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Frey DI, Morozov EG, Smirnova DA. Sea level anomalies affect the ocean circulation at abyssal depths. Sci Rep 2023; 13:20829. [PMID: 38012378 PMCID: PMC10682481 DOI: 10.1038/s41598-023-48074-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/22/2023] [Indexed: 11/29/2023] Open
Abstract
Abyssal channels are the key points controlling bottom circulation of the World Ocean. They provide meridional transport of the coldest Antarctic Bottom Water between deep-water basins influencing the meridional overturning circulation and the climate on a global scale. Here we show that the synoptic variability of deep-water flows including blocking abyssal currents between deep ocean basins is related to sea level anomalies observed over the channels. Our results demonstrate that processes at the ocean surface have a more significant connection with the bottom circulation than it was considered earlier. This study opens a discussion of the importance of mesoscale eddies and air-sea interactions on water exchange between abyssal basins, meridional heat transport in the ocean, and possible responses of the ocean to the observed sea level rise in a changing climate.
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Affiliation(s)
- D I Frey
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia.
- Marine Hydrophysical Institute, Russian Academy of Sciences, Sevastopol, Russia.
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia.
| | - E G Morozov
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
| | - D A Smirnova
- Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
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Zhou C, Xiao X, Zhao W, Yang J, Huang X, Guan S, Zhang Z, Tian J. Increasing deep-water overflow from the Pacific into the South China Sea revealed by mooring observations. Nat Commun 2023; 14:2013. [PMID: 37037814 PMCID: PMC10085979 DOI: 10.1038/s41467-023-37767-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 03/30/2023] [Indexed: 04/12/2023] Open
Abstract
Cold and dense water from the North Pacific Ocean that spills through the Luzon Strait, the only deep conduit between the South China Sea (SCS) and the Pacific Ocean, renews deep-water mass, modulates hydrographic and biogeochemical cycles, and drives abyssal and overturning circulations in the SCS. The variability of this key oceanic process, however, has been poorly studied, mainly due to a lack of sustained observations. A comprehensive observational program that started in 2009 has provided 12 years of continuous time series of velocity and volume transport within the Luzon Strait. Here we show the observation-based assessment of decadal trends of deep-water transport through this vital passage. With the estimated 12-year mean volume transport of the deep-water overflow into the SCS of 0.84 ± 0.39 Sv (1 Sv = 106 m3 s-1), a significant linear upward trend of 9% is revealed during this period. This is consistent with long-term changes in satellite-observed ocean bottom pressure. The results of this study may have broad implications for the overturning circulations and biogeochemical processes, including carbon cycles in this region.
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Affiliation(s)
- Chun Zhou
- Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Key Laboratory of Ocean Observation and Information of Hainan Province/Sanya Oceanographic Institution, Ocean University of China, Qingdao/Sanya, China
- Laoshan Laboratory, Qingdao, China
| | - Xin Xiao
- Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Key Laboratory of Ocean Observation and Information of Hainan Province/Sanya Oceanographic Institution, Ocean University of China, Qingdao/Sanya, China
| | - Wei Zhao
- Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Key Laboratory of Ocean Observation and Information of Hainan Province/Sanya Oceanographic Institution, Ocean University of China, Qingdao/Sanya, China.
- Laoshan Laboratory, Qingdao, China.
| | - Jiayan Yang
- Woods Hole Oceanographic Institution, Woods Hole, 02543, MA, USA
| | - Xiaodong Huang
- Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Key Laboratory of Ocean Observation and Information of Hainan Province/Sanya Oceanographic Institution, Ocean University of China, Qingdao/Sanya, China
- Laoshan Laboratory, Qingdao, China
| | - Shoude Guan
- Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Key Laboratory of Ocean Observation and Information of Hainan Province/Sanya Oceanographic Institution, Ocean University of China, Qingdao/Sanya, China
- Laoshan Laboratory, Qingdao, China
| | - Zhiwei Zhang
- Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Key Laboratory of Ocean Observation and Information of Hainan Province/Sanya Oceanographic Institution, Ocean University of China, Qingdao/Sanya, China
- Laoshan Laboratory, Qingdao, China
| | - Jiwei Tian
- Frontier Science Center for Deep Ocean Multispheres and Earth System (FDOMES) and Physical Oceanography Laboratory, Key Laboratory of Ocean Observation and Information of Hainan Province/Sanya Oceanographic Institution, Ocean University of China, Qingdao/Sanya, China.
