Author: Marina

Séférian, R., Berthet, S., Yool, A., Palmiéri, J., Bopp, L., Tagliabue, A., Kwiatkowski, L., Aumont, O., Christian, J., Dunne, J., Gehlen, M., Ilyina, T., John, J. G., Li, H., Long, M. C., Luo, J. Y., Nakano, H., Romanou, A., Schwinger, J., … Yamamoto, A. (2020). Tracking Improvement in Simulated Marine Biogeochemistry Between CMIP5 and CMIP6. Current Climate Change Reports, 6(3), 95–119. https://doi.org/10.1007/s40641-020-00160-0

Summary:

Increasing availability of ocean biogeochemical data, as well as an improved understanding of the underlying processes, allows advances in the marine biogeochemical components of the current generation of ESMs. The present study scrutinizes the extent to which marine biogeochemistry components of ESMs have progressed between the 5th and the 6th phases of the Coupled Model Intercomparison Project (CMIP).

Robson, J., Aksenov, Y., Bracegirdle, TJ, Dimdore-Miles, O., Griffiths, PT, Grosvenor, DP, Hodson, DLR, Keeble, J., MacIntosh, C., Megann, A., Osprey, S., Povey, AC, Schröder, D., Yang, M., Archibald, AT, Carslaw, KS, Gray, L., Jones, C., Kerridge, B.,… Wilcox, LJ (2020). The Evaluation of the North Atlantic Climate System in UKESM1 Historical Simulations for CMIP6. Journal of Advances in Modeling Earth Systems, 12 (9), e2020MS002126. https://doi.org/10.1029/2020MS002126

Summary:

The North Atlantic climate system plays an important role in regulating Earth’s climate, and variability within the Atlantic can have important impacts on society. However, we do not understand all the linkages between different parts of the North Atlantic. Furthermore, climate simulations, which are an essential tool for improving our understanding, have shortcomings that can affect their utility. New developments in Earth System climate simulations could remedy these shortcomings. The extent to which the addition of complex Earth system developments have changed or improved the simulation of the physical climate is still unknown. In this paper, a multidisciplinary evaluation of the North Atlantic climate in simulations made with the UK’s Earth System Model, UKESM1 is presented. The simulations made with UKESM1 capture many aspects of the North Atlantic climate and that human activities have a large impact on the North Atlantic in UKESM1. Nevertheless, some shortcomings of the simulations, many of which are like those seen in physical climate simulations are highlighted. The authors stressed the importance of further development of both the physical and Earth system components to improve climate simulations in the future.

Frölicher, T. L., Aschwanden, M. T., Gruber, N., Jaccard, S. L., Dunne, J. P., & Paynter, D. (2020). Contrasting Upper and Deep Ocean Oxygen Response to Protracted Global Warming. Global Biogeochemical Cycles, 34 (8), e2020GB006601. https://doi.org/10.1029/2020GB006601

Summary:

It is well established that the ocean is currently losing dissolved oxygen (O₂) in response to ocean warming (the solubility of O₂ decreases with increasing seawater temperature resulting in less O₂ available to marine life). However, the long‐term equilibrium response of O₂ to a warmer climate is neither well quantified nor understood. In this study, multimillennial global warming simulations with a comprehensive Earth system model was used to show that the equilibrium response in ocean O₂ differs fundamentally from the ongoing transient response. The deep ocean is better ventilated and oxygenated compared to preindustrial conditions, even though the deep ocean is substantially warmer. In contrast, O₂ in most of the upper tropical ocean is substantially depleted. This study emphasizes the millennial‐scale impact of global warming on marine life, with some impacts emerging many centuries or even millennia after atmospheric CO₂ has stabilized.

Policy relevant message:

The impact of global climate change on marine life not only is already clearly visible and well recorded, but the millennial‐scale impact of global warming will also emerge many centuries or even millennia after atmospheric CO₂ has stabilized.

