Royal Netherlands Institute for Sea Research
Phone number
+31 (0)222 36 9442
Ocean Systems (OCS)
Head of Analytical Laboratory
  • Particle fluxes in the oceans
  • Planktonic foraminifera
  • Sedimentation and sediment formation
  • Climate change

Dr. Geert-Jan Brummer

Head of Analytical Laboratory

‘Decreasing amount of “snow” on ocean mountain tops’

‘Calcium-carbonate-producing organisms are the finger on the pulse of ocean climate’, says NIOZ oceanographer and endowed professor at VU Amsterdam, Geert-Jan Brummer. ‘Therefore, the tiny plants and animals that produce calcium carbonate are also key to understanding the past, present and future of the climate. Plankton that produces calcium carbonate thrives better or worse depending on the temperature, amount of sunlight, mixing of water during storms, and CO2 levels. It also means there are seasons in the blooming of calcium-carbonate-producing phytoplankton. In summer, a warm layer of water develops at the top of the ocean that does not mix easily with deeper, colder water. In that warm, isolated layer, nutrients are rapidly consumed as a result of which plankton growth is inhibited. In winter, there is little sunlight, and the water is too cold for algal blooms. This means that calcium-carbonate-producing plankton usually blooms in spring and autumn and that these blooming periods shift with the changing climate.’

Seasons in the archive

‘The presence or absence of plankton cannot be understood without considering those seasons, which are still recognisable when dead plankton sinks to the ocean floor. In samples from the ocean floor, we can still identify the seasons from the past from the remains of species that thrive at specific temperatures. We, therefore, investigate plankton in both the water column and ocean floor. We measure sinking plankton using fully automatic measurement stations, “sediment traps”, which we have anchored to the ocean floor using long cables.’

‘Strangely enough, we see that the “mountain tops” on the ocean floor are somewhat similar to the mountains on land: the “snow line” is shifting under the influence of the changing climate. For example, on top of the mid-Atlantic Ridge, there is a white layer of sunken calcium carbonate skeletons from dead plankton. The deeper you go, the less calcium carbonate there is on the slopes, because it has dissolved due to the shifting chemical balance in the deep ocean. However, the undersea snow line is moving ever higher due to the increasing CO2 concentrations as more CO2 ends up in the ocean water from the atmosphere. Studying the archives of the ocean floor subsequently teaches us what this can mean for sea life and ultimately life on land.’

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Research interests & personal motivation

As a scientist at Royal NIOZ and extra-ordinary Professor at the VU-Amsterdam, I pursue how sediments are formed under recent and past conditions of ocean-climate change. Topics range from seasonal particle production by biomineralising ocean plankton, to Sharan dust deposition, current transport of bottom sediment and coral carbonate geochemistry in response to changing ocean-climate. Through collaborative projects in ocean-going research , mainly in the Atlantic and western Indian Ocean I am addressing research questions pertaining to:

•        Sediment genesis: the pathways of production, transformation and accumulation fluxes of sedimentary matter, notably biogenic carbonates, silica and organic compounds.

•        Ocean-climate change: anthropogenic and natural variability of biogeochemical cycling and thermohaline circulation; high-resolution paleoceanography.

•        Planktonic foraminifera: biodiversity and population dynamics, seasonality and intermittency of export fluxes, isotope and chemical composition, dissolution and sediment mixing; proxy validation, evolutionary paleoceanography.

•        Physical forcing mechanisms: effects of stratification and mixing, eddy transports, thermo-haline circulation, re-suspension and sediment focussing.

