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Increases in terrestrially derived carbon stimulate organic carbon processing and CO2 emissions in boreal aquatic ecosystems
Recent increases in the dissolved organic carbon (DOC) content of northern aquatic systems are likely to lead to increases in CO2 emissions, yet the mechanisms are poorly understood. Here, evidence from hundreds of Canadian aquatic systems suggests a causal link between DOC concentrations and CO2flux.
- Jean-François Lapierre
- , François Guillemette
- & Paul A. del Giorgio
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Rapid interhemispheric climate links via the Australasian monsoon during the last deglaciation
The global monsoon is considered to have provided an important interhemispheric climate link during deglaciation, but direct evidence is lacking. Here, climate evidence from speleothems suggests that rapid latitudinal displacements of the Australasian monsoon play a key role in deglacial warming.
- Linda K. Ayliffe
- , Michael K. Gagan
- & Bambang W. Suwargadi
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Observed thinning of Totten Glacier is linked to coastal polynya variability
Totten Glacier discharges the largest volume of ice in East Antarctica, but the mechanisms causing its recent thinning are relatively unknown. Khazendar et al.combine remote-sensing data with high-resolution ice–ocean modelling to link this recent thinning to reduced sea ice production in polynyas.
- A. Khazendar
- , M.P. Schodlok
- & M.R. van den Broeke
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Pink marine sediments reveal rapid ice melt and Arctic meltwater discharge during Dansgaard–Oeschger warmings
Meltwater pulses from Northern Hemisphere ice sheets are strongly implicated in past millennial-scale shifts in ocean circulation, yet direct evidence is sparse. Here, a 30,000-year glacial meltwater history for the Svalbard–Barents Sea ice sheet is reconstructed in a marine sediment core.
- Tine L. Rasmussen
- & Erik Thomsen
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Carbon isotope records reveal precise timing of enhanced Southern Ocean upwelling during the last deglaciation
Upwelling of CO2 from the Southern Ocean may have played a key role in deglacial warming, but marine sediment studies are hindered by inaccurate chronologies. Siani et al. present new surface reservoir 14C ages derived from tephra and show that deglacial CO2escape was synchronous with Antarctic warming.
- Giuseppe Siani
- , Elisabeth Michel
- & Anna Lourantou
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Palaeoclimate reconstructions reveal a strong link between El Niño-Southern Oscillation and Tropical Pacific mean state
The El Niño-Southern Oscillation is one of the largest sources of global climate variability, yet our understanding relative to the Topical Pacific mean state is poor. Here, geochemical analyses of marine plankton reveal a strong link between zonal sea-surface temperatures and ENSO variability.
- Aleksey Yu Sadekov
- , Raja Ganeshram
- & Alexander W. Tudhope
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Deoxygenation alters bacterial diversity and community composition in the ocean’s largest oxygen minimum zone
Oxygen minimum zones in the global ocean have an important role in biogeochemical cycles, yet their response to climate change is poorly understood. Here, the authors show that bacterial community composition is tightly coupled to dissolved oxygen and is likely to fundamentally change as the oceans warm.
- J. Michael Beman
- & Molly T. Carolan
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Earthworms facilitate carbon sequestration through unequal amplification of carbon stabilization compared with mineralization
The presence of earthworms in soil may significantly increase CO2 emissions, but the impacts of earthworms on net carbon sequestration are poorly understood. Zhang et al. introduce a new concept by which the effects of earthworms on the balance of carbon mineralization and stabilization can be quantified.
- Weixin Zhang
- , Paul F. Hendrix
- & Shenglei Fu
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Photochemical reflectance index as an indirect estimator of foliar isoprenoid emissions at the ecosystem level
Isoprene and monoterpenes, emitted by terrestrial plants, have an important role in both plant biology and environment, but they are poorly quantified at the ecosystem level. Peñuelas et al.show that the photochemical reflectance index can be used to indirectly estimate foliar isoprenoid emissions remotely.
