Descent into the Icehouse

Lead Research Organisation: University of Southampton
Department Name: School of Ocean and Earth Science

Abstract

For the majority (~80 %) of the last 600 million years or so the planet was considerably warmer and wetter than today, and largely ice free - it was in what is known as a 'greenhouse climate state'. The alternate mode, like today, where ice caps blanket both poles - a so called 'icehouse state', is a relatively rare condition for the climate system to be in. Over the last 600 million years the transitions between the two states tend to be rapid and each had dramatic consequences for life on Earth. The most recent of these fundamental climate transitions began around 50 million years ago and culminated at ~34 million years ago at the Eocene/Oligocene boundary with the rapid growth of the Antarctic Ice Sheet. Due to the nature of the rock record, this most recent transition is the best studied and most well documented of the greenhouse to icehouse switches, but nonetheless the processes responsible are still much debated. The most popular hypothesis is that it was caused by a decline in the atmospheric concentration of CO2 - an important greenhouse gas. Although it has been recently confirmed that the final rapid switch at the Eocene/Oligocene boundary was associated with a dramatic decline in CO2, it has also been suggested that CO2 may not have been the main driver of the overall transition. There are instead a number of potential candidates that fall broadly into two camps - either this climate transition was driven purely by processes internal to the Earth (such as uplift of the Himalaya, ocean circulation, or volcanic outgassing of CO2) or it involved some, or all, aspects of the Earth surface, including biology, that can serve to cause and amplify change in a number of important ways. Due to the burning of fossil fuels, atmospheric CO2 concentrations may reach values typical of the greenhouse world of the Eocene by the end of this century. It is therefore becoming imperative to better understand the role of CO2 in driving these natural cycles of Earths climate, and consequently, the principal aim of this proposal is to determine the main driver of this most recent and dramatic switch in climate state. We will achieve this using a multidisciplinary approach that has aspects of both new data collection and computer modelling. The new data we will generate will involve revised estimates of CO2 concentrations and globally widespread estimates of ocean temperature, environmental parameters that cannot be directly determined for the past. We will study the fossil remains of sea-dwelling microscopic organisms, the foraminifers and coccolithophorids. These organisms are very abundant in the mud on the floor of the oceans, providing an invaluable archive of past ocean climate data, and by looking at the chemical composition of their shells or the organic compounds they biosynthesise we can determine how warm or how acidic the ocean was. And from such parameters, we can also deduce how much CO2 was in their environment. Armed with this improved understanding of how the climate system evolved leading up to the greenhouse-icehouse transition we can better investigate the natural processes that caused the change. Given the complex nature of the climate system this is best done with a variety of sophisticated computer modelling approaches. Crucially, it is only by guiding these computer simulations with the new data we have generated that we can isolate which of the myriad of potential processes was responsible for triggering this fundamental shift in climate and better determine how they impacted the evolution of life.

Publications

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Fenton IS (2016) The impact of Cenozoic cooling on assemblage diversity in planktonic foraminifera. in Philosophical transactions of the Royal Society of London. Series B, Biological sciences

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Foster GL (2013) Relationship between sea level and climate forcing by CO2 on geological timescales. in Proceedings of the National Academy of Sciences of the United States of America

 
Description We have explored the causes of the "descent into the ice house" - the latest transition from greenhouse climate state to ice house climate state. We have found that changes in the position of the continents was not an important part of this transistion instead it was caused by a decline in the levels of atmospheric CO2. Furthermore, by determining the CO2 content of the atmosphere 34 to 50 million years ago we are able to determine that climate sensitivity was similar in the geological past as encapsulated in climate models.
Exploitation Route The results of this project will feed into the next and future reports of the IPCC. these reports have a large reach.



We have held a display of the work related to this project at Ocean and Earth Day held at NOCS. This event attracted >3000 members of the public.
This research will be of great interest and use to palaeoclimate scientists seeking to understand the climate of the Eocene and for climate modellers seeking to test their models on warm climates of the past.



