Addressing ocean acidification as part of sustainable ocean development

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Brill for personal use, not for redistribution. The definitive version was published in Ocean Yearbook 27, edited by Aldo Chircop, Scott Coffen-Smout, and Moira McConnell, :29-46. Leiden: Brill (Martinus Nijhoff), 2013. ISBN: 9789004250451.Many of the declarations and outcome documents from prior United Nations international meetings address ocean issues such as fishing, pollution, and climate change, but they do not address ocean acidification. This progressive alteration of seawater chemistry caused by uptake of atmospheric carbon dioxide (CO2) is an emerging issue of concern that has potential consequences for marine ecosystems and the humans that depend on them. Addressing ocean acidification will require mitigation of global CO2 emissions at the international level accompanied by regional marine resource use adaptations that reduce the integrated pressure on marine ecosystems while the global community works towards implementing permanent CO2 emissions reductions. Addressing ocean acidification head-on is necessary because it poses a direct challenge to sustainable development targets such as the Millennium Development Goals, and it cannot be addressed adequately with accords or geoengineering plans that do not specifically decrease atmospheric carbon dioxide levels. Here, we will briefly review the current state of ocean acidification knowledge and identify several mitigation and adaptation strategies that should be considered along with reductions in CO2 emissions to reduce the near-term impacts of ocean acidification. Our goal is to present potential options while identifying some of their inherent weaknesses to inform decisionmaking discussions, rather than to recommend adoption of specific policies. While the reduction of CO2 emissions should be the number one goal of the international community, it is unlikely that the widespread changes and infrastructure redevelopment necessary to accomplish this will be achieved soon, before ocean acidification’s short-term impacts become significant. Therefore, a multi-faceted approach must be employed to address this growing problem

Age characteristics of a shelf-break eddy in the western Arctic and implications for shelf-basin exchange

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C02018, doi:10.1029/2007JC004429.Radioisotope evaluation of a cold-core, anticyclonic eddy surveyed in September 2004 on the Chukchi Sea continental slope was used to determine its age since formation over the shelf environment. Because the eddy can be shown to have been generated near the shelf break, initial conditions for several age-dependent tracers could be relatively well constrained. A combination of 228Ra/226Ra, excess 224Ra, and 228Th/228Ra suggested an age on the order of months. This age is consistent with the presence of elevated concentrations of nutrients, organic carbon, suspended particles, and shelf-derived neritic zooplankton within the eddy compared to ambient offshore water in the Canada Basin but comparable to values measured in the Chukchi shelf and shelf-break environment. Hence this feature, at the edge of the deep basin, was poised to deliver biogeochemically significant shelf material to the central Arctic Ocean.This work was supported by National Science Foundation Polar Programs grants OPP-662690 and OPP-66040N to the University of Miami (DK), and Office of Naval Research grant N00014-02-1-0317 (RP)

Arctic in Rapid Transition (ART) : science plan

The Arctic is undergoing rapid transformations that have brought the Arctic Ocean to the top of international political agendas. Predicting future conditions of the Arctic Ocean system requires scientific knowledge of its present status as well as a process-based understanding of the mechanisms of change. The Arctic in Rapid Transition (ART) initiative is an integrative, international, interdisciplinary pan-Arctic program to study changes and feedbacks among the physical and biogeochemical components of the Arctic Ocean and their ultimate impacts on biological productivity. The goal of ART is to develop priorities for Arctic marine science over the next decade. Three overarching questions form the basis of the ART science plan: (1) How were past transitions in sea ice connected to energy flows, elemental cycling, biological diversity and productivity, and how do these compare to present and projected shifts? (2) How will biogeochemical cycling respond to transitions in terrestrial, gateway and shelf-to-basin fluxes? (3) How do Arctic Ocean organisms and ecosystems respond to environmental transitions including temperature, stratification, ice conditions, and pH? The integrated approach developed to answer the ART key scientific questions comprises: (a) process studies and observations to reveal mechanisms, (b) the establishment of links to existing monitoring programs, (c) the evaluation of geological records to extend time-series, and (d) the improvement of our modeling capabilities of climate-induced transitions. In order to develop an implementation plan for the ART initiative, an international and interdisciplinary workshop is currently planned to take place in Winnipeg, Canada in October 2010