Linked news

Wednesday 24 January 2018
Koralen van 'Darwin' verklaren schommelingen in mondiale opwarmingssnelheid
De aarde warmt snel op door de menselijke uitstoot van broeikasgassen, maar ook natuurlijke factoren spelen een rol bij variaties in de opwarmingssnelheid. Metingen van de mondiale oppervlaktetemperaturen laten soms onderbrekingen zien in de…

Linked blogs

Monday 05 July 2021
Rain determines Saharan dust deposition across the subtropical north Atlantic Ocean
New dusty paper out: rain determines the seasonality in dust deposition across the subtropical north Atlantic Ocean. In their new paper that appeared online in the Journal of Geophysical Research, Michèlle van der Does and colleagues present the…
Tuesday 07 April 2020
New dusty paper out: Saharan dust versus Amazon River water
In their new paper that appeared today in the open-access version of Limnology & Oceanography, entitled “Multiple drivers of production and particle export in the western tropical North Atlantic”, Laura Korte and colleagues present a comprehensive…
Friday 13 March 2020
New dusty paper out: Transatlantic Saharan dust fluxes
In their new paper that appeared today in the journal Geophysical Research Letters, Michèlle van der Does and colleagues present the first continuous two-year record of Transatlantic Saharan-dust fluxes, which they compare to modelled dust fluxes…
Tuesday 05 November 2019
Expedition 64PE464: DUST2019
From 11 to 23 November 2019 we have been chasing Saharan dust once more. On 11 November RV Pelagia has left the port of Las Palmas de Gran Canaria (Spain) to sail south for a two-week expedition to service both the dust-collecting buoys "Carmen" and…
Friday 07 December 2018
DUST | PhD Defence Michèlle van der Does
As of today, Michèlle van der Does may call herself a PhD; she successfully defended her thesis "Saharan dust from a marine perspective: transport and deposition along a transect in the Atlantic Ocean" at the Vrije Universiteit Amsterdam. A committee…
Tuesday 16 October 2018
PhD defence Laura Korte
From this day on, Laura Korte may call herself a PhD; she successfully defended her thesis “Saharan dust deposition in the equatorial North Atlantic Ocean and its impact on particle export fluxes” at the Vrije Universiteit Amsterdam. A committee of…
Tuesday 09 January 2018
NICO 2 samples Saharan dust
NICO expedition leg 2 was designed to study the impact of Saharan dust on the marine environment and they are sailing right through a Saharan-dust outbreak.
Friday 20 October 2017
Saharan dust and Amazon freshwaters cause algal blooms
New findings suggest that both Saharan dust and freshwater from the Amazon may have led to algal blooms in the western equatorial Atlantic Ocean. Those are the conclusions of a new paper published by Catarina Guerreiro and colleagues in the…
Tuesday 17 October 2017
Dust (and smoke) is in the air!
Cyclone Ophelia draws Sahara dust and Iberian smoke to northern Europe
Sunday 10 September 2017
New dust paper published by Carmen Friese
The manuscript by Carmen Friese (MARUM) has now been published as "full" paper in the open-access journal Atmospheric Chemistry & Physics. The paper is entitled: "Seasonal provenance changes in present-day Saharan dust collected in and off…

