FN Archimer Export Format PT J TI Projected decreases in future marine export production: the role of the carbon flux through the upper ocean ecosystem BT AF LAUFKOTTER, Charlotte VOGT, Meike GRUBER, Nicolas AUMONT, Olivier BOPP, Laurent DONEY, Scott C. DUNNE, John P. HAUCK, Judith JOHN, Jasmin G. LIMA, Ivan D. SEFERIAN, Roland VOLKER, Christoph AS 1:1,6;2:1;3:1;4:7;5:2;6:3;7:5;8:4;9:5;10:3;11:8;12:4; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:; C1 Swiss Fed Inst Technol, Inst Biogeochem & Pollutant Dynam, Environm Phys, Zurich, Switzerland. CEA UVSQ CNRS, IPSL, LSCE, UMR8212, Gif Sur Yvette, France. Woods Hole Oceanog Inst, Dept Marine Chem & Geochem, Woods Hole, MA 02543 USA. Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Bremerhaven, Germany. NOAA, Geophys Fluid Dynam Lab, Princeton, NJ USA. Princeton Univ, NOAA, Geophys Fluid Dynam Lab, Princeton, NJ 08544 USA. Ctr IRD Bretagne, Lab Phys Oceans, Plouzane, France. Meteo France, CNRS, CNRM, 42 Ave Gaspard Coriolis, F-31057 Toulouse, France. C2 ETH ZURICH, SWITZERLAND CEA, FRANCE WHOI, USA INST A WEGENER, GERMANY NOAA, USA UNIV PRINCETON, USA IRD, FRANCE CNRM (METEO FRANCE), FRANCE UM LOPS IF 3.851 TC 103 UR https://archimer.ifremer.fr/doc/00600/71205/69576.pdf https://archimer.ifremer.fr/doc/00600/71205/69577.pdf https://archimer.ifremer.fr/doc/00600/71205/69578.pdf LA English DT Article AB Accurate projections of marine particle export production (EP) are crucial for predicting the response of the marine carbon cycle to climate change, yet models show a wide range in both global EP and their responses to climate change. This is, in part, due to EP being the net result of a series of processes, starting with net primary production (NPP) in the sunlit upper ocean, followed by the formation of particulate organic matter and the subsequent sinking and remineralisation of these particles, with each of these processes responding differently to changes in environmental conditions. Here, we compare future projections in EP over the 21st century, generated by four marine ecosystem models under the high emission scenario Representative Concentration Pathways (RCP) 8.5 of the Intergovernmental Panel on Climate Change (IPCC), and determine the processes driving these changes. The models simulate small to modest decreases in global EP between -1 and -12 %. Models differ greatly with regard to the drivers causing these changes. Among them, the formation of particles is the most uncertain process with models not agreeing on either magnitude or the direction of change. The removal of the sinking particles by remineralisation is simulated to increase in the low and intermediate latitudes in three models, driven by either warming-induced increases in remineralisation or slower particle sinking, and show insignificant changes in the remaining model. Changes in ecosystem structure, particularly the relative role of diatoms matters as well, as diatoms produce larger and denser particles that sink faster and are partly protected from remineralisation. Also this controlling factor is afflicted with high uncertainties, particularly since the models differ already substantially with regard to both the initial (presentday) distribution of diatoms (between 11-94% in the Southern Ocean) and the diatom contribution to particle formation (0.6-3.8 times higher than their contribution to biomass). As a consequence, changes in diatom concentration are a strong driver for EP changes in some models but of low significance in others. Observational and experimental constraints on ecosystem structure and how the fixed carbon is routed through the ecosystem to produce export production are urgently needed in order to improve current generation ecosystem models and their ability to project future changes. PY 2016 SO Biogeosciences SN 1726-4170 PU Copernicus Gesellschaft Mbh VL 13 IS 13 UT 000381099900013 BP 4023 EP 4047 DI 10.5194/bg-13-4023-2016 ID 71205 ER EF