Lam, V. W. Y., Allison, E. H., Bell, J. D., Blythe, J., Cheung, W. W. L., Frölicher, T. L., Gasalla, M. A., & Sumaila, U. R. (2020). Climate change, tropical fisheries and prospects for sustainable development. Nature Reviews Earth & Environment, 1(9), 440–454. https://doi.org/10.1038/s43017-020-0071-9

Summary:

Tropical fisheries substantially contribute to the well-being of societies in both the tropics and the extratropics, the latter through ‘telecoupling’ — linkages between distant human–natural systems. Tropical marine habitats and fish stocks, however, are vulnerable to the physical and biogeochemical oceanic changes associated with rising greenhouse gases. These changes to fish stocks, and subsequent impacts on fish production, have substantial implications for the UN Sustainable Development Goals. In this Review, the effects of climate change on tropical marine fisheries are synthesised, highlighting the socio-economic impacts to both tropical and extratropical nations, and discuss potential adaptation measures. Driven by ocean warming, acidification, deoxygenation and sea-level rise, the maximum catch potential of tropical fish stocks in some tropical exclusive economic zones is projected to decline by up to 40% by the 2050s under the RCP8.5 emissions scenario, relative to the 2000s. Climate-driven reductions in fisheries production and alterations in fish-species composition will subsequently increase the vulnerability of tropical countries with limited adaptive capacity. Thus, given the billions of people dependent on tropical marine fisheries in some capacity, there is a clear need to account for the effects of climate change on these resources and identify practical adaptations when building climate-resilient sustainable-development pathways.

Schlunegger, S., Rodgers, KB, Sarmiento, JL, Ilyina, T., Dunne, JP, Takano, Y., Christian, JR, Long, MC, Frölicher, TL, Slater, R., & Lehner, F. (2020). Time of Emergence and Large Ensemble Intercomparison for Ocean Biogeochemical Trends. Global Biogeochemical Cycles, 34 (8), e2019GB006453. https://doi.org/10.1029/2019GB006453

Summary:

Man‐made climate change is causing physical, chemical, and biological changes in the ocean. In this study the Earth system models (climate models with an interactive carbon cycle) were used to estimate when these man‐made changes will be significantly larger than, and therefore distinguishable from, natural fluctuations in the climate and oceans. The models investigated in this study agreed that changes in sea surface temperature and the strength of the ocean carbon sink should already or will soon be detectable in the current observational record. Changes in the upper ocean biological cycling of carbon, photosynthetic activity, and salinity, however, are less certain and will take many more decades of monitoring in order for man‐made changes to potentially become visible. The authors examined sources of uncertainty inherent to projecting the ocean’s future over the coming decades and found that uncertainty in the ocean’s natural variability can be as important as uncertainty across different climate models and uncertainty in how much carbon humans will emit.

Kwiatkowski, L., Torres, O., Bopp, L., Aumont, O., Chamberlain, M., Christian, JR, Dunne, JP, Gehlen, M., Ilyina, T., John, JG, Lenton, A ., Li, H., Lovenduski, NS, Orr, JC, Palmieri, J., Santana-Falcón, Y., Schwinger, J., Séférian, R., Stock, CA,… Ziehn, T. (2020). Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections. Biogeosciences, 17 (13), 3439–3470. https://doi.org/10.5194/bg-17-3439-2020

Summary:

In this study, 21st century projections of marine biogeochemistry in the CMIP6 Earth system models were assessed. These models represent the most up-to-date understanding of climate change. The models generally project greater surface ocean warming, acidification, subsurface deoxygenation, and euphotic nitrate reductions but lesser primary production declines than the previous generation of models. This has major implications for the impact of anthropogenic climate change on marine ecosystems.

