impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of terrestrial ecosystems

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 105; no. 2; pp. 449 - 453
• Main Authors: Kürschner, Wolfram M, Kvacek, Zlatko, Dilcher, David L
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15.01.2008; National Acad Sciences
• Series: From the Cover
• Subjects: Animals; Atmospherics; Biological Evolution; Biomass; C4 plants; Carbon dioxide; Carbon Dioxide - chemistry; Climate; Climate change; Climate models; Climate proxies; Diet; Ecosystem; elevated atmospheric gases; Environmental Monitoring; Flowers & plants; Fossils; Geological Phenomena; Geological time; Geology; Ginkgo biloba; Herbivores; Laurophyllum pseudoprinceps; Laurus; Laurus abchasica; Laurus nobilis; Mammals; Models, Biological; Nonnative species; Ocotea; Ocotea foetens; Ocotea hradekensis; Paleobotany; Paleoclimatology; Physical Sciences; Plants - metabolism; Proxy reporting; Proxy statements; stomata; stomata frequency; stomatal density; Temperature; Terrestrial ecosystems; Time; Time Factors; trees; Vegetation
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0708588105

The Miocene is characterized by a series of key climatic events that led to the founding of the late Cenozoic icehouse mode and the dawn of modern biota. The processes that caused these developments, and particularly the role of atmospheric CO₂ as a forcing factor, are poorly understood. Here we present a CO₂ record based on stomatal frequency data from multiple tree species. Our data show striking CO₂ fluctuations of [almost equal to]600-300 parts per million by volume (ppmv). Periods of low CO₂ are contemporaneous with major glaciations, whereas elevated CO₂ of 500 ppmv coincides with the climatic optimum in the Miocene. Our data point to a long-term coupling between atmospheric CO₂ and climate. Major changes in Miocene terrestrial ecosystems, such as the expansion of grasslands and radiations among terrestrial herbivores such as horses, can be linked to these marked fluctuations in CO₂.