Plankton, from the last ice age to the year 3

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Climate forcing of the environment and biota has been happening since time immemorial, human forcing only for the past 200 years or so. This paper considers, first, climatic changes over the past 30 000 years, as indicated by plankton and their effects on plankton. Only fossilizable plankton can be observed: principally foraminifera, radiolaria, and pteropods in the zooplankton, and their food, principally coccolithophores, diatoms, and dinoflagellate cysts, in the phytoplankton. The soft-bodied zooplankton species—especially copepods—that lived with them can only be inferred. Large, abrupt climate changes took place, aided by positive feedback. Second, this paper attempts to predict how human forcing in the form of anthropogenic climate change is likely to affect marine ecosystems in the future. Past predictions have underestimated the speed at which warming is actually happening: positive feedback has been unexpectedly strong. Thus, the melting of snow and ice, by reducing the earth's albedo, has increased the amount of solar energy absorbed. Also, warming of the surface (water and land) has caused outgassing of methane from buried clathrates (hydrates), and methane is a strong greenhouse gas. Currently, predictions emphasize one or the other of two contrasted alternatives: abrupt cooling caused by a shutdown of the thermohaline circulation (the “ocean conveyor”) or abrupt warming caused by copious outgassing of methane. Both arguments (the former from oceanographers and the latter from geophysicists) are equally persuasive, and I have chosen to explore the methane alternative, because I am familiar with an area (the Beaufort Sea and Mackenzie Delta) where outgassing has recently (2007) been detected and is happening now: in the Arctic Ocean and the Canadian Arctic Archipelago, where disappearance of the ice will affect currents, temperature, thermocline, salinity, upwelling, and nutrients, with consequent effects on the zooplankton.