carbon dioxide into the atmosphere. This carbon dioxide may have caused an interval of intense global warming, contributing to the extinction of the dinosaurs.

Response of the southern Greenland Ice Sheet during the last two deglaciations
Anders E. Carlson et al., University of Wisconsin-Madison, Department of Geosciences, 1215 West Dayton St., 104 Wilkinson, Madison, Wisconsin 53703, USA. Pages 359-362.

The greatest uncertainty in predictions of future sea-level rise in response to global warming is the contribution from Earth’s remaining ice sheets. This uncertainty stems, at least in part, from a limited understanding of ice sheet sensitivity to a warming climate, with current ice sheet models suggesting a relatively slow response of the Greenland Ice Sheet to global warming. Carlson et al.’s new records of southern Greenland Ice Sheet summer melting for the last two deglaciations provide a continuous history of how fast this ice sheet responded to the last two "natural" climate warming events. These data indicate that the Greenland Ice Sheet responded essentially synchronously with the warming climate, suggesting that this ice sheet is very sensitive to climate change. In particular, this implies that the current negative mass loss from the Greenland Ice Sheet may actually be the beginning of an accelerating trend in response to the small temperature warming attributable to anthropogenic greenhouse gases, rather than a short-lived oscillation in mass balance.

Geomorphic response to uplift along the Dragon’s Back pressure ridge, Carrizo Plain, California
George E. Hilley, Dept. of Geological and Environmental Sciences, 450 Serra Mall, Braun Hall, Bldg. 320, Stanford University, Stanford, California 94305-2115, USA; and J Ramon Arrowsmith, Arizona State University, Department of Geological Sciences, Tempe, Arizona 85287, USA. Pages 367-370.