- Josep Peñuelas
- , Giovanni Marino
- & Iolanda Filella
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| Open AccessTime-calibrated Milankovitch cycles for the late Permian
The astronomical time scale is an essential geochronological tool, but is presently limited to the Cenozoic and Mesozoic eras. Here, Wuet al.time-calibrate Milankovitch cycles identified in strata from South China and extend this essential tool into the late Permian.
- Huaichun Wu
- , Shihong Zhang
- & Tianshui Yang
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Pacific deep circulation and ventilation controlled by tidal mixing away from the sea bottom
The global ocean conveyor belt, a key element of climate change, carries heat, carbon and various dissolved materials in the deep ocean. Here, the authors’ ocean model simulations demonstrate that tide-induced mixing away from the sea bottom is driving the Pacific branch of this conveyor belt.
- Akira Oka
- & Yoshihiro Niwa
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Siberian larch forests and the ion content of thaw lakes form a geochemically functional entity
Hitherto, Siberian vegetation was not considered to cause the south-to-north ion content gradient of thaw lakes. Herzschuh et al.propose that higher evapotranspiration in larch forests compared with that in the tundra leads to local salt accumulation in permafrost soils, which are transported as solutes to nearby lakes.
- Ulrike Herzschuh
- , Luidmila A. Pestryakova
- & H. John B. Birks
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Conventional tree height–diameter relationships significantly overestimate aboveground carbon stocks in the Central Congo Basin
Accurate estimates of tropical forest carbon stocks are needed for policies to reduce emissions from loss of forests. By looking at a central area in the Congo Basin, Kearsleyet al.find that inconsistencies in height–diameter relationships across Central Africa cause overestimations between regions.
- Elizabeth Kearsley
- , Thales de Haulleville
- & Hans Verbeeck
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| Open AccessDistinct iron isotopic signatures and supply from marine sediment dissolution
The dissolution of iron from sediments along ocean margins may stimulate photosynthesis and moderate global climate. This study shows how margin sediments supply iron in varying amounts between regions, and by distinct mechanisms, which may be due to geological characteristics and hydrological controls on land.
- William B. Homoky
- , Seth G. John
- & Rachel A. Mills
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Flow velocities of Alaskan glaciers
Alaskan mountain glaciers are losing ice and contribute to sea level rise, but contributions from specific ice-loss mechanisms are not known. Here, calving losses in Central Alaska are found to equal 36% of the net regional mass change each year and regional flux is dictated largely by snow accumulation rates.
- Evan W. Burgess
- , Richard R. Forster
- & Christopher F. Larsen
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Turbulence drives microscale patches of motile phytoplankton
Patchiness in the distribution of phytoplankton promotes many of the ecological interactions that underpin the marine food web. This study shows that turbulence, ubiquitous in the ocean, counter-intuitively ‘unmixes’ a population of motile phytoplankton, generating intense, small-scale patchiness in its distribution.
- William M. Durham
- , Eric Climent
- & Roman Stocker
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| Open AccessMorphology and mixing state of individual freshly emitted wildfire carbonaceous particles
Biomass burning is a major source of carbonaceous particles, including tar balls and soot, that affect earth’s climate. Studying a wildfire plume, this work identifies two types of tar balls and classifies soot according to its mixing state with implications for the calculation of aerosol radiative forcing.
- Swarup China
- , Claudio Mazzoleni
- & Manvendra K. Dubey
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Role of biogenic silica in the removal of iron from the Antarctic seas
Iron plays a key role in controlling biological production in the Southern Ocean, yet mechanisms regulating iron availability are not completely understood. Here, Ingall et al.show that structural incorporation of reduced, organic iron into biogenic silica represents a new and substantial removal pathway.
- Ellery D. Ingall
- , Julia M. Diaz
- & Jay A. Brandes
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| Open AccessHuman deforestation outweighs future climate change impacts of sedimentation on coral reefs
Forest cover up-river influences the sediments reaching coral reefs, but how this relationship is affected by future climate change is not clear. In a study of the Malagasy coral reefs, Maina et al.find that regional land-use management is more important than mediating climate change for reducing reef sedimentation.
