Positive Feedback

Not to be alarmist, but here's some alarming news: Scientists have found that warming oceans have a reduced ability to support phytoplankton, the tiny marine organisms that not only serve as the basis of the entire ocean food chain but also help to moderate the climate by sequestering vast amounts of carbon in the ocean. (Forget that old story about the Amazon rainforest being the "Lungs of the Earth"; phytoplankton are the real workhorses when it comes to planetary respiration.) The scary thing is that this could conceivably trigger a positive feedback loop whereby warming oceans lead to higher carbon dioxide concentrations in the atmosphere which in turn exacerbate rising ocean temperatures which further limit phytoplankton productivity which leads to still more carbon in the atmosphere, etc., etc., etc.. This story doesn't do much to quantify the problem -- i.e., just how much has phytoplankton production been affected by warming? -- but it does seem like something to keep an eye on.