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Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years.

https://arctichealth.org/en/permalink/ahliterature294791
Source
Nature. 2018 04; 556(7700):227-230
Publication Type
Historical Article
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Date
04-2018
Author
David J R Thornalley
Delia W Oppo
Pablo Ortega
Jon I Robson
Chris M Brierley
Renee Davis
Ian R Hall
Paola Moffa-Sanchez
Neil L Rose
Peter T Spooner
Igor Yashayaev
Lloyd D Keigwin
Author Affiliation
Department of Geography, University College London, London, UK. d.thornalley@cantab.net.
Source
Nature. 2018 04; 556(7700):227-230
Date
04-2018
Language
English
Publication Type
Historical Article
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Keywords
Arctic Regions
Atlantic Ocean
Climate Change - statistics & numerical data
Convection
Fresh Water - analysis
Greenland
History, 15th Century
History, 16th Century
History, 17th Century
History, 18th Century
History, 19th Century
History, 20th Century
History, 21st Century
History, Medieval
Ice Cover - chemistry
Newfoundland and Labrador
Oceans and Seas
Reproducibility of Results
Seawater - analysis
Time Factors
Water Movements
Abstract
The Atlantic meridional overturning circulation (AMOC) is a system of ocean currents that has an essential role in Earth's climate, redistributing heat and influencing the carbon cycle1, 2. The AMOC has been shown to be weakening in recent years 1 ; this decline may reflect decadal-scale variability in convection in the Labrador Sea, but short observational datasets preclude a longer-term perspective on the modern state and variability of Labrador Sea convection and the AMOC1, 3-5. Here we provide several lines of palaeo-oceanographic evidence that Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately AD 1850) compared with the preceding 1,500 years. Our palaeoclimate reconstructions indicate that the transition occurred either as a predominantly abrupt shift towards the end of the LIA, or as a more gradual, continued decline over the past 150 years; this ambiguity probably arises from non-AMOC influences on the various proxies or from the different sensitivities of these proxies to individual components of the AMOC. We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA-sourced from melting glaciers and thickened sea ice that developed earlier in the LIA-weakened Labrador Sea convection and the AMOC. The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet 6 . Our results suggest that recent decadal variability in Labrador Sea convection and the AMOC has occurred during an atypical, weak background state. Future work should aim to constrain the roles of internal climate variability and early anthropogenic forcing in the AMOC weakening described here.
Notes
CommentIn: Nature. 2018 Apr;556(7700):149 PMID 29643490
CommentIn: Nature. 2018 Apr;556(7700):180-181 PMID 29636556
PubMed ID
29643484 View in PubMed
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Biogenic volatile organic compound emissions along a high arctic soil moisture gradient.

https://arctichealth.org/en/permalink/ahliterature290127
Source
Sci Total Environ. 2016 Dec 15; 573:131-138
Publication Type
Journal Article
Date
Dec-15-2016
Author
Sarah Hagel Svendsen
Frida Lindwall
Anders Michelsen
Riikka Rinnan
Author Affiliation
Terrestrial Ecology Section, Department of Biology, University of Copenhagen, Universitetsparken 15, DK -2100 Copenhagen E, Denmark; Center for Permafrost (CENPERM), Department of Geoscience and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK -1350 Copenhagen K, Denmark.
Source
Sci Total Environ. 2016 Dec 15; 573:131-138
Date
Dec-15-2016
Language
English
Publication Type
Journal Article
Keywords
Air Pollutants - analysis
Arctic Regions
Climate change
Ecosystem
Environmental Monitoring - methods
Ericaceae - growth & development
Greenland
Rosaceae - growth & development
Salix - growth & development
Soil - chemistry
Volatile Organic Compounds - analysis
Water - analysis
Abstract
Emissions of biogenic volatile organic compounds (BVOCs) from terrestrial ecosystems are important for the atmospheric chemistry and the formation of secondary organic aerosols, and may therefore influence the climate. Global warming is predicted to change patterns in precipitation and plant species compositions, especially in arctic regions where the temperature increase will be most pronounced. These changes are potentially highly important for the BVOC emissions but studies investigating the effects are lacking. The aim of this study was to investigate the quality and quantity of BVOC emissions from a high arctic soil moisture gradient extending from dry tundra to a wet fen. Ecosystem BVOC emissions were sampled five times in the July-August period using a push-pull enclosure technique, and BVOCs trapped in absorbent cartridges were analyzed using gas chromatography-mass spectrometry. Plant species compositions were estimated using the point intercept method. In order to take into account important underlying ecosystem processes, gross ecosystem production, ecosystem respiration and net ecosystem production were measured in connection with chamber-based BVOC measurements. Highest emissions of BVOCs were found from vegetation communities dominated by Salix arctica and Cassiope tetragona, which had emission profiles dominated by isoprene and monoterpenes, respectively. These results show that emissions of BVOCs are highly dependent on the plant cover supported by the varying soil moisture, suggesting that high arctic BVOC emissions may affect the climate differently if soil water content and plant cover change.
PubMed ID
27552736 View in PubMed
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The biogeography of red snow microbiomes and their role in melting arctic glaciers.

