Cores to Climate – Do our lakes hold a clue to the past? by Dr Carol Cotterill

Windermere is a beautiful part of the English Lake District and the BGS have been working here for many years, discovering lots about the glacial and post-glacial history of the region. This April, a team went back for a further two weeks of intense and dirty fieldwork collecting cores of the lake bed sediments. Last week they finished sampling on one of the cores (more coming about that process later in the week). So why exactly is this lengthy study necessary, why is all this hard graft essential?

 Hard graft on and after Windermere

Dr Carol Cotterill explains:

Taking cores of the lake sediments will allow us to carry out a full suite of investigative work, looking into a number of different areas including:

• Detailed analysis of glacial / pro-glacial varves, enabling us to accurately track seasonal climate fluctuations such as winter ice freezing and summer thaws and glacier advance and retreat pulses.
• Detailed analysis of anthropogenic pollution signals, both in their distribution across the lake and whether the signals tie into specific catchment drainage areas, but also in  the depth downcore. Dating of these upper sediments will help us establish when the pollution signals began to influence the lake.
• Pollen and diatom analysis – can we spot significant events such as Heinrich Events and the introduction of “exotic” plant species by the Victorian gardeners? We also hope to get a series of dates that will help us tie down these events.
• Paleomagnetic analysis including paleosecular and intensity values  – what was the Earth’s geomagnetic field doing over the UK and can we use these cores to refine the UK master curve?
• pH, bulk carbon and deltaC13 analysis to help guide our understanding of reservoir effects in freshwater lakes.
• The micro and macro deformation observed within lake “flows” – how can flows be triggered; do they move as a cohesive de-coupled unit or as a mass flow; why are they often limited to a specific time period within Windermere – what triggered this mass behaviour across the lake?
• Does the pollution signal help explain why certain fish species are now under threat, and how their spawning behaviours have changed between the two sub-basins of Windermere?  

These are some of the questions arising from the integrated datasets so far, and I expect more is to come as we delve deeper into the natural laboratory that Windermere is proving to be! As you can see the list above covers a wide range of disciplines and experts – a fantastic chance for BGS to collaborate on a wide range of science, and fully exploit the potential from this integrated lake surveying programme.