Ocean acidification: latest worrying report

A report published by the International Geosphere-Biosphere Project predicts a dramatic increase in ocean acidity – 170 % by the year 2100 – due to carbon dioxide emissions. Such an increase can have serious implications for the marine ecosystem, and potentially have large socio-economic effects on our society. These results were presented on the 18th of November at the Warsaw Climate Change Conference.

Ocean Acidification

Carbon dioxide (CO2) concentration in the atmosphere is increasing due to human activities, such as the burning of fossil fuels; since the beginning of the industrial revolution, CO2 atmospheric concentration has become 40 times higher.  This causes concern, as CO2 is a greenhouse gas; indeed, some people believe that carbon dioxide is responsible for the increase in the Earth’s temperature (global warming).

Furthermore, a higher CO2 concentration is considered a danger for the oceans, as it causes ocean acidification.

Carbon dioxide from the atmosphere is actually partially absorbed by the seas/oceans – generally a quarter of atmospheric CO2 end up being dissolved in water. Due to the acidic nature of CO2, this causes an increase in the acidity of the oceans (a decrease in the value of the pH).

Possible Consequences of Ocean Acidification

The possible consequences of ocean acidification cause concern among scientists. It is feared, in fact, that an excessive decrease in the pH may harm species living in the oceans, such as corals and other calcareous plankton. Moreover, this may also affect oceans’ currents and/or the Earth’s radiation budget.

Researchers have performed several studies and experiments to better understand the consequences of ocean acidification; scientists have also considered theoretical studies, to try to predict the long term effects of this phenomenon.

Report by the International Geosphere-Biosphere Project

On the 14th of November 2013, a report on the current level of ocean acidification and on the possible consequences was published by the International Geosphere-Biosphere Project (IGBP). This an international programme which investigates different parts of the Earth system, the links between them and their interactions with human systems. This report summarizes the results of the Third Symposium on the Ocean in a High CO2 World, which was held in California in September 2012. It was the largest meeting of experts in ocean acidification, attended by 540 people from 37 different countries.

The results of this report were also presented in Warsaw, at the Climate Change Conference, on the 18th of November 2013.

Dramatic Acidity Increase

One of the most important and worrying results presented in the report is that the ocean acidity could increase as much as 170 % by the year 2100. This prediction was made considering a high CO2 emission scenario – that is, a “business as usual” situation – with emissions continuing to increase at the current trend, without any mitigation measures implemented.

A decrease in carbon dioxide emissions, on the other hand, would cause a decrease in the ocean acidification process.

According to the IGBP, both statements have a “very high level” of confidence; this means that there is robust evidence to support them, and there is a high level of agreement within the scientific community.

Acid: Effects on Ocean Life

Other points highlighted in the report are about the effects that such high acidification can have on the various marine species. In some cases, for example seagrasses and other phytoplankton, lower pH seems to favor their growth. In many other cases, however, researchers expect the opposite to happen. Species such as corals, for instance, could be severely damaged; in fact their erosion could outpace reef formation, leading eventually to the disappearance of this species; this statement has a “high level” of confidence.

These negative effects may also be enhanced by other stress factors the oceans are subjected to. These include higher UV irradiation (due to the ozone depletion), overfishing, pollution and eutrophication.

Ocean Acidification: Wider Impacts

Shellfish (mussels, oysters and pteropods) are also quite sensitive to acidification, and the effects on the growth, and therefore on the availability, of these species can also have socio-economic impacts on society. In fact, the estimated global commercial value of these molluscs is about $ 24 billion; moreover, in some cases, this commerce is very important at a local level.

Furthermore, in some small communities in island states, shellfish represent an important source of protein; their limited availability could hence have an effect on the health of the whole community.

Although it is likely that there will be an impact on these areas, the scientists could not predict which will be the costs associated with it.

Acid in the Ocean, Carbon Dioxide in the Air: Very Important Topic

Decoded Science spoke to Professor Jean Pierre Gattuso , from the Laboratoire de Oceánographie de Villefrache (France), one of the scientists involved in the study.

“This reports shows that ocean acidification can have greater implications than we thought and reach some aspects of life/society we did not think about. We are already seeing some of the effects, but others may will visible only on a long term scale.

The key message is that lowering the carbon dioxide emission and reducing other forms of pollution could have a positive impact on ocean acidification; therefore, we have to move in this direction.”

Even the smallest ocean life will feel an impact if we don’t reduce carbon dioxide emissions – and those effects could snowball to affect the rest of the world. Today’s a good day to start riding a bike to work.

Sources

IGBP. Ocean acidification. Summary for policymakers. (2013). Accessed November 2013.

Clara Piccirillo, decodedScience, 18 November 2013. Article.


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