Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models

Ocean ecosystems are increasingly stressed by human-induced changes of their physical, chemical and biological environment. Among these changes, warming, acidification, deoxygenation and changes in primary productivity by marine phytoplankton can be considered as four of the major stressors of open ocean ecosystems. Due to rising atmospheric CO 2 in the coming decades, these changes will be amplified. Here, we use the most recent simulations performed in the framework of the Coupled Model Intercomparison Project 5 to assess how these stressors may evolve over the course of the 21st century. The 10 Earth system models used here project similar trends in ocean warming, acidification, deoxygenation and reduced primary productivity for each of the IPCC's representative concentration pathways (RCPs) over the 21st century. For the "business-as-usual" scenario RCP8.5, the model-mean changes in the 2090s (compared to the 1990s) for sea surface temperature, sea surface pH, global O 2 content and integrated primary productivity amount to p2.73 (±0.72) °C, −0.33 (±0.003) pH unit, −3.45 (±0.44)% and −8.6 (±7.9)%, respectively. For the high mitigation scenario RCP2.6, corresponding changes are +0.71 (±0.45) °C, −0.07 (±0.001) pH unit, −1.81 (±0.31)% and −2.0 (±4.1)%, respectively, illustrating the effectiveness of extreme mitigation strategies. Although these stressors operate globally, they display distinct regional patterns and thus do not change coincidentally. Large decreases in O 2 and in pH are simulated in global ocean intermediate and mode waters, whereas large reductions in primary production are simulated in the tropics and in the North Atlantic. Although temperature and pH projections are robust across models, the same does not hold for projections of subsurface O 2 concentrations in the tropics and global and regional changes in net primary productivity. These high uncertainties in projections of primary productivity and subsurface oxygen prompt us to continue inter-model comparisons to understand these model differences, while calling for caution when using the CMIP5 models to force regional impact models.

[1]  John P. Dunne,et al.  A measured look at ocean chlorophyll trends , 2011, Nature.

[2]  H. Pörtner,et al.  Influence of elevated CO2 concentrations on thermal tolerance of the edible crab Cancer pagurus , 2007 .

[3]  Keith Lindsay,et al.  Upper Ocean Ecosystem Dynamics and Iron Cycling in a Global 3 D Model by , 2004 .

[4]  K. Lindsay,et al.  Climate-mediated changes to mixed-layer properties in the Southern Ocean : assessing the phytoplankton response , 2007 .

[5]  A. Oschlies,et al.  Mismatch between observed and modeled trends in dissolved upper-ocean oxygen over the last 50 yr , 2012 .

[6]  N. Bindoff,et al.  Observed decreases in oxygen content of the global ocean , 2011 .

[7]  Melanie Abecassis,et al.  Ocean's least productive waters are expanding , 2008 .

[8]  Elena Litchman,et al.  A Global Pattern of Thermal Adaptation in Marine Phytoplankton , 2012, Science.

[9]  Richard J. Matear,et al.  Southern Ocean acidification: A tipping point at 450-ppm atmospheric CO2 , 2008, Proceedings of the National Academy of Sciences.

[10]  L. Talley,et al.  Chapter 5.4 Mode waters , 2001 .

[11]  Reto Knutti,et al.  The equilibrium sensitivity of the Earth's temperature to radiation changes , 2008 .

[12]  L. Bopp,et al.  Water masses as a unifying framework for understanding the Southern Ocean Carbon Cycle , 2010 .

[13]  L. Bopp,et al.  Globalizing results from ocean in situ iron fertilization studies , 2006 .

[14]  Nicolas Gruber,et al.  Ocean deoxygenation in a warming world. , 2010, Annual review of marine science.

[15]  F. Joos,et al.  Revision of the global carbon budget due to changing air‐sea oxygen fluxes , 2002 .

[16]  Scott C. Doney,et al.  The Growing Human Footprint on Coastal and Open-Ocean Biogeochemistry , 2010, Science.

