30 Oct - 5 Nov
Nature vol. 502
1. Gradual demise of a thin southern Laurentian ice sheet recorded by Mississippi drainage
Andrew D. Wickert, Jerry X. Mitrovica, Carlie Williams & Robert S Anderson
doi: 10.1038/nature12609
Four models of North American deglacial ice-sheet history were tested with the input of δ18O records from the Gulf of Mexico into a water- mixing model. Three were found to overestimate the post-LGM meltwater volume by a factor of 1.6-3.6. The last, based on ice physics, was found to be broadly consistent with the oxygen records.
2. Decoupling of soil nutrient cycles as a function of aridity in global drylands
Manuel Delgado-Baquerizo, Fernando T. Maestre, Antonio Gallardo, Matthew A. Bowker, Matthew D. Wallenstein, Jose Luis Quero, Victoria Ochoa, Beatriz Gozalo, Miguel García-Gómez, Santiago Soliveres, Pablo García-Palacios, Miguel Berdugo, Enrique Valencia, Cristina Escolar, Tulio Arredondo, Claudia Barraza-Zepeda, Donaldo Bran, José Antonio Carreira, Mohamed Chaieb, Abel A. Conceição, Mchich Derak, David J. Eldridge, Adrián Escudero, Carlos I. Espinosa, Juan Gaitán, M. Gabriel Gatica, Susana Gómez-González, Elizabeth Guzman, Julio R. Gutiérrez, Adriana Florentino, Estela Hepper, Rosa M. Hernández, Elisabeth Huber-Sannwald, Mohammad Jankju, Jushan Liu, Rebecca L. Mau, Maria Miriti, Jorge Monerris, Kamal Naseri, Zouhaier Noumi, Vicente Polo, Aníbal Prina, Eduardo Pucheta, Elizabeth Ramírez, David A. Ramírez-Collantes, Roberto Romão, Matthew Tighe, Duilio Torres, Cristian Torres-Díaz, Eugene D. Ungar, James Val, Wanyoike Wamiti, Deli Wang & Eli Zaady
doi: 10.1038/nature12670
Aridity was found to have a negative effect on organic carbon and nitrogen concentration of global dryland soil, but a positive one on inorganic phosphorus concentration. This may cause a decoupling of nutrient cycles resulting in perturbations of ecosystem functionality.
3. DMSP biosynthesis by an animal and its role in coral thermal stress response
Jean-Baptiste Raina, Dianne M. Tapiolas, Sylvain Forêt, Adrian Lutz, David Abrego, Janja Ceh, François O. Seneca, Peta L. Clode, David G. Bourne, Bette L. Willis & Cherie A. Motti
doi: 10.1038/nature12677
Dimethylsulphoniopropionate (DMSP) was previously thought to be biologically produced only by algae and some plants, but was found in this study to be formed by two common reef-building coral species, Acropora millepora and Acropora tenuis. Synthesis was increased when the corals were under thermal stress (may aid their survival in those conditions). As DMSP is converted to dimethylsulphide (DMS) gas by marine bacteria and is thus a major source of atmospheric sulphur, effects of climate change on corals may result in further problems due to the reduction of coral-produced DMSP.
Science vol. 342
4. Pacific Ocean heat content during the past 10 000 years
Yair Rosenthal, Braddock K. Linsley, Delia W. Oppo
doi: 10.1126/science.1240837
High-resolution proxy records from sediment cores were used to reconstruct ocean heat content (OHC) in the Pacific 10 000 years beyond the instrumental record. The findings support the view that the Holocene Thermal Maximum, the Medieval Warm Period and the Little Ice Age occurred globally. Global surface temperature changes during the Holocene and Common Era were found to be small but led to relatively large OHC differences.
5. Industry lobbying derails trawling ban in Europe
Tania Rabesandratana
doi: 10.1126/science.342.6158.544
The European Parliament’s Fisheries Committee will vote on 4 November whether to curb deep-sea trawling and bottom gillnetting, practices which cause damage to marine ecosystems. Industry opposition may lead to a watered-down regulation that will impose restrictions but not end them.
6. Dust unto dust
Mary C. Scholes, Robert J. Scholes
doi: 10.1126/science.1244579
Soil erosion, salinity accumulation and nutrient depletion have dramatically reduced the inherent productivity of many lands. About 1% of global land area is degraded every year. Soil fertility must be managed sustainably in order to achieve lasting food and environmental security.
