"On the beach of that inflamed sea..."
Phytoplankton play a key role in supporting many other organisms. In this sense they are like coral reefs, although they are probably even more important to ocean ecosystem function and global fish stocks.
Michael Behrenfeld of Oregan State University, who is lead author of study, gives a sense of how vital and yet how marginal they may be when he says "phytoplankton are limited to just a thin veneer of the ocean surface where there is enough sunlight to sustain photosynthesis".
Because phytoplankton generate half of the oxygen produced on Earth as well as consuming enormous quantities of CO2, says Oscar Schofield of Rutgers University, even a small change in the collective health of the organisms "has a huge impact for life as we know it on this planet."
(The paper by Behrenfeld et al comes shortly one from Southampton, noted here, which I haven't read but which sounds as if it covers some similar ground).
It seems not all the news is necessarily bad. Behrenfeld is reported as saying that warming oceans mean increased plankton activity in polar waters, and possibly an increase in the diversity of marine ecosystems worldwide, although further research is needed.
But for high drama turn to the publication in Science (8 Dec) of evidence, derived in part from the record in fossilised plankton, suggesting that climate is more sensitive than often thought to the release of CO2. The paper by Mark Pagani of Yale University and others indicates that if the source of a massive release of CO2 into the atmosphere 55 million years ago was ancient plant material, then for each doubling of atmospheric CO2 concentration, the Earth could warm by at least 2.2 ºC and possibly twice this much.
But if ancient methane was the cause, as many believe, the situation could be "even more dire". In that case, says Ken Caldeira of the Carnegie Institution, a doubling of atmospheric CO2 concentration would warm the Earth by over 5.6 ºC.
"If that’s what happened," says Caldeira, "we could be in for a mighty toasty future."