The Tipping Point – Documentaire de Laurence Jourdan (France, 2010; in French)

Un an après le rapport des Nations unies qui prédisait la disparition totale des poissons de notre planète en 2050, le scénario catastrophe se poursuit. Chaque jour, 25 millions de tonnes de gaz carbonique (soit le tiers des émissions de l’hom­me) sont absorbés par les océans et accélèrent fatalement leur acidification. Ces mêmes océans produisant la moitié de notre oxygène ­vital, autant dire que The Tipping Point (traduire : le point de non-retour) n’augure rien de bon.

Effects of changes in carbonate chemistry speciation on Coccolithus braarudii: a discussion of coccolithophorid sensitivities (update)

Ocean acidification and associated shifts in carbonate chemistry speciation induced by increasing levels of atmospheric carbon dioxide (CO2) have the potential to impact marine biota in various ways. The process of biogenic calcification, for instance, is usually shown to be negatively affected. In coccolithophores, an important group of pelagic calcifiers, changes in cellular calcification rates in response to changing ocean carbonate chemistry appear to differ among species. By applying a wider CO2 range we show that a species previously reported insensitive to seawater acidification, Coccolithus braarudii, responds both in terms of calcification and photosynthesis, although at higher levels of CO2. Thus, observed differences between species seem to be related to individual sensitivities while the underlying mechanisms could be the same. On this basis we develop a conceptual model of coccolithophorid calcification and photosynthesis in response to CO2-induced changes in seawater carbonate chemistry speciation.

Launch of MedSeA web site

The European Mediterranean Sea Acidification in a changing climate (MedSeA) initiative is a newly funded project by the European Commission under Framework Program 7. It involves 16 institutions from 10 countries.

MedSeA will assess uncertainties, risks and thresholds related to Mediterranean acidification at organismal, ecosystem and economical scales. It will also emphasize conveying the acquired scientific knowledge to a wider audience of reference users, while suggesting policy measures for adaptation and mitigation that will vary from one region to another.