[17]  Corinna Hoose,et al.  The Norwegian Earth System Model, NorESM1-M - Part 1: Description and basic evaluation , 2012 .

[18]  Nicolas Gruber,et al.  The Oceanic Sink for Anthropogenic CO2 , 2004, Science.

[19]  S. Khatiwala,et al.  Reconstruction of the history of anthropogenic CO2 concentrations in the ocean , 2009, Nature.

[20]  Pierre Friedlingstein,et al.  Uncertainties in CMIP5 Climate Projections due to Carbon Cycle Feedbacks , 2014 .

[21]  T. Midorikawa,et al.  Decrease of dissolved oxygen after the mid‐1980s in the western North Pacific subtropical gyre along the 137°E repeat section , 2012 .

[22]  T. Roy,et al.  Assessment of Southern Ocean water mass circulation and characteristics in CMIP5 models: Historical bias and forcing response , 2013 .

[23]  Syukuro Manabe,et al.  Simulated response of the ocean carbon cycle to anthropogenic climate warming , 1998, Nature.

[24]  Christoph Heinze,et al.  Evaluation of the carbon cycle components in the Norwegian Earth System Model (NorESM) , 2012 .

[25]  U. Riebesell,et al.  Enhanced biological carbon consumption in a high CO2 ocean , 2006, Nature.

[26]  K. Taylor,et al.  Forcing, feedbacks and climate sensitivity in CMIP5 coupled atmosphere‐ocean climate models , 2012 .

[27]  Andreas Oschlies,et al.  Can we predict the direction of marine primary production change under global warming? , 2011 .

[28]  F. Joos,et al.  Climate-induced interannual variability of marine primary and export production in three global coupled climate carbon cycle models , 2008 .

[29]  H. Pörtner,et al.  Oxygen- and capacity-limitation of thermal tolerance: a matrix for integrating climate-related stressor effects in marine ecosystems , 2010, Journal of Experimental Biology.

[30]  S. Doney,et al.  An intermediate complexity marine ecosystem model for the global domain , 2001 .

[31]  J. Dufresne,et al.  Aerosol and ozone changes as forcing for climate evolution between 1850 and 2100 , 2013, Climate Dynamics.

[32]  John P. Dunne,et al.  Data‐based estimates of suboxia, denitrification, and N2O production in the ocean and their sensitivities to dissolved O2 , 2012 .

[33]  Karl E. Taylor,et al.  An overview of CMIP5 and the experiment design , 2012 .

[34]  N. Bates,et al.  Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean , 2012 .

[35]  Keith Lindsay,et al.  Upper ocean ecosystem dynamics and iron cycling in a global three‐dimensional model , 2004 .

[36]  Scott C. Doney,et al.  Projected 21st century decrease in marine productivity: a multi-model analysis , 2009 .

[37]  Stefano Schiavon,et al.  Climate Change 2007: The Physical Science Basis. , 2007 .

[38]  M. Gehlen,et al.  The response of marine carbon and nutrient cycles to ocean acidification: Large uncertainties related to phytoplankton physiological assumptions , 2011 .

[39]  D. Gilbert,et al.  Evidence for greater oxygen decline rates in the coastal ocean than in the open ocean , 2009 .

[40]  R. Feely,et al.  Spatial variability and decadal trend of the oceanic CO2 in the western equatorial Pacific warm/fresh water , 2009 .

[41]  K. Taylor.  Summarizing multiple aspects of model performance in a single diagram , 2001 .

[42]  A. Oschlies,et al.  Simulated 21st century's increase in oceanic suboxia by CO2‐enhanced biotic carbon export , 2008 .

[43]  A. Fischlin,et al.  Ecosystems, their properties, goods and services , 2007 .

[44]  A. Ishida,et al.  Impact of rapid sea-ice reduction in the Arctic Ocean on the rate of ocean acidification , 2011 .

[45]  P. Falkowski,et al.  Photosynthetic rates derived from satellite‐based chlorophyll concentration , 1997 .

