Featured
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Article |
Large anomalies in lower stratospheric water vapour and ice during the 2015–2016 El Niño
The El Niño of 2015–2016 was unusual and exceptionally strong. Satellite observations and modelling suggest that convective lofting and sublimation of ice particles during this event contributed to moistening of the lower stratosphere.
- Melody A. Avery
- , Sean M. Davis
- & Andrew E. Dessler
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Article |
Regionally strong feedbacks between the atmosphere and terrestrial biosphere
Understanding biosphere–atmosphere feedback loops can improve forecasts of climate and vegetation resilience. Analyses of satellite observations reveal that feedbacks are strong in regions that determine the net terrestrial carbon balance.
- Julia K. Green
- , Alexandra G. Konings
- & Pierre Gentine
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Correspondence |
Save northern high-latitude catchments
- Hjalmar Laudon
- , Christopher Spence
- & Doerthe Tetzlaff
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Article |
Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination
Groundwater that predates the Holocene is commonly assumed to be unaffected by modern contamination. A global analysis of fossil groundwater suggests that modern contaminants are present in deep wells that tap fossil aquifers.
- Scott Jasechko
- , Debra Perrone
- & James W. Kirchner
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Article |
Groundwater salinity influenced by Holocene seawater trapped in incised valleys in the Red River delta plain
Brackish to salty waters have been found in inland areas of delta aquifers. Geophysical data and modelling suggest that salty groundwater in the Red River delta originates from trapped seawater contained in underlying Holocene marine deposits.
- Flemming Larsen
- , Long Vu Tran
- & Nhan Quy Pham
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Correspondence |
Reply to 'Limited Late Antique cooling'
- Ulf Büntgen
- , Vladimir S. Myglan
- & Alexander V. Kirdyanov
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Article |
Microbially driven export of labile organic carbon from the Greenland ice sheet
Glacial systems are important sources of dissolved organic carbon to downstream ecosystems. Observations of carbon dynamics on the Greenland ice sheet reveal substantial melt season production and export of microbial dissolved organic carbon.
- Michaela Musilova
- , Martyn Tranter
- & Alexandre M. Anesio
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Article |
Mobility and persistence of methane in groundwater in a controlled-release field experiment
Most monitoring of methane well leakage focuses on emissions of methane gas to the atmosphere. In a controlled-release field experiment, significant methane also persisted in aquifer groundwater due to lateral migration along bedding planes.
- Aaron G. Cahill
- , Colby M. Steelman
- & Beth L. Parker
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Article |
Globally important nitrous oxide emissions from croplands induced by freeze–thaw cycles
Large fluxes of nitrous oxide occur when frozen soils thaw. Field measurements and mathematical models suggest that freeze–thaw events are responsible for 17 to 28% of nitrous oxide emitted from agricultural soils globally.
- Claudia Wagner-Riddle
- , Katelyn A. Congreves
- & Mario Tenuta
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Article |
Black-carbon absorption enhancement in the atmosphere determined by particle mixing state
Mixing with non-black carbon can enhance the radiative effect of black-carbon aerosols. Lab and field measurements of aerosol properties reveal that the mass ratio of black to non-black carbon determines the amount of enhancement.
- Dantong Liu
- , James Whitehead
- & James D. Allan
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Article |
Iron persistence in a distal hydrothermal plume supported by dissolved–particulate exchange
The largest known hydrothermal plume moves dissolved iron halfway across the Pacific. In situ measurements show that dissolved and particulate iron transport is facilitated by reversible exchange of dissolved iron onto organic compounds.
- Jessica N. Fitzsimmons
- , Seth G. John
- & Robert M. Sherrell
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Editorial |
Cleaner urban air tomorrow?
Air pollution in large cities remains a persistent public health problem. Adapting air quality forecasts for use by decision makers could help mitigate severe pollution events.
