Skip to main content

Oligocene discussion day

By
On the 16th of May, the University of Bristol held a half-day meeting devoted to the discussion of the Oligocene epoch (34 to 23 million years ago [Ma]). The Oligocene is a period of relative climate stability following the establishment of permanent ice sheets on Antarctica (34Ma). By the early Miocene (23Ma), atmospheric CO2 was low enough to allow the development of northern hemispheric ice sheets1. As a result, the Oligocene may have been the only time in the Cenozoic era (65-0Ma) during which a unipolar glaciation could exist.

Despite this, the Oligocene has received little attention from the Cenozoic palaeoclimate community. The aim of this event was to promote awareness of the Oligocene and encourage future research within this field.

Ellen Thomas, currently in Bristol on sabbatical from Yale, and David Armstrong-McKay, from the National Oceanography Centre (NOC), began the morning session with a series of talks devoted to the late Eocene and early Oligocene. Ellen discussed the Eocene-Oligocene transition (34Ma) from both a modern2 and historical3 perspective while David outlined the competing hypothesis put forward to explain the event4.   Dierderik Liebrand, also from the NOC, followed this with a talk on late Oligocene and early Miocene (24-19Ma) cyclostratigraphy5.  Following lunch, Bridget Wade gave an hour-long seminar on the Eocene-Oligocene boundary (34Ma)6 and the middle Oligocene (24-30Ma)7. Bridget’s talk doubled as a departmental seminar in the School of Geography.




Figure 1: A compilation of benthic foraminifera oxygen isotope values. During the Oligocene, this reflects a combination of ice volume and temperature7

The event was hosted by Gordon Inglis, a PhD student in the School of Chemistry, and was funded by Professor Rich Pancost (Global Change) and Professor Paul Valdes (School of Geography).

--------------

For more information, please consult the following references:

1. Zachos, et al. (2008) An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics: Nature, v. 451, p. 279-283
2. Liu, Z. et al (2009) Global cooling during the Eocene-Oligocene transition: Science, v. 323, p. 1187-1190
3. Kennett and Shackleton (1976) Oxygen isotopic evidence for the development of the psychrosphere 38 Myr ago: Nature, v. 260, p. 513-515
4. Merico, A, et al. (2008) Eocene/Oligocene ocean de-acidifiation linked to Antarctic glaciation by sea level fall: Nature, v. 452, p. 979-982
5. Liebrand, D., et al. (2011) Antarctic ice sheets and oceanographic response to eccentricity forcing during the early Miocene: Climate of the Past, v. 7, p. 869-880
6. Wade, B., et al (2011) Multiproxy record of abrupt sea-surface cooling across the Eocene-Oligocene transition in the Gulf of Mexico: Geology, v. 40, p. 159-162
7.  Wade, B. And Palike, H., (2004) Oligocene climate dynamics: Palaeoceanography, v. 19, PA4019


Popular posts from this blog

Converting probabilities between time-intervals

By
This is the first in an irregular sequence of snippets about some of the slightly more technical aspects of uncertainty and risk assessment.  If you have a slightly more technical question, then please email me and I will try to answer it with a snippet. Suppose that an event has a probability of 0.015 (or 1.5%) of happening at least once in the next five years. Then the probability of the event happening at least once in the next year is 0.015 / 5 = 0.003 (or 0.3%), and the probability of it happening at least once in the next 20 years is 0.015 * 4 = 0.06 (or 6%). Here is the rule for scaling probabilities to different time intervals: if both probabilities (the original one and the new one) are no larger than 0.1 (or 10%), then simply multiply the original probability by the ratio of the new time-interval to the original time-interval, to find the new probability. This rule is an approximation which breaks down if either of the probabilities is greater than 0.1. For example
Read more

Cabot office weekly roundup – 20 July 2012

By
Herbert Huppert This week we have been holding our Cabot Summer School on risk and uncertainty in natural hazards .   The week has gone very well and I have received some very positive comments from attendees.   We had some fantastic speakers including Herbert Huppert, Jonty Rougier, Steve Sparks, Willy Aspinall, Li Chen, Tamsin Edwards, Philippa Bayley and Thorsten Wagener.   Cabot would like to say a great big thank you to all of you for making the Cabot Summer School such a success.   We’re very much looking forward to next year. Paul F. Hoffman This week, Cabot member Rich Pancost secured Paul F. Hoffman of Snowball Earth fame as the next Science Faculty Colloquium speaker in September.   I saw the new templates for our website today.   Its all looking good and I’m quite excited about the implementation of its new look.   By the end of the summer I hope to have it all up and running. We would like to congratulate Cabot member Professor Mark Eisler and
Read more

Discussing Rio+20 at the House of Lords

By
Last month I went to the House of Lords for a meeting of the All party group for international development and the environment.  The morning’s question was: Where next for sustainable development after Rio+20?  I’ll give a brief resume of who said what, with some of my thoughts following over the next weeks.... Joan Walley , MP for Stoke-on-Trent North opened the morning's reflections on Rio.  She chairs the Environmental Audit Committee which monitors action across different government departments. At the top level, Rio lacked vision and clear objectives. Her select committee really tried to engage with government, but there was no commitment from the PM that he was going, and no clear vision from them.  She felt the process needs to be reinvigorated - connecting, collaborating, and understanding the details - e.g. how the proposed Sustainable Development Goals will link with the Millennium Development Goals. Stephen Hale from Oxfam   asked how do we accelerate the p
Read more