[46]  John P. Dunne,et al.  Enhanced nutrient supply to the California Current Ecosystem with global warming and increased stratification in an earth system model , 2010 .

[47]  Fei-xue Fu,et al.  Nutrient Cycles and Marine Microbes in a CO2-Enriched Ocean , 2009 .

[48]  E. Manzini,et al.  Role of stratospheric dynamics in the ozone–carbon connection in the Southern Hemisphere , 2013, Climate Dynamics.

[49]  A. Paulmier,et al.  Oxygen minimum zones (OMZs) in the modern ocean , 2009 .

[50]  Rainer Knust,et al.  Climate Change Affects Marine Fishes Through the Oxygen Limitation of Thermal Tolerance , 2007, Science.

[51]  R. Gates,et al.  The Effect of Ocean Acidification on Calcifying Organisms in Marine Ecosystems: An Organism to Ecosystem Perspective , 2010 .

[52]  Fei-xue Fu,et al.  CO2 control of Trichodesmium N2 fixation, photosynthesis, growth rates, and elemental ratios: Implications for past, present, and future ocean biogeochemistry , 2007 .

[53]  A. Thomson,et al.  The representative concentration pathways: an overview , 2011 .

[54]  Nancy Knowlton,et al.  Climate change impacts on marine ecosystems. , 2012, Annual review of marine science.

[55]  Christoph Heinze,et al.  An isopycnic ocean carbon cycle model , 2009 .

[56]  W. Richard,et al.  TEMPERATURE AND PHYTOPLANKTON GROWTH IN THE SEA , 1972 .

[57]  A. Oschlies,et al.  Anticorrelated observed and modeled trends in dissolved oceanic oxygen over the last 50 years , 2012 .

[58]  Kimio Hanawa,et al.  Observations: Oceanic Climate Change and Sea Level , 2007 .

[59]  Krista,et al.  GFDL’s ESM2 Global Coupled Climate–Carbon Earth System Models. Part II: Carbon System Formulation and Baseline Simulation Characteristics* , 2013 .

[60]  Carlos M. Duarte,et al.  Thresholds of hypoxia for marine biodiversity , 2008, Proceedings of the National Academy of Sciences.

[61]  Peter E. Thornton,et al.  Preindustrial-Control and Twentieth-Century Carbon Cycle Experiments with the Earth System Model CESM1(BGC) , 2014 .

[62]  M. Vichi,et al.  Impacts of natural and anthropogenic climate variations on North Pacific plankton in an Earth System Model , 2012 .

[63]  Taro Takahashi,et al.  Skill metrics for confronting global upper ocean ecosystem-biogeochemistry models against field and remote sensing data , 2009 .

[64]  A. Gnanadesikan,et al.  Understanding why the volume of suboxic waters does not increase over centuries of global warming in an Earth System Model , 2012 .

[65]  Corinne Le Quéré,et al.  Climate Change 2013: The Physical Science Basis , 2013 .

[66]  M. Gehlen,et al.  Skill assessment of three earth system models with common marine biogeochemistry , 2013, Climate Dynamics.

[67]  R. Knutti,et al.  Robustness and uncertainties in the new CMIP5 climate model projections , 2013 .

[68]  Marcello Vichi,et al.  A generalized model of pelagic biogeochemistry for the global ocean ecosystem. Part I: Theory , 2007 .

[69]  F. Joos,et al.  Natural variability and anthropogenic trends in oceanic oxygen in a coupled carbon cycle–climate model ensemble , 2009 .

[70]  N. Gruber,et al.  Oxygen trends over five decades in the North Atlantic , 2012 .

[71]  Gurvan Madec,et al.  Potential impact of climate change on marine export production , 2001 .

[72]  F. Joos,et al.  Oxygen and indicators of stress for marine life in multi-model global warming projections , 2012 .

