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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Research project: Past and Present Ocean Acidification

Currently Active: 

Global warming is not the only consequence of rising levels of CO2 in the atmosphere. CO2 from anthropogenic sources is excessively emitted into the atmosphere before dissolving into the ocean to form carbonic acid. This increase in ocean acidity is known as Ocean Acidification (OA). Along with limiting our emissions it is vital to predict what effect such acidification will have on marine life and chemical processes in the ocean. Marine calcifiers make their shells and skeletons using calcium carbonate, and may be particularly affected. Although the recent rate of acidification is unprecedented in geological history, one way to get a better understanding of how the Earth system will respond to acidification in the future is to examine its behaviour in the geological and more recent past. 

Image Source: Pages Workshop Report Series 99-1. Annual Records of Tropical Systems (PAGES/CLIVAR)
Coral Core X-ray

Key Questions

  • What are the magnitude of ancient abrupt acidification events? Do thresholds exist in the climate system?
  • Can we use geochemical techniques to reconstruct the magnitude of historical acidification? What does this tell us about how organisms have already been impacted by ocean acidification (OA)?






Coral Drilling (Source: K Castillo)
Coral Drilling (Source: K Castillo)

How do we do it?

  • Quantitative reconstruction of the pH change during ancient OA events, such as the Palaeocene-Eocene thermal maximum (PETM), are lacking. 
  • Similarly, the magnitude of historical (i.e. last 200 years) acidification at any one location is unknown due to a lack of seawater pH measurements beyond the 1980's.
  • We use cutting edge isotopic techniques linked with ocean biogeochemical models to reconstruct the ocean pH change across these abrupt events.
  • Records of the biotic response to both ancient and historical OA can then used to identify critical thresholds and provide insights into the likely behaviour of marine calcifiers to future acidification.



CO2 Model
CO2 Model

Key Contacts

Prof Gavin Foster (Principal Investigator)

Prof Toby Tyrrell (Principal Investigator)

Dr Marcus Gutjahr (Research Fellow)

Dr Sam Gibbs (Senior Research Fellow)

Miss Sara Fowell (Postgraduate Research Student)

Prof Justin Ries (UNC Chapel Hill, Collaborator)

Dr Nick Kamenos (Glasgow, Collaborator)

Dr Branwen Williams (Claremont Colleges, Collaborator)

Prof Paul Pearson (Cardiff, Collaborator)

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