- Laoshan Laboratory, Qingdao, China.
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Novichkova AA, Chertoprud ES, Azovsky AI. Composition, characteristics and long-term variability of the freshwater microcrustacean fauna of the Faroe Islands. J NAT HIST 2020. [DOI: 10.1080/00222933.2019.1704587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Anna A. Novichkova
- Department of Hydrobiology, Biological Faculty, Moscow State University, Moscow, Russia
- Laboratory for Ecology of Aquatic Communities and Invasions, Laboratory for Synecology, A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia
| | - Elena S. Chertoprud
- Department of Hydrobiology, Biological Faculty, Moscow State University, Moscow, Russia
- Laboratory for Ecology of Aquatic Communities and Invasions, Laboratory for Synecology, A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia
| | - Andrey I. Azovsky
- Department of Hydrobiology, Biological Faculty, Moscow State University, Moscow, Russia
- P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia
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Gallego A, O'Hara Murray R, Berx B, Turrell WR, Beegle-Krause CJ, Inall M, Sherwin T, Siddorn J, Wakelin S, Vlasenko V, Hole LR, Dagestad KF, Rees J, Short L, Rønningen P, Main CE, Legrand S, Gutierrez T, Witte U, Mulanaphy N. Current status of deepwater oil spill modelling in the Faroe-Shetland Channel, Northeast Atlantic, and future challenges. MARINE POLLUTION BULLETIN 2018; 127:484-504. [PMID: 29475689 DOI: 10.1016/j.marpolbul.2017.12.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 11/30/2017] [Accepted: 12/01/2017] [Indexed: 05/20/2023]
Abstract
As oil reserves in established basins become depleted, exploration and production moves towards relatively unexploited areas, such as deep waters off the continental shelf. The Faroe-Shetland Channel (FSC, NE Atlantic) and adjacent areas have been subject to increased focus by the oil industry. In addition to extreme depths, metocean conditions in this region characterise an environment with high waves and strong winds, strong currents, complex circulation patterns, sharp density gradients, and large small- and mesoscale variability. These conditions pose operational challenges to oil spill response and question the suitability of current oil spill modelling frameworks (oil spill models and their forcing data) to adequately simulate the behaviour of a potential oil spill in the area. This article reviews the state of knowledge relevant to deepwater oil spill modelling for the FSC area and identifies knowledge gaps and research priorities. Our analysis should be relevant to other areas of complex oceanography.
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Affiliation(s)
| | | | | | | | | | - Mark Inall
- Scottish Association for Marine Science, UK
| | | | | | | | | | | | | | - John Rees
- Centre for Environment Fisheries and Aquaculture Science, UK
| | | | | | - Charlotte E Main
- National Oceanography Centre, Southampton, UK; University of Southampton, UK
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North Atlantic warming during Dansgaard-Oeschger events synchronous with Antarctic warming and out-of-phase with Greenland climate. Sci Rep 2016; 6:20535. [PMID: 26847384 PMCID: PMC4742819 DOI: 10.1038/srep20535] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 01/05/2016] [Indexed: 11/12/2022] Open
Abstract
The precise reason for the differences and out-of-phase relationship between the abrupt Dansgaard-Oeschger warmings in the Nordic seas and Greenland ice cores and the gradual warmings in the south-central Atlantic and Antarctic ice cores is poorly understood. Termed the bipolar seesaw, the differences are apparently linked to perturbations in the ocean circulation pattern. Here we show that surface and intermediate-depth water south of Iceland warmed gradually synchronously with the Antarctic warming and out of phase with the abrupt warming of the Nordic seas and over Greenland. The hinge line between areas showing abrupt and gradual warming was close to the Greenland-Scotland Ridge and the marine system appears to be a ‘push-and-pull’ system rather than a seesaw system. ‘Pull’ during the warm interstadials, when convection in the Nordic seas was active; ‘push’ during the cold stadials, when convection stopped and warm water from the south-central Atlantic pushed northward gradually warming the North Atlantic and Nordic seas.
