Update: Ocean Acidification


News release

Public release date: 21-May-2008


European Science Foundation


Ocean acidification — another undesired side effect of fossil fuel-burning


Up to now, the oceans have buffered climate 

change considerably by absorbing almost one third 

of the worldwide emitted carbon dioxide. The 

oceans represent a significant carbon sink, but 

the uptake of excess CO2 stemming from man’s 

burning of fossil fuels comes at a high cost: 

ocean acidification.


Research on ocean acidification is a newly 

emerging field and was one of the major topics at 

this year’s European Geosciences Union (EGU) 

General Assembly held in Vienna in April. The 

European Science Foundation EUROCORES (European 

Collaborative Research) programme EuroCLIMATE, 

which addresses in particular global carbon cycle 

dynamics, organized and co-sponsored several 

sessions on ocean acidification.


The chemistry is very straight-forward: ocean 

acidification is linearly related to the amount 

of CO2 we produce. CO2 dissolves in the ocean, 

reacts with seawater and decreases the pH. Since 

the industrial revolution, the oceans have become 

30 percent more acidic (from 8.2 pH to 8.1 pH). 

“Under a “business as usual scenario, predictions 

for the end of the century are that we will lower 

the surface ocean pH by 0.4 pH units, which means 

that the surface oceans will become 150 percent 

more acidic – and this is a ‘hell of a lot’ “, 

said Jelle Bijma, chair of the EuroCLIMATE 

programme Scientific Committee and a 

biogeochemist at the Alfred-Wegener-Institute 

Bremerhaven. “Ocean acidification is more rapid 

than ever in the history of the earth and if you 

look at the pCO2 (partial pressure of carbon 

dioxide) levels we have reached now, you have to 

go back 35 million years in time to find the 

equivalents” continued Bijma. A maximum allowed 

change in pH, where the system is still 

controllable, needs to be found. This is a major 

challenge considering the multifaceted unknowns 

that still are to be clarified. This so-called 

“tipping point” is currently estimated to allow a 

drop of about 0.2 pH units, a value that could be 

reached in as near as 30 years. More research and 

further modeling needs to be undertaken to verify 

the predictions.


The expected biological impact of ocean 

acidification remains still uncertain. Most 

calcifying organisms such as corals, mussels, 

algae and plankton investigated so far, respond 

negatively to the more acidic ocean waters. 

Because of the increased acidity, less carbonate 

ions are available, which means the calcification 

rates of the organisms are decreasing and thus 

their shells and skeletons thinning. However, a 

recent study suggested that a specific form of 

single-celled algae called coccolithophores 

actually gets stimulated by elevated pCO2 levels 

in the oceans, creating even bigger uncertainties 

when it comes to the biological response. “There 

are thousands of calcifying organisms on earth 

and we have investigated only six to ten of them, 

we need to have a much better understanding of 

the physiological mechanisms” demanded 

Jean-Pierre Gattuso, a speaker from Laboratoire 

d’Océanographie Villefranche invited by 

EuroCLIMATE. In addition, higher marine life 

forms are likely to be affected by the rapidly 

acidifying oceans and entire food webs might be 



So far, hardly any economic impact assessments of 

ocean acidification exist, but with the fragile 

marine ecosystems under threat, it can be assumed 

that fisheries and many coastal economies will be 

severely affected. Many of these societies depend 

on the sea as their main source of food and the 

loss of species is highly detrimental to them; 

coral reefs serve as highly valuable tourist 

destinations and as natural protections against 

natural hazards such as tsunamis. Together with 

climate change, ocean acidification poses a major 

challenge to the oceans as a human habitat.


“Ocean acidification is happening today and it’s 

happening on top of global warming, so we are in 

double trouble” stated Bijma. Only a serious cut 

of CO2 emission can reduce ocean acidification. 

Therefore, knowledge on ocean acidification is 

being disseminated and awareness among 

policymakers and the general public raised. “We 

need to make sure that the message gets delivered 

to the right people at the right time” urged 

Carol Turley, lead author of the Nobel 

prize-winning IPCC report and scientist at the 

Plymouth Marine Laboratory. According to her, a 

concise integrated opinion of leading scientists 

is necessary, and it would be useful for policy 

makers to devote one integrated chapter on the 

impacts of climate change including ocean 

acidification on the marine environment in a 

future IPCC report.


European science has taken the initiative to act 

and gain more urgently needed insight on this 

phenomenon of global change; an EU project on 

ocean acidification will be launched next month. 

The European Geosciences Union (EGU), an 

influential interdisciplinary organization, is 

also being proactive: “EGU is in the process of 

putting together a position statement on ocean 

acidification” said Gerald Ganssen, President of 

the EGU. As a result attained at a strategic 

workshop held in January, the ESF is currently 

producing a ‘Science Policy Briefing’ which is to 

be targeted at the major stakeholders and actors 

in the field. In addition it was felt that the 

issue of ocean acidification needs to be 

addressed in a pan-European effort and that more 

intensive European collaboration is required, 

which could be achieved through one of the ESF 

Science Synergy tools such as EUROCORES.




Notes to the editors:


The aim of the European Collaborative Research 

(EUROCORES) Scheme is to enable researchers in 

different European countries to develop 

collaboration and scientific synergy in areas 

where European scale and scope are required to 

reach the critical mass necessary for top class 

science in a global context. The scheme provides 

a flexible framework which allows national basic 

research funding and performing organisations to 

join forces to support excellent European 

research in and across all scientific areas. The 

European Science Foundation (ESF) provides 

scientific coordination and support for 

networking activities of funded scientists 

currently through the EC FP6 Programme, under 

contract no. ERAS-CT-2003-980409. Research 

funding is provided by participating national 



The climate for the next century, and thereafter, 

is expected to be largely different from the 

present and the recent past. CO2 concentration is 

expected to reach levels unequalled over the past 

millions of years. Temperature is also rising 

rapidly. The last 150 years of meteorological 

observations and the reconstruction over the last 

millennium display a quite uniform climate. Only 

the reconstruction of paleoclimates extending 

much further back in time can help build a 

database with a broader climatic diversity. Such 

a database will, in addition, offer the 

possibility to test the reliability and 

robustness of the models used for future climate 

scenarios and thus to better understand how the 

climate system works. EuroCLIMATE focuses both on 

reconstructing past climates using different 

well-dated and calibrated proxy records and on 

modelling climate and climate variations for a 

better understanding of the underlying physical, 

chemical and biological processes involved.


The European Science Foundation (ESF) provides a 

platform for its Member Organisations to advance 

European research and explore new directions for 

research at the European level. Established in 

1974 as an independent non-governmental 

organisation, the ESF currently serves 77 Member 

Organisations across 30 countries.


For further information on EuroCLIMATE, please go to www.esf.org/euroclimate


For further information on the EUROCORES Scheme, 

please go to www.esf.org/eurocores




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