In present-day climates both temporal and spatial variations in precipitation can be significant, with substantial influence on ecosystems and human societies. Coupled atmosphere–ocean climate models have shown that small-scale global temperature variations can substantially alter the global precipitation budget and especially the regional distribution of rainfall. For instance, all future global warming scenarios predict global precipitation to increase between 1.4% and 2.3% per one degree of warming (IPCC2007), which can be attributed to a higher water-holding capacity of the atmosphere at elevated temperatures. However, regional variations in precipitation change can vary significantly.
Terrestrial palaeo-precipitation values can be estimated by palaeobotanical proxy-methods, as well as zoological methods. One of the latter uses herpetofaunal assemblages (Böhme et al. 2006). Principally, the method is based on the observation that climate and especially precipitation serves as a direct predictor for the herpetofaunal distribution and species richness and yields robust and widely applicable modelling results. According to their ecophysiological strategies and adaptations to maintain thermoregulation, water balance and gas exchange, amphibians and reptiles (excluding non-fossorial snakes) are assorted into six ecophysiologic groups. The relative frequencies of these groups show in recent communities a highly significant correlation to the mean annual precipitation, with mean prediction errors between 250 and 275 mm. The application of this palaeoprecipitation tool to fossil assemblages with rich amphibian and reptile records (low taphonomical bias with respect to herpetofauna) from alluvial sediments, paleosoils, caves, fissure fillings, pond and swamp deposits, and channel-fill sediments, expand significantly the spectrum of palaeoenvironments from which precipitation data can be obtained. This methodology is especially powerful in the ‘dry end’ of the climate system.
The application of this method to the Neogene terrestrial archive of Eurasia provides a new and deeper inside into regional climate and ecosystem evolution and their driving global mechanisms.
A large database of hundreds of suitable fossil locality provides a dense and continuous precipitation record over Europe.
By this we are also able to reconstruct non-analogous climates (climate states which has no analogues today), like the Late Miocene washhouse climates (Böhme et al. 2008). A washhouse climate is a extra-tropical climate, characterized by warm-subtropical temperature and a significantly enhanced hydrologic cycle.
Böhme, M., Ilg, A., Ossig, A. & Küchenhoff, H. 2006: New method to estimate paleoprecipitation using fossil amphibians and reptiles and the middle and late Miocene precipitation gradients in Europe.- Geology 34(6): 425-428; doi: 10.1130/G22460.1; 2 figures, 1 table, Data Repository item 2006083.
Böhme, M., Ilg, A., Winkelhofer, M. 2008: Late Miocene "washhouse" climate in Europe.- Earth Planet. Sci. Lett. 275(3-4): 393-401, doi:10.1016/j.epsl.2008.09.011.
Böhme, M., Winklhofer, M., Ilg, A. 2011: Miocene precipitation in Europe: Temporal trends and spatial gradients.- Palaeogeography, Palaeoclimatology, Palaeoecology 304: 212-218, doi:10.1016/j.palaeo.2010.09.028.
Böhme M., Vasilyan D., Winklhofer M. 2012. Habitat tracking, range dynamics and palaeoclimatic signiﬁcance of Eurasian giant salamanders (Cryptobranchidae) — indications for elevated Central Asian humidity during Cenozoic global warm periods. Palaeogeography, Palaeoclimatology, Palaeoecology doi:10.1016/j.palaeo.2012.04.032.
Vasilyan, D., Böhme M. 2012: Pronounced Peramorphosis in Lissamphibians— (Urodela, Cryptobranchidae) from the Paleocene–Eocene Thermal Maximum of Mongolia. - PLoS ONE 7(9): e40665