BIOACID Programme - Natural Environment Research Council

1. Project background
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BIOACID: Biological Impacts of Ocean Acidification
The world’s oceans help moderating climate change thanks to their extensive capacity to store
anthropogenic carbon dioxide. Since pre-industrial times, the oceans have sequestered nearly half
of the fossil fuel CO2 released into the atmosphere and presently take up approximately 30% of
current CO2 emissions (Sabine et al. 2004). As CO2 enters the surface ocean it reacts with
seawater and generates changes in carbonate chemistry already measurable today (Figure 1). In
case of unabated CO2 emissions, the resulting changes in seawater chemistry will, in the course
of this century, expose marine organisms to conditions which they may not have experienced
during their recent evolutionary history (Raven et al., 2005). This raises concerns regarding the
biological, ecological, biogeochemical, and societal implications of ocean acidification.
Fig. 1: Measured changes in surface ocean CO 2 partial pressure (pCO 2) and pH at the European Station for
Time-series in the Ocean off the Canary Islands (ESTOC), the Hawaii Ocean Time-series Station
(HOT) and the Bermuda Atlantic Times Series station (BATS). Since 1750, surface ocean pH has
decreased by 0.12 units (calculated). Since 1980, pH has decreased by 0.02 units per decade (measured).
Source: IPCC 4 th Assessment Report (2007)
In its Special Report “The Future Oceans – Warming up, Rising High, Turning Sour”, the
German Advisory Council on Global Change (WBGU, Berlin 2006) states: “Because of the
importance of the consequences of ocean acidification, research in this area should be intensified
considerably. As long as there is no general scientific consensus about the tolerable limit for the
effects of acidification, a margin of safety according to the precautionary principle should be
observed. The suggestion of the WBGU to prevent a pH decrease of more than 0.2 is oriented
toward the goal of avoiding an aragonite undersaturation in the ocean surface layer. If it is found
that other intolerable damages already occur before reaching aragonite undersaturation, then the
guard rail will have to be adjusted accordingly.” (see Fig. 2)