Report

Late Miocene Atmospheric CO2 Concentrations and the Expansion of C4 Grasses

See allHide authors and affiliations

Science  06 Aug 1999:
Vol. 285, Issue 5429, pp. 876-879
DOI: 10.1126/science.285.5429.876

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Abstract

The global expansion of C4 grasslands in the late Miocene has been attributed to a large-scale decrease in atmospheric carbon dioxide (CO2) concentrations. This triggering mechanism is controversial, in part because of a lack of direct evidence for change in the partial pressure of CO2(pCO2) and because other factors are also important determinants in controlling plant-type distributions. Alkenone-based pCO2 estimates for the late Miocene indicate that pCO2 increased from 14 to 9 million years ago and stabilized at preindustrial values by 9 million years ago. The estimates presented here provide no evidence for major changes in pCO2 during the late Miocene. Thus, C4 plant expansion was likely driven by additional factors, possibly a tectonically related episode of enhanced low-latitude aridity or changes in seasonal precipitation patterns on a global scale (or both).

  • * Present address: Earth Science Department, University of California, Santa Cruz, CA 95064, USA.

View Full Text