Ocean acidification

The term ocean acidification is used to describe the ongoing decrease in ocean pH caused by human CO2 emissions, such as the burning of fossil fuels. This is having an adverse effect on many important marine species such as corals, oysters, crabs and plankton. Due to the unprecedented rate of acidification these vulnerable organisms may not have time to evolve mechanisms to cope with the changing chemistry of the ocean.

PML has been instrumental in developing the understanding of the effects of ocean acidification on the marine environment. Through laboratory and field experiments, observations and ecosystem modelling our research has shown how the chemistry of the ocean is changing; and what affect this is having on marine organisms, ecosystems and biodiversity.

A key finding has been that the impact of ocean acidification is strongly dependent on interaction with other stressors associated with global change, notably temperature increases. We have also demonstrated that ocean acidification is having a marked effect upon ocean chemistry beyond the carbonate cycle, most notably the nitrogen cycle and production of climate-relevant trace gases such as DMS and halocarbons.

PML monitors ocean acidification utilising existing platforms, including the Atlantic Meridional Transect (AMT) and the Western Channel Observatory (WCO). The WCO dataset provides the longest running record of ocean acidification in the UK. This freely available data underpins much of our current understanding of the interplay between the chemistry of the ocean and biological processes.

PML are also developing techniques to assess ocean acidification using satellites, which will enable monitoring on a global scale with a relatively low-cost when compared to in situ measurements.

Making a difference

PML has been pivotal in monitoring and communicating the impacts of OA, raising awareness and inspiring action at the highest political levels.

This influence has culminated in ocean acidification research informing international emissions targets, with the significant inclusion of ocean ecosystems in the UN Paris Agreement and the development of a UN Sustainable Development Target on ocean acidification (SDG14.3). PML are helping to ensure the UK meets international obligations including as a founding partner of the Global Ocean Acidification Observing Network (GOA-ON) and by delivering its North East Atlantic Hub.

You can read more about our contribution into enquiries and policy on our impact page.


GOA-ON NE Atlantic hub

NE Atlantic logo with black text and a compass forming part of the O letterPML coordinate the Northeast Atlantic hub that forms part GOA-ON. The key role of the hub is to promote a common methodology for recording measurements, encourage submission to National Data Centres and cataloguing of this data on a central global portal to map effort and identify gaps. This ensures that member states fulfil their obligations under SDG14.3 by providing the measurements needed to meet this target.

Selected key publications

Queiros, AM; Fernandes, JA; Nunes, J; Rastrick, S; Mieszkowska, N; Artioli, Y; Yool, A; Calosi, P; Arvanitidis, C; Findlay, HS; Barange, M; Cheung, W; Widdicombe, S. 2015 Scaling up experimental ocean acidification and warming research: from individuals to the ecosystem. Global Change Biology, 21 (1). 130-143. 10.1111/gcb.12675

Hopkins, FE; Archer, SD. 2014 Consistent increase in dimethyl sulphide (DMS) in response to high CO2 in five shipboard bioassays from contrasting NW European waters [in special issue: Field investigation of ocean acidification effects in northwest European seas] Biogeosciences Discussions, 11. 2267-2303. 10.5194/bgd-11-2267-2014

Widdicombe, S; Spicer, JI. 2008 Predicting the impact of ocean acidification on benthic biodiversity: What can animal physiology tell us?. Journal of Experimental Marine Biology and Ecology, 366. 187 - 197. 10.1016/j.jembe.2008.07.024

Widdicombe, S., Blackford, J., Lowe, D., Turley, C. 2007. The implication for the marine environment of CO2 (IMCO2), No. COAL R310, BERR/Pub URN 08/687. 81pp.

Related projects

North East Atlantic hub of the Global Ocean Acidification Observing Network

North East Atlantic hub of the Global Ocean Acidification Observing Network

Contact: Dr Helen Findlay

The North East Atlantic Ocean Acidification Hub was established to serve European countries that are conducting monitoring, and other OA activities...


Atlantic Meridional Transect Ocean Flux from Satellite Campaign (AMT4OceanSatFlux)

Contact: Dr Gavin H. Tilstone

The AMT4OceanSatFlux project will measure the flux of carbon dioxide (CO2) between the atmosphere and the ocean utilising a state-of-the-art eddy...


Pathways and emissions of climate-relevant trace gases in a changing Arctic Ocean (PETRA)

Contact: Dr Andy Rees

The Arctic Ocean is a rapidly changing environment, with rising temperatures leading to an ongoing decline in sea ice and shifting conditions for...

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