Dust storms in northern China and their significance for the concept of the Anthropocene

A key scientific issue in the study of the Anthropocene is the determination of the corresponding stratigraphic marker in geological archives. The arid and semi-arid regions of Asia are the second largest dust source on Earth, and their release,transport and deposition of dust affect global climate change, as well as marine and terrestrial biogeochemical cycles. Over the past ～2000 years, human activity has outpaced natural climatic variability as the dominant control of dust storms in northern China. Thus, exploring the potential of anthropogenic Asian dust as a marker of the Anthropocene and its impacts on lake ecosystems may contribute to an improved definition of the characteristics and timing of the Anthropocene. In this context, we measured spectrally-inferred chlorophyll a from the sediments of an undisturbed alpine lake in northern China, and compared the results with dust storm data from the same cores and with regional climatic records. Asian dust is a widely distributed, globally significant signal of human activity, and it is also well preserved in various geological archives; hence, we propose anthropogenic dust can be considered as a potential marker of the Anthropocene. Anthropogenic dust signals in stratigraphic records during the past ～2000 years differ substantially from those during the early and middle Holocene, which demonstrates that, at least since～2000 years ago, human activity has exceeded the natural forcing of dust transport in northern China. We therefore propose that there are spatial and temporal differences in the onset of the Anthropocene, as defined by anthropogenic dust deposition, which is therefore time-transgressive. Our spectrally-inferred chlorophyll a record is consistent with dust storm activity over the past～2000 years(except since the 1950s), suggesting that anthropogenic dust storms were the dominant control on lake primary production. Prior to the 1950s the interactions of the East Asian summer monsoon(EASM), human activity, dust storms and lake ecosystems resulted in a shift from a pattern in which “human activity outpaced the EASM as the dominant control on the Earth surface system” to one in which, after the 1950s, “human activity became the dominant factor influencing the EASM and the Earth surface system”. In the future this pattern may trend towards one in which there is the “sustainable development of humans and the environment”. We suggest that, in order to better understand the interactions of human activity, climate and environment,future research on the Anthropocene should focus on its time-transgressive characteristics and regional differences, in addition to the “Great Acceleration”.