Beyond the academic users (reached through standard publication routes) we have engaged members of the public through our website (url below) and in contributing to a number of well visited blogs



(http://www.skepticalscience.com/Carbon-Dioxide-the-Dominant-Control-on-Global-Temperature-and-Sea-Level-Over-the-Last-40-Million-Years.html#commenthead



http://www.scienceomega.com/article/759/off-balance-the-co2-and-sea-level-seesaw)



Our work was also highlighted in Editors choice in Nature climate change, featured on BBC, Daily Mail and other online sources.
Sectors Environment

URL http://www.thefosterlab.org/blog/2016/4/25/ancient-marine-sediments-provide-clues-to-future-climate-change
 
Description This research has contributed to the knowledge base regarding the causes and consequences of climate change. It has also directly fed into the latest IPCC report (of which PI Foster was a contributing author)
First Year Of Impact 2011
Sector Environment
Impact Types Policy & public services

 
Description Ocean and Earth Day 2013 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Interacted and answered questions relating to the Descent into the Icehouse and palaeoclimate in general.

Visits to website increased
Year(s) Of Engagement Activity 2013
URL http://descentintotheicehouse.org.uk/a-fantastic-ocean-and-earth-day-at-national-oceanography-centre...
 
Description Ocean and Earth Day 2014 & 2015 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact The general public were engaged with at the National Oceanographic Centre Ocean and Earth Day. The activity involved a stall where future climate change was put in it geological context.
Year(s) Of Engagement Activity 2014,2015
 
Description Public Engagement 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Following the publication of Foster et al. 2017 in Nature Communication we engaged with the media, through The Conversation (https://theconversation.com/we-are-heading-for-the-warmest-climate-in-half-a-billion-years-says-new-study-73648) which has >50K reads. Our work was also picked up by the mainstream media (e.g. https://www.theguardian.com/environment/climate-consensus-97-per-cent/2017/apr/17/humans-on-the-verge-of-causing-earths-fastest-climate-change-in-50m-years) and popular science literature (https://www.newscientist.com/article/2126776-co2-set-to-hit-levels-not-seen-in-50-million-years-by-2050/) and podcast (https://www.scientificamerican.com/podcast/episode/climate-420-million-years-ago-poised-for-comeback/)
Year(s) Of Engagement Activity 2017
URL https://theconversation.com/we-are-heading-for-the-warmest-climate-in-half-a-billion-years-says-new-...
 
Description Public engagement via involvement in article for National Geographic Magazine 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact After appearing in the magazine I was contacted by several members of the public for dicussion

Following my featuring in National Geographic the following additional activities arose:

Blog for Skeptical Science (http://www.skepticalscience.com/Carbon-Dioxide-the-Dominant-Control-on-Global-Temperature-and-Sea-Level-Over-the-Last-40-Million-Years.html#commenthead)
Blog for Science Omega (http://www.scienceomega.com/article/759/off-balance-the-co2-and-sea-level-seesaw)
Year(s) Of Engagement Activity 2013
URL http://descentintotheicehouse.org.uk/as-the-planet-warms-the-sea-rises-how-will-we-face-the-danger-o...
 
Description Royal Society Discussion Meeting on hyperthermals 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact We held a Royal Society discussion and satellite meeting on Hyperthermals: rapid and extreme global warming in our geological past. The meeting was open to the public and we had over 100 attendees.
Year(s) Of Engagement Activity 2017
URL https://royalsociety.org/science-events-and-lectures/2017/09/hyperthermals/
 
Description Royal Society MP-Scientist pairing scheme 2011-12 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact PI Gavin Foster was involved with the Royal Society MP-Scientist pairing scheme. Gavin was paired with MP for Romsey and Southampton North Caroline Nokes. Caroline visited NOC in Feb 2012, Gavin went to westminster in Nov 2011.
Year(s) Of Engagement Activity 2011,2012
URL http://descentintotheicehouse.org.uk/caroline-nokes-mp-visit-at-noc/
 
Description School visits (as part of University of Bristols ChemLabS outreach program) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact The presentation sparked questions and discussion afterwards

Nothing reported
Year(s) Of Engagement Activity 2014
 
Description Scientists on the Road 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Children asked many questions of the scientists involved.

Increase in website hits and follow up communication
Year(s) Of Engagement Activity 2013
URL http://descentintotheicehouse.org.uk/scientists-on-the-road-travel-to-science-festivals/