Name: Brooke Johnson
Age: 34
Year of Study: 2nd
Department: Earth Sciences
Research Group: Chemical Sedimentology

What are you researching: I am attempting to quantify the effects of fluctuating oxygen levels (aka unstable redox) in marine environments on the ecosystems within them them, over very long timescales. Cold water can hold more dissolved oxygen than warm water; this is why polar marine animals tend to be larger than non polar counterparts. One of the consequences of a world with warmer oceans is that the water can’t dissolve as much oxygen and so the oxygen levels decrease. Another consequence of a warming climate is that it rains more.This, along with industrial farming, washes more nutrients into the oceans causing blooms of algae that further use up the remaining oxygen. This process of nutrient increase and algal blooms (called eutrophication) combined with low oxygen is called Oceanic Anoxia, and is lethal to most marine life. This is a growing problem in modern oceans with so called ‘dead zones’ spreading further and lasting longer each year. As well as being catastrophic for marine ecology, it is also devastating for the large numbers of people who rely on marine fisheries, particularly in the developing world.

Anoxic events are found throughout Earth’s history, usually as a result of rapid warming caused by large scale long lived volcanic events called Large Igneous Provinces, e.g. the Karoo-Ferrar LIP which erupted in the Early Jurassic. These anoxic episodes are generally associated with extinction events and the formation of black shales, the source of our oil. By studying these ancient events through the geology of the rocks they left behind we can observe environmental and ecological changes on time scales far longer than is possible than when studying modern climate change.

If the idea of contributing to the study of the impacts of climate change are not enough to pique your interest, there are some less impactful but still important reasons to study these events. As well as causing extinctions and producing the oil that powers our civilisation, fluctuating oxygen levels may have shaped the course of the evolution of early life. To understand this, I am looking at black shales from 1.4 billion years ago, to understand if unstable redox played a part in the transition from simple bacteria to complex cells with nuclei. I am also looking at rocks from 500-460 million years ago to see if unstable redox delayed the transition from simple ecosystems dominated by seafloor grazing and scavenging to complex animal ecosystems with the modern niches we recognise today. These ages may seem distant to the point of abstraction, but these events are part of a story that has shaped the world we live in and that we are intrinsically part of.

Academic background: Short version: I studied a Geology BSc at Birkbeck College, University of London, then came straight to Oxford.

Long version: I’ve loved Natural History and science in general since I was a wee lad and always wanted to be a Palaeontologist. Unfortunately, I hated secondary school, really struggled academically, and was told that university and a science career was beyond my abilities. After leaving school with minimal qualifications, I spent many years working in various jobs from crisp factories to call centers until a friend suggested I do an online degree in Geology. Originally this was to alleviate the crushing boredom and lack of fulfillment I experienced in the call center. I really enjoyed the degree and did really well to the point where the head of department at Birkbeck recommended that I apply to Oxford or Cambridge. I did, and now I am here getting paid to do what I love!

Motivation: I find Natural History fascinating in a way that is hard to express.It is the story of how a wet chunk of rock orbiting a fairly standard star, and the simple microbes that inhabited it, changed over billions of years to become the modern world. In particular, it is the story of a certain species of ape that learned to take the universe apart and put it back together as chairs or universities or the internet! It is beyond cool and interesting and engaging and I want to understand it all and then share it with anyone and everyone I can get to listen.

Funniest fieldwork story: I saw someone get their phone stolen by monkeys who ransomed it back in exchange for fruit while we were on the side of a volcano.

The best and the worst of the PhD so far: Most of what I do could be classed as a best bit, the only things I could class as the worst would be knowing that I only have one lifetime and will never even explore, let alone understand, a fraction of the things I want to understand. Also referencing, referencing is the worst.

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