Ocean acidification in the surface waters of the Pacific-Arctic boundary regions

Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 2 (2015): 122-135, doi:10.5670/oceanog.2015.36.The continental shelves of the Pacific-Arctic Region (PAR) are especially vulnerable to the effects of ocean acidification (OA) because the intrusion of anthropogenic CO2 is not the only process that can reduce pH and carbonate mineral saturation states for aragonite (Ωarag). Enhanced sea ice melt, respiration of organic matter, upwelling, and riverine inputs have been shown to exacerbate CO2 -driven ocean acidification in high-latitude regions. Additionally, the indirect effect of changing sea ice coverage is providing a positive feedback to OA as more open water will allow for greater uptake of atmospheric CO2 . Here, we compare model-based outputs from the Community Earth System Model with a subset of recent ship-based observations, and take an initial look at future model projections of surface water Ωarag in the Bering, Chukchi, and Beaufort Seas. We then use the model outputs to define benchmark years when biological impacts are likely to result from reduced Ωarag. Each of the three continental shelf seas in the PAR will become undersaturated with respect to aragonite at approximately 30-year intervals, indicating that aragonite undersaturations gradually progress upstream along the flow path of the waters as they move north from the Pacific Ocean. However, naturally high variability in Ωarag may indicate higher resilience of the Bering Sea ecosystem to these low-Ωarag conditions than the ecosystems of the Chukchi and the Beaufort Seas. Based on our initial results, we have determined that the annual mean for Ωarag will pass below the current range of natural variability in 2025 for the Beaufort Sea and 2027 for the Chukchi Sea. Because of the higher range of natural variability, the annual mean for Ωarag for the Bering Sea does not pass out of the natural variability range until 2044. As Ωarag in these shelf seas slips below the present-day range of large seasonal variability by mid-century, the diverse ecosystems that support some of the largest commercial and subsistence fisheries in the world may be under tremendous pressure.This project was funded by the National Science Foundation (PLR- 1041102 and AGS-1048827)

Formation and transport of corrosive water in the Pacific Arctic region

This paper is not subject to U.S. copyright. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 152 (2018): 67-81, doi:10.1016/j.dsr2.2018.05.020.Ocean acidification (OA), driven by rising anthropogenic carbon dioxide (CO2), is rapidly advancing in the Pacific Arctic Region (PAR), producing conditions newly corrosive to biologically important carbonate minerals like aragonite. Naturally short linkages across the PAR food web mean that species-specific acidification stress can be rapidly transmitted across multiple trophic levels, resulting in widespread impacts. Therefore, it is critical to understand the formation, transport, and persistence of acidified conditions in the PAR in order to better understand and project potential impacts to this delicately balanced ecosystem. Here, we synthesize data from process studies across the PAR to show the formation of corrosive conditions in colder, denser winter-modified Pacific waters over shallow shelves, resulting from the combination of seasonal terrestrial and marine organic matter respiration with anthropogenic CO2. When these waters are subsequently transported off the shelf, they acidify the Pacific halocline. We estimate that Barrow Canyon outflow delivers ~2.24 Tg C yr-1 to the Arctic Ocean through corrosive winter water transport. This synthesis also allows the combination of spatial data with temporal data to show the persistence of these conditions in halocline waters. For example, one study in this synthesis indicated that 0.5–1.7 Tg C yr-1 may be returned to the atmosphere via air-sea gas exchange of CO2 during upwelling events along the Beaufort Sea shelf that bring Pacific halocline waters to the ocean surface. The loss of CO2 during these events is more than sufficient to eliminate corrosive conditions in the upwelled Pacific halocline waters. However, corresponding moored and discrete data records indicate that potentially corrosive Pacific waters are present in the Beaufort shelfbreak jet during 80% of the year, indicating that the persistence of acidified waters in the Pacific halocline far outweighs any seasonal mitigation from upwelling. Across the datasets in this large-scale synthesis, we estimate that the persistent corrosivity of the Pacific halocline is a recent phenomenon that appeared between 1975 and 1985. Over that short time, these potentially corrosive waters originating over the continental shelves have been observed as far as the entrances to Amundsen Gulf and M’Clure Strait in the Canadian Arctic Archipelago. The formation and transport of corrosive waters on the Pacific Arctic shelves may have widespread impact on the Arctic biogeochemical system and food web reaching all the way to the North Atlantic.National Science Foundation Grant PLR-1303617