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News & Views |
Early phosphorus redigested
Atmospheric oxygen was maintained at low levels throughout huge swathes of Earth's early history. Estimates of phosphorus availability through time suggest that scavenging from anoxic, iron-rich oceans stabilized this low-oxygen world.
- Simon W. Poulton
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Perspective |
Historical carbon dioxide emissions caused by land-use changes are possibly larger than assumed
The net carbon flux on land comprises emissions from land-use change and uptake by vegetation. An evaluation of vegetation models suggests that emissions from land-use change, and thus the terrestrial sink, may be substantially underestimated.
- A. Arneth
- , S. Sitch
- & S. Zaehle
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News & Views |
Chronicling a medieval eruption
The climatic response to the eruption of the Samalas Volcano in 1257 has been elusive. Medieval archives tell of a spatially variable reaction, with Europe and Japan experiencing severe cold compared to relative warmth in North America.
- Francis Ludlow
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Article |
Climate response to the Samalas volcanic eruption in 1257 revealed by proxy records
The climatic response to the 1257 Samalas eruption is unclear. Analyses of proxy data and medieval archives suggest that the eruption triggered some of the coldest summers of the past millennium, but only in some Northern Hemisphere regions.
- Sébastien Guillet
- , Christophe Corona
- & Clive Oppenheimer
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Article |
A key role for green rust in the Precambrian oceans and the genesis of iron formations
Large iron deposits formed episodically in the Archaean oceans. Experimental data and geochemical modelling suggest that green rust was an important contributor to the formation of these deposits and the Archaean iron cycle in general.
- I. Halevy
- , M. Alesker
- & Y. Feldman
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Article |
Carbon sequestration in an expanded lake system during the Toarcian oceanic anoxic event
The Toarcian anoxic event was linked to a massive release of carbon to the atmosphere. Geochemical data suggest that organic carbon burial in large lacustrine systems was key to the recovery of the carbon cycle.
- Weimu Xu
- , Micha Ruhl
- & Erdem F. Idiz
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Article |
Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentation
Bacteria have been assumed to dominate organic matter decomposition in marine sediments. In flow-through reactor experiments, algae were revealed to be primarily responsible for anaerobically metabolizing organic matter in permeable sediments.
- Michael F. Bourke
- , Philip J. Marriott
- & Perran L. M. Cook
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Letter |
Substantial global carbon uptake by cement carbonation
Cement production is a source of CO2. Analysis of carbonation, a process that sequesters CO2 during the lifetime of cement, suggests that between 1930 and 2013, it has offset 43% of CO2 emissions from cement production globally.
- Fengming Xi
- , Steven J. Davis
- & Zhu Liu
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News & Views |
Ocean dissolved organics matter
Large quantities of organic carbon are stored in the ocean, but its biogeochemical behaviour is elusive. Size–age–composition relations now quantify the production of tiny organic molecules as a major pathway for carbon sequestration.
- Rainer M. W. Amon
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Letter |
Pacific carbon cycling constrained by organic matter size, age and composition relationships
Organic matter represents a large pool of carbon in the ocean. Radiocarbon and chemical analyses suggest that larger particles are preferentially remineralized in the Pacific Ocean, with smaller particles and molecules persisting longer.
- Brett D. Walker
- , Steven R. Beaupré
- & Ellen R. M. Druffel
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Letter |
Tropospheric ozone change from 1980 to 2010 dominated by equatorward redistribution of emissions
Ozone is an air pollutant and a greenhouse gas. Simulations with a global chemistry transport model reveal that the spatial distribution of ozone precursor emissions dominates the global ozone burden, and that emissions in the tropics matter most.
- Yuqiang Zhang
- , Owen R. Cooper
- & J. Jason West
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Editorial |
The metals disconnect
Economic development in a sustainable fashion is metals-intensive. If we cannot afford to ban mining, regulation must be more effective.
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Article |
Global climate forcing of aerosols embodied in international trade
International trade links regions of production and consumption. Analyses with a multiregional input–output model based on trade data reveal that much of East Asia’s aerosol radiative forcing is tied to consumption in developed countries.
