Enhanced warming of the <scp>N</scp>orthwest <scp>A</scp>tlantic <scp>O</scp>cean under climate change

Saba, Vincent S.; Griffies, Stephen M.; Anderson, W.; Winton, Michael; Alexander, Michael A.; Delworth, Thomas L.; Hare, Jonathan A.; Harrison, Matthew; Rosati, Anthony; Vecchi, Gabriel A.; Zhang, Rong

doi:10.1002/2015jc011346

Cited by 370 publications

(264 citation statements)

References 31 publications

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“…5 joins a growing body of evidence for amplified climate change impacts at higher trophic levels (24)(25)(26). Projected regional changes in catch may exceed 50%, far above oft-cited modest-to-moderate global NPP trends under climate change (42), and adding urgency to efforts to understand the combination of large-scale and local processes influencing regional climate change impacts on marine resources (45)(46)(47)(48). The same trophodynamic mechanisms operating on spatial NPP gradients to sharpen inter-LME catch differences in the contemporary ocean steepened NPP trends under climate change.…”

Section: Resultsmentioning

confidence: 99%

Reconciling fisheries catch and ocean productivity

Stock

John

Rykaczewski

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

233

255

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Photosynthesis fuels marine food webs, yet differences in fish catch across globally distributed marine ecosystems far exceed differences in net primary production (NPP). We consider the hypothesis that ecosystem-level variations in pelagic and benthic energy flows from phytoplankton to fish, trophic transfer efficiencies, and fishing effort can quantitatively reconcile this contrast in an energetically consistent manner. To test this hypothesis, we enlist global fish catch data that include previously neglected contributions from small-scale fisheries, a synthesis of global fishing effort, and plankton food web energy flux estimates from a prototype high-resolution global earth system model (ESM). After removing a small number of lightly fished ecosystems, stark interregional differences in fish catch per unit area can be explained (r = 0.79) with an energy-based model that (i) considers dynamic interregional differences in benthic and pelagic energy pathways connecting phytoplankton and fish, (ii) depresses trophic transfer efficiencies in the tropics and, less critically, (iii) associates elevated trophic transfer efficiencies with benthic-predominant systems. Model catch estimates are generally within a factor of 2 of values spanning two orders of magnitude. Climate change projections show that the same macroecological patterns explaining dramatic regional catch differences in the contemporary ocean amplify catch trends, producing changes that may exceed 50% in some regions by the end of the 21st century under high-emissions scenarios. Models failing to resolve these trophodynamic patterns may significantly underestimate regional fisheries catch trends and hinder adaptation to climate change.fisheries catch | primary production | ocean productivity | climate change | food webs N early 50 years ago, John Ryther (1) published his seminal work "Photosynthesis and Fish Production in the Sea" in which he hypothesized that differences in net primary production (NPP) alone could not explain stark differences in fish catch across disparate marine ecosystems. Drawing upon "trophic dynamic" principles governing the transfer of energy through ecosystems (2), he hypothesized that synergistic interactions between NPP differences, the length of food chains connecting phytoplankton and fish, and the efficiency of trophic transfers were required to reconcile catch differences. The trophodynamic principles drawn upon by Ryther now underpin diverse models and indicators used in ecosystem-based marine resource management (3-5), yet stubborn uncertainties in the relationship between ocean productivity and fish catch persist. Official catch reports often omit globally significant discards and small-scale artisanal and subsistence catch (6). Uncertain differences in fishing effort and impacts of fishing history complicate attribution of catch differences to "bottom-up" considerations of ocean productivity or "top-down" fishing effects (7). Difficulties directly observing and estimating trophodynamic properties, including NPP (8),...

