An epic voyage in the making - p733

doi:10.1038/ngeo669

The plan to drill through the entire oceanic crust is ambitious and exciting, and well worth the expense.

Full Text - An epic voyage in the making | PDF (80 KB) - An epic voyage in the making

Bridging the biodiversity gap - p733

doi:10.1038/ngeo688

As climate change continues to erode biodiversity, the two disciplines need to improve their dialogue.

Full Text - Bridging the biodiversity gap | PDF (80 KB) - Bridging the biodiversity gap

Early twentieth-century warming - pp735 - 736

Stefan Brönnimann

doi:10.1038/ngeo670

Full Text - Early twentieth-century warming | PDF (124 KB) - Early twentieth-century warming

CO₂ emissions from forest loss - pp737 - 738

G. R. van der Werf, D. C. Morton, R. S. DeFries, J. G. J. Olivier, P. S. Kasibhatla, R. B. Jackson, G. J. Collatz & J. T. Randerson

doi:10.1038/ngeo671

Deforestation is the second largest anthropogenic source of carbon dioxide to the atmosphere, after fossil fuel combustion. Following a budget reanalysis, the contribution from deforestation is revised downwards, but tropical peatlands emerge as a notable carbon dioxide source.

Full Text - CO2 emissions from forest loss | PDF (111 KB) - CO2 emissions from forest loss | Supplementary information

Our choice from the recent literature - p739

doi:10.1038/ngeo672

Full Text - Our choice from the recent literature | PDF (153 KB) - Our choice from the recent literature

Geodynamo: A matter of boundaries - pp741 - 742

Bruce Buffett

doi:10.1038/ngeo673

The use of more realistic parameters in numerical geodynamo simulations tends to generate less Earth-like magnetic fields. This paradox could be resolved by considering uniform heat flux instead of uniform temperature at the core's surface.

Full Text - GeodynamoA matter of boundaries | PDF (271 KB) - GeodynamoA matter of boundaries

Subject Categories: Structural geology, tectonics and geodynamics | Geomagnetism, palaeomagnetism and core processes

See also: Letter by Sakuraba & Roberts

Atmospheric science: Nitrous oxide delays ozone recovery - pp742 - 743

Martyn Chipperfield

doi:10.1038/ngeo678

The stratospheric ozone layer has undergone severe depletion as a result of anthropogenic halocarbons. Although the Montreal Protocol has provided relief, anthropogenic emissions of another substance, nitrous oxide, are set to dominate ozone destruction.

Full Text - Atmospheric scienceNitrous oxide delays ozone recovery | PDF (141 KB) - Atmospheric scienceNitrous oxide delays ozone recovery

Subject Category: Atmospheric science

Palaeoceanography: Tracking ancient sea ice - pp743 - 744

Niels Nørgaard-Pedersen

doi:10.1038/ngeo676

Sea ice is an integral component of the climate system, but a difficult one to reconstruct. Biochemical tracers preserved in marine sediments now reveal the waxing and waning of sea ice since the Last Glacial Maximum in an Arctic Ocean gateway.

Full Text - PalaeoceanographyTracking ancient sea ice | PDF (214 KB) - PalaeoceanographyTracking ancient sea ice

Subject Category: Palaeoclimate and palaeoceanography

See also: Letter by Müller et al.

Tectonics: Soaking slabs - pp744 - 746

Magali I. Billen

doi:10.1038/ngeo674

Faults that develop in subducting slabs act as conduits for sea water. Numerical modelling indicates that pressure gradients resulting from the bending of slabs may then drive the water deep into their interior.

Full Text - TectonicsSoaking slabs | PDF (254 KB) - TectonicsSoaking slabs

Subject Category: Structural geology, tectonics and geodynamics

See also: Letter by Faccenda et al.

