Global phytoplankton decline over the past century


In the oceans, ubiquitous microscopic phototrophs (phytoplankton) account for approximately half the production of organic matter on Earth. Analyses of satellite-derived phytoplankton concentration (available since 1979) have suggested decadal-scale fluctuations linked to climate forcing, but the length of this record is insufficient to resolve longer-term trends. Here we combine available ocean transparency measurements and in situ chlorophyll observations to estimate the time dependence of phytoplankton biomass at local, regional and global scales since 1899. We observe declines in eight out of ten ocean regions, and estimate a global rate of decline of 1% of the global median per year. Our analyses further reveal interannual to decadal phytoplankton fluctuations superimposed on long-term trends. These fluctuations are strongly correlated with basin-scale climate indices, whereas long-term declining trends are related to increasing sea surface temperatures. We conclude that global phytoplankton concentration has declined over the past century; this decline will need to be considered in future studies of marine ecosystems, geochemical cycling, ocean circulation and fisheries.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Data availability.
Figure 2: Local-scale trends in phytoplankton.
Figure 3: Regional and global trends in phytoplankton.
Figure 4: Temporal variability in phytoplankton trends.
Figure 5: Effects of climate variability on phytoplankton.
Figure 6: Physical drivers of phytoplankton trends.


  1. 1

    Field, C. B., Behrenfeld, M. J., Randerson, J. T. & Falkowski, P. Primary production of the biosphere: integrating terrestrial and oceanic components. Science 281, 237–240 (1998)

  2. 2

    Chassot, E. et al. Global marine primary production constrains fisheries catches. Ecol. Lett. 13, 495–505 (2010)

  3. 3

    Murtugudde, I., Beauchamp, R. J., McClain, C. R., Lewis, M. R. & Busalacchi, A. Effects of penetrative radiation on the upper tropical ocean circulation. J. Clim. 15, 470–486 (2002)

  4. 4

    Sabine, C. L. et al. The oceanic sink for anthropogenic CO2 . Science 305, 367–371 (2004)

  5. 5

    Roemmich, D. & McGowan, J. Climatic warming and the decline of zooplankton in the California current. Science 267, 1324–1326 (1995)

  6. 6

    McClain, C. R. A decade of satellite ocean color observations. Annu. Rev. Mar. Sci. 1, 19–42 (2009)

  7. 7

    Gregg, W. W. & Conkright, M. E. Decadal changes in global ocean chlorophyll. Geophys. Res. Lett. 29, 1730–1734 (2002)

  8. 8

    Gregg, W. W., Casey, N. W. & McClain, C. R. Recent trends in global ocean chlorophyll. Geophys. Res. Lett. 32, 1–5 (2005)

  9. 9

    Antoine, D., Morel, A., Gordon, H. R., Banzon, V. F. & Evans, R. H. Bridging ocean color observations of the 1980s and 2000s in search of long-term trends. J. Geophys. Res. 110, 1–22 (2005)

  10. 10

    Behrenfeld, M. J. et al. Climate-driven trends in contemporary ocean productivity. Nature 444, 752–755 (2006)

  11. 11

    Martinez, E., Antoine, D., D'Ortenzio, F. & Gentili, B. Climate-driven basin-scale decadal oscillations of oceanic phytoplankton. Science 326, 1253–1256 (2009)

  12. 12

    Falkowski, P. G., Barber, R. T. & Smetacek, V. Biogeochemical controls and feedbacks on ocean primary production. Science 281, 200–206 (1998)

  13. 13

    Raitsos, D. E., Reid, P. C., Lavender, S. J., Edwards, M. & Richardson, A. J. Extending the SeaWiFS chlorophyll data set back 50 years in the northeast Atlantic. Geophys. Res. Lett. 32, 1–4 (2005)

  14. 14

    Ryther, J. H. & Yentsch, C. S. The estimation of phytoplankton production in the ocean from chlorophyll and light data. Limnol. Oceanogr. 2, 281–286 (1957)

  15. 15

    Henson, S. A. et al. Detection of anthropogenic climate change in satellite records of ocean chlorophyll and productivity. Biogeosciences 7, 621–640 (2010)

  16. 16

    Jeffrey, S. W., Mantoura, R. F. C. & Wright, S. W. Phytoplankton Pigments in Oceanography Vol. 10 (UNESCO, 1997)

  17. 17

    Falkowski, P. & Wilson, C. Phytoplankton productivity in the North Pacific ocean since 1900 and implications for absorption of anthropogenic CO2 . Nature 358, 741–743 (1992)

  18. 18

    Lewis, M. R., Kuring, N. & Yentsch, C. Global patterns of ocean transparency: implications for the new production of the open ocean. J. Geophys. Res. 93, 6847–6856 (1988)

  19. 19

    Hastie, T. & Tibshirani, R. Generalized additive models. Stat. Sci. 1, 297–318 (1986)

  20. 20

    Ware, D. M. & Thomson, R. E. Bottom-up ecosystem trophic dynamics determine fish production in the Northeast Pacific. Science 308, 1280–1284 (2005)