- Joseph Maina
- , Hans de Moel
- & Jan E. Vermaat
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| Open AccessDevelopment of Middle Stone Age innovation linked to rapid climate change
The South African archaeological record contains evidence of the early flourishing of the human mind. Ziegler et al. provide new paleoclimate reconstructions, which suggest that rapid fluctuations in global climate have played a key role in the evolution of these early human cultures.
- Martin Ziegler
- , Margit H. Simon
- & Rainer Zahn
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Another rapid event in the carbon-14 content of tree rings
A strong increase in atmospheric 14C was measured in tree rings at AD 774 to 775, providing potential evidence of large cosmic ray fluxes to Earth, but the cause of this event is unclear. Here, Miyake et al. report a second 14C event in AD 993, which suggests that the most likely cause was a large solar proton event.
- Fusa Miyake
- , Kimiaki Masuda
- & Toshio Nakamura
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| Open AccessInitialized near-term regional climate change prediction
Near-term climate prediction is an information tool used in climate adaptation services. This study analyses the quality of the predictions, showing that near-term climate forecasts have good skill in predicting temperature at regional scales, where most of the skill is attributed to atmospheric composition changes.
- F. J. Doblas-Reyes
- , I. Andreu-Burillo
- & G. J. van Oldenborgh
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| Open AccessOcean lead at the termination of the Younger Dryas cold spell
The abrupt ending of the Younger Dryas cooling episode marked the onset of the present interglacial and was the most prominent climate change in the Earth’s recent history. This study shows evidence for a sequence of events with a leading role of the ocean at the transition into the present day warm Holocene epoch.
- Christof Pearce
- , Marit-Solveig Seidenkrantz
- & Søren M. Kristiansen
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Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric CO2 levels
Carbon isotope excursions (CIEs) measured in marine and terrestrial substrates indicate large-scale changes in the global carbon cycle. Schubert and Jahren show that larger-amplitude CIEs measured in terrestrial substrates reflect increased carbon isotope fractionation by land plants under elevated atmospheric CO2.
- Brian A. Schubert
- & A. Hope Jahren
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| Open AccessObservations from old forests underestimate climate change effects on tree mortality
It is thought that only climate change drives temporal tree mortality increases in old forests. Here, Luo and Chen show that both forest dynamics and climate change drive temporal tree mortality increases in young and old forests, and that climate change-associated mortality increases are higher in the young forests.
- Yong Luo
- & Han Y. H. Chen
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| Open AccessIncreased ventilation of Antarctic deep water during the warm mid-Pliocene
It is thought that during the mid-Pliocene warm period the Atlantic Meridional Overturning Circulation (AMOC) must have been stronger than today. Here, using proxy data compilation and simulation, Zhang et al.show that the two observations used to support stronger AMOC may not necessitate its increased strength.
- Zhongshi Zhang
- , Kerim H. Nisancioglu
- & Ulysses S. Ninnemann
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| Open AccessOne mechanism contributing to co-variability of the Atlantic inflow branches to the Arctic
The branched inflow of warm Atlantic Water to the Arctic has been known for more than a hundred years, yet what controls the relative strengths of the two pathways remains poorly understood. Here, the authors identify the role of atmospheric circulation over the northern Barents Sea in controlling inflow.
- Vidar S. Lien
- , Frode B. Vikebø
- & Øystein Skagseth
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| Open AccessSolar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times
A full understanding of the penetration of solar wind plasma into the Earth’s magnetosphere, during geomagnetically quiet times, remains elusive. Using multi-spacecraft data, Shi et al.find unexpected entry of the solar wind into the high-latitude magnetosphere and suggest a probable entry mechanism.
- Q.Q. Shi
- , Q.-G. Zong
- & E. Lucek
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Climate change patterns in Amazonia and biodiversity
The long-term hydroclimate variability in Amazonia and its influence on biodiversity remain poorly understood. Here, new speleothem oxygen isotope records characterize spatial–temporal changes in precipitation and provide new insights to understanding the west–east contrasting pattern of biodiversity in Amazonia.
