Contrasting Controls of Acidification Metrics Across Environmental Gradients in the North Pacific and the Adjunct Arctic Ocean: Insight From a Transregional Study
About: This article is published in Geophysical Research Letters.The article was published on 2021-10-16. It has received 6 citations till now. The article focuses on the topics: Arctic.
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TL;DR: Sensitivity of global ocean biogeochemical dynamics to ecosystem structure in a future climate and model methods for Marine Science are described.
Abstract: Marine Carbon BiogeochemistryBiogeochemical Cycles and ClimateGlobal Biogeochemical Cycles in the Climate SystemOcean Dynamics and the Carbon CycleLive Long and EvolveBiogeochemistry of Marine Dissolved Organic MatterOcean Biogeochemical DynamicsMarine Ecosystems and Global ChangeBiological OceanographyNitrogen in the SeaBiogeochemistry of EstuariesInteractions of C, N, P and S Biogeochemical Cycles and Global ChangeGlobal EnvironmentComputational Science — ICCS 2004The Oceans and ClimateMarine Microbiome and Biogeochemical Cycles in Marine Productive AreasMetal Ions in Biological Systems, Volume 43 Biogeochemical Cycles of ElementsNitrogen in the Marine EnvironmentIntroduction to Marine BiogeochemistryOcean Circulation and ClimatePrimary Productivity and Biogeochemical Cycles in the SeaThe Biogeochemical Cycle of Silicon in the OceanChemical OceanographyTowards a Model of Ocean Biogeochemical ProcessesOcean Dynamics and the Carbon CycleOcean BiogeochemistryParticle Analysis in OceanographyBiogeochemical CyclesBiogeochemical Dynamics at Major River-Coastal InterfacesThe Ocean Carbon Cycle and ClimateSensitivity of global ocean biogeochemical dynamics to ecosystem structure in a future climateModeling Methods for Marine ScienceAn Introduction to the Chemistry of the SeaEncyclopedia of Ocean SciencesCO2 in Seawater: Equilibrium, Kinetics, IsotopesThe Biogeochemical Cycle of Silicon in the OceanKuroshio CurrentThe Mediterranean Sea in the Era of Global Change 1Ocean Biogeochemical DynamicsOcean Mixing
472 citations
TL;DR: In this article , the authors report rapid acidification in the Arctic Ocean, with rates three to four times higher than in other ocean basins, and attribute it to changing sea ice coverage on a decadal time scale.
Abstract: The Arctic Ocean has experienced rapid warming and sea ice loss in recent decades, becoming the first open-ocean basin to experience widespread aragonite undersaturation [saturation state of aragonite (Ωarag) < 1]. However, its trend toward long-term ocean acidification and the underlying mechanisms remain undocumented. Here, we report rapid acidification there, with rates three to four times higher than in other ocean basins, and attribute it to changing sea ice coverage on a decadal time scale. Sea ice melt exposes seawater to the atmosphere and promotes rapid uptake of atmospheric carbon dioxide, lowering its alkalinity and buffer capacity and thus leading to sharp declines in pH and Ωarag. We predict a further decrease in pH, particularly at higher latitudes where sea ice retreat is active, whereas Arctic warming may counteract decreases in Ωarag in the future. Description Acceleration in the Arctic The Arctic is warming at a rate faster than any comparable region on Earth, with a consequently rapid loss of sea ice there. Qi et al. found that this sea ice loss is causing more uptake of atmospheric carbon dioxide by surface water and driving rapid acidification of the western Arctic Ocean, at a rate three to four times higher than that of the other ocean basins. They attribute this finding to melt-driven addition of freshwater and the resulting changes in seawater chemistry. —HJS The western Arctic Ocean is rapidly acidifying due to sea ice loss.
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TL;DR: In this paper , the authors show that the acidification rate of the North Pacific subtropical mode water (STMW) during 2005-2020 is about two times of that during 1993-2005, which is due to cooling-driven enhanced CANT accumulation in the formation waters in the recent period.
