More than twenty years ago, a biological regulation of climate was proposed whereby emissions of dimethyl sulphide from oceanic phytoplankton resulted in the formation of aerosol particles that acted as cloud condensation nuclei in the marine boundary layer. In this hypothesis—referred to as CLAW—the increase in cloud condensation nuclei led to an increase in cloud albedo with the resulting changes in temperature and radiation initiating a climate feedback altering dimethyl sulphide emissions from phytoplankton. Over the past two decades, observations in the marine boundary layer, laboratory studies and modelling efforts have been conducted seeking evidence for the CLAW hypothesis. The results indicate that a dimethyl sulphide biological control over cloud condensation nuclei probably does not exist and that sources of these nuclei to the marine boundary layer and the response of clouds to changes in aerosol are much more complex than was recognized twenty years ago. These results indicate that it is time to retire the CLAW hypothesis.
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Twomey, S. The influence of pollution on the shortwave albedo of clouds. J. Atmos. Sci. 34, 1149–1152 (1977)
Sunda, W., Kieber, D. J., Kiene, R. P. & Huntsman, S. An antioxidant function for DMSP and DMS in marine algae. Nature 418, 317–320 (2002)
Vallina, S. M. & Simo, R. Strong relationship between DMS and the solar radiation dose over the global surface ocean. Science 315, 506–508 (2007)
Bates, T. S., Lamb, B. K., Guenther, A. B., Dignon, J. & Stoiber, R. E. Sulfur emissions to the atmosphere from natural sources. J. Atmos. Chem. 14, 315–337 (1992)
Andreae, M. O. et al. Dimethylsulfide in the marine atmosphere. J. Geophys. Res. 90, 12891–12900 (1985)
Shaw, G. E. Bio-controlled thermostasis involving the sulphur cycle. Clim. Change 5, 297–303 (1983)
Charlson, R. J., Lovelock, J. E., Andreae, M. O. & Warren, S. G. Oceanic phytoplankton, atmospheric sulphur, cloud albedo, and climate. Nature 326, 655–661 (1987)This paper introduced the CLAW hypothesis proposing the link between marine biota and climate.
Andreae, M. O. Marine aerosol chemistry at Cape Grim, Tasmania and Townsville, Queensland. J. Geophys. Res. 87, 8875–8885 (1982)
Savoie, D. L. & Prospero, J. M. Particle size distribution of nitrate and sulphate in the marine atmosphere. Geophys. Res. Lett. 9, 1207–1210 (1982)
Hobbs, P. V. Simultaneous airborne measurements of cloud condensation nuclei and sodium-containing particles over the ocean. Q. J. R. Meteorol. Soc. Soc 97, 263–271 (1971)
Ayers, G. P. & Gras, J. L. Seasonal relationship between cloud condensation nuclei and aerosol methanesulphonate in marine air. Nature 353, 834–835 (1991)This paper presented the coherence in the seasonality of DMS-derived particulate phase sulphur species and CCN at Cape Grim, Tasmania.
Ayers, G. P., Cainey, J. M., Gillett, R. W. & Ivey, J. P. Atmospheric sulphur and cloud condensation nuclei in marine air in the southern hemisphere. Phil. Trans. R. Soc. Lond. B 352, 203–211 (1997)
Andreae, M. O., Elbert, W. & de Mora, S. J. Biogenic sulphur emissions and aerosols over the tropical South Atlantic. 3. Atmospheric dimethylsulfide, aerosols, and cloud condensation nuclei. J. Geophys. Res. 100 (D6). 11335–11356 (1995)
Hegg, D. A., Ferek, R. J., Hobbs, P. V. & Radke, L. F. Dimethyl sulfide and cloud condensation nucleus correlations in the northeast Pacific Ocean. J. Geophys. Res. 96 (D7). 13189–13191 (1991)
Parungo, F. P., Nagamoto, C. T., Rosinski, J. & Haagenson, P. L. A study of marine aerosols over the Pacific Ocean. J. Atmos. Chem. 4, 199–226 (1986)
Pósfai, M., Anderson, J. R. & Buseck, P. R. Constituents of a remote Pacific marine aerosol: A TEM study. Atmos. Environ. 28, 1747–1756 (1994)
McInnes, L., Covert, D. & Baker, B. The number of sea-salt, sulfate, and carbonaceous particles in the marine atmosphere: EM measurements consistent with the ambient size distribution. Tellus 49B, 300–313 (1997)
Murphy, D. M. et al. Influence of sea-salt on aerosol radiative properties in the Southern Ocean marine boundary layer. Nature 392, 62–65 (1998)This paper provided direct observational evidence of significant numbers of CCN-size particles containing sea salt and organics in the remote MBL.