Planetary science: Wet moon dry Earth - p746

Ninad Bondre

doi:10.1038/ngeo679

Full Text - Planetary scienceWet moon dry Earth | PDF (144 KB) - Planetary scienceWet moon dry Earth

Geomorphology: Rivers split as mountains grow - pp747 - 748

Mikaël Attal

doi:10.1038/ngeo675

Mountain landscapes are shaped by tectonics and climate. A series of laboratory experiments has documented a mechanism by which mountain river networks split as the geometry of a mountain evolves in response to an orographic precipitation gradient.

Full Text - GeomorphologyRivers split as mountains grow | PDF (169 KB) - GeomorphologyRivers split as mountains grow

Subject Category: Geomorphology

See also: Letter by Bonnet

Water pollution: Urban waste - p748

Anna Armstrong

doi:10.1038/ngeo680

Full Text - Water pollutionUrban waste | PDF (143 KB) - Water pollutionUrban waste

Atmospheric science: ENSO and the stratosphere - pp749 - 750

Elisa Manzini

doi:10.1038/ngeo677

The El Niño/Southern Oscillation phenomenon is the most prominent source of climate variability. Emerging evidence suggests that its signature is not limited to the lower layers of the atmosphere.

Full Text - Atmospheric scienceENSO and the stratosphere | PDF (115 KB) - Atmospheric scienceENSO and the stratosphere

Subject Category: Atmospheric science

The dark side of marine carbon - p750

doi:10.1038/ngeo664

Full Text - The dark side of marine carbon | PDF (98 KB) - The dark side of marine carbon

Interglacial diversity - pp751 - 755

P. C. Tzedakis, D. Raynaud, J. F. McManus, A. Berger, V. Brovkin & T. Kiefer

doi:10.1038/ngeo660

Past interglacials can be thought of as a series of natural experiments in which boundary conditions varied considerably. Examination of the palaeoclimate record of the past 800,000 years reveals a large diversity among interglacials in terms of their intensity, duration and internal variability.

Abstract - Interglacial diversity | Full Text - Interglacial diversity | PDF (229 KB) - Interglacial diversity | Supplementary information

Subject Category: Palaeoclimate and palaeoceanography

Emergence of sprite streamers from screening-ionization waves in the lower ionosphere - pp757 - 760

Alejandro Luque & Ute Ebert

doi:10.1038/ngeo662

Sprite discharges above thunderclouds, at altitudes of 40–90 km, are usually created by a strong positive cloud-to-ground lightning flash. A numerical discharge model of the process suggests that sprite streamers are generated through the collapse of a downward-propagating screening-ionization wave in the lower ionosphere.

First Paragraph - Emergence of sprite streamers from screening-ionization waves in the lower ionosphere | Full Text - Emergence of sprite streamers from screening-ionization waves in the lower ionosphere | PDF (4,565 KB) - Emergence of sprite streamers from screening-ionization waves in the lower ionosphere | Supplementary information

Subject Categories: Atmospheric science | Space physics

Sea surface cooling at the Equator by subsurface mixing in tropical instability waves - pp761 - 765

J. N. Moum, R.-C. Lien, A. Perlin, J. D. Nash, M. C. Gregg & P. J. Wiles

doi:10.1038/ngeo657

Changes in the sea surface temperature of equatorial waters have critical effects on the large-scale atmospheric circulation. Shipboard measurements of turbulence kinetic-energy dissipation rate indicate that seasonal surface cooling in the central equatorial Pacific may be largely caused by mixing induced by tropical instability waves.

First Paragraph - Sea surface cooling at the Equator by subsurface mixing in tropical instability waves | Full Text - Sea surface cooling at the Equator by subsurface mixing in tropical instability waves | PDF (2,150 KB) - Sea surface cooling at the Equator by subsurface mixing in tropical instability waves | Supplementary information

Subject Category: Oceanography

Shrinking and splitting of drainage basins in orogenic landscapes from the migration of the main drainage divide - pp766 - 771

Stephane Bonnet

doi:10.1038/ngeo666

Many mountain ranges have asymmetric topography and drainage patterns. Laboratory experiments show that tectonic uplift combined with a precipitation gradient will cause the drainage divide to migrate towards the drier side of the mountain range, thereby triggering the splitting of drainage basins on the dry side of the range.