Abstract: Recent studies suggest that the formation and motion of the North Pacific subtropical mode water (STMW) play an important role in oceanic uptake, transport and storage of anthropogenic CO2 (CANT). However, the variability of STMW acidification rate and its control mechanisms remain unclear. Here we show that the STMW acidification rate during 2005–2020 is about two times of that during 1993–2005, which is due to the cooling‐driven enhanced CANT accumulation in the formation waters in the recent period. The rapid rates of CANT accumulation and acidification are consistently observed in the entire region across 137°–149°E regulated by STMW transport. Moreover, the tracer‐based (Δ14C and δ13C) analyses also indicate that the accelerated accumulation of CANT could be traced back to the surface formation waters via STMW formation. The vertical and horizontal consistencies imply the memory function of mode waters in retaining the anthropogenic carbon fingerprint during its formation and transport.
References
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TL;DR: 13 models of the ocean–carbon cycle are used to assess calcium carbonate saturation under the IS92a ‘business-as-usual’ scenario for future emissions of anthropogenic carbon dioxide and indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously.
Abstract: Today's surface ocean is saturated with respect to calcium carbonate, but increasing atmospheric carbon dioxide concentrations are reducing ocean pH and carbonate ion concentrations, and thus the level of calcium carbonate saturation. Experimental evidence suggests that if these trends continue, key marine organisms—such as corals and some plankton—will have difficulty maintaining their external calcium carbonate skeletons. Here we use 13 models of the ocean–carbon cycle to assess calcium carbonate saturation under the IS92a 'business-as-usual' scenario for future emissions of anthropogenic carbon dioxide. In our projections, Southern Ocean surface waters will begin to become undersaturated with respect to aragonite, a metastable form of calcium carbonate, by the year 2050. By 2100, this undersaturation could extend throughout the entire Southern Ocean and into the subarctic Pacific Ocean. When live pteropods were exposed to our predicted level of undersaturation during a two-day shipboard experiment, their aragonite shells showed notable dissolution. Our findings indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously.
4,244 citations
"Contrasting Controls of Acidificati..." refers background in this paper
...…(Gruber et al., 2019; Friedlingstein et al., 2020; Sabine et al., 2004) to alleviate global climate change, however, at the expense of causing ocean acidification (OA) once CO2 dissolves in the ocean and reacts with seawater (Doney et al., 2009; Feely et al., 2004, 2009; Orr et al., 2005)....
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...The well-known effect of OA includes not only the addition of hydrogen ion ([H+]) and decline of pH but also the decreased calcium carbonate (CaCO3) saturation state which subsequently threatens the marine ecosystem (Cai et al., 2020, 2021; Cornwall et al., 2021; Doney et al., 2009, 2020; Feely et al., 2004, 2009, 2012; Gattuso et al., 2015; Orr et al., 2005)....
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National Oceanic and Atmospheric Administration1, University of California, Los Angeles2, Princeton University3, Pohang University of Science and Technology4, Atlantic Oceanographic and Meteorological Laboratory5, University of Kiel6, Commonwealth Scientific and Industrial Research Organisation7, University of Miami8, United States Department of Energy9, Spanish National Research Council10
TL;DR: Using inorganic carbon measurements from an international survey effort in the 1990s and a tracer-based separation technique, the authors estimate a global oceanic anthropogenic carbon dioxide (CO2) sink for the period from 1800 to 1994 of 118 19 petagrams of carbon.
Abstract: Using inorganic carbon measurements from an international survey effort in the 1990s and a tracer-based separation technique, we estimate a global oceanic anthropogenic carbon dioxide (CO2) sink for the period from 1800 to 1994 of 118 19 petagrams of carbon. The oceanic sink accounts for48% of the total fossil-fuel and cement-manufacturing emissions, implying that the terrestrial biosphere was a net source of CO 2 to the atmosphere of about 39 28 petagrams of carbon for this period. The current fraction of total anthropogenic CO2 emissions stored in the ocean appears to be about one-third of the long-term potential. Since the beginning of the industrial period in the late 18th century, i.e., over the anthropocene (1), humankind has emitted large quantities of CO2 into the atmosphere, mainly as a result of fossil-fuel burning, but also because of land-use practices, e.g., deforestation (2). Measurements and reconstructions of the atmospheric CO2 history reveal, however, that less than half of these emissions remain in the atmosphere (3). The anthropogenic CO2 that did not accumulate in the atmosphere must have been taken up by the ocean, by the land biosphere, or by a combination of both. The relative roles of the ocean and land biosphere as sinks for anthropogenic CO2 over the anthropocene are currently not known. Although the anthropogenic CO2 budget for the past two decades, i.e., the 1980s and 1990s, has been investigated in detail (3), the estimates of the ocean sink have not been based on direct measurements of changes in the oceanic inventory of dissolved inorganic carbon (DIC). Recognizing the need to constrain the oceanic uptake, transport, and storage of anthropogenic CO 2 for the anthropocene and to provide a baseline for future estimates of oceanic CO 2 uptake, two international ocean research programs, the World Ocean Circulation Experiment (WOCE) and the Joint Global Ocean Flux Study (JGOFS), jointly conducted a comprehensive survey of inorganic carbon distributions in the global ocean in the 1990s (4). After completion of the U.S. field program in 1998, a 5-year effort was begun to compile and rigorously quality-control the U.S. and international data sets, in
3,291 citations
TL;DR: The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research as mentioned in this paper, and both are only imperfect analogs to current conditions.