  21. 21

    Vantrepotte, V. & Melin, F. Temporal variability of 10-year global SeaWiFS time-series of phytoplankton chlorophyll a concentration. ICES J. Mar. Sci. 66, 1547–1556 (2009)

  22. 22

    Polovina, J. J., Howell, E. A. & Abecassis, M. Ocean's least productive waters are expanding. Geophys. Res. Lett. 35 L03618 10.1029/2007GL031745 (2008)

  23. 23

    Pauly, D. & Christensen, V. Primary production required to sustain global fisheries. Nature 374, 255–257 (1995)

  24. 24

    Behrenfeld, M. J., Boss, E., Siegel, D. A. & Shea, D. M. Carbon-based ocean productivity and phytoplankton physiology from space. Glob. Biogeochem. Cycles 19, 1–14 (2005)

  25. 25

    Yoder, J. A. & Kennelly, M. A. Seasonal and ENSO variability in global ocean phytoplankton chlorophyll derived from 4 years of SeaWiFS measurements. Glob. Biogeochem. Cycles 17, 1–24 (2003)

  26. 26

    Behrenfeld, M. J. et al. Biospheric primary production during an ENSO transition. Science 291, 2594–2597 (2001)

  27. 27

    Wiggert, J. D., Murtugudde, R. G. & Christian, J. R. Annual ecosystem variability in the tropical Indian Ocean: results of a coupled bio-physical ocean general circulation model. Deep Sea Res. II 53, 644–676 (2006)

  28. 28

    Mann, K. H. & Lazier, J. R. N. Dynamics of Marine Ecosystems (Blackwell, 1991)

  29. 29

    Dickson, R. R., Kelly, P. M., Colebrook, J. M., Wooster, W. S. & Cushing, D. H. North winds and production in the production in the eastern North Atlantic. J. Plankton Res. 10, 151–169 (1988)

  30. 30

    Fromentin, J. M. & Planque, B. Calanus and environment in the eastern North Atlantic. 2. Influence of the North Atlantic Oscillation on C. finmarchicus and C. helgolandicus . Mar. Ecol. Prog. Ser. 134, 111–118 (1996)

  31. 31

    Paytan, A. et al. Toxicity of atmospheric aerosols on marine phytoplankton. Proc. Natl Acad. Sci. USA 10, 4601–4605 (2009)

  32. 32

    Montes-Hugo, M. et al. Recent changes in phytoplankton communities associated with rapid regional climate change along the western Antarctic peninsula. Science 323, 1470–1473 (2009)

  33. 33

    Broecker, W. S., Sutherland, S. & Peng, T.-H. A possible 20th century slowdown of Southern Ocean deep water formation. Science 286, 1132–1134 (1999)

  34. 34

    Frank, K. T., Petrie, B., Choi, J. S. & Leggett, W. C. Trophic cascades in a formerly cod-dominated ecosystem. Science 308, 1621–1623 (2005)

  35. 35

    Doney, S. C. Plankton in a warmer world. Nature 444, 695–696 (2006)

  36. 36

    Richardson, A. J. & Schoeman, D. S. Climate impact on plankton ecosystems in the Northeast Atlantic. Science 305, 1609–1612 (2004)

  37. 37

    Worm, B. & Lotze, H. K. in Climate and Global Change: Observed Impacts on Planet Earth (ed. Letcher, T.) 263–279 (Elsevier, 2009)

  38. 38

    Brander, K. M. Global fish production and climate change. Proc. Natl Acad. Sci. USA 104, 19709–19714 (2007)

  39. 39

    Cooper, H. & Hedges, L. V. The Handbook of Research Synthesis (Russell Sage Foundation, 1994)

Download references


We are grateful to all data providers, to J. Mills-Flemming, W. Blanchard, M. Dowd, C. Field and C. Minto for statistical advice, to T. Boyer, J. Smart, D. Ricard and D. Tittensor for help with data extraction, and to J. Mills-Flemming, W. Blanchard, W. Li, H. Lotze, C. Muir and M. Dowd for critical review. Funding was provided by the Natural Sciences and Engineering Research Council of Canada, the US Office of Naval Research, the Canada Foundation for Climate and Atmospheric Sciences, the National Aeronautics and Space Administration, the Sloan Foundation (Census of Marine Life FMAP Program), and the Lenfest Ocean Program.

Author information

The study was initiated by B.W. and M.R.L. in collaboration with the late R.A. Myers. Data were compiled by D.G.B. and M.R.L.; D.G.B. conducted the analyses and drafted the manuscript. All authors discussed the results and contributed to the writing of the manuscript.

Correspondence to Daniel G. Boyce.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Methods, References, Supplementary Tables S1-S3 and Supplementary Figures S1-S9 with legends. (PDF 4276 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Boyce, D., Lewis, M. & Worm, B. Global phytoplankton decline over the past century. Nature 466, 591–596 (2010).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.