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Six Decades of Northeast Atlantic Phytoplankton Productivity

Paper Reviewed
Raitsos, D.E., Pradhan, Y., Lavender, S.J., Hoteit, I., McQuatters-Gollop, A., Reid, P.C. and Richardson, A.J. 2014. From silk to satellite: half a century of ocean color anomalies in the Northeast Atlantic. Global Change Biology 20: 2117-2123.

According to Raitsos et al. (2014), "changes in phytoplankton dynamics influence marine biogeochemical cycles, climate processes and food webs, with substantial social and economic consequences," and they add that large-scale assessments of phytoplankton biomass have been obtained from two different remote sensing satellites, the Coastal Zone Color Scanner (CZCS, 1979-1986) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS, 1998-2010). However, they note that "due to the large gap between the two satellite eras and differences in sensor characteristics, comparison of the absolute values retrieved from the two instruments remains challenging." Rising to meet on that challenge, and employing a unique in situ ocean color dataset that spans more than half a century, in the present work Raitsos et al. merged the two satellite-derived chlorophyll-a (Chl-a) histories to produce a six-decade-long history of phytoplankton productivity over the Northeast Atlantic Ocean and the North Sea. And what did that history show?

The seven scientists report their unique re-analysis revealed "a clear increasing pattern of Chl-a," along with "a longer growing season and higher seasonal biomass," noting in particular that "the Phytoplankton Color Index appeared to have increased by 23% after the mid-1980s." And they further relate that the new Chl-a history "parallels the oscillations of the Northern Hemisphere Temperature since 1948."

In discussing their findings, Raitsos et al. say their results "and almost all the literature support the assertion that phytoplankton biomass is increasing in the Northeast Atlantic and the North Sea," mentioning in particular the satellite studies of Gregg and Conkright (2002), Antoine et al. (2005) and Martinez et al. (2009), the in situ studies of Reid et al. (1998), Edwards et al. (2001), McQuatters-Gollop et al. (2011) and Wernand et al. (2013), as well as the modeled data sets of Hensen et al. (2009). Such findings stand in stark contrast to climate alarmist claims and give serious pause to concerns that future temperature increases and declines in oceanic pH will decimate marine life, for despite what the alarmists refer to as unprecedented temperatures and CO2 concentrations of the past millennium, phytoplankton of the Northeast Atlantic are no worse for the wear. In fact, truth be told, they are faring far better.

Antoine, D., Morel, A., Gordon, H.R., Banzon, V.F. and Evans, R.H. 2005. Bridging ocean color observations of the 1980s and 2000s in search of long-term trends. Journal of Geophysical Research 110: 10.1029/2004JC002620.

Edwards, M., Reid, P.C. and Planque, B. 2001. Long-term and regional variability of phytoplankton biomass in the Northeast Atlantic (1960-1995). ICES Journal of Marine Sciences 58: 39-49.

Gregg, W.W. and Conkright, M.E. 2002. Decadal changes in global ocean chlorophyll. Geophysical Research Letters 29: 10.1029/2002GL014689 .

Henson, S., Raitsos, D., Dunne, J.P. and McQuatters-Gollop, A. 2009. Decadal variability in biogeochemical models comparison with a 50-year ocean color dataset. Geophysical Research Letters 36: 10.1029/2009GL040874.

Martinez, E., Antoine, D., D'Ortenzio, F. and Gentili, B. 2009. Climate-driven basin-scale decadal oscillations of oceanic phytoplankton. Science 326: 10.1126/science.1177012.

McQuatters-Gollop, A., Reid, P.C., Edwards, M., Burkill, P.H., Castellani, C., Batten, S., Gieskes, W., Beare, D., Bidigare, R.R., Head, E., Johnson, R, .Kahru, M., Koslow, J.A. and Pena, A. 2011. Is there a decline in marine phytoplankton? Nature 472: 10.1038/nature09950.

Reid, P.C., Edwards, M., Hunt, H.G. and Warner, A. 1998. Phytoplankton change in the North Atlantic. Nature 391: 10.1038/35290.

Wernand, M.R., van der Woerd, H.J. and Gieskes, W.W.C. 2013. Trends in ocean color and chlorophyll concentration from 1889 to 2000 worldwide. PLOS ONE 8: e63766.

Posted 9 October 2014