Ocean plankton absorbs less CO2 than expected - life -

Even phytoplankton are letting us down when it comes to global warming. These microscopic ocean-dwelling plants, which were thought to be gobbling up atmospheric carbon dioxide, are apparently not doing as well as was hoped.
In the past, satellite images of ocean colour were the main tool for measuring photosynthetic biomass: the greener the ocean the more CO2 was being taken up by the phytoplankton. This idea now seems to be misleading.
Peter Strutton of Oregon State University and colleagues studied phytoplankton fluorescence in the tropical Pacific using data from 12 years and 58,000 kilometres of ship transects and found that the phytoplankton are making far less chlorophyll than expected. They reason that in nutrient-poor waters like the tropical Pacific, phytoplankton are starved of nitrates and iron. Because of this they produce a pigment-protein complex that is not chlorophyll but shows up just as green in satellite images. They calculate that this means 2.5 billion tonnes less CO2 is being absorbed each year than was thought (Nature, vol 442, p 1025).
From issue 2567 of New Scientist magazine, 30 August 2006, page 15