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Sandø AB, Nilsen JEØ, Eldevik T, Bentsen M. Mechanisms for variable North Atlantic-Nordic seas exchanges. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012jc008177] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Köhl A, Siegismund F, Stammer D. Impact of assimilating bottom pressure anomalies from GRACE on ocean circulation estimates. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc007623] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Zheng Y, Giese BS. Ocean heat transport in Simple Ocean Data Assimilation: Structure and mechanisms. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jc005190] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Graham CT, Harrod C. Implications of climate change for the fishes of the British Isles. JOURNAL OF FISH BIOLOGY 2009; 74:1143-1205. [PMID: 20735625 DOI: 10.1111/j.1095-8649.2009.02180.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Recent climatic change has been recorded across the globe. Although environmental change is a characteristic feature of life on Earth and has played a major role in the evolution and global distribution of biodiversity, predicted future rates of climatic change, especially in temperature, are such that they will exceed any that has occurred over recent geological time. Climate change is considered as a key threat to biodiversity and to the structure and function of ecosystems that may already be subject to significant anthropogenic stress. The current understanding of climate change and its likely consequences for the fishes of Britain and Ireland and the surrounding seas are reviewed through a series of case studies detailing the likely response of several marine, diadromous and freshwater fishes to climate change. Changes in climate, and in particular, temperature have and will continue to affect fish at all levels of biological organization: cellular, individual, population, species, community and ecosystem, influencing physiological and ecological processes in a number of direct, indirect and complex ways. The response of fishes and of other aquatic taxa will vary according to their tolerances and life stage and are complex and difficult to predict. Fishes may respond directly to climate-change-related shifts in environmental processes or indirectly to other influences, such as community-level interactions with other taxa. However, the ability to adapt to the predicted changes in climate will vary between species and between habitats and there will be winners and losers. In marine habitats, recent changes in fish community structure will continue as fishes shift their distributions relative to their temperature preferences. This may lead to the loss of some economically important cold-adapted species such as Gadus morhua and Clupea harengus from some areas around Britain and Ireland, and the establishment of some new, warm-adapted species. Increased temperatures are likely to favour cool-adapted (e.g. Perca fluviatilis) and warm-adapted freshwater fishes (e.g. roach Rutilus rutilus and other cyprinids) whose distribution and reproductive success may currently be constrained by temperature rather than by cold-adapted species (e.g. salmonids). Species that occur in Britain and Ireland that are at the edge of their distribution will be most affected, both negatively and positively. Populations of conservation importance (e.g.Salvelinus alpinus and Coregonus spp.) may decline irreversibly. However, changes in food-web dynamics and physiological adaptation, for example because of climate change, may obscure or alter predicted responses. The residual inertia in climate systems is such that even a complete cessation in emissions would still leave fishes exposed to continued climate change for at least half a century. Hence, regardless of the success or failure of programmes aimed at curbing climate change, major changes in fish communities can be expected over the next 50 years with a concomitant need to adapt management strategies accordingly.
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Affiliation(s)
- C T Graham
- Department of Zoology, Ecology and Plant Science, University College Cork, Ireland
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10
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Observed and modelled stability of overflow across the Greenland–Scotland ridge. Nature 2008; 455:519-22. [DOI: 10.1038/nature07302] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Accepted: 07/31/2008] [Indexed: 11/08/2022]
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11
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Kleiven HKF, Kissel C, Laj C, Ninnemann US, Richter TO, Cortijo E. Reduced North Atlantic deep water coeval with the glacial Lake Agassiz freshwater outburst. Science 2007; 319:60-4. [PMID: 18063758 DOI: 10.1126/science.1148924] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
An outstanding climate anomaly 8200 years before the present (B.P.) in the North Atlantic is commonly postulated to be the result of weakened overturning circulation triggered by a freshwater outburst. New stable isotopic and sedimentological records from a northwest Atlantic sediment core reveal that the most prominent Holocene anomaly in bottom-water chemistry and flow speed in the deep limb of the Atlantic overturning circulation begins at approximately 8.38 thousand years B.P., coeval with the catastrophic drainage of Lake Agassiz. The influence of Lower North Atlantic Deep Water was strongly reduced at our site for approximately 100 years after the outburst, confirming the ocean's sensitivity to freshwater forcing. The similarities between the timing and duration of the pronounced deep circulation changes and regional climate anomalies support a causal link.