- Hai Cheng
- , Ashish Sinha
- & Augusto S. Auler
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| Open AccessHigh heat flow and ocean acidification at a nascent rift in the northern Gulf of California
Active seafloor spreading has been documented in some of the tectonically active basins of the Gulf of California. This work presents new geophysical and geochemical data as evidence that active seafloor spreading is also occurring in the northernmost Wagner and Consag basins of the Gulf.
- Rosa Ma Prol-Ledesma
- , Marco-Antonio Torres-Vera
- & Carlos Robinson
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Holocene winter climate variability in mid-latitude western North America
Mineral cave deposits—speleothems—provide a record of past rainfall changes. This study presents a speleothem data-set from southwestern Oregon, revealing winter climate change over the past 13,000 years with abrupt transitions between warm-dry and cold-wet regimes influenced by solar forcing.
- Vasile Ersek
- , Peter U. Clark
- & R. Lawrence Edwards
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Atmospheric phosphorus deposition may cause lakes to revert from phosphorus limitation back to nitrogen limitation
Increased atmospheric input of nitrogen has shifted planktonic lake nutrient systems from natural nitrogen to human-induced phosphorus limitation. This study proposes that decades of increased atmospheric phosphorus in the Pyrenean lake district may have reverted the system from phosphorus back to nitrogen-limited.
- L. Camarero
- & J. Catalan
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| Open AccessPronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1
During the last glacial termination, the North Atlantic experienced a cold interval, but its impact on tropical climate variability is not clear. Here, a fossil Tahiti coral record shows that tropical sea surface temperature varied actively during this event, consistent with climate model simulations.
- Thomas Felis
- , Ute Merkel
- & Miriam Pfeiffer
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| Open AccessSurface changes in the North Atlantic meridional overturning circulation during the last millennium
Palaeoclimate proxies, such as shells, record past ocean changes. A radiocarbon study based on a shell chronology from the Icelandic shelf is used to track changes in ocean circulation and climate for the past 1,350 years, suggesting a declining influence of North Atlantic surface waters on the Icelandic shelf over the last millennium.
- Alan D. Wanamaker Jr
- , Paul G. Butler
- & Christopher A. Richardson
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The oceanic biological pump modulates the atmospheric transport of persistent organic pollutants to the Arctic
Persistent organic pollutants can reach and pollute pristine environments, such as the Arctic Ocean, through atmospheric transport. This study shows that the oceanic biological pump can sequester atmospheric polychlorinated biphenyls, reducing the transport of pollutants to the Arctic Ocean.
- Cristóbal Galbán-Malagón
- , Naiara Berrojalbiz
- & Jordi Dachs
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Abyssal undular vortices in the Eastern Mediterranean basin
Small-scale ocean dynamics can have wide reaching impacts on the larger-scale ocean circulation. Using temperature and velocity data, this study shows the presence of abyssal vortices in the Eastern Mediterranean basin, adding complexity to the structure and evolution of water masses in this region.
- A. Rubino
- , F. Falcini
- & A. Capone
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| Open AccessPotential regime shift in decreased sea ice production after the Mertz Glacier calving
The calving of the Mertz Glacier occurred in 2010 in East Antarctica, brought on by the re-positioning of a large iceberg. Using satellite data, this study shows a reduction in sea ice production following the calving, interpreted as a potential regime shift towards reduced sea ice production for the coming decades.
- T. Tamura
- , G.D. Williams
- & K.I. Ohshima
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| Open AccessTwo centuries of limited variability in subtropical North Atlantic thermocline ventilation
Ocean circulation moves heat and gases between the ocean and atmosphere, impacting the carbon cycle at decadal timescales. Here, a radiocarbon coral record of ocean mixing from Bermuda suggests that the formation of mode water, and thus carbon uptake, have been more stable over the past 200 years than previously thought.
- Nathalie F. Goodkin
- , Ellen R. M. Druffel
- & Scott C. Doney
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Power laws reveal phase transitions in landscape controls of fire regimes
Understanding the environmental controls of past wildfires is difficult due to the lack of records of weather or vegetation. This study shows, using cross-scale analysis, how power laws associated with fire-event time series can identify critical thresholds in landscape dynamics in a rapidly changing climate.