Leck, C. & Bigg, E. K. Comparison of sources and nature of the tropical aerosol with the summer high Arctic aerosol. Tellus 60B, 118–126 (2008)
Russell, L. M., Hawkins, L. N., Frossard, A. A., Quinn, P. K. & Bates, T. S. Carbohydrate-like composition of submicron atmospheric particles and their production from ocean bubble bursting. Proc. Natl Acad. Sci. USA 107, 6652–6657 (2010)
Hawkins, L. N. & Russell, L. M. Polysaccharides, proteins, and phytoplankton fragments: four chemically distinct types of marine primary organic aerosol classified by single particle spectromicroscopy. Adv. Meteorol. 2010, 612132 (2010)
Clarke, A. D., Owens, S. R. & Zhou, J. An ultrafine sea-salt flux from breaking waves: implications for cloud condensation nuclei in the remote marine atmosphere. J. Geophys. Res. 111, D06202 (2006)
Campuzano-Jost, P. et al. Near-real-time measurement of sea-salt aerosol during the SEAS campaign: comparison of emission-based sodium detection with an aerosol volatility technique. J. Atmos. Ocean. Technol. 20, 1421–1430 (2003)
O’Dowd, C. D. & Smith, M. H. Physicochemical properties of aerosols over the northeast Atlantic: evidence for wind-speed-related submicron sea-salt aerosol production. J. Geophys. Res. 98 (D1). 1137–1149 (1993)
Dinger, J. E., Howell, H. B. & Wojciechowski, T. A. On the source and composition of cloud nuclei in a subsident air mass over the north Atlantic. J. Atmos. Sci. 27, 791–797 (1970)
O’Dowd, C. D., Smith, M. H. & Jennings, S. G. Submicron particle, radon, and soot carbon characteristics over the Northeast Atlantic. J. Geophys. Res. 98, 1123–1135 (1993)
Twohy, C. H. & Anderson, J. R. Droplet nuclei in non-precipitating clouds: composition and size matter. Environ. Res. Lett. 3, 045002. 1–9 (2008)This paper provided direct observational evidence of cloud droplets formed primarily through nucleation on sea-salt particles.
Peter, J. A., Blyth, A. M., Brooks, B., Lingard, J. & Smith, M. H. On the composition of Caribbean maritime aerosol particles measured during RICO. Q. J. R. Meteorol. Soc. 134, 1059–1063 (2008)
Fuhrman, J. A. Marine viruses and their biogeochemical and ecological effects. Nature 399, 541–548 (1999)
Wells, M. L. & Goldberg, E. D. Occurrence of small colloids in sea water. Nature 353, 342–344 (1991)
Biersmith, A. & Benner, R. Carbohydrates in phytoplankton and freshly produced dissolved organic matter. Mar. Chem. 63, 131–144 (1998)
Hedges, J. I. Global biogeochemical cycles: progress and problems. Mar. Chem. 39, 67–93 (1992)
Facchini, M. C. et al. Primary submicron marine aerosol dominated by insoluble organic colloids and aggregates. Geophys. Res. Lett. 35, L17814 (2008)
Leck, C. & Bigg, E. K. Evolution of the marine aerosol—a new perspective. Geophys. Res. Lett. 32, L19803 (2005)
Bigg, E. K. Sources, nature, and influence on climate of marine airborne particulates. Environ. Chem. 4, 155–161 (2007)This paper described an organic alternative to DMS as a source of CCN to the MBL.