Wind-driven mixing causes a reduction in the strength of the continental shelf carbon pump in the Chukchi Sea

The Chukchi Sea is thought to be a globally important sink of atmospheric CO2 due to the summertime drawdown of surface pCO2 by phytoplankton and subsequent shelf-to-basin transport of CO2-enriched subsurface waters into the upper halocline of the Arctic Ocean. Here we show that annually occurring storm-induced mixing events during autumn months disrupt water column stratification and stir up remineralized carbon from subsurface waters to the surface, leading to CO2 outgassing to the atmosphere. Our analysis provides a new understanding of the dynamics of carbon cycling in the region and suggests that late season wind events are strong and frequent enough to significantly decrease the carbon sink strength of the Chukchi Sea on a scale of relevance to the global carbon cycle. These results highlight the importance of obtaining data with more complete seasonal and spatial coverage in order to accurately constrain regional to basin-scale carbon flux budgets

Establishing priorities for interdisciplinary Arctic Ocean Science

Arctic in Rapid Transition (ART) Initiation Workshop; Fairbanks, Alaska, 7–9 November 2009; The Arctic is undergoing rapid environmental and economic transformations. Recent climate warming, which is simplifying access to oil and gas resources, enabling trans-Arctic shipping, and shifting the distribution of harvestable resources, has brought the Arctic Ocean to the top of national and international political agendas. Scientific knowledge of the present status of the Arctic Ocean and a process-based understanding of the mechanisms of change are required to make useful predictions of future conditions throughout the Arctic region. A step toward improving scientists' capacity to predict future Arctic change was undertaken with the Second International Conference on Arctic Research Planning (ICARP II) meeting in 2005 (http://web.arcticportal.org/iasc/icarp). As the ICARP II process came to a close, the Arctic in Rapid Transition (ART) initiative developed out of an effort to synthesize the several ICARP II science plans specific to the Arctic marine environment

Significant biologically mediated CO2 uptake in the pacific arctic during the late open water season.

Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(2), (2019):821-843, doi:10.1029/2018JC014568.Shifting baselines in the Arctic atmosphere‐sea ice‐ocean system have significant potential to alter biogeochemical cycling and ecosystem dynamics. In particular, the impact of increased open water duration on lower trophic level productivity and biological CO2 sequestration is poorly understood. Using high‐resolution observations of surface seawater dissolved O2/Ar and pCO2 collected in the Pacific Arctic in October 2011 and 2012, we evaluate spatial variability in biological metabolic status (autotrophy vs heterotrophy) as constrained by O2/Ar saturation (∆O2/Ar) as well as the relationship between net biological production and the sea‐air gradient of pCO2 (∆pCO2). We find a robust relationship between ∆pCO2 and ∆O2/Ar (correlation coefficient of −0.74 and −0.61 for 2011 and 2012, respectively), which suggests that biological production in the late open water season is an important determinant of the air‐sea CO2 gradient at a timeframe of maximal ocean uptake for CO2 in this region. Patchiness in biological production as indicated by ∆O2/Ar suggests spatially variable nutrient supply mechanisms supporting late season growth amidst a generally strongly stratified and nutrient‐limited condition.We thank the Captain, crew, and marine technicians of the USCGC Healy for their shipboard support. We also thank anonymous reviewers for providing useful feedback that improved this manuscript. This work was supported by NSF awards 1232856 and 1504394 to L.W.J. T.T. was supported by a grant NA150AR4320064 from Climate Program Office/NOAA and R.P. by NSF PLR‐1504333 and OPP‐1702371. All O2 and O2/Ar data and metadata are available at Arcticdata.io, doi:10.18739/A21G22, and pCO2 data are available at www.ldeo.columbia.edu/CO2 as well as from the NOAA National Centers for Environmental Information Ocean Carbon Data System at https://www.nodc.noaa.gov/ocads/.2019-07-1