- Donald McKenzie
- & Maureen C. Kennedy
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Three decades of high-resolution coastal sea surface temperatures reveal more than warming
A detailed assessment of near-shore temperature changes is needed for improved forecasts of the consequences of coastal warming. Here, changes in coastal sea surface temperature are estimated, showing that although 71% of the world's coastlines are warming, the rates of change have varied spatially.
- Fernando P. Lima
- & David S. Wethey
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Enhanced sea-ice export from the Arctic during the Younger Dryas
The Younger Dryas cold period is thought to have occurred mainly due to the release of fresh water into the North Atlantic from the glacial Lake Agassiz. Here, sedimentary and geochemical data from the central Arctic Ocean support the hypothesis of a northward route drainage event from Lake Agassiz during the Younger Dryas.
- Christelle Not
- & Claude Hillaire-Marcel
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Migrating deformation in the Central Andes from enhanced orographic rainfall
Active shortening in the Central Andes shifted from the western to the eastern margin between 10-7 Myr ago, but the mechanism of formation is still unclear. Here, using critical wedge theory and local-scale fault friction calculations, this shift is proposed to have been controlled by changes in erosion patterns.
- Kevin Norton
- & Fritz Schlunegger
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Experimental drying intensifies burning and carbon losses in a northern peatland
Peatlands are a sink for atmospheric carbon dioxide and make up a large soil carbon reservoir. Here, studies of the interaction between drainage and fire show that long-term carbon emissions will likely exceed rates of carbon uptake, reducing the northern peatland carbon sink.
- M.R. Turetsky
- , W.F. Donahue
- & B.W. Benscoter
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Osmium evidence for synchronicity between a rise in atmospheric oxygen and Palaeoproterozoic deglaciation
The Early Palaeoproterozoic saw glaciations and a rise in atmospheric oxygen, but the link between these two changes is poorly understood. Here, osmium isotope records from sedimentary rocks indicate synchronicity between an episode of increasing oxygen and a glacial transition.
- Yasuhito Sekine
- , Katsuhiko Suzuki
- & Teruyuki Maruoka
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Silver hake tracks changes in Northwest Atlantic circulation
Many organisms are responding to a warming climate by shifts in spatial distribution. The poleward movement of silver hake,Merluccius bilinearis, over the last forty years is related to the position of the Gulf Stream and Atlantic meridional overturning circulation through changes in local bottom water temperature.
- Janet A. Nye
- , Terrence M. Joyce
- & Jason S. Link
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Long-term projections and acclimatization scenarios of temperature-related mortality in Europe
The sensitivity of human populations to rising global temperatures is not yet fully understood. The authors describe the link between temperature and daily mortality in over 200 European regions and calculate projections of mortality from climate models under greenhouse gas scenario simulations.
- Joan Ballester
- , Jean-Marie Robine
- & Xavier Rodó
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| Open AccessSouth China Sea hydrological changes and Pacific Walker Circulation variations over the last millennium
Tropical Pacific hydrology affects the global climate through the strength of the Pacific Walker Circulation. Yanet al. reconstruct variations in the Pacific Walker Circulation in the South China Sea over the last millennium and find that less precipitation fell during warmer and more rainfall during cool periods.
- Hong Yan
- , Liguang Sun
- & Wenhan Cheng
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| Open AccessMapping the evolving strain field during continental breakup from crustal anisotropy in the Afar Depression
The spatial and temporal scales over which continental breakup occurs by mechanical deformation and magma intrusion remain controversial. Keiret al. quantify anisotropy across the Afar Triple Junction using S-wave splitting from earthquakes to evaluate the strain in a region of continental breakup.
- Derek Keir
- , M. Belachew
- & J.V. Rowland
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Observational constraints indicate risk of drying in the Amazon basin
Assessments of future water availability in South America are uncertain based on multiple coupled general circulation models. Shiogamaet al.identify global-scale metrics for measuring the reliability of water resource assessments, and indicate a higher probability of drying in the Amazon basin.
- Hideo Shiogama
- , Seita Emori
- & Toru Nozawa