Decho, A. W. Microbial exopolymer secretions in ocean environments: their role(s) in food webs and marine processes. Oceanogr. Mar. Biol. Ann. Rev. 28, 73–153 (1990)
Bigg, E. K. & Leck, C. The composition of fragments of bubbles bursting at the ocean surface. J. Geophys. Res. 113, D11209 (2008)
O’Dowd, C. D. et al. Biogenically-driven organic contribution to marine aerosol. Nature 431, 676–680 (2004)
Keene, W. C. et al. Chemical and physical characteristics of nascent aerosols produced by bursting bubbles at a model air-sea interface. J. Geophys. Res. 112, D21202 (2007)
Tyree, C. A., Hellion, V. M., Alexandrova, O. A. & Allen, J. O. Foam droplets generated from natural and artificial seawaters. J. Geophys. Res. 112, D12204 (2007)
Hultin, K. A. H. et al. In situ laboratory sea spray production during the Marine Aerosol Production 2006 cruise on the northeastern Atlantic Ocean. J. Geophys. Res. 115, D06201 (2010)
Fuentes, E., Coe, H., Green, D., de Leeuw, G. & McFiggans, G. On the impacts of phytoplankton-derived organic matter on the properties of marine aerosol—Part 1: Source fluxes. Atmos. Chem. Phys. 10, 9295–9317 (2010)
Bigg, E. K., Leck, C. & Tranvik, L. Particulates of the surface microlayer of open water in the central Arctic Ocean in summer. Mar. Chem. 91, 131–141 (2004)
Covert, D. S., Kapustin, V. N., Quinn, P. K. & Bates, T. S. New particle formation in the marine boundary layer. J. Geophys. Res. 97, 20581–20589 (1992)
Warren, D. R. & Seinfeld, J. H. Prediction of aerosol concentration resulting from a burst of nucleation. J. Colloid Interf. Sci. 105, 136–142 (1985)
Pirjola, L., O’Dowd, C. D., Brooks, I. M. & Kulmala, M. Can new particle formation occur in the clean marine boundary layer? J. Geophys. Res. 105 (D21). 26,531–26,546 (2000)
Clarke, A. D. et al. Particle production in the remote marine atmosphere: cloud outflow and subsidence during ACE-1. J. Geophys. Res. 103 (D13). 16,397–16,409 (1998)This paper was one of the first to provide unambiguous evidence of an upper tropospheric source of sulphur particles to the marine boundary layer.
Ehn, M. et al. in Nucleation and Atmospheric Aerosols: 17th International Conference (Galway, Ireland, 2007) (eds O’Dowd, C. D. & Wagner, P. E. ) 1,102–1, 105 (Springer, 2007)
Davison, B. et al. Dimethyl sulfide, methyl sulfonic acid, and physicochemical aerosol properties in Atlantic air from the United Kingdom to Halley Bay. J. Geophys. Res. 101, 22,855–22,867 (1996)
O’Dowd, C. D. et al. Biogenic sulphur emissions and inferred non-sea-salt sulfate cloud condensation nuclei in and around Antarctica. J. Geophys. Res. 102, 12839–12854 (1997)
Cainey, J. & Harvey, M. Dimethylsulfide, a limited contributor to new particle formation in the clean marine boundary layer. Geophys. Res. Lett. 29 1128 10.1029/2001GL014439 (2002)
Hegg, D. A., Radke, L. F. & Hobbs, P. V. Particle production associated with marine clouds. J. Geophys. Res. 95, 13,917–13,926 (1990)
Perry, K. D. & Hobbs, P. V. Further evidence for particle nucleation in clear air adjacent to marine cumulus clouds. J. Geophys. Res. 99, 22,803–22,818 (1994)
Hoppel, W. A., Frick, G. M., Fitzgerald, J. & Larson, R. E. Marine boundary layer measurements of new particle formation and the effects nonprecipitating clouds have on aerosol size distributions. J. Geophys. Res. 99, 14,443–14,459 (1994)
Clarke, A. D., Li, Z. & Litchy, M. Aerosol dynamics in the equatorial Pacific marine boundary layer: microphysics, diurnal cycles, and entrainment. Geophys. Res. Lett. 23, 733–736 (1996)
Raes, F. Entrainment of free-tropospheric aerosol as a regulating mechanism for cloud condensation nuclei in the remote marine boundary layer. J. Geophys. Res. 100, 2893–2903 (1995)
Pierce, J. R. & Adams, P. J. Global evaluation of CCN formation by direct emission of sea salt and growth of ultrafine sea salt. J. Geophys. Res. 111, D06203 (2006)
Kazil, J., Lovejoy, E. R., Barth, M. C. & O’Brien, K. Aerosol nucleation over oceans and the role of galactic cosmic rays. Atmos. Chem. Phys. 6, 4905–4924 (2006)