NIOZ publications

  • 2023
    Chaabane, S.; de Garidel-Thoron, T.; Giraud, X.; Schiebel, R.; Beaugrand, G.; Brummer, G.-J.; Casajus, N.; Greco, M.; Grigoratou, M.; Howa, H.; Jonkers, L.; Kucera, M.; Kuroyanagi, A.; Meilland, J.; Monteiro, F.; Mortyn, G.; Almogi-Labin, A.; Asahi, H.; Avnaim-Katav, S.; Bassinot, F.; Davis, C.V.; Field, D.B.; Hernández-Almeida, I.; Herut, B.; Hosie, G.; Howard, W.; Jentzen, A.; Johns, D.G.; Keigwin, L.; Kitchener, J.; Kohfeld, K.E.; Lessa, D.V.O.; Manno, C.; Marchant, M.; Ofstad, S.; Ortiz, J.D.; Post, A.; Rigual-Hernandez, A.; Rillo, M.C.; Robinson, K.; Sagawa, T.; Sierro, F.; Takahashi, K.T.; Torfstein, A.; Venancio, I.; Yamasaki, M.; Ziveri, P. (2023). The FORCIS database: A global census of planktonic Foraminifera from ocean waters. Scientific Data 10(1).
  • 2022
    Brummer, G.-J. A.; Kucera, M. (2022). Taxonomic review of living planktonic foraminifera. J. Micropalaeontol. 41: 29-74.
    de Garidel-Thoron, T.; Chaabane, S.; Giraud, X.; Meilland, J.; Jonkers, L.; Kucera, M.; Brummer, G.-J. A.; Grigoratou, M.; Monteiro, F.M.; Greco, M.; Mortyn, P.G.; Kuroyanagi, A.; Howa, H.; Beaugrand, G.; Schiebel, R. (2022). The foraminiferal response to climate stressors project: tracking the community response of planktonic foraminifera to historical climate change. Front. Mar. Sci. 9: 827962.
    Jonkers, L.; Brummer, G.-J. A.; Meilland, J.; Groeneveld, J.; Kucera, M. (2022). Variability in Neogloboquadrina pachyderma stable isotope ratios from isothermal conditions: implications for individual foraminifera analysis. Clim. Past 18(1): 89-101.
    Meilland, J.; Cornuault, P.; Morard, R.; Brummer, G.-J. A.; Kucera, M. (2022). Identification guide to extant planktonic foraminifera. Part 1: Family Candeinidae and genera Berggrenia, Bolivina, Dentigloborotalia, and Neogallitellia. ICES Identification Leaflets for Plankton = Fiches d'identification du plancton, 196. ICES: Copenhagen.
  • 2021
    Guerreiro, C.V.; Baumann, K.-H.; Brummer, G.-J. A.; Valente, A.; Fischer, G.; Ziveri, P.; Brotas, V.; Stuut, J.-B (2021). Carbonate fluxes by coccolithophore species between NW Africa and the Caribbean: implications for the biological carbon pump. Limnol. Oceanogr. 66(8): 3190-3208.
    Leupold, M.; Pfeiffer, M.; Watanabe, T.K.; Reuning, L.; Garbe-Schönberg, D.; Shen, C.-C.; Brummer, G.-J. A. (2021). El Niño–Southern Oscillation and internal sea surface temperature variability in the tropical Indian Ocean since 1675. Clim. Past 17(1): 151-170.
    Mekkes, L.; Sepúlveda-Rodríguez, G.; Bielkinaite, G.; Wall-Palmer, D.; Brummer, G.-J. A.; Dämmer, L.K.; Huisman, J.; van Loon, E.; Renema, W.; Peijnenburg, K.T.C.A. (2021). Effects of ocean acidification on calcification of the sub-Antarctic pteropod Limacina retroversa. Front. Mar. Sci. 8: 581432.
    van der Does, M.; Brummer, G.-J. A.; Korte, L.F.; Stuut, J.-B.W. (2021). Seasonality in Saharan dust across the Atlantic Ocean: From atmospheric transport to seafloor deposition. JGR: Atmospheres 126(11): e2021JD034614.
  • 2020
    Brummer, G.-J. A.; Metcalfe, B.; Feldmeijer, W.; Prins, M.A.; van 't Hoff, J.; Ganssen, G.M. (2020). Modal shift in North Atlantic seasonality during the last deglaciation. Clim. Past 16(1): 265-282.
