Ocean acidification, the other carbon dioxide problem

The world’s oceans, acting as a gigantic carbon sink, have taken up about a third of the carbon dioxide (CO2) released into the atmosphere by human activities. A synthesis of more than 350 publications on the effects of ocean acidification, presented at the COP23, the latest climate summit held in Bonn, Germany,  reveals that almost half of the marine animal species tested reacted negatively to already moderate increases in seawater CO2 concentrations. The study's lead author, Prof Ulf Riebesell from the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany, told BBC News: "At the end of the day, these changes will affect the many services the ocean provides to us."

Ocean acidification is a change in the ocean chemistry that occurs when CO2 from the atmosphere dissolves in seawater. Since the industrial revolution, the average pH at the ocean surface has dropped from 8.2 to 8.1. This tiny step on the logarithmic pH scale translates into a 30 per cent increase in acidity. At the same time, the ocean absorbs more than 90 per cent of the heat that is generated by the greenhouse effect. By providing this invaluable service the ocean slows down global climate change. If this natural store were not to exist, our planet would heat up much more and much faster than we observe today.

Quantifying the effects of ocean acidification on marine organisms and their habitats. BIOACID, one of the largest research programs on ocean acidification, has contributed to  unravelling the underlying mechanisms of the phenomenon for eight years. Supported by Federal Ministry of Education and Research (BMBF), and coordinated by te GEOMAR Helmholtz Centre for Ocean Research Kiel, scientists working under the programme have studied how marine creatures are affected by acidification during different life stages; how these reactions reverberate through the marine food web; and whether the challenges can be mitigated by evolutionary adaptation. Ultimately, the aim is to identify the potential thresholds associated with ocean acidification, evaluate potential socio-economic consequences and identify viable management options. 

Resources: BIOACID publications on ocean acidification | Reaching the Paris climate target // Important BIOACID results |