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12
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Quadfasel D, Käse R. Present-day manifestation of the Nordic Seas Overflows. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/173gm07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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13
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Discovery and quantification of the Atlantic meridional overturning circulation: The Importance of 25°N. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/173gm03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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14
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Schott FA, Brandt P. Circulation and deep water export of the subpolar North Atlantic during the 1990's. OCEAN CIRCULATION: MECHANISMS AND IMPACTS—PAST AND FUTURE CHANGES OF MERIDIONAL OVERTURNING 2007. [DOI: 10.1029/173gm08] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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15
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Song YT. Estimation of interbasin transport using ocean bottom pressure: Theory and model for Asian marginal seas. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jc003189] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Ezer T. Topographic influence on overflow dynamics: Idealized numerical simulations and the Faroe Bank Channel overflow. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jc003195] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Arnell NW, Tompkins EL, Adger WN. Eliciting information from experts on the likelihood of rapid climate change. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2005; 25:1419-31. [PMID: 16506972 DOI: 10.1111/j.1539-6924.2005.00689.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The threat of so-called rapid or abrupt climate change has generated considerable public interest because of its potentially significant impacts. The collapse of the North Atlantic Thermohaline Circulation or the West Antarctic Ice Sheet, for example, would have potentially catastrophic effects on temperatures and sea level, respectively. But how likely are such extreme climatic changes? Is it possible actually to estimate likelihoods? This article reviews the societal demand for the likelihoods of rapid or abrupt climate change, and different methods for estimating likelihoods: past experience, model simulation, or through the elicitation of expert judgments. The article describes a survey to estimate the likelihoods of two characterizations of rapid climate change, and explores the issues associated with such surveys and the value of information produced. The surveys were based on key scientists chosen for their expertise in the climate science of abrupt climate change. Most survey respondents ascribed low likelihoods to rapid climate change, due either to the collapse of the Thermohaline Circulation or increased positive feedbacks. In each case one assessment was an order of magnitude higher than the others. We explore a high rate of refusal to participate in this expert survey: many scientists prefer to rely on output from future climate model simulations.
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Affiliation(s)
- Nigel W Arnell
- Tyndall Centre for Climate Change Research, School of Geography, University of Southampton, Highfield, Southampton, SO17, 1BJ, UK.
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Bryden HL, Longworth HR, Cunningham SA. Slowing of the Atlantic meridional overturning circulation at 25° N. Nature 2005; 438:655-7. [PMID: 16319889 DOI: 10.1038/nature04385] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Accepted: 10/28/2005] [Indexed: 11/09/2022]
Abstract
The Atlantic meridional overturning circulation carries warm upper waters into far-northern latitudes and returns cold deep waters southward across the Equator. Its heat transport makes a substantial contribution to the moderate climate of maritime and continental Europe, and any slowdown in the overturning circulation would have profound implications for climate change. A transatlantic section along latitude 25 degrees N has been used as a baseline for estimating the overturning circulation and associated heat transport. Here we analyse a new 25 degrees N transatlantic section and compare it with four previous sections taken over the past five decades. The comparison suggests that the Atlantic meridional overturning circulation has slowed by about 30 per cent between 1957 and 2004. Whereas the northward transport in the Gulf Stream across 25 degrees N has remained nearly constant, the slowing is evident both in a 50 per cent larger southward-moving mid-ocean recirculation of thermocline waters, and also in a 50 per cent decrease in the southward transport of lower North Atlantic Deep Water between 3,000 and 5,000 m in depth. In 2004, more of the northward Gulf Stream flow was recirculating back southward in the thermocline within the subtropical gyre, and less was returning southward at depth.
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Affiliation(s)
- Harry L Bryden
- National Oceanography Centre, Empress Dock, Southampton SO14 3ZH, UK.