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Section: Resultsmentioning

confidence: 99%

Reconciling fisheries catch and ocean productivity

Stock

John

Rykaczewski

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

233

255

View full text Add to dashboard Cite

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“…At ~1° horizontal resolution, the CMIP5 models do not adequately resolve many processes including ocean eddies, coastal upwelling, and interactions with topographic features, and where western boundary currents separate from the coast. While a few studies have used higher resolution models to assess the effects of climate change on SSTs (e.g., Chamberlain et al, 2012 andSaba et al, 2016), they have focused on a small region or are based on a single model run with idealized forcing. A broader assessment of climate change on a wide array of ocean variables, using additional forcing scenarios and higher resolution models, and at daily time scales are all warranted.…”

Section: Summary and Discussionmentioning

confidence: 99%

Projected sea surface temperatures over the 21st century: Changes in the mean, variability and extremes for large marine ecosystem regions of Northern Oceans

Alexander

Scott

Friedland

et al. 2018

Elementa: Science of the Anthropocene

Self Cite

203

191

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Global climate models were used to assess changes in the mean, variability and extreme sea surface temperatures (SSTs) in northern oceans with a focus on large marine ecosystems (LMEs) adjacent to North America, Europe, and the Arctic Ocean. Results were obtained from 26 models in the Community Model Intercomparison Project Phase 5 (CMIP5) archive and 30 simulations from the National Center for Atmospheric Research Large Ensemble Community Project (CESM-LENS). All of the simulations used the observed greenhouse gas concentrations for 1976–2005 and the RCP8.5 “business as usual” scenario for greenhouse gases through the remainder of the 21st century. In general, differences between models are substantially larger than among the simulations in the CESM-LENS, indicating that the SST changes are more strongly affected by model formulation than internal climate variability. The annual SST trends over 1976–2099 in the 18 LMEs examined here are all positive ranging from 0.05 to 0.5°C decade–1. SST changes by the end of the 21st century are primarily due to a positive shift in the mean with only modest changes in the variability in most LMEs, resulting in a substantial increase in warm extremes and decrease in cold extremes. The shift in the mean is so large that in many regions SSTs during 2070–2099 will always be warmer than the warmest year during 1976–2005. The SST trends are generally stronger in summer than in winter, as greenhouse gas heating is integrated over a much shallower climatological mixed layer depth in summer than in winter, which amplifies the seasonal cycle of SST over the 21st century. In the Arctic, the mean SST and its variability increases substantially during summer, when it is ice free, but not during winter when a thin layer of ice reforms and SSTs remain near the freezing point.

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“…In the Arctic, differences in the halosteric signal (not shown), due to differences in the oceanic response to precipitation, evaporation, runoff, and sea ice melt, explain most of the spread. In the Gulf Stream extension it is probably due to model errors and biases resulting from a misrepresentation of the Gulf Stream position and the coarse resolution of coupled CMIP5 models that do not adequately resolve regional dynamics (Saba et al 2016). …”

Section: A Contribution From Dynamic Sea Levelmentioning

confidence: 99%

Evaluating Model Simulations of Twentieth-Century Sea-Level Rise. Part II: Regional Sea-Level Changes

et al. 2017

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Twentieth-century regional sea level changes are estimated from 12 climate models from phase 5 of the Climate Model Intercomparison Project (CMIP5). The output of the CMIP5 climate model simulations was used to calculate the global and regional sea level changes associated with dynamic sea level, atmospheric loading, glacier mass changes, and ice sheet surface mass balance contributions. The contribution from groundwater depletion, reservoir storage, and dynamic ice sheet mass changes are estimated from observations as they are not simulated by climate models. All contributions are summed, including the glacial isostatic adjustment (GIA) contribution, and compared to observational estimates from 27 tide gauge records over the twentieth century . A general agreement is found between the simulated sea level and tide gauge records in terms of interannual to multidecadal variability over 1900-2015. But climate models tend to systematically underestimate the observed sea level trends, particularly in the first half of the twentieth century. The corrections based on attributable biases between observations and models that have been identified in Part I of this two-part paper result in an improved explanation of the spatial variability in observed sea level trends by climate models. Climate models show that the spatial variability in sea level trends observed by tide gauge records is dominated by the GIA contribution and the steric contribution over 1900-2015. Climate models also show that it is important to include all contributions to sea level changes as they cause significant local deviations; note, for example, the groundwater depletion around India, which is responsible for the low twentieth-century sea level rise in the region.

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Enhanced warming of the Northwest Atlantic Ocean under climate change

Cited by 370 publications

References 31 publications

Reconciling fisheries catch and ocean productivity

Reconciling fisheries catch and ocean productivity

Projected sea surface temperatures over the 21st century: Changes in the mean, variability and extremes for large marine ecosystem regions of Northern Oceans

Evaluating Model Simulations of Twentieth-Century Sea-Level Rise. Part II: Regional Sea-Level Changes

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