- Jintai Lin
- , Dan Tong
- & Dabo Guan
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News & Views |
Indo-Gangetic groundwater threat
Increasing groundwater extraction supports hundreds of millions of people across the Indo-Gangetic Basin. Data suggests that despite the increase in withdrawals, groundwater depletion is localized and the most widespread threat is contamination.
- Scott Fendorf
- & Shawn G. Benner
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Letter |
Groundwater quality and depletion in the Indo-Gangetic Basin mapped from in situ observations
Increasing groundwater abstraction in the Indo-Gangetic Basin poses a threat to groundwater supplies. In situ observations reveal that sustainable groundwater in much of the region is limited more by contamination than depletion.
- A. M. MacDonald
- , H. C. Bonsor
- & S. K. Yadav
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Article |
Redox-induced lower mantle density contrast and effect on mantle structure and primitive oxygen
The origin of large-scale mantle heterogeneities remains enigmatic. Experiments show that different oxygen fugacities lead to density differences in lower-mantle materials, which lead to a heterogeneously oxidized mantle in simulations.
- Tingting Gu
- , Mingming Li
- & Kanani K. M. Lee
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Editorial |
Not just carbon widgets
Forests are important for the global carbon cycle, and for mitigating greenhouse gas emissions. However, the role forests play in carbon sequestration should not eclipse everything else we value them for.
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Letter |
Reorganization of the North Atlantic Oscillation during early Holocene deglaciation
Laurentide ice-sheet retreat continued into the mid-Holocene. Speleothem-based precipitation records suggest the cessation of melt led to the establishment of the present precipitation patterns associated with the North Atlantic Oscillation.
- Jasper A. Wassenburg
- , Stephan Dietrich
- & Adrian Immenhauser
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News & Views |
The return of ethane
Ethane emissions can lead to ozone pollution. Measurements at 49 sites show that long-declining atmospheric ethane concentrations started rising in 2010 in the Northern Hemisphere, largely due to greater oil and gas production in the USA.
- Hannele Hakola
- & Heidi Hellén
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Letter |
Reversal of global atmospheric ethane and propane trends largely due to US oil and natural gas production
Atmospheric non-methane hydrocarbon concentrations began declining in the 1970s. Surface and column measurements show that Northern Hemisphere ethane concentrations are now rising, probably due to North American oil and natural gas emissions.
- Detlev Helmig
- , Samuel Rossabi
- & Andrea Pozzer
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Editorial |
Earth's changeable atmosphere
Billions of years ago, high atmospheric greenhouse gas concentrations were vital to life's tenuous foothold on Earth. Despite new constraints, the composition and evolution of Earth's early atmosphere remains hazy.
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Letter |
Space-based detection of missing sulfur dioxide sources of global air pollution
Sulfur dioxide is a key air contaminant. A satellite-based emissions inventory reveals a number of hitherto unknown sources, with a cluster around the Persian Gulf, and identifies large discrepancies with conventional inventories in some regions.
- Chris A. McLinden
- , Vitali Fioletov
- & Joanna Joiner
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News & Views |
A hump in ocean–air exchange
Semivolatile organic compounds from fossil fuels or incomplete combustion are ubiquitous. A suite of circumglobal measurements of their oceanic and atmospheric concentrations reveals large carbon fluxes through the deposition of these compounds.
- Christopher M. Reddy
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Letter |
High atmosphere–ocean exchange of semivolatile aromatic hydrocarbons
The global transport and fate of semivolatile aromatic hydrocarbons and their relevance for the carbon cycle are poorly quantified. Global measurements in paired atmospheric and ocean samples suggest that their contribution is substantial.
- Belén González-Gaya
- , María-Carmen Fernández-Pinos
- & Jordi Dachs
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Letter |
Airborne soil organic particles generated by precipitation
Airborne organic particles affect Earth’s climate. Imaging of particles after rain events and experimental irrigation shows that water drop impaction of soils generates solid organic particles, with impacts on clouds and radiation absorption.