Annual sea-air CO2fluxes in the Bering Sea: insights from new autumn and winter observations of a seasonally ice-covered continental shelf

High-resolution data collected from several programs have greatly increased the spatiotemporal resolution of pCO2(sw) data in the Bering Sea, and provided the first autumn and winter observations. Using data from 2008 to 2012, monthly climatologies of sea-air CO2 fluxes for the Bering Sea shelf area from April to December were calculated, and contributions of physical and biological processes to observed monthly sea-air pCO2 gradients (?pCO2) were investigated. Net efflux of CO2 was observed during November, December, and April, despite the impact of sea surface cooling on ?pCO2. Although the Bering Sea was believed to be a moderate to strong atmospheric CO2 sink, we found that autumn and winter CO2 effluxes balanced 65% of spring and summer CO2 uptake. Ice cover reduced sea-air CO2 fluxes in December, April, and May. Our estimate for ice-cover corrected fluxes suggests the mechanical inhibition of CO2 flux by sea-ice cover has only a small impact on the annual scale (<2%). An important data gap still exists for January to March, the period of peak ice cover and the highest expected retardation of the fluxes. By interpolating between December and April using assumptions of the described autumn and winter conditions, we estimate the Bering Sea shelf area is an annual CO2 sink of ?6.8 Tg C yr?1. With changing climate, we expect warming sea surface temperatures, reduced ice cover, and greater wind speeds with enhanced gas exchange to decrease the size of this CO2 sink by augmenting conditions favorable for greater wintertime outgassing

The Arctic in Rapid Transition (ART) Initiative: integrating priorities for Arctic marine science over the next decade

The Arctic is currently undergoing rapid environmental and economic transformations. Recent and ongoing climate warming which is simplifying access to oil and gas resources, enabling trans-Arctic shipping and shifting the distribution of harvestable resources, has brought the Arctic Ocean to the top of national and international political agendas. Scientific knowledge of the present status of the Arctic Ocean and the process-based understanding needed to make predictions throughout the arctic region are thus urgently required. A step towards improving our capacity to predict future arctic change was undertaken with the Second International Conference on Arctic Research Planning (ICARP II) meetings in 2005 and 2006 which brought together scientists, policymakers, research managers, arctic residents and other stakeholders interested in the future of arctic climate change research. The Arctic in Rapid Transition (ART) Initiative developed out of an effort to synthesize the several resulting ICARP II science plans specific to the marine environment and has been a process driven by the early career scientists of the ICARP II Marine Roundtable. To this end, the ART Initiative is an integrative, international, multi-disciplinary, long-term pan-Arctic program to study changes and feedbacks among the physical characteristics and biogeochemical cycles of the Arctic Ocean and its' resulting capacity for biological productivity. The first ART workshop was held in Fairbanks, Alaska in November 2009 with 58 participants, the results of which will help to develop a science and implementation plan that integrates, updates and develops priorities for arctic marine science over the next decade. Our focus within the ART Initiative will be to bridge gaps in knowledge not only across disciplinary boundaries (e.g., geology, biology, physical oceanography, geochemistry and meteorology), but also across geographic boundaries (e.g., shelves, margins and the central Arctic Ocean) and temporal boundaries (e.g., paleo/geologic records, current process observations and future modeling studies). This interdisciplinary, international and integrated temporal approach of the ART Initiative will provide a means to better understand and predict change and ultimate responses in the Arctic Ocean system. More information about the ART Initiative can be found at www.aosb.org/art.html