Past records of ocean acidification - the Palaeogene hyperthermals

Lead Research Organisation: University of Bristol
Department Name: Earth Sciences

Abstract

Since the discovery of fire and the development of agriculture, humans have been releasing carbon dioxide (CO2) to the Earth's atmosphere. We have known about the effect that burning of fossil fuels and deforestation has on the amount of CO2 in the atmosphere as well as its influence on global temperatures for many years now. However, the CO2 we put in the atmosphere does not all just stay there / because CO2 reacts with water, about a third of current fossil fuel emissions is removed by the ocean. This effect would be really helpful for us in preventing more extreme global warming from taking place, except ... in past few years scientists have realized that because CO2 dissolved in seawater creates a weak acid, we are causing the pH of the ocean to steadily decrease in a process known as 'ocean acidification'. There are currently about 380 molecules of CO2 in the atmosphere for every million of all gases combined ('parts per million' or ppm). Atmospheric CO2 is predicted to steadily increase in the coming decades, reaching 450-550 ppm by the year 2050 / a concentration that our Planet has not experienced in at least the past 3 million years. As atmospheric CO2 increases, so does the rate at which it will dissolve in seawater, forcing the pH of the surface ocean lower and lower. It is likely that ocean pH will reach values seen only rarely since the time of the Dinosaurs. Most organisms alive in the ocean today have never experienced such a large change in all their evolutionary history. Is this important? From laboratory experiments it seems that ocean acidification will affect marine organisms, particularly those that make shells and skeletons out of calcium carbonate, because calcium carbonate minerals become less stable as waters become more acidic and will eventually dissolve. If we fail to control CO2 emissions to keep ocean pH change within the limits calcifying organisms can cope with in the future, we may see dissolution of their shells, slower growth, failure to reproduce, dwarfism, or reduced activity, with impacts further the ecosystem. Unrestricted industrial activities may even push these organisms over an ecological precipice and cause extinctions. So what is going to happen in the future? In the geological past, organisms normally had thousands to millions of years to adapt and evolve in response to global environmental change. Although the global environmental change we are causing now is many hundreds of times faster, it would still take laboratory experiments conducted over decades to tell us whether marine organisms will be able to adapt to ocean acidification. By the time we know the answer, it may be too late! Luckily, there is an alternative path; one that lies hidden in rocks. The geological record, stored in the mud at the bottom of the ocean is packed with millions of microfossils that record how much change organisms can tolerate and how much is too much. We will take samples of ancient sediments that have been drilled from the ocean floor, analyse these samples using a range of state-of-the-art techniques involving detailed laboratory analyses, and apply complex computer models to help make complete sense of the numbers. This will tell us how the pH of the ocean changed in the past. By linking this information with observations of ecosystem changes and species extinctions will provide vital clues to what changes in marine ecosystems we might expect in the future if we do not make much greater efforts to curtail our greenhouse gas emissions now.

Publications

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Dunkley Jones T (2010) A Palaeogene perspective on climate sensitivity and methane hydrate instability. in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

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Foster LC (2013) Surviving rapid climate change in the deep sea during the Paleogene hyperthermals. in Proceedings of the National Academy of Sciences of the United States of America

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Haywood AM (2011) Are there pre-Quaternary geological analogues for a future greenhouse warming? in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

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Hönisch B (2012) The geological record of ocean acidification. in Science (New York, N.Y.)

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Jennions S (2014) Eocene Thermal Maximum 2: benthic ecosystems and ocean circulation in the SE Atlantic Ocean in Rendiconti online della Società Geologica Italiana

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Schmidt D (2011) Ocean acidification in the freezer in Antarctic Science

 
Description Predicting the impact of ongoing anthropogenic CO2 emissions on calcifying marine organisms is complex, due to the synergy between direct changes (acidification) and indirect changes through climate change (e.g., warming, changes in ocean circulation and deoxygenation). Laboratory experiments, particularly on longer-lived organisms, tend to be too short to reveal the potential of organisms to acclimatise, adapt or evolve, and usually do not incorporate multiple stressors.

We studied two examples of rapid carbon release in the geological record, Eocene Thermal Maximum 2 (ETM-2 ~53.2 Ma) and the Paleocene Eocene Thermal Maximum (PETM ~55.53 Ma), the best analogs over the last 65 Ma for future ocean acidification related to high atmospheric CO2 levels.

We use benthic foraminifers, which suffered severe extinction during the PETM, as a model group. Using Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM), we reconstruct the calcification response of survivor species and find, contrary to expectations, that calcification significantly increased during the PETM. In contrast, there was no significant response to the smaller ETM-2, which was associated with a minor change in diversity only.

These observations suggest that there is a response-threshold for extinction and calcification-response, while highlighting the utility of the geological record in helping constrain the sensitivity of biotic response to environmental change.
Exploitation Route We have contributed and continue to do so to the MCCIP partnership to inform end users of our science about the results.