    de Bar, M.W.; Weiss, G.M.; Yildiz, C.; Rampen, S.W.; Lattaud, J.; Bale, N.J.; Mienis, F.; Brummer, G.-J. A.; Schulz, H.; Rush, D.; Kim, J.-H.; Donner, B.; Knies, J.; Lückge, A.; Stuut, J.-B.W.; Sinninghe Damsté, J.S; Schouten, S. (2020). Global temperature calibration of the Long chain Diol Index in marine surface sediments. Org. Geochem. 142: 103983.
    Korte, L.F.; Brummer, G.-J. A.; van der Does, M.; Guerreiro, C.V.; Mienis, F.; Munday, C.I.; Ponsoni, L.; Schouten, S.; Stuut, J.-B.W. (2020). Multiple drivers of production and particle export in the western tropical North Atlantic. Limnol. Oceanogr. 65(9): 2108-2124.
    Livsey, C.M.; Kozdon, R.; Bauch, D.; Brummer, G.-J. A.; Jonkers, L.; Orland, I.; Hill, T.M.; Spero, H.J. (2020). High‐Resolution Mg/Ca and δ18O patterns in modern Neogloboquadrina pachyderma from the Fram Strait and Irminger Sea. Paleoceanography and Paleoclimatology 35(9).
    Moura, A.; Muniz, A.A.; Mullis, E.; Wilson, J.M.; Vieira, R.P.; Almeida, A.A.; Pinto, E.; Brummer, G.-J.A.; van Gaever, P.; Gonçalves, J.M.S.; Correia, A.T. (2020). Population structure and dynamics of the Atlantic mackerel (Scomber scombrus) in the North Atlantic inferred from otolith chemical and shape signatures. Fish. Res. 230: 105621.
    van der Does, M.; Brummer, G.-J. A.; Crimpen; Korte, L.F.; Mahowald, N.M.; Merkel, U.; Yu; Zuidema; Stuut, J.-B.W. (2020). Tropical rains controlling deposition of Saharan dust across the North Atlantic Ocean. Geophys. Res. Lett. 47(5): e2019GL086867.
    van Dijk, I.; Raitzsch, M.; Brummer, G.-J. A.; Bijma, J. (2020). Novel method to image and quantify cogwheel structures in foraminiferal shells. Front. Ecol. Evol. 8: 567231.
  • 2019
    de Bar, M.W.; Ullgren, J.E.; Thunnell, R.C.; Wakeham, S.G.; Brummer, G.-J. A.; Stuut, J.-B.W.; Sinninghe Damsté, J.S; Schouten, S. (2019). Long-chain diols in settling particles in tropical oceans: insights into sources, seasonality and proxies. Biogeosciences 16(8): 1705-1727.
    Guerreiro, C.V.; Baumann, K.-H.; Brummer, G.-J. A.; Korte, L.F.; Sá, C.; Stuut, J.-B.W. (2019). Transatlantic gradients in calcifying phytoplankton (coccolithophore) fluxes. Prog. Oceanogr. 176: 102140.
    Meilland, J.; Siccha, M.; Weinkauf, M.F.G.; Jonkers, L.; Morard, R.; Baranowski, U.; Baumeister, A.; Bertlich, J.; Brummer, G.-J. A.; Debray, P.; Fritz-Endres, T.; Groeneveld, J.; Magerl, L.; Munz, P.; Rillo, M.C.; Schmidt, C.; Takagi, H.; Theara, G.; Kucera, M. (2019). Highly replicated sampling reveals no diurnal vertical migration but stable species-specific vertical habitats in planktonic foraminifera. J. Plankton Res. 41(2): 127-141.
    Morard, R.; Füllberg, A.; Brummer, G.-J. A.; Greco, M.; Jonkers, L.; Wizemann, A.; Weiner, A.K.M.; Darling, K.; Siccha, M.; Ledevin, R. (2019). Genetic and morphological divergence in the warm-water planktonic foraminifera genus Globigerinoides. PLoS One 14(12): e0225246.
  • 2018
    Dorschel, B.; Jensen, L.; Arndt, J. E.; Brummer, G.-J.; de Haas, H.; Fielies, A.; Franke, D.; Jokat, W.; Krocker, R.; Kroon, D.; Pätzold, J.; Schneider, R.R.; Spieß, V.; Stollhofen, H.; Uenzelmann-Neben, G.; Watkeys, M.; Wiles, E. (2018). The Southwest Indian Ocean bathymetric compilation (swIOBC). Geochem. Geophys. Geosyst. 19(3): 968-976.
    Hennekam, R.; Zinke, J.; van Sebille, E.; ten Have, M.; Brummer, G.-J. A.; Reichart, G.-J. (2018). Cocos (Keeling) corals reveal 200 years of multidecadal modulation of southeast Indian Ocean hydrology by Indonesian throughflow. Paleoceanography and Paleoclimatology 33: 48-60.