Abstract: Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.
2,995 citations
TL;DR: The in situ CaCO3 dissolution rates for the global oceans from total alkalinity and chlorofluorocarbon data are estimated, and the future impacts of anthropogenic CO2 on Ca CO3 shell–forming species are discussed.
Abstract: Rising atmospheric carbon dioxide (CO 2 ) concentrations over the past two centuries have led to greater CO2 uptake by the oceans. This acidification process has changed the saturation state ofthe oceans with respect to calcium carbonate (CaCO3) particles. Here we estimate the in situ CaCO3 dissolution rates for the global oceans from total alkalinity and chlorofluorocarbon data, and we also discuss the future impacts of anthropogenic CO2 on CaCO3 shell– forming species. CaCO 3 dissolution rates, ranging from 0.003 to 1.2 micromoles per kilogram per year, are observed beginning near the aragonite saturation horizon. The total water column CaCO 3 dissolution rate for the global oceans is approximately 0.5 0.2 petagrams ofCaCO 3-C per year, which is approximately 45 to 65% ofthe export production ofCaCO 3 . Atmospheric CO 2 concentrations oscillated be
2,140 citations
"Contrasting Controls of Acidificati..." refers background in this paper
...…(Gruber et al., 2019; Friedlingstein et al., 2020; Sabine et al., 2004) to alleviate global climate change, however, at the expense of causing ocean acidification (OA) once CO2 dissolves in the ocean and reacts with seawater (Doney et al., 2009; Feely et al., 2004, 2009; Orr et al., 2005)....
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...Ωarag is proportional to concentrations of Ca 2+ and CO3 2− (Feely et al., 2004), therefore it is more sensitive to changes in salinity and TA than pH....
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TL;DR: It is shown that the Arctic warming is strongest at the surface during most of the year and is primarily consistent with reductions in sea ice cover, and suggests that strong positive ice–temperature feedbacks have emerged in the Arctic, increasing the chances of further rapid warming and sea ice loss.
Abstract: The rise in Arctic near-surface air temperatures has been almost twice as large as the global average in recent decades-a feature known as 'Arctic amplification'. Increased concentrations of atmospheric greenhouse gases have driven Arctic and global average warming; however, the underlying causes of Arctic amplification remain uncertain. The roles of reductions in snow and sea ice cover and changes in atmospheric and oceanic circulation, cloud cover and water vapour are still matters of debate. A better understanding of the processes responsible for the recent amplified warming is essential for assessing the likelihood, and impacts, of future rapid Arctic warming and sea ice loss. Here we show that the Arctic warming is strongest at the surface during most of the year and is primarily consistent with reductions in sea ice cover. Changes in cloud cover, in contrast, have not contributed strongly to recent warming. Increases in atmospheric water vapour content, partly in response to reduced sea ice cover, may have enhanced warming in the lower part of the atmosphere during summer and early autumn. We conclude that diminishing sea ice has had a leading role in recent Arctic temperature amplification. The findings reinforce suggestions that strong positive ice-temperature feedbacks have emerged in the Arctic, increasing the chances of further rapid warming and sea ice loss, and will probably affect polar ecosystems, ice-sheet mass balance and human activities in the Arctic.
1,842 citations
"Contrasting Controls of Acidificati..." refers background in this paper
...Meanwhile, in the context of climate change, emerging sea-ice melt and the subsequent desalination in the Arctic and Antarctic (Garbe et al., 2020; Parkinson, 2019; Screen & Simmonds, 2010) will also reduce pH and Ωarag....
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