- Bingbing Wang
- , Tristan H. Harder
- & Alexander Laskin
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News & Views |
The fate of phosphorus
Phosphorus is essential for food production, but it is also a key cause of eutrophication. Estimates of phosphorus flux for the past 40–70 years reveal that large river basins can experience phases of phosphorus accumulation and depletion.
- Julien Némery
- & Josette Garnier
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Letter |
Long-term accumulation and transport of anthropogenic phosphorus in three river basins
Phosphorus fertilizer use has roughly quadrupled in the past century. Budgets constructed from historical data show that phosphorus rapidly accumulates in river basins during periods of high inputs and continues to mobilize after inputs decline.
- Stephen M. Powers
- , Thomas W. Bruulsema
- & Fusuo Zhang
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Letter |
Large increases in Arctic biogenic volatile emissions are a direct effect of warming
Volatile organic compounds can affect air quality and climate. Experimental warming of vegetated tundra plots in Greenland increased biogenic volatile organic compound emissions from vegetation and soils by 260%, as a direct effect.
- Magnus Kramshøj
- , Ida Vedel-Petersen
- & Riikka Rinnan
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Letter |
Biological role in the transformation of platinum-group mineral grains
Microbes can mineralize metals such as gold. Observations of platinum-group mineral grains and incubation experiments reveal that bacteria can also transform these metals, which could affect their mobility in surface environments.
- Frank Reith
- , Carla M. Zammit
- & Joël Brugger
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News & Views |
Greenhouse warming unleashed
Human activity alters the atmospheric composition, which leads to global warming. Model simulations suggest that reductions in emission of sulfur dioxide from Europe since the 1970s could have unveiled rapid Arctic greenhouse gas warming.
- Thorsten Mauritsen
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Letter |
High aerosol acidity despite declining atmospheric sulfate concentrations over the past 15 years
Atmospheric sulfate levels are thought to determine the pH of small aerosol particles. Thermodynamic analysis of field aerosol data reveals that fine particles remain acidic in the southeastern United States despite large sulfate reductions.
- Rodney J. Weber
- , Hongyu Guo
- & Athanasios Nenes
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News & Views |
Clues to hidden copper deposits
Economic-grade deposits of copper are hard to find. The aluminium content of magmatic rocks at the surface may provide an indicator of ore deposits buried deep below.
- Jeremy Richards
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News & Views |
Phytoplankton in a witch's brew
Natural seafloor hydrocarbon seeps are responsible for roughly half of the oil released into the ocean. As these oils and gases rise to the surface, they transport nutrients upwards, benefiting phytoplankton in the upper sunlit layer.
- Michael Behrenfeld
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News & Views |
Your feet's too big
Humanity's nitrogen pollution footprint has increased by a factor of six since the 1930s. A global analysis reveals that a quarter of this nitrogen pollution is associated with the production of internationally traded products.
- James N. Galloway
- & Allison M. Leach
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Letter |
Elevated surface chlorophyll associated with natural oil seeps in the Gulf of Mexico
Natural hydrocarbon seeps account for up to 47% of the oil released into the oceans. In situ and remote measurements of chlorophyll concentrations suggest that natural hydrocarbons enhance productivity in surface waters in the Gulf of Mexico.
- N. A. D’souza
- , A. Subramaniam
- & J. P. Montoya
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Letter |
High solar cycle spectral variations inconsistent with stratospheric ozone observations
Variability in solar UV radiation is uncertain, but it affects Earth’s climate. Simulations of the ozone response to various data sets of spectral solar irradiance show that high-amplitude solar variability is inconsistent with ozone observations.
- W. T. Ball
- , J. D. Haigh
- & W. Schmutz
Hotspots of soil N2O emission enhanced through water absorption by plant residue
Limited Late Antique cooling