Regional impacts of global climate change: a local humid phase in central Iberia in a late Miocene drying world

摘要

The end of the Miocene was an eventful period of changes in climate and geography, and a restructuring of terrestrial plant and mammals. The tendency towards global aridification has attracted much recent interest, making the late Miocene a striking case-study for testing current and near-future scenarios involving global warming. Little is known about the consequences of global changes in temperature and precipitation at regional or local scales. Given its geographical position and extraordinary fossil record, the Iberian Peninsula offers many insights into short- and long-term shifts in climate, and the local response. Here, we explore the diet and ecology of large-mammals through tooth-wear patterns, and examine changes in local climate and habitat conditions in central Spain in a period (9.1-6.3 Ma) for which there exists a dearth of palaeoenvironmental information. Relatively dry climates and open-woodland landscapes evolved locally during the late Vallesian and early Turolian (9.0-7.7 Ma). Unexpectedly, we detect a period of high precipitation and a peak of humidity at the end of the Turolian (7.0 Ma) that prompted the development of wetter, more forested habitats, suggesting that the traditional view of the late Miocene as a steppe landscape is a misconception. We also find a period of relatively drier and warmer conditions from the early Ventian onwards. Overall, our finding that a local episode of increased humidity in central Spain was synchronous with a global warming trend in Europe provides evidence that the greatest climatic changes may have an opposite impact at regional and local scales.