https://arctichealth.org/en/permalink/ahliterature294854
Source
Nat Commun. 2016 06 22; 7:11968
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
06-22-2016
Author
Stefanie Lutz
Alexandre M Anesio
Rob Raiswell
Arwyn Edwards
Rob J Newton
Fiona Gill
Liane G Benning
Author Affiliation
Cohen Laboratories, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
Source
Nat Commun. 2016 06 22; 7:11968
Date
06-22-2016
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Keywords
Arctic Regions
Bacteria - classification
Biodiversity
Biomass
Chlorophyta - classification
Climate change
Fatty acids
Freezing
Geography
Greenland
Ice Cover - microbiology
Iceland
Microbiota
Pigmentation
RNA, Ribosomal, 16S - genetics
Seasons
Sequence Analysis, DNA
Snow - microbiology
Species Specificity
Sweden
Abstract
The Arctic is melting at an unprecedented rate and key drivers are changes in snow and ice albedo. Here we show that red snow, a common algal habitat blooming after the onset of melting, plays a crucial role in decreasing albedo. Our data reveal that red pigmented snow algae are cosmopolitan as well as independent of location-specific geochemical and mineralogical factors. The patterns for snow algal diversity, pigmentation and, consequently albedo, are ubiquitous across the Arctic and the reduction in albedo accelerates snow melt and increases the time and area of exposed bare ice. We estimated that the overall decrease in snow albedo by red pigmented snow algal blooms over the course of one melt season can be 13%. This will invariably result in higher melt rates. We argue that such a 'bio-albedo' effect has to be considered in climate models.
Notes
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PubMed ID
27329445 View in PubMed
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A cascade of warming impacts brings bluefin tuna to Greenland waters.

https://arctichealth.org/en/permalink/ahliterature260665
Source
Glob Chang Biol. 2014 Aug;20(8):2484-91
Publication Type
Article
Date
Aug-2014
Author
Brian R MacKenzie
Mark R Payne
Jesper Boje
Jacob L Høyer
Helle Siegstad
Source
Glob Chang Biol. 2014 Aug;20(8):2484-91
Date
Aug-2014
Language
English
Publication Type
Article
Keywords
Animals
Climate change
Ecosystem
Food chain
Greenland
Seawater
Temperature
Tuna
Abstract
Rising ocean temperatures are causing marine fish species to shift spatial distributions and ranges, and are altering predator-prey dynamics in food webs. Most documented cases of species shifts so far involve relatively small species at lower trophic levels, and consider individual species in ecological isolation from others. Here, we show that a large highly migratory top predator fish species has entered a high latitude subpolar area beyond its usual range. Bluefin tuna, Thunnus thynnus Linnaeus 1758, were captured in waters east of Greenland (65°N) in August 2012 during exploratory fishing for Atlantic mackerel, Scomber scombrus Linnaeus 1758. The bluefin tuna were captured in a single net-haul in 9-11 °C water together with 6 tonnes of mackerel, which is a preferred prey species and itself a new immigrant to the area. Regional temperatures in August 2012 were historically high and contributed to a warming trend since 1985, when temperatures began to rise. The presence of bluefin tuna in this region is likely due to a combination of warm temperatures that are physiologically more tolerable and immigration of an important prey species to the region. We conclude that a cascade of climate change impacts is restructuring the food web in east Greenland waters.
PubMed ID
24824677 View in PubMed
Less detail

