In March 2020, the third and final instalment of my PhD research made its way into Climate of the Past. In that article, I do my best to synthesise all I learnt over 5 years about an event that occurred 34 million years ago called the Eocene-Oligocene Transition. (Just so we are all on the same page: palaeoclimate scientists are interested in this period of the Earth’s history as it is when the first major Antarctic Ice Sheet appeared; before then Antarctica was warm and at least partially forested.)
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| An image of what Antarctica might have looked like at the onset of the Eocene-Oligocene Transition. |
Four and a half years ago I wrote a piece for the Cabot Institute Blog about using a climate model to understand this point in the Earth’s history, and how many questions remained in our understanding. Why was the Earth so hot beforehand? What caused it to cool and eventually for Antarctica to glaciate? What other important changes would have occurred around the world at this time? At the time, I focussed particularly on the latter question.
The more time I spent trying to answer some of these questions, predictably (as is the way with science), the more complex some of them became. In the end, for my own peace of mind, I simply tried to bring together as much information as I could from lots of different sources to try to create a picture with some sort of clarity. I focussed on the high latitude Southern Hemisphere, because that is where a lot of the action was occurring at the Eocene-Oligocene Transition and it is also where models potentially have some difficulties in reproducing the climate.
To build up this picture, I used multiple climate model simulations of the period from two different modelling groups and compared these to the biggest dataset of proxy records of Southern Hemisphere climate 34 million years ago that I could compile by myself. Just reading and compiling all of the data from papers took me around a year. Not solidly (I had lots of other things to do too), but even still, reading papers solidly is very difficult in my opinion. Synthesising all of that different information into something coherent in my head is also something that I cannot force to happen quickly. It comes when it is ready.
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| Some of the complied proxy data for the high latitude Southern Hemisphere the Eocene-Oligocene Transition included in Kennedy-Asser et al. (2020). |
This blog is written by Cabot Institute member Alan Kennedy-Asser, a Research Associate at the School of Geographical Sciences, University of Bristol. You can follow Alan on Twitter @EzekielBoom.
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| Alan Kennedy-Asser |