[73]  Nicolas Gruber,et al.  Warming up, turning sour, losing breath: ocean biogeochemistry under global change , 2011, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[74]  R. Lukas,et al.  Physical and biogeochemical modulation of ocean acidification in the central North Pacific , 2009, Proceedings of the National Academy of Sciences.

[75]  Dongxiao Zhang,et al.  Atlantic Meridional Overturning Circulation (AMOC) in CMIP5 Models: RCP and Historical Simulations , 2013 .

[76]  Pierre Friedlingstein,et al.  Twenty-First-Century Compatible CO2 Emissions and Airborne Fraction Simulated by CMIP5 Earth System Models under Four Representative Concentration Pathways , 2013, Journal of Climate.

[77]  E. Maier‐Reimer,et al.  Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms , 2005, Nature.

[78]  B. Worm,et al.  Global phytoplankton decline over the past century , 2010, Nature.

[79]  D. Pauly,et al.  Primary production required to sustain global fisheries , 1995, Nature.

[80]  F. Kobashi,et al.  Review on North Pacific Subtropical Countercurrents and Subtropical Fronts: role of mode waters in ocean circulation and climate , 2012, Journal of Oceanography.

[81]  Andreas Oschlies,et al.  Future changes in climate, ocean circulation, ecosystems, and biogeochemical cycling simulated for a business‐as‐usual CO2 emission scenario until year 4000 AD , 2008 .

[82]  Scott C. Doney,et al.  Detection of anthropogenic climate change in satellite records of ocean chlorophyll and productivity , 2010 .

[83]  H. Pörtner.  Ecosystem effects of ocean acidification in times of ocean warming: a physiologist’s view , 2008 .

[84]  A. Kirkevåg,et al.  The Norwegian Earth System Model, NorESM1-M – Part 1: Description and basic evaluation of the physical climate , 2013 .

[85]  S. Bony,et al.  Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5 , 2013, Climate Dynamics.

[86]  David A. Siegel,et al.  Climate-driven trends in contemporary ocean productivity , 2006, Nature.

[87]  I. Totterdell,et al.  Production and export in a global ocean ecosystem model , 2001 .

[88]  B. Stevens,et al.  Climate and carbon cycle changes from 1850 to 2100 in MPI‐ESM simulations for the Coupled Model Intercomparison Project phase 5 , 2013 .

[89]  Basile Michaelidis,et al.  Synergistic effects of temperature extremes, hypoxia, and increases in CO2 on marine animals: From Earth history to global change , 2005 .

[90]  J. Sprintall,et al.  Expanding Oxygen-Minimum Zones in the Tropical Oceans , 2008, Science.

[91]  M. Heimann,et al.  Climate‐induced oceanic oxygen fluxes: Implications for the contemporary carbon budget , 2002 .

[92]  Ronald,et al.  GFDL’s ESM2 Global Coupled Climate–Carbon Earth System Models. Part I: Physical Formulation and Baseline Simulation Characteristics , 2012 .

[93]  Nathaniel L. Bindoff,et al.  Detecting an external influence on recent changes in oceanic oxygen using an optimal fingerprinting method , 2012 .

[94]  G. Danabasoglu,et al.  The Community Climate System Model Version 4 , 2011 .

[95]  S. Nixon,et al.  On the size of the Peru upwelling ecosystem , 2001 .

[96]  John F. B. Mitchell,et al.  The next generation of scenarios for climate change research and assessment , 2010, Nature.

[97]  F. Joos,et al.  Imminent ocean acidification in the Arctic projected with the NCAR global coupled carbon cycle-climate model , 2009 .

[98]  Andrea Alessandri,et al.  Global and regional ocean carbon uptake and climate change: sensitivity to a substantial mitigation scenario , 2011 .

[99]  Hongmei Li,et al.  Global ocean biogeochemistry model HAMOCC: Model architecture and performance as component of the MPI‐Earth system model in different CMIP5 experimental realizations , 2013 .

[100]  L. Bopp,et al.  Role of mode and intermediate waters in future ocean acidification: Analysis of CMIP5 models , 2013 .