Spracklen, D. V. et al. Evaluation of a global aerosol microphysics model against size-resolved particle statistics in the marine atmosphere. Atmos. Chem. Phys. 7, 2073–2090 (2007)
Merikanto, J., Spracklen, D. V., Mann, G. W., Pickering, S. J. & Carslaw, K. S. Impact of nucleation on global CCN. Atmos. Chem. Phys. 9, 8601–8616 (2009)
Korhonen, H., Carslaw, K. S., Spracklen, D. V., Mann, G. W. & Woodhouse, M. T. Influence of oceanic dimethyl sulfide emissions on cloud condensation nuclei concentrations and seasonality over the remote Southern Hemisphere oceans: a global model study. J. Geophys. Res. 113, D15204 (2008)
Woodhouse, M. T., Mann, G. W., Carslaw, K. S. & Boucher, O. New directions: the impact of oceanic iron fertilization on cloud condensation nuclei. Atmos. Environ. 42, 5728–5730 (2008)
Roelofs, G. J. A GCM study of organic matter in marine aerosol and its potential contribution to cloud drop activation. Atmos. Chem. Phys. 8, 709–719 (2008)
de Leeuw, G. et al. Production flux of sea spray aerosol. Rev. Geophys. 49, 2010RG000349 (2011)
O’Dowd, C. D. et al. A combined organic-inorganic sea-spray source function. Geophys. Res. Lett. 35, L01801 (2008)
Woodhouse, M. T. et al. Low sensitivity of cloud condensation nuclei to changes in the sea-air flux of dimethyl-sulphide. Atmos. Chem. Phys. 10, 7545–7559 (2010)This study modelled the sensitivity of CCN to changes in the sea-to-air flux of DMS and found it to be low, such that the role of DMS in climate regulation is very weak.
Carslaw, K. S. et al. A review of natural aerosol interactions and feedbacks within the Earth system. Atmos. Chem. Phys. 10, 1701–1737 (2010)
Wood, R. Cancellation of aerosol indirect effects in marine stratocumulus through cloud thinning. J. Atmos. Sci. 64, 2657–2669 (2007)
Stevens, B. & Feingold, G. Untangling aerosol effects on clouds and precipitation in a buffered system. Nature 461, 607–613 (2009)
Small, J. D., Chuang, P. Y., Feingold, G. & Jiang, H. Can aerosol decrease cloud lifetime? Geophys. Res. Lett. 36, L16806 (2009)
Zuidema, P., Xue, H. & Feingold, G. Shortwave radiative impacts from aerosol effects on marine shallow cumuli. J. Atmos. Sci. 65, 1979–1990 (2008)
Toole, D. A. & Siegel, D. A. Light-driven cycling of dimethylsulfide (DMS) in the Sargasso Sea: closing the loop. Geophys. Res. Lett. 31, L09308 (2004)
Vallina, S. M., Simo, R. & Manizza, M. Weak response of oceanic dimethylsulfide to upper mixing shoaling induced by global warming. Proc. Natl Acad. Sci. USA 104, 16004–16009 (2007)This studied modelled the sensitivity of DMS seawater concentrations to a 50% increase in CO 2 and found it to be too low to be a significant offset for global warming.
Gunson, J. R. et al. Climate sensitivity to ocean dimethyl sulphide emissions. Geophys. Res. Lett. 33, L07701 (2006)
Latham, J. & Smith, M. H. Effect on global warming of wind-dependent aerosol generation at the ocean surface. Nature 347, 372–373 (1990)
Korhonen, H. et al. Aerosol climate feedback due to decadal increases in Southern Hemisphere wind speeds. Geophys. Res. Lett. 37 L02805 10.1029.2009GL041320 (2010)
Yang, X.-Y., Huang, R. X. & Wang, D. X. Decadal changes of wind stress over the Southern Ocean associated with Antarctic ozone depletion. J. Clim. 20, 3395–3410 (2007)
We thank our PhD adviser R. J. Charlson for guidance early in our scientific careers. This review should be seen as ‘coming both to praise and bury Caesar’ in that the good that the CLAW hypothesis has done will far outlive its use. We also thank W. E. Asher for comments on this manuscript. This is PMEL contribution number 3697.
The authors declare no competing financial interests.
About this article
Cite this article
Quinn, P., Bates, T. The case against climate regulation via oceanic phytoplankton sulphur emissions. Nature 480, 51–56 (2011). https://doi.org/10.1038/nature10580
Nature Communications (2021)
Scientific Reports (2021)
Journal of Earth System Science (2021)
Journal of Oceanology and Limnology (2021)