First Paragraph - Shrinking and splitting of drainage basins in orogenic landscapes from the migration of the main drainage divide | Full Text - Shrinking and splitting of drainage basins in orogenic landscapes from the migration of the main drainage divide | PDF (1,728 KB) - Shrinking and splitting of drainage basins in orogenic landscapes from the migration of the main drainage divide | Supplementary information

Subject Category: Geomorphology

See also: News and Views by Attal

Variability of sea-ice conditions in the Fram Strait over the past 30,000 years - pp772 - 776

Juliane Müller, Guillaume Massé, Rüdiger Stein & Simon T. Belt

doi:10.1038/ngeo665

Sea ice is a critical component of the climate and oceanographic system in the North Atlantic Ocean. A biomarker record reveals millennial-scale and glacial–interglacial fluctuations in sea-ice coverage in the northernmost Atlantic Ocean over the past 30,000 years.

First Paragraph - Variability of sea-ice conditions in the Fram Strait over the past 30,000 years | Full Text - Variability of sea-ice conditions in the Fram Strait over the past 30,000 years | PDF (4,258 KB) - Variability of sea-ice conditions in the Fram Strait over the past 30,000 years

Subject Categories: Cryospheric science | Palaeoclimate and palaeoceanography

See also: related Backstory | News and Views by Nørgaard-Pedersen

Warm and wet conditions in the Arctic region during Eocene Thermal Maximum 2 - pp777 - 780

Appy Sluijs, Stefan Schouten, Timme H. Donders, Petra L. Schoon, Ursula Röhl, Gert-Jan Reichart, Francesca Sangiorgi, Jung-Hyun Kim, Jaap S. Sinninghe Damsté & Henk Brinkhuis

doi:10.1038/ngeo668

The Eocene Thermal Maximum 2 occurred 53.5 million years ago in response to elevated atmospheric carbon dioxide levels. Geochemical and microfossil analyses of Arctic sediments show that the during this event the surface of the Arctic Ocean warmed and freshened, and the coldest month mean temperatures did not fall below 8 ^°C.

First Paragraph - Warm and wet conditions in the Arctic region during Eocene Thermal Maximum 2 | Full Text - Warm and wet conditions in the Arctic region during Eocene Thermal Maximum 2 | PDF (1,705 KB) - Warm and wet conditions in the Arctic region during Eocene Thermal Maximum 2 | Supplementary information

Subject Category: Palaeoclimate and palaeoceanography

Generation of banded iron formations by internal dynamics and leaching of oceanic crust - pp781 - 784

Yifeng Wang, Huifang Xu, Enrique Merino & Hiromi Konishi

doi:10.1038/ngeo652

Banded iron formations are plentiful in the rocks representing early Earth, but the mechanisms by which they formed remain controversial. Geochemical modelling indicates that the hydrothermal leaching of low-aluminium ocean crust and subsequent chemical reactions in iron- and silica-rich hydrothermal fluids could have triggered the alternating deposition of iron and silica-dominated sediments.

First Paragraph - Generation of banded iron formations by internal dynamics and leaching of oceanic crust | Full Text - Generation of banded iron formations by internal dynamics and leaching of oceanic crust | PDF (1,839 KB) - Generation of banded iron formations by internal dynamics and leaching of oceanic crust | Supplementary information

Subject Categories: Biogeochemistry | Volcanology, mineralogy and petrology

Distribution of melt beneath Mount St Helens and Mount Adams inferred from magnetotelluric data - pp785 - 789

Graham J. Hill, T. Grant Caldwell, Wiebke Heise, Darren G. Chertkoff, Hugh M. Bibby, Matt K. Burgess, James P. Cull & Ray A. F. Cas

doi:10.1038/ngeo661

The cause of high electrical conductivity in the middle crust beneath the Pacific Northwest region of the US is not clear. New electrical-resistivity data reveal a connection between this regional conductor and a localized conductor beneath a prominent volcano in the region, suggesting that the anomalous conductivity is due to the presence of partial melts.