Committed sea-level rise for the next century from Greenland ice sheet dynamics during the past decade.

https://arctichealth.org/en/permalink/ahliterature134459
Source
Proc Natl Acad Sci U S A. 2011 May 31;108(22):8978-83
Publication Type
Article
Date
May-31-2011
Author
Stephen F Price
Antony J Payne
Ian M Howat
Benjamin E Smith
Author Affiliation
Fluid Dynamics and Solid Mechanics Group, Los Alamos National Laboratory, T3 MS B216, Los Alamos, NM 87545, USA. sprice@lanl.gov
Source
Proc Natl Acad Sci U S A. 2011 May 31;108(22):8978-83
Date
May-31-2011
Language
English
Publication Type
Article
Keywords
Climate change
Global warming
Greenland
Humans
Ice
Ice Cover
Models, Statistical
Models, Theoretical
Seasons
Time Factors
Water Movements
Abstract
We use a three-dimensional, higher-order ice flow model and a realistic initial condition to simulate dynamic perturbations to the Greenland ice sheet during the last decade and to assess their contribution to sea level by 2100. Starting from our initial condition, we apply a time series of observationally constrained dynamic perturbations at the marine termini of Greenland's three largest outlet glaciers, Jakobshavn Isbræ, Helheim Glacier, and Kangerdlugssuaq Glacier. The initial and long-term diffusive thinning within each glacier catchment is then integrated spatially and temporally to calculate a minimum sea-level contribution of approximately 1 ± 0.4 mm from these three glaciers by 2100. Based on scaling arguments, we extend our modeling to all of Greenland and estimate a minimum dynamic sea-level contribution of approximately 6 ± 2 mm by 2100. This estimate of committed sea-level rise is a minimum because it ignores mass loss due to future changes in ice sheet dynamics or surface mass balance. Importantly, > 75% of this value is from the long-term, diffusive response of the ice sheet, suggesting that the majority of sea-level rise from Greenland dynamics during the past decade is yet to come. Assuming similar and recurring forcing in future decades and a self-similar ice dynamical response, we estimate an upper bound of 45 mm of sea-level rise from Greenland dynamics by 2100. These estimates are constrained by recent observations of dynamic mass loss in Greenland and by realistic model behavior that accounts for both the long-term cumulative mass loss and its decay following episodic boundary forcing.
PubMed ID
21576500 View in PubMed
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Consequences of rapid ice sheet melting on the Sahelian population vulnerability.