    Mezger, E.M.; de Nooijer, L.J.; Siccha, M.; Brummer, G.-J. A.; Kucera, M.; Reichart, G.-J. (2018). Taphonomic and ontogenetic effects on Na/Ca and Mg/Ca in spinose planktonic foraminifera from the Red Sea. Geochem. Geophys. Geosyst. 19(11): 4174-4194.
  • 2017
    Carvalho, M.G.; Moreira, C.; Cardoso, J.F.M.F.; Brummer, G.-J. A.; van Gaever, P.; van der Veer, H.W.; Queiroga, H.; Santos, P.T.; Correia, A.T. (2017). Movement, connectivity and population structure of the intertidal fish Lipophrys pholis as revealed by otolith oxygen and carbon stable. Mar. Biol. Res. 137(7): 764-773.
    Guerreiro, C.V.; Baumann, K.-H.; Brummer, G.-J. A.; Fischer, G.; Korte, L.F.; Merkel, U.; Sá, C.; de Stigter, H.; Stuut, J.-B.W. (2017). Coccolithophore fluxes in the open tropical North Atlantic: influence of thermocline depth, Amazon water, and Saharan dust. Biogeosciences 14(20): 4577-4599.
    Korte, L.F.; Brummer, G.-J. A.; van der Does, M.; Guerreiro, C.V.; Hennekam, R.; van Hateren, J.A.; Jong, D.; Munday, C.I.; Schouten, S.; Stuut, J-B W. (2017). Downward particle fluxes of biogenic matter and Saharan dust across the equatorial North Atlantic. Atmos. Chem. Phys. 17(9): 6023-6040.
  • 2016
    Jonkers, L.; Buse, B.; Brummer, G.-J. A.; Hall, I.R. (2016). Chamber formation leads to Mg/Ca banding in the planktonic foraminifer Neogloboquadrina pachyderma. Earth Planet. Sci. Lett. 451: 177–184.
    Mezger, E.M.; de Nooijer, L.J.; Boer, W.; Brummer, G.-J.A.; Reichart, G.-J. (2016). Salinity controls on Na incorporation in Red Sea planktonic foraminifera. Paleoceanography 31(12): 1562–1582.
    van der Does, M.; Korte, L.F.; Munday, C.I.; Brummer, G.-J. A.; Stuut, J-B W. (2016). Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic. Atmos. Chem. Phys. 16: 13697–13710.
  • 2015
    Feldmeijer, W.; Metcalfe, B.; Brummer, G.-J.A.; Ganssen, G. (2015). Reconstructing the depth of the permanent thermocline through the morphology and geochemistry of the deep dwelling planktonic foraminifer Globorotalia truncatulinoides. Paleoceanography 30(1): 1-22.
    Kasper, S.; van der Meer, M.T.J.; Castañeda, I.S; Tjallingii, R.; Brummer, G.J.A.; Sinninghe Damsté, J.S.; Schouten, S. (2015). Testing the alkenone D/H ratio as a paleo indicator of sea surface salinity in a coastal ocean margin (Mozambique Channel). Org. Geochem. 78: 62-68.
    Metcalfe, B.; Feldmeijer, W.; de Vringer-Picon, W.; Brummer, G.-J.A.; Peeters, F.J.C.; Ganssen, G.M. (2015). Late Pleistocene glacial–interglacial shell-size–isotope variability in planktonic foraminifera as a function of local hydrography. Biogeosciences 12(15): 4781-4807.
    Scussolini, P.; Scussolini, G.; Brummer, G.-J.A.; Peeters, F.J.C. (2015). Saline Indian Ocean waters invaded the South Atlantic thermocline during glacial termination II. Geology (Boulder Colo.) 43(2): 139-142.
    Steinhardt, J.; Cléroux, C.; de Nooijer, L.J.; Brummer, G.-J.A.; Zahn, R.; Ganssen, G.; Reichart, G.-J. (2015). Reconciling single-chamber Mg / Ca with whole-shell d18O in surface to deep-dwelling planktonic foraminifera from the Mozambique Channel. Biogeosciences 12: 2411-2429.
    Steinhardt, J.; de Nooijer, L.J.; Brummer, G.-J.A.; Reichart, G.J. (2015). Profiling planktonic foraminiferal crust formation. Geochem. Geophys. Geosyst. 16: 2409-2430.
