It is interesting to note that the recent definition of the beginning of the Holocene with reference to ice cores (Walker et al., 2009) fails the criterion of

being recognizable well into the future because of the geologically ephemeral nature of ice. Some geological boundaries are characterized by distinct geochemical markers; for example, the iridium anomaly at the Cretaceous–Neogene boundary, which is thought to have GS-7340 mw been caused by a meteorite impact. The Anthropocene will leave numerous clear markers including synthetic organic compounds and radionuclides as well as sedimentological memories of sudden CO2 release and ocean acidification (Zalasiewicz et al., 2011b). Many older geological boundaries were defined by disjunctures in the fossil record marked by first appearances or extinctions (Sedgwick, 1852). However, the age of these has changed with improvements in radiometric age dating; for example, the beginning of the Cambrian has moved by 28 million years since 1980. There is abundant evidence that we are currently experiencing the Earth’s sixth great mass extinction event (Barnosky et al., 2011), which will be another hallmark of the Anthropocene. The changes that mark the beginning of the Anthropocene are certainly changes of sufficient magnitude to justify a geological boundary (Steffen et al., 2011), whereas the gradual

or small-scale changes in regional environments at earlier times were not. The term Palaeoanthropocene is introduced here to mark the time interval before the industrial revolution during which anthropogenic effects Caspase inhibitor clinical trial on landscape and environment can be recognized but before the burning of fossil fuels produced a huge crescendo in anthropogenic effects. The beginning

of the Palaeoanthropocene is difficult to define and will remain so: it is intended as a transitional period, which is not easily fixed in time. We emphasize that we do not intend it to compete for recognition as a geological epoch: it serves to delineate the time interval in which anthropogenic environmental change began to occur but in which changes were insufficient to leave a global record for millions of years. Although it covers a time period of interest to many scientific disciplines stretching from archaeology Histamine H2 receptor and anthropology to palaeobotany, palaeogeography, palaeoecology and palaeoclimate, its beginning is necessarily transitional on a global scale because it involves changes that are small in magnitude and regional in scale. The history of human interference with the environment can be represented on a logarithmic timescale ( Fig. 1), resulting in three approximately equal areas. In the Anthropocene, major changes (orange) have been imposed on natural element cycles (black bar) that were typical of pre-human times. The Palaeoanthropocene includes the Holocene (beginning 11,700 years ago) and probably much of the Pleistocene (2.