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20
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Abstract
Declining salinities signify that large amounts of fresh water have been added to the northern North Atlantic Ocean since the mid-1960s. We estimate that the Nordic Seas and Subpolar Basins were diluted by an extra 19,000 +/- 5000 cubic kilometers of freshwater input between 1965 and 1995. Fully half of that additional fresh water-about 10,000 cubic kilometers-infiltrated the system in the late 1960s at an approximate rate of 2000 cubic kilometers per year. Patterns of freshwater accumulation observed in the Nordic Seas suggest a century time scale to reach freshening thresholds critical to that portion of the Atlantic meridional overturning circulation.
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Affiliation(s)
- Ruth Curry
- Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA 02543, USA.
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Smith JN. Iodine 129/CFC 11 transit times for Denmark Strait Overflow Water in the Labrador and Irminger Seas. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004jc002516] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Hansen B, Østerhus S, Quadfasel D, Turrell W. Climate science. Already the day after tomorrow? Science 2004; 305:953-4. [PMID: 15310882 DOI: 10.1126/science.1100085] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Bogi Hansen
- Faroese Fisheries Laboratory, FO-110 Torshavn, Faroe Islands.
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Abstract
Observations of sea surface height reveal that substantial changes have occurred over the past decade in the mid- to high-latitude North Atlantic Ocean. TOPEX/Poseidon altimeter data show that subpolar sea surface height increased during the 1990s, and the geostrophic velocity derived from altimeter data exhibits declining subpolar gyre circulation. Combining the data from earlier satellites, we find that subpolar circulation may have been weaker in the late 1990s than in the late 1970s and 1980s. Direct current-meter observations in the boundary current of the Labrador Sea support the weakening circulation trend of the 1990s and, together with hydrographic data, show that the mid- to late 1990s decline extends deep in the water column. Analysis of the local surface forcing suggests that the 1990s buoyancy forcing has a dynamic effect consistent with altimetric and hydrographic observations: A weak thermohaline forcing allows the decay of the domed structure of subpolar isopycnals and weakening of circulation.
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Affiliation(s)
- Sirpa Häkkinen
- NASA Goddard Space Flight Center, Code 971, Greenbelt, MD 20771, USA.
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Srokosz MA. Rapid climate change: scientific challenges and the new NERC programme. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2003; 361:2061-2078. [PMID: 14558909 DOI: 10.1098/rsta.2003.1243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this paper the scientific challenges of observing, modelling, understanding and predicting rapid changes in climate are discussed, with a specific focus on the role of the Atlantic thermohaline circulation. The palaeo and present-day observational and modelling studies being carried out to meet these challenges, under the aegis of a new NERC Rapid Climate Change thematic programme (RAPID), are outlined. In particular, the paper describes the work being done to monitor changes in the meridional overturning circulation of the North Atlantic. The paper concludes with some speculative comments about potential mechanisms for rapid changes.
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Affiliation(s)
- M A Srokosz
- Southampton Oceanography Centre, European Way, Southampton SO14 3ZH, UK.
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Dickson RR, Curry R, Yashayaev I. Recent changes in the North Atlantic. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2003; 361:1917-1934. [PMID: 14558901 DOI: 10.1098/rsta.2003.1237] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
It has long been recognized that the Atlantic meridional overturning circulation (MOC) is potentially sensitive to greenhouse-gas and other climate forcing, and that changes in the MOC have the potential to cause abrupt climate change. However, the mechanisms remain poorly understood and our ability to detect these changes remains incomplete. Four main (interrelated) types of ocean change in particular are associated in the literature with greenhouse-gas forcing. These are: a slowing of MOC overturning rate; changes in northern seas which might effect a change in Atlantic overturning, including changes in the freshwater flux from the Arctic, and changes in the transport and/or hydrographic character of the northern overflows which ventilate the deep Atlantic; a change in the trans-ocean gradients of steric height (both zonal and meridional) which might accompany a change in the MOC; and an intensification of the global water cycle. Though as yet we have no direct measure of the freshwater flux passing from the Arctic to the Atlantic either via the Canadian Arctic Archipelago or along the East Greenland Shelf, and no direct measure yet of the Atlantic overturning rate, we examine a wide range of time-series from the existing hydrographic record for oceanic evidence of the other anticipated responses. Large amplitude and sustained changes are found (or indicated by proxy) over the past three to four decades in the southward transport of fresh waters along the Labrador shelf and slope, in the hydrography of the deep dense overflows from Nordic seas, in the transport of the eastern overflow through Faroe Bank Channel, and in the global hydrologic cycle. Though the type and scale of changes in ocean salinity are consistent with an amplification of the water cycle, we find no convincing evidence of any significant, concerted slowdown in the Atlantic overturning circulation.