PNAS vol. 110
7. Isotopic composition of atmospheric nitrate in a tropical marine boundary layer
Joel Savarino, Samuel Morin, Joseph Erbland, Francis Grannec, Matthew D. Patey, William Vicars, Becky Alexander & Eric P. Achterberg
doi: 10.1073/pnas.1216639110
Multi-isotopic composition of atmospheric nitrate in the tropical marine boundary layer (MBL) was observed at the Cape Verde Atmospheric Observatory in order to characterise its reactive chemical composition. Observed oxygen isotope ratios were found to be compatible with nitrate formation chemistry. A possible link between NO2/NOx ratio and nitrogen isotopic content of nitrate was indicated, which may point to seasonal changes in photochemical equilibrium among NOx species.
8. Pathways for Neoarchaean pyrite formation constrained by mass-independent sulphur isotopes
James Farquhar, John Cliff, Aubrey L. Zerkle, Alexey Kamyshny, Simon W. Poulton, Mark Claire, David Adams, Brian Harms
doi: 10.1073/pnas.1218851110
Secondary ion mass spectrometry (SIMS) analyses were used to examine the origin and significance between various sulphur isotopes in Neoarchaean rocks, and resulting implications on pyrite formation pathways. Existence of a significant non-sulphate pool of reactive sulphur may have masked isotopic evidence for widespread activity of sulphate reducers in the geological record.
9. SO2 photoexcitation mechanism links mass-independent sulphur isotopic fractionation in cryospheric sulphate to climate impacting volcanism
Sohei Hattori, Johan A. Schmidt, Matthew S. Johnson, Sebastian O. Danielache, Akinori Yamada, Yuichiro Ueno & Naohiro Yoshida
doi: 10.1073/pnas.1213153110
A correlation between volcanic plumes that reach the stratosphere and mass-independent anomalies in sulphur isotopes in glacial sulphate has been observed in recent research. Photoexcitation of SO2 was found to link the two, allowing quantification of historic volcanic explosivity and magnitude.
10. Interannual variation of water isotopologues at Vostok indicates a contribution from stratospheric water vapour
Renato Winkler, Amaelle Landais, Camille Risi, Melanie Baroni, Alexey Ekaykin, Jean Jouzel, Jean Robert Petit, Frederic Prie, Benedicte Minster & Sonia Falourd
doi: 10.1073/pnas.1215209110
Combined measurements of water isotopologues at Vostok revealed a unique signature that cannot be explained solely by climatic features. Using general circulation and isotopic distillation models, stratospheric water vapour was found to contribute to the ∆17O-excess record.
11. Tales of volcanoes and El-Niño southern oscillations with the oxygen isotope anomaly of sulphate aerosols
Robina Shaheen, Mariana Abauanza, Teresa L. Jackson, Justin McCabe, Joel Savarino & Mark H. Thiemens
doi: 10.1073/pnas.1213149110
A high-resolution, 22-year record of the oxygen-triple isotopic composition of sulphate aerosols from a South Pole snow pit was analysed. Observed variation in isotopic anomalies was linked to ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Significant amounts of sulphate aerosol are ejected during volcanic events, which are known to affect ENSO strength. ∆17O of sulphate aerosols were thus found to be capable of recording extreme phases of naturally occurring climate cycles.
Nature Geoscience vol. 6
12. Contribution of ocean overturning circulation to tropical rainfall peak in the Northern Hemisphere
Dargan M. W. Frierson, Yen-Ting Hwang, Neven S. Fučkar, Richard Seager, Sarah M. Kang, Aaron Donohoe, Elizabeth A. Maroon, Xiaojuan Liu & David S. Battisti
doi:1038/ngeo1987
Satellite observations of Earth’s energy budget, atmospheric reanalyses and global climate model simulations were used to study tropical rainfall. Meridional overturning circulation was shown to contribute significantly to hemispheric asymmetry in tropical rainfall by transporting heat from the Southern to the Northern Hemisphere, pushing the tropical rain band north. This was previously attributed mostly to hemispheric asymmetry in ocean temperature induced by tropical landmasses.
13. Meridional shifts of the Atlantic intertropical convergence zone since the Last Glacial Maximum
Jennifer A. Arbuszewski, Peter B. deMenocal, Caroline Cléroux, Louisa Bradtmiller & Alan Mix
doi: 10.1038/ngeo1961
Paired Mg/Ca and δ18O measurements of planktonic foraminifera for ocean sediment cores were used to reconstruct past changes in tropical surface ocean temperature and salinity in the Atlantic Ocean over the past 25 000 years. Low-salinity, high-temperature surface waters associated with the intertropical convergence zone (ITCZ) migrated southward of their present position during the Last Glacial Maximum and northward during the warmer early Holocene. The ITCZ was suggested to move latitudinally over the ocean, instead of expanding or contracting.