  • 2014
    Booij, K.; van Bommel, R.; van Aken, H.M.; van Haren, H.; Brummer, G.J.A.; Ridderinkhof, H. (2014). Passive sampling of nonpolar contaminants at three deep-ocean sites. Environ. Pollut. 195: 101-108.
    Steinhardt, J.; Cléroux, C.; Ullgren, J.E.; de Nooijer, L.J.; Durgadoo, J.V.; Brummer, G.J.A.; Reichart, G.J. (2014). Anti-cyclonic eddy imprint on calcite geochemistry of several planktonic foraminiferal species in the Mozambique Channel. Mar. Micropaleontol. 113: 20–33.
    van der Lubbe, J.L.; Tjallingii, R.; Prins, M.A.; Brummer, G.-J.A.; Jung, S.J.H.; Kroon, D.; Schneider, R.R. (2014). Sedimentation patterns off the Zambezi River over the last 20,000 years. Mar. Geol. 355: 189–201.
  • 2013
    Grove, C.A.; Zinke, J.; Peeters, F.; Park, W.; Scheufen, T.; Kasper, S.; Randriamanantsoa, B.; McCulloch, M.T.; Brummer, G.J.A. (2013). Madagascar corals reveal a multidecadal signature of rainfall and river runoff since 1708. Clim. Past 9(2): 641-656.
    Grove, G.A.; Brummer, G.J.A.; Kasper, S.; Zinke, J.; Pfeiffer, M.; Garbe-Schonberg, D. (2013). Confounding effects of coral growth and high SST variability on skeletal Sr/Ca: Implications for coral paleothermometry. Geochem. Geophys. Geosyst. 14(4): 1277-1293.
    Jonkers, L.; Jiménez-Amat, P.; Mortyn, P.G.; Brummer, G.-J.A. (2013). Seasonal Mg/Ca variability of N. pachyderma (s) and G. bulloides: Implications for seawater temperature reconstruction. Earth Planet. Sci. Lett. 376: 137-144.
  • 2012
    Fallet, U.; Castañeda, I.S; Henry-Edwards, A; Richter, T.O.; Boer, W.; Schouten, S.; Brummer, G.J. (2012). Sedimentation and burial of organic and inorganic temperature proxies in the Mozambique Channel, SW Indian Ocean. Deep-Sea Res., Part 1, Oceanogr. Res. Pap. 59: 37-53.
    Grove, C.A.; Zinke, J.; Scheufen, T.; Maina, J.; Epping, E.; Boer, W.; Randriamanantsoa, B.; Brummer, G.-J.A. (2012). Spatial linkages between coral proxies of terrestrial runoff across a large embayment in Madagascar. Biogeosciences 9(8): 3063-3081.
    Jonkers, L.; de Nooijer, L.J.; Reichart, G.J.; Zahn, R.; Brummer, G.-J.A. (2012). Encrustation and trace element composition of Neogloboquadrina dutertrei assessed from single chamber analyses - implications for paleotemperature estimates. Biogeosciences 9(11): 4851-4860.
    Jonkers, L.; Prins, M.A.; Moros, M.; Weltje, G.J.; Troelstra, S.R.; Brummer, G.J.A. (2012). Temporal offsets between surface temperature, ice-rafting and bottom flow speed proxies in the glacial (MIS 3) northern North Atlantic. Quat. Sci. Rev. 48: 43-53.
    Nagtegaal, R.; Grove, C.A.; Kasper, S.; Zinke, J.; Brummer, G.J.A. (2012). Spectral luminescence and geochemistry of coral aragonite: Effects of whole-core treatment. Chem. Geol. 318: 6-15.
  • 2011
    Fallet, U.; Ullgren, J.E; Castañeda, I.S.; van Aken, H.M.; Schouten, S.; Ridderinkhof, H.; Brummer, G.J.A. (2011). Contrasting variability in foraminiferal and organic paleotemperature proxies in sedimenting particles of the Mozambique Channel (SW Indian Ocean). Geochim. Cosmochim. Acta 75(20): 5834-5848.
    Ganssen, G.M.; Peeters, F.J.C.; Metcalfe, B.; Anand, P.; Jung, S.J.H.; Kroon, D.; Brummer, G.-J.A. (2011). Quantifying sea surface temperature ranges of the Arabian Sea for the past 20 000 years. Clim. Past 7: 1337–1349.
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