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Affiliation(s)
- Robert R Dickson
- Centre for Environment, Fisheries and Aquaculture Science, Pakefield Road, Lowestoft NR33 OHT, UK
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Drinkwater KF, Belgrano A, Borja A, Conversi A, Edwards M, Greene CH, Ottersen G, Pershing AJ, Walker H. the response of marine ecosystems to climate variability associated with the North Atlantic Oscillation. THE NORTH ATLANTIC OSCILLATION: CLIMATIC SIGNIFICANCE AND ENVIRONMENTAL IMPACT 2003. [DOI: 10.1029/134gm10] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Visbeck M, Chassignet EP, Curry RG, Delworth TL, Dickson RR, Krahmann G. The ocean's response to North Atlantic Oscillation variability. THE NORTH ATLANTIC OSCILLATION: CLIMATIC SIGNIFICANCE AND ENVIRONMENTAL IMPACT 2003. [DOI: 10.1029/134gm06] [Citation(s) in RCA: 181] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Furevik T, Bentsen M, Drange H, Johannessen JA, Korablev A. Temporal and spatial variability of the sea surface salinity in the Nordic Seas. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jc001118] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tore Furevik
- Nansen Environmental and Remote Sensing Center; Bergen Norway
- Geophysical Institute; University of Bergen; Bergen Norway
| | - Mats Bentsen
- Nansen Environmental and Remote Sensing Center; Bergen Norway
| | - Helge Drange
- Nansen Environmental and Remote Sensing Center; Bergen Norway
| | - Johnny A. Johannessen
- Nansen Environmental and Remote Sensing Center; Bergen Norway
- Geophysical Institute; University of Bergen; Bergen Norway
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Abstract
Oceans cover more than two-thirds of our blue planet. The waters move in a global circulation system, driven by subtle density differences and transporting huge amounts of heat. Ocean circulation is thus an active and highly nonlinear player in the global climate game. Increasingly clear evidence implicates ocean circulation in abrupt and dramatic climate shifts, such as sudden temperature changes in Greenland on the order of 5-10 degrees C and massive surges of icebergs into the North Atlantic Ocean --events that have occurred repeatedly during the last glacial cycle.
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Affiliation(s)
- Stefan Rahmstorf
- Potsdam Institute for Climate Impact Research, PO Box 601203, 14412 Potsdam, Germany
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Dickson B, Yashayaev I, Meincke J, Turrell B, Dye S, Holfort J. Rapid freshening of the deep North Atlantic Ocean over the past four decades. Nature 2002; 416:832-7. [PMID: 11976679 DOI: 10.1038/416832a] [Citation(s) in RCA: 417] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The overflow and descent of cold, dense water from the sills of the Denmark Strait and the Faroe Shetland channel into the North Atlantic Ocean is the principal means of ventilating the deep oceans, and is therefore a key element of the global thermohaline circulation. Most computer simulations of the ocean system in a climate with increasing atmospheric greenhouse-gas concentrations predict a weakening thermohaline circulation in the North Atlantic as the subpolar seas become fresher and warmer, and it is assumed that this signal will be transferred to the deep ocean by the two overflows. From observations it has not been possible to detect whether the ocean's overturning circulation is changing, but recent evidence suggests that the transport over the sills may be slackening. Here we show, through the analysis of long hydrographic records, that the system of overflow and entrainment that ventilates the deep Atlantic has steadily changed over the past four decades. We find that these changes have already led to sustained and widespread freshening of the deep ocean.
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Affiliation(s)
- Bob Dickson
- Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft NR33 OHT, UK.
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