https://arctichealth.org/en/permalink/ahliterature291613
Source
Proc Natl Acad Sci U S A. 2017 06 20; 114(25):6533-6538
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
06-20-2017
Author
Dimitri Defrance
Gilles Ramstein
Sylvie Charbit
Mathieu Vrac
Adjoua Moïse Famien
Benjamin Sultan
Didier Swingedouw
Christophe Dumas
François Gemenne
Jorge Alvarez-Solas
Jean-Paul Vanderlinden
Author Affiliation
Laboratoire des Sciences du Climat et de l'Environnement, Institut Pierre Simon Laplace, Commissariat à l'Energie Atomique et aux Energies Alternatives - CNRS - Université de Saint-Quentin-en-Yvelines, Université Paris-Saclay, 91141 Gif-Sur-Yvette, France; dimitri.defrance@ird.fr.
Source
Proc Natl Acad Sci U S A. 2017 06 20; 114(25):6533-6538
Date
06-20-2017
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Keywords
Climate Change - statistics & numerical data
Computer simulation
Freezing
Fresh Water
Global Warming - statistics & numerical data
Greenland
Humans
Ice Cover
Models, Theoretical
Seawater
Time Factors
Water Movements
Abstract
The acceleration of ice sheet melting has been observed over the last few decades. Recent observations and modeling studies have suggested that the ice sheet contribution to future sea level rise could have been underestimated in the latest Intergovernmental Panel on Climate Change report. The ensuing freshwater discharge coming from ice sheets could have significant impacts on global climate, and especially on the vulnerable tropical areas. During the last glacial/deglacial period, megadrought episodes were observed in the Sahel region at the time of massive iceberg surges, leading to large freshwater discharges. In the future, such episodes have the potential to induce a drastic destabilization of the Sahelian agroecosystem. Using a climate modeling approach, we investigate this issue by superimposing on the Representative Concentration Pathways 8.5 (RCP8.5) baseline experiment a Greenland flash melting scenario corresponding to an additional sea level rise ranging from 0.5 m to 3 m. Our model response to freshwater discharge coming from Greenland melting reveals a significant decrease of the West African monsoon rainfall, leading to changes in agricultural practices. Combined with a strong population increase, described by different demography projections, important human migration flows could be potentially induced. We estimate that, without any adaptation measures, tens to hundreds million people could be forced to leave the Sahel by the end of this century. On top of this quantification, the sea level rise impact over coastal areas has to be superimposed, implying that the Sahel population could be strongly at threat in case of rapid Greenland melting.
Notes
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PubMed ID
28584113 View in PubMed
Less detail

Continuous summer export of nitrogen-rich organic matter from the Greenland Ice Sheet inferred by ultrahigh resolution mass spectrometry.

https://arctichealth.org/en/permalink/ahliterature264617
Source
Environ Sci Technol. 2014 Dec 16;48(24):14248-57
Publication Type
Article
Date
Dec-16-2014
Author
Emily C Lawson
Maya P Bhatia
Jemma L Wadham
Elizabeth B Kujawinski
Source
Environ Sci Technol. 2014 Dec 16;48(24):14248-57
Date
Dec-16-2014
Language
English
Publication Type
Article
Keywords
Carbon
Climate change
Ecosystem
Fourier Analysis
Greenland
Ice Cover - chemistry
Mass Spectrometry - methods
Nitrogen - chemistry
Seasons
Time Factors
Abstract
Runoff from glaciers and ice sheets has been acknowledged as a potential source of bioavailable dissolved organic matter (DOM) to downstream ecosystems. This source may become increasingly significant as glacial melt rates increase in response to future climate change. Recent work has identified significant concentrations of bioavailable carbon and iron in Greenland Ice Sheet (GrIS) runoff. The flux characteristics and export of N-rich DOM are poorly understood. Here, we employed electrospray ionization (ESI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to determine the elemental compositions of DOM molecules in supraglacial water and subglacial runoff from a large GrIS outlet glacier. We provide the first detailed temporal analysis of the molecular composition of DOM exported over a full melt season. We find that DOM pools in supraglacial and subglacial runoff are compositionally diverse and that N-rich material is continuously exported throughout the melt season, as the snowline retreats further inland. Identification of protein-like compounds and a high proportion of N-rich DOM, accounting for 27-41% of the DOM molecules identified by ESI FT-ICR MS, may suggest a microbial provenance and high bioavailability of glacially exported DOM to downstream microbial communities.
PubMed ID
25375225 View in PubMed
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Cultural adaptation, compounding vulnerabilities and conjunctures in Norse Greenland.

