Bringing 210Pb dating into the 21st century

In this collaborative project between the UK and the USA, we will apply a newly developed and highly promising statistical technique to a large number of lakes as important natural archives of past environmental change. Understanding how our planet works is one of NERC's core strategies, and global change is a topic of extreme societal importance and urgency. Indeed, the UK recently declared a climate emergency. Humans have caused massive changes to lakes and watersheds worldwide, especially over the past two centuries. Moreover, lakes act as records of the historical dynamics of climate, environments, ecosystems, erosion and other human impacts, because their mud stores indirect or proxy environmental information such as pollen or stable isotopes as it accumulates over centuries to millennia. In order to compare different time-series on a unified calendar scale, and thus to reveal rates of change and possible mechanisms for the recorded environmental changes, reliable chronologies are essential.

Radioactive isotopes such as Pb-210 or C-14 are the most commonly used tool to construct lake chronologies. However, especially Pb-210 dating comes with large and often poorly quantified uncertainties which cannot be resolved using currently available classical statistical methods. A newly developed Bayesian alternative provides much enhanced chronologies than can span further back in time, provide better precision estimates, and for the first time can systematically include C-14 and other types of dating information.

By collaborating with world-leading laboratories on lake records and Pb-210 dating, we will pool our resources and apply our new technique to a varied range of lake cores dated by Pb-210. The Minnesota lab is closely affiliated with the University of Minnesota, and together they attract hundreds of national and global visitors to obtain the best possible natural archives of past environmental change. Through this collaboration, we will be able to further develop our method and produce enhanced chronologies for many hundreds of existing natural records, including some challenging ones. Last but not least, through a range of workshops, by releasing our open-source tools for free, and by demonstrating the advantages of our new approach to individual lab visitors, we will disseminate our methods to a large number of researchers within the UK, the US, and further afield, and thus influence future research into recent environmental change.

Enhanced documentation and measurement of environmental changes within lake records provides better evidence to support decision making. This research project will enable existing and future 210Pb-based chronologies to become more transparent, systematic, comparable, robust, reliable, precise and accurate. As such, our research has a strong potential to positively impact a large amount of applied research into recent environmental change over the highly relevant past 1-2 centuries, including but not limited to studies on sea level change, pollution, ecosystem change, degradation and restoration.