We have contributed to the IPCC report WGII to inform policy makers about the unexpected outcomes of our research. The PI was lead author of the ocean chapter (AR5 WGII Chapter 6) which included a historical view on climate change impacts on marine ecosystems.
Sectors Environment

 
Description The information has been included in the IPCC WGII AR5 Chapter 6 thereby providing important constraints on the impact of climate change on past ecosystems for policy makers. The importance of rate of change has been highlighted up to the Summery for Policy makers. The information is also included on a UK scale in the MCCIP report 2014
First Year Of Impact 2013
Sector Environment,Government, Democracy and Justice,Other
Impact Types Societal,Policy & public services

 
Description IPCC
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in other policy documents
 
Description Marine climate change impact partnership
Geographic Reach National 
Policy Influence Type Citation in other policy documents
 
Description Bristol Alumni funding
Amount £80,000 (GBP)
Organisation University of Bristol 
Department Campaigns and Alumni Relations Office (CARO)
Sector Academic/University
Country United Kingdom
Start 01/2011 
End 04/2014
 
Description Leverhulme Grant
Amount £162,000 (GBP)
Organisation The Leverhulme Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 01/2012 
End 02/2015
 
Description Leverhulme visiting Professorship Ellen Thomas
Amount £39,000 (GBP)
Organisation The Leverhulme Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 01/2013 
End 06/2013
 
Description UK OA RP
Amount £65,000 (GBP)
Funding ID UK Ocean acidification Reserach Program 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 10/2012 
End 03/2015
 
Title EBSD on foraminifers 
Description Assessment of quality of preservation of fossil carbonate for isotope analysis using Electron Backscatter diffraction 
Type Of Material Data analysis technique 
Provided To Others? No  
Impact A paper is currently under review which would make the method accessible. 
 
Title calcification data 
Description Synchrotron based calcification data for benthic foraminifers for the PETM and ETM2 
Type Of Material Database/Collection of data 
Year Produced 2013 
Provided To Others? Yes  
Impact publication of data in PNAS Inclusion of finding in IPCC report 
URL http://www.pnas.org/content/110/23/9273.abstract
 
Title d11B analysis with the NERC ionprobe facility 
Description d11B analysis with the NERC ionprobe facility Our grant resulted in a large investment of time by the ion probe team to improve the analytical technique, move the measurements to a new instrument and improve the quality of the data. 
Type Of Material Data analysis technique 
Provided To Others? No  
Impact A paper with the method and the results is currently under review 
 
Description New collaboration with Baerbel Hoenisch and NSF workshop organisation 
Organisation Columbia University
Department Lamont Doherty Earth Observatory
Country United States 
Sector Academic/University 
PI Contribution New collaboration with Baerbel Hoenisch and NSF workshop organisation
Start Year 2010
 
Description link to dPETM 
Organisation University of Leeds
Country United Kingdom 
Sector Academic/University 
PI Contribution We have provided data to assess the ETM2, a post ocean acidification event which augments modelling efforts at Leeds
Collaborator Contribution The link to the none Bristol partners in the dPETM grant (also NERC funded) resulted in additional insights from climate models into the nature of our findings. These influence the interpretation and hence usefulness of this past Ocean acidification event for policy makers
Impact A paper is currently under review in Paleoceanography
Start Year 2010
 
Description BBC "Points West" on Ocean acidification 2010 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact BBC "Points West" on Ocean acidification 2010, TV interview

Increased awareness of the general public about the impact of ocean acidification on marine ecosystems
Year(s) Of Engagement Activity 2010
 
Description Interview for BBC world on Ocean acidification 2010 
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 Public/other audiences
Results and Impact Interview for BBC world on Ocean acidification 2010

It is hard to assess the impact of a radio interview but there is clear evidence that the awareness of the impacts of Ocean acidification have risen due to a number of communicators of which I consider myself to be one.
Year(s) Of Engagement Activity 2010
 
Description Paleo-ocean acidification and carbon cycle perturbation events 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Hönisch, B., Schmidt, D.N., Barker, S. and Zachos, J. 2011. Paleo-ocean acidification and carbon cycle perturbation events. Pages News, 19(1): 35.

increased awareness of this new concern of environmental impacts of CO2
Year(s) Of Engagement Activity 2011
 
Description School Visit (Grammar School Salisbury) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact I gave a presentation on Ocean acidification to the largest cohort of AS and A level Geology pupils in the country with a q and A session at the end. In addition to informing the pupils I also briefed the teachers with information.

questions from the students, raising curiosity, novel research disseminated.
Year(s) Of Engagement Activity 2013
 
Description University of Michigan Smith Lecture, Ann Arbor 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact University of Michigan Smith Lecture, Ann Arbor, to undergraduates, graduates and other academics

Stimulation of discussion amongst both the undergradute and graduate students.
Year(s) Of Engagement Activity 2010