Friday, 15 March 2019

Tropical palaeoclimate meeting as temperatures break records in the UK…by Heather Moorhouse

The DeepCHALLA group meeting in February 2019
In 2018, the UK NERC-funded collaborators of the International Continental scientific Drilling Program - DeepCHALLA project met in Cambridge amidst a Siberian blast, known as the “Beast from the East”, as temperatures plummeted and ice and snow disrupted UK travel. In 2019 however, the scientists met in tropical Lancaster, during maximum temperature records for the month of February. It is predicted that weather events will be increasingly unpredictable, variable and extreme, and the temperature differences between our two meetings merely serves to highlight the future under climate change.
 
This is why projects such as DeepCHALLA are important. If we can improve our understanding of what drives long-term climatic variability, we can then improve our predictions about what might happen in the future. Such predictions can help communities improve resilience to climate change. DeepCHALLA is a collaboration of scientists looking into ~250,000 years of climate and environmental change in equatorial east Africa. Much of our knowledge about global climate systems come from the poles so this is a fundamental research gap in which to explore.

The DeepCHALLA group meeting in February 2018
The meeting this February in Lancaster consisted of NERC-funded UK scientists from BGS, Cambridge University, Lancaster University, SUERC and Queens University, Belfast; alongside collaborators from Belgium and Israel. We have been looking into a variety of proxies from a lake sediment core taken  from Lake Challa, a deep volcanic crater lake on the Kenyan-Tanzanian border. There have been some exciting reconstructions of the past environment using the volcanic ash, radioactive isotopes, palaeomagnetic signals, and chemical markers from phytoplankton remains found within the sediments.

My role at Lancaster has involved working with the BGS group, to prepare samples from the organic matter and the phytoplankton remains found within the sediment. In other words, we have been looking at the chemical markers stored within these proxies that provide a unique snapshot of the environment at certain times in the lakes history. Specifically, we have been using these proxies to help understand changes in lake carbon cycling using the carbon isotopes and ratios of precipitation versus evaporation of the lake using the oxygen isotopes. We are particularly interested in the period known as the African “mega-droughts”, unprecedented periods of drought that lasted millennia and were believed to have occurred around 130-90 thousand years before present. Nearly (but not quite all…) of the laboratory analyses are complete and so, the next steps will involve bringing together all the proxies across the entire project, in order to provide a robust chronology of the “mega-droughts” and other events, and determine how the landscape and lake has evolved over time and how the climate may have helped shape this.

Heather is a post doctoral research assistant on the NERC funded grant (between Lancaster, BGS, Cambridge, Belfast, SUERC) based at Lancaster University.

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