Franke, A., Blenckner, T., Duarte, C. M., Ott, K., Fleming, L. E., Antia, A., Reusch, T. B. H., Bertram, C., Hein, J., Kronfeld-Goharani, U., Dierking, J., Kuhn, A., Sato, C., van Doorn, E., Wall, M., Schartau, M., Karez, R., Crowder, L., Keller, D., … Prigge, E. (2020). Operationalizing Ocean Health: Toward Integrated Research on Ocean Health and Recovery to Achieve Ocean Sustainability. One Earth, 2(6), 557–565. https://doi.org/10.1016/j.oneear.2020.05.013

Summary:

Protecting the ocean has become a major goal of international policy as human activities increasingly endanger the integrity of the ocean ecosystem, often summarized as “ocean health.” By and large, efforts to protect the ocean have failed because, among other things, (1) the underlying socio-ecological pathways have not been properly considered, and (2) the concept of ocean health has been ill defined. Collectively, this paper prevents an adequate societal response as to how ocean ecosystems and their vital functions for human societies can be protected and restored. The authors reviewed the confusion surrounding the term “ocean health” and suggested an operational ocean-health framework in line with the concept of strong sustainability. Given the accelerating degeneration of marine ecosystems, the restoration of regional ocean health will be of increasing importance. The advocated transdisciplinary and multi-actor framework presented in this study, can help to advance the implementation of more active measures to restore ocean health and safeguard human health and well-being.

Terhaar, J., Tanhua, T., Stöven, T., Orr, J. C., & Bopp, L. (2020). Evaluation of Data-Based Estimates of Anthropogenic Carbon in the Arctic Ocean. Journal of Geophysical Research: Oceans, 125(6), e2020JC016124. https://doi.org/10.1029/2020JC016124

Summary:

The Arctic Ocean is particularly vulnerable to ocean acidification, a process that is mainly driven by the uptake of anthropogenic carbon (C_ant) from the atmosphere. Although C_ant concentrations cannot be measured directly in the ocean, they have been estimated using data‐based methods and as a result, the total amount of C_ant in the Arctic Ocean in 2005 was 8% higher and was estimated to be 3.3 ± 0.3 Pg C. In this study the authors estimated that all Arctic waters, from surface to depth, would become corrosive to aragonite by the middle of the next century even if atmospheric CO₂ could be stabilized at 540 ppm.

Policy relevant message:

All Arctic waters, from surface to depth, will become corrosive to essential chemical carbonic species by the middle of the next century even if atmospheric CO₂ could be stabilized at 540 ppm (>416 ppm as of February 2021¹).

¹ https://www.esrl.noaa.gov/gmd/ccgg/trends/

Fernandes, J. A., Rutterford, L., Simpson, S. D., Butenschön, M., Frölicher, T. L., Yool, A., Cheung, W. W. L., & Grant, A. (2020). Can we project changes in fish abundance and distribution in response to climate? Global Change Biology, 26(7), 3891–3905. https://doi.org/10.1111/gcb.15081

Summary:

Large scale and long-term changes in fish abundance and distribution in response to climate change have been simulated using both statistical and process-based models. However, national and regional fisheries management requires also shorter-term projections on smaller spatial scales, and these need to be validated against fisheries data. A 26-year long time series of fish surveys with high spatial resolution in the North East Atlantic provides a unique opportunity to assess the ability of models to correctly simulate the changes in fish distribution and abundance that occurred in response to climate variability and change. In this study, a model forced by physical-biogeochemical output from eight ocean models was used to simulate changes in fish abundance and distribution at scales down to a spatial resolution of 0.5°. When comparing the model simulation with the available fish survey, authors concluded that predictions based on different biogeochemical models are often more similar to each other than they are to the survey data, except for some pelagic species. Additionally, the authors stressed that model results can be used to guide fisheries management at larger spatial scales, but more caution is needed at smaller scales.

Policy relevant message:

Large scale and long-term changes in fish abundance and distribution in response to climate change can be used to guide fisheries management.

Cael, B. B., Chase, A., & Boss, E. (2020). Information content of absorption spectra and implications for ocean color inversion. Appl. Opt., 59(13), 3971–3984. https://doi.org/10.1364/AO.389189

Summary:

The increasing use of hyperspectral optical data in oceanography, both in situ and via remote sensing, holds the potential to significantly advance characterization of marine ecology and biogeochemistry because, in principle, it can provide much more detailed inferences of ecosystem properties via inversion. This study focuses on complementary approaches to quantify the degrees of freedom in hyperspectral measurements in the case of in situ particulate absorption measurements, though these approaches can also be used on other such data, e.g., ocean colour remote sensing.