https://arctichealth.org/en/permalink/ahliterature126637
Source
Proc Natl Acad Sci U S A. 2012 Mar 6;109(10):3658-63
Publication Type
Article
Date
Mar-6-2012
Author
Andrew J Dugmore
Thomas H McGovern
Orri Vésteinsson
Jette Arneborg
Richard Streeter
Christian Keller
Author Affiliation
Geography, School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, Scotland, United Kingdom. andrew.dugmore@ed.ac.uk
Source
Proc Natl Acad Sci U S A. 2012 Mar 6;109(10):3658-63
Date
Mar-6-2012
Language
English
Publication Type
Article
Keywords
Animals
Climate
Climate change
Culture
Disasters - history
Environment
Geography
Greenland
History, Ancient
Humans
Mammals
Residence Characteristics
Abstract
Norse Greenland has been seen as a classic case of maladaptation by an inflexible temperate zone society extending into the arctic and collapse driven by climate change. This paper, however, recognizes the successful arctic adaptation achieved in Norse Greenland and argues that, although climate change had impacts, the end of Norse settlement can only be truly understood as a complex socioenvironmental system that includes local and interregional interactions operating at different geographic and temporal scales and recognizes the cultural limits to adaptation of traditional ecological knowledge. This paper is not focused on a single discovery and its implications, an approach that can encourage monocausal and environmentally deterministic emphasis to explanation, but it is the product of sustained international interdisciplinary investigations in Greenland and the rest of the North Atlantic. It is based on data acquisitions, reinterpretation of established knowledge, and a somewhat different philosophical approach to the question of collapse. We argue that the Norse Greenlanders created a flexible and successful subsistence system that responded effectively to major environmental challenges but probably fell victim to a combination of conjunctures of large-scale historic processes and vulnerabilities created by their successful prior response to climate change. Their failure was an inability to anticipate an unknowable future, an inability to broaden their traditional ecological knowledge base, and a case of being too specialized, too small, and too isolated to be able to capitalize on and compete in the new protoworld system extending into the North Atlantic in the early 15th century.
Notes
Cites: Proc Natl Acad Sci U S A. 2010 Mar 23;107(12):5306-1020212157
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Cites: Arctic Anthropol. 2007;44(1):12-3621847839
PubMed ID
22371594 View in PubMed
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Detrending phenological time series improves climate-phenology analyses and reveals evidence of plasticity.

https://arctichealth.org/en/permalink/ahliterature295656
Source
Ecology. 2017 Mar; 98(3):647-655
Publication Type
Journal Article
Date
Mar-2017
Author
Amy M Iler
David W Inouye
Niels M Schmidt
Toke T Høye
Author Affiliation
Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, DK-8000, Aarhus C, Denmark.
Source
Ecology. 2017 Mar; 98(3):647-655
Date
Mar-2017
Language
English
Publication Type
Journal Article
Keywords
Climate change
Colorado
Ecosystem
Flowers
Greenland
Phenotype
Seasons
Temperature
Abstract
Time series have played a critical role in documenting how phenology responds to climate change. However, regressing phenological responses against climatic predictors involves the risk of finding potentially spurious climate-phenology relationships simply because both variables also change across years. Detrending by year is a way to address this issue. Additionally, detrending isolates interannual variation in phenology and climate, so that detrended climate-phenology relationships can represent statistical evidence of phenotypic plasticity. Using two flowering phenology time series from Colorado, USA and Greenland, we detrend flowering date and two climate predictors known to be important in these ecosystems: temperature and snowmelt date. In Colorado, all climate-phenology relationships persist after detrending. In Greenland, 75% of the temperature-phenology relationships disappear after detrending (three of four species). At both sites, the relationships that persist after detrending suggest that plasticity is a major component of sensitivity of flowering phenology to climate. Finally, simulations that created different strengths of correlations among year, climate, and phenology provide broader support for our two empirical case studies. This study highlights the utility of detrending to determine whether phenology is related to a climate variable in observational data sets. Applying this as a best practice will increase our understanding of phenological responses to climatic variation and change.
PubMed ID
27984645 View in PubMed
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28 records – page 1 of 3.