First Paragraph - Distribution of melt beneath Mount St Helens and Mount Adams inferred from magnetotelluric data | Full Text - Distribution of melt beneath Mount St Helens and Mount Adams inferred from magnetotelluric data | PDF (1,789 KB) - Distribution of melt beneath Mount St Helens and Mount Adams inferred from magnetotelluric data | Supplementary information

Subject Category: Structural geology, tectonics and geodynamics

Deep slab hydration induced by bending-related variations in tectonic pressure - pp790 - 793

Manuele Faccenda, Taras V. Gerya & Luigi Burlini

doi:10.1038/ngeo656

Geophysical data reveal that at subduction zones oceanic plates could be pervasively hydrated for several kilometres below the crust–mantle boundary. Numerical experiments suggest that such deep hydration is facilitated by negative pressure gradients that lead to the downward pumping of water along bending-related normal faults.

First Paragraph - Deep slab hydration induced by bending-related variations in tectonic pressure | Full Text - Deep slab hydration induced by bending-related variations in tectonic pressure | PDF (992 KB) - Deep slab hydration induced by bending-related variations in tectonic pressure | Supplementary information

Subject Category: Structural geology, tectonics and geodynamics

See also: News and Views by Billen

Weakening of calcium iridate during its transformation from perovskite to post-perovskite - pp794 - 797

Simon A. Hunt, Donald J. Weidner, Li Li, Liping Wang, Nicolas P. Walte, John P. Brodholt & David P. Dobson

doi:10.1038/ngeo663

Magnesium silicate perovskite, the dominant mineral in the lower mantle, is thought to transform into a post-perovskite phase in the mantle's lowermost region. Laboratory experiments suggest substantial weakening could occur during the transformation from perovskite to post-perovskite, which could explain the anomalous physical properties of the lowermost mantle.

First Paragraph - Weakening of calcium iridate during its transformation from perovskite to post-perovskite | Full Text - Weakening of calcium iridate during its transformation from perovskite to post-perovskite | PDF (708 KB) - Weakening of calcium iridate during its transformation from perovskite to post-perovskite | Supplementary information

Subject Category: Structural geology, tectonics and geodynamics

Core formation and metal–silicate fractionation of osmium and iridium from gold - pp798 - 801

James M. Brenan & William F. McDonough

doi:10.1038/ngeo658

Both core formation and the late addition of extraterrestrial material have been invoked to explain the abundances and relative proportions of iron-loving elements in the Earth's mantle. High-temperature experiments suggest that the concentration of gold is consistent with core formation, but the amounts of osmium and iridium require later inputs of extraterrestrial material.

First Paragraph - Core formation and metal-silicate fractionation of osmium and iridium from gold | Full Text - Core formation and metal–silicate fractionation of osmium and iridium from gold | PDF (592 KB) - Core formation and metal–silicate fractionation of osmium and iridium from gold | Supplementary information

Subject Category: Oceanography

Generation of a strong magnetic field using uniform heat flux at the surface of the core - pp802 - 805

Ataru Sakuraba & Paul H. Roberts

doi:10.1038/ngeo643

Numerical simulations that assume realistic core-fluid viscosities have been unsuccessful in fully reproducing the unique characteristics of the Earth's geomagnetic field. An evaluation of boundary conditions suggests that the prescription of a uniform heat flux at the core's surface could generate a more Earth-like magnetic field.

First Paragraph - Generation of a strong magnetic field using uniform heat flux at the surface of the core | Full Text - Generation of a strong magnetic field using uniform heat flux at the surface of the core | PDF (1,600 KB) - Generation of a strong magnetic field using uniform heat flux at the surface of the core | Supplementary information

Subject Category: Geomagnetism, palaeomagnetism and core processes

See also: News and Views by Buffett

Ancient ice - p808

doi:10.1038/ngeo681

Abstract - Ancient ice | Full Text - Ancient ice | PDF (169 KB) - Ancient ice

See also: Letter by Müller et al.