Name: Ritwika Sengupta
Age: 23
Year of study: 2nd Year
Department/research group: Earth Sciences

What are you researching: My project involves studying sphaerosiderites, which are small iron carbonate spheres. These form in wetlands such as bogs and can be found throughout the geological record.

You might be wondering why I chose to study this particular mineral…

Sphaerosiderites can reveal a huge amount about rainfall in the past, and by default about the climate. In today’s hotly contested climate debate, study of past climate forms an important part of understanding how our Earth responds to climate change. This growing field involves people from a variety of disciplines including Earth Sciences, Chemistry, Physics and Biology.

Nature stores signals of past climate in a number of ways. For instance, corals record the seasonality of the seawater they are growing from, ice records the oxygen isotope composition of the precipitation at the time of formation and shells of marine organisms are influenced by the temperature of the water. In a similar fashion, sphaerosiderites grow in wetlands, from water originating from rainfall over continents. They preserve the oxygen isotope composition of the rainwater at the time of their formation. Oxygen isotope ratios are strongly dependent on temperature and ice cover, and so can be used to reconstruct past changes in rainfall.

My work concentrates on the Early Cretaceous (130 million years ago), during which there were major climatic changes. Knowing the changes in rainfall patterns during this time period is important for understanding the Earth’s response to a changing climate.

ricky
I went to a summer school on Palaeoclimatology in Urbino, Italy this summer. The area had beautiful geology, renaissance history and great ice cream!

Academic background: I studied a Geology undergraduate (MSci) at Imperial College London before starting my PhD at Oxford as part of the NERC Environmental Research Doctoral Training Programme (DTP). I was interested in environmental research during my Master’s thesis, working on Carbon Capture Storage leakage remediation. But I quickly realised my real passion was in geochemistry and application of this to climate.

Motivation: My motivation to work on this project lies in an interest in past climate change. This can help us to understand the myriad of effects climate change has had in the past and perhaps the future! Also the Mesozoic Era is far more fun than the present.

Funniest fieldwork story: My backpack once rolled down the side of a steep mountain in Kinlochleven, Scotland, while everyone watched… and laughed.

The best moment of the PhD so far: Best moment so far has been getting an email from someone and being able to actually understand what they are saying. Also pretty pictures from the Scanning Electron Microscope.

The worst moment of the PhD so far:  The worst part is probably realising how long it takes to do anything and how technology is always out to get me.

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