Beyond Climate: The Emerging Science of a Low pH-High CO2

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Monterey Bay Aquarium Research Institute

2004

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Introduction

From its inception ICES has had a creative tension between the demands and linkages of fisheries

and hydrography, and has superbly balanced those needs for more than a century of science. This

has always seemed to me to be wise, and it is the extension of that theme towards the later part of

the 21st century that is the subject of my lecture today. My message is simple; there are massive,

and until very recently unrecognized, changes of geologic scale taking places in the ocean as we

have entered the anthropocene era, and these may very well have profound impacts on ocean

ecosystems world wide. I hope that unraveling these effects so that we do not go blindly into this

brave new world will be a task for ICES scientists.

One hundred years ago Martin Knudsen and colleagues in a small laboratory in Denmark laid down

the basis for the gravimetric measurement of ocean salinity (Knudsen, 1901; Forch, Knudsen and

Sorensen, 1902). But if the equivalent sea water samples were to be measured today, even with the

crude procedures of the time, a different result would be obtained. Ocean salinity has increased,

not by evaporation of water but by the massive quantity of carbon dioxide added by mankind

(Brewer, 1997); Knudsen could simply have weighed the difference, and chemistry is now impacting

hydrography.

While the climate impacts of increasing atmospheric CO2 levels have received great attention the

direct effects of this enormous CO2 enrichment of the upper ocean have had little discussion. That

is about to change for ocean chemistry is being altered on a scale not seen for millions of years,

and there are very basic questions on the impact on ecosystems and biogeochemical cycles to

which we simply do not yet have answers.