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(Ramanathan et aZ., 1985). This is not to say that the Earth climate was at any time in a
steady state, but rather that the present rate of change might be much more rapid than
normally resulting from geophysical events (e.g. glaciations, plate tectonics, etc.) Terrestrial
ecosystems (e.g. forests) may be unable to cope with changes occurring over decades instead
of centuries or millennia. In addition, rising sea level combined with subsiding continental
masses and increasing frequency of storms might endanger many coastal areas and cities.
It has been estimated that up to about half the CO2 released since the beginning of the
industrial era has probably been absorbed by the oceans (Sundquist, 1985). Carbon dioxide
transferred into the deep oceanic waters is effectively removed from the atmosphere for
centuries, thus reducing the magnitude of global warming. Carbon dioxide enters the upper
ocean by gas exchange across the air-sea interface or as dissolved compounds in river waters;
it can be transferred to deep waters by two general pathways: (1) ocean-scale transport of
dissolved inorganic and organic carbon by deep convection, and (2) local sinking of biogenic
particles from the surface into the deep sea. The second pathway is orders of magnitude faster
than the first one (days/weeks vs. decades/centuries; see Legendre and Gosselin, 1989). Close
to the surface (euphotic layer), solar light fuels the photosynthetic incorporation of inorganic
carbon into organic molecules by microalgae, a fraction of which sinks to deep waters (as
intact cells, faecal pellets, marine snow) or is actively transported by vertically migrating
organisms. This export pathway is known as the "biological CO 2 pump" (Volk and Hoffert,
1985). Understanding and quantifying this biological pump, as well as the other CO 2 export
pathways, is central to the Joint Global Ocean Flux Study (JGOFS; e.g. Brewer et aZ., 1986;
Platt et aZ., 1989a), which is an integral part of the International Geosphere-Biosphere
Programme.
Another area of growing concern for the scientific community is the present state of exploited
marine renewable resources. Many authors have pointed out that the models used for stock
management are inadequate, and that the general relationship between primary production and
fish yield, which is probably mediated by the success of larval recruitment to the adult
popUlation, still eludes understanding (see Lasker, 1988, and Rothschild, 1988), potentially
(Ramanathan et aZ., 1985). This is not to say that the Earth climate was at any time in a
steady state, but rather that the present rate of change might be much more rapid than
normally resulting from geophysical events (e.g. glaciations, plate tectonics, etc.) Terrestrial
ecosystems (e.g. forests) may be unable to cope with changes occurring over decades instead
of centuries or millennia. In addition, rising sea level combined with subsiding continental
masses and increasing frequency of storms might endanger many coastal areas and cities.
It has been estimated that up to about half the CO2 released since the beginning of the
industrial era has probably been absorbed by the oceans (Sundquist, 1985). Carbon dioxide
transferred into the deep oceanic waters is effectively removed from the atmosphere for
centuries, thus reducing the magnitude of global warming. Carbon dioxide enters the upper
ocean by gas exchange across the air-sea interface or as dissolved compounds in river waters;
it can be transferred to deep waters by two general pathways: (1) ocean-scale transport of
dissolved inorganic and organic carbon by deep convection, and (2) local sinking of biogenic
particles from the surface into the deep sea. The second pathway is orders of magnitude faster
than the first one (days/weeks vs. decades/centuries; see Legendre and Gosselin, 1989). Close
to the surface (euphotic layer), solar light fuels the photosynthetic incorporation of inorganic
carbon into organic molecules by microalgae, a fraction of which sinks to deep waters (as
intact cells, faecal pellets, marine snow) or is actively transported by vertically migrating
organisms. This export pathway is known as the "biological CO 2 pump" (Volk and Hoffert,
1985). Understanding and quantifying this biological pump, as well as the other CO 2 export
pathways, is central to the Joint Global Ocean Flux Study (JGOFS; e.g. Brewer et aZ., 1986;
Platt et aZ., 1989a), which is an integral part of the International Geosphere-Biosphere
Programme.
Another area of growing concern for the scientific community is the present state of exploited
marine renewable resources. Many authors have pointed out that the models used for stock
management are inadequate, and that the general relationship between primary production and
fish yield, which is probably mediated by the success of larval recruitment to the adult
popUlation, still eludes understanding (see Lasker, 1988, and Rothschild, 1988), potentially