Alan Kennedy – Cabot Institute for the Environment blog

Natural Systems and Processes Poster Session 2015. Image credit Amanda Woodman-Hardy

The Natural Systems and Processes Poster Session (NSPPS) is, it appears, now quite an establishment in Bristol: 2016 will be the event’s ninth year. What is it, and what has secured its place in the University of Bristol calendar for all these years?

Well, as the name suggests, it is an academic poster session welcoming pretty much anything relating to the science of the natural world. It turns out this description covers a lot of science, with representatives from Earth Sciences, Geographical Sciences, Physics, Life Sciences, Engineering, Chemistry and Mathematics. It’s a fascinating melting pot of ideas with some quirky and abstract topics on show, but each being a tiny, crucial cogwheel in the Earth’s system. The range of topics can show off the University’s diverse scientific community, spark collaborations and simply baffle all at the same time.

Besides the ‘boring’ scientific part of the event, NSPPS is a great occasion. Set in the Wills Memorial Building Great Hall, there is a plentiful stock of free food and drink and the social side of the event is great. Often the people carrying out the research are even more colourful than the science itself (especially after some free drinks). The social side also ensures the whole event is very relaxed, making it a great opportunity to get some practice and early feedback on your poster and presentation skills before taking on external conferences. Maybe you’re thinking of going to EGU in April? Then this is the perfect warm up. Added to that, there is healthy competition with entrants battling it out for a series of prizes from staff and student votes for the best posters. They’re proper prizes too (I can verify, last year I won an Acer tablet for the staff vote), so it’s definitely worth entering!

So here’s why NSPPS is still live and kicking after 9 years: diverse science, diverse people, laid back atmosphere, prizes and (of course) free food and drink.

Where? When? Great Hall, Wills Memorial Building. 2 pm – 5 pm, Monday 7 March.
Abstract submission deadline: midnight, Friday 29 February.
Full details at https://tiny.cc/nspps
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This blog is written by Alan Kennedy from the School of Geographical Sciences at the University of Bristol. This blog post was edited from Alan’s blog post at Ezekial Boom.

Alan Kennedy

Composite satellite image of what the Earth may have looked like prior to Antarctic
glaciation during the late Eocene (image by Alan Kennedy).

The Eocene-Oligocene Transition occurred approx. 34 million years ago and was one of the biggest climatic shifts since the end of the Cretaceous (with the extinction of the dinosaurs). The Earth dramatically cooled and the Antarctic ice sheet first formed, but the cause and nature of the cooling remain uncertain. Using a climate model, HadCM3L, we looked at the effect of ice sheet growth and palaeogeographical change (i.e. continental reconfiguration as Australia separated from Antarctica) on the Earth’s steady-state climate. We utilised four simulations: a late Eocene palaeogeography with and without an ice sheet and an early Oligocene palaeogeography with and without an ice sheet.

The formation of the Antarctic ice sheet causes a similar atmospheric response for both palaeogeographies: cooling of the air over Antarctica, intensification of the polar atmospheric cell and increased winds over the Southern Ocean. The sea surface temperature response to the growth of ice is very different, however, between the two palaeogeographies. For the Eocene palaeogeography there is a 6°C warming in the South Pacific sector of the Southern Ocean in response to ice growth, but very little change (or even a slight cooling) for the Oligocene palaeogeography. Why, under the same forcing (the appearance of the ice sheet), do these different palaeogeographies have such different sea surface temperature responses?

The stronger winds over the Southern Ocean force more-saline water from the southern Indian Ocean into the less-saline southern Pacific Ocean. This is particularly important for the Eocene simulations, where the narrow gap between Australia and Antarctica limits flow from the Indian to the Pacific Ocean. As salinity in the southern Pacific Ocean increases the water becomes denser and sinks, releasing heat. This accounts for the increase in sea surface temperature in the Eocene simulations. In the Oligocene simulations, flow is already much greater between the Indian and Pacific Oceans, and so there is no marked increase in density, sinking or sea surface temperature following glaciation. There is only a mild cooling due to the presence of the large, cold ice sheet.

Whether in reality the dominant ocean response to glaciation was warming or cooling may have impacted the growth of the ice sheet at this major transition in the Earth’s history. However, more importantly, this research highlights that sensitivity to subtle changes in palaeogeography can potentially have very large effects on the modelled climatic response to an event such as Antarctic glaciation. This could be very important for understanding palaeoclimate records and interpreting climate model results.

This research, carried out by Alan Kennedy, Dr Alex Farnsworth and Prof Dan Lunt of the Cabot Institute and University of Bristol with others, is featured in a special issue of the Philosophical Transactions of the Royal Society A. The full special issue on the theme of ‘Feedbacks on climate in the Earth System’ and the paper can be accessed here.

Special issue cover (image from Royal Society).

Citation: Kennedy A.T., Farnsworth A., Lunt D.J., Lear C.H., & Markwick P.J. (2015) Atmospheric and oceanic impacts of Antarctic glaciation across the Eocene–Oligocene transition. Phil. Trans. R. Soc. A, 373, 20140419, doi:10.1098/rsta.2014.0419.
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This blog is written by Alan Kennedy from the School of Geographical Sciences at the University of Bristol. This blog post was edited from Alan’s blog post at Ezekial Boom.

Alan Kennedy