ALBERT

Beschreibung: Nature Geoscience 7, 860 (2014). doi:10.1038/ngeo2301 Author: Jay J. Ague Aqueous subduction-zone fluids contain CO2 and methane. New calculations indicate that these fluids also host a wide array of organic carbon species, in concentrations sufficient to influence the deep carbon cycle.

Beschreibung: Nature Geoscience 7, 925 (2014). doi:10.1038/ngeo2278 Authors: Devin McPhillips, Paul R. Bierman & Dylan H. Rood

Beschreibung: Nature Geoscience 7, 920 (2014). doi:10.1038/ngeo2284 Authors: Peter B. Reich, Sarah E. Hobbie & Tali D. Lee

Beschreibung: Nature Geoscience 7, 931 (2014). doi:10.1038/ngeo2296 Author: Colin Goldblatt, Tyler D. Robinson, Kevin J. Zahnle & David Crisp

Beschreibung: Nature Geoscience 7, 321 (2014). doi:10.1038/ngeo2163 Climate change could compromise food security over the coming century. Scientists working towards mitigation and adaptation have to win over those who work on the land.

Beschreibung: Nature Geoscience 7, 324 (2014). doi:10.1038/ngeo2153 Authors: Paolo D'Odorico & Maria Cristina Rulli Large tracts of agricultural land are being bought up by external investors. Turning the land into a commodity can have detrimental effects, for generations to come, on the local communities that sell or lease the land.

Beschreibung: Nature Geoscience 7, 328 (2014). doi:10.1038/ngeo2158 Author: Tamara Goldin

Beschreibung: Nature Geoscience 7, 329 (2014). doi:10.1038/ngeo2145 Author: Sanjoy M. Som A dense early atmosphere has been invoked to explain the strong greenhouse effect inferred for early Mars. Yet an analysis of the smallest impact craters suggests that the atmospheric pressure on Mars 3.6 billion years ago was surprisingly low.

Beschreibung: Nature Geoscience 7, 335 (2014). doi:10.1038/ngeo2137 Authors: Edwin S. Kite, Jean-Pierre Williams, Antoine Lucas & Oded Aharonson The decay of the martian atmosphere—which is dominated by carbon dioxide—is a component of the long-term environmental change on Mars from a climate that once allowed rivers to flow to the cold and dry conditions of today. The minimum size of craters serves as a proxy for palaeopressure of planetary atmospheres, because thinner atmospheres permit smaller objects to reach the surface at high velocities and form craters. The Aeolis Dorsa region near Gale crater on Mars contains a high density of preserved ancient craters interbedded with river deposits and thus can provide constraints on atmospheric density at the time of fluvial activity. Here we use high-resolution images and digital terrain models from the Mars Reconnaissance Orbiter to identify ancient craters in deposits in Aeolis Dorsa that date to about 3.6 Gyr ago and compare their size distribution with models of atmospheric filtering of impactors. We obtain an upper limit of 0.9 ± 0.1 bar for the martian atmospheric palaeopressure, rising to 1.9 ± 0.2 bar if rimmed circular mesas—interpreted to be erosionally-resistant fills or floors of impact craters—are excluded. We assume target properties appropriate for desert alluvium: if sediment had rock-mass strength similar to bedrock at the time of impact, the paleopressure upper limit increases by a factor of up to two. If Mars did not have a stable multibar atmosphere at the time that the rivers were flowing—as suggested by our results—then a warm and wet CO2/H2O greenhouse is ruled out, and long-term average temperatures were most likely below freezing.

Beschreibung: Nature Geoscience 7, 376 (2014). doi:10.1038/ngeo2119 Authors: Gregor Knorr & Gerrit Lohmann

Beschreibung: Nature Geoscience 7, 322 (2014). doi:10.1038/ngeo2151 Author: Joseph M. Craine Livestock production accounts for a significant fraction of global anthropogenic greenhouse gas emissions. Progress in mitigating the adverse environmental impacts of this industry can be improved by shifting research emphases and fostering communication between researchers and ranchers.

Beschreibung: Nature Geoscience 7, 328 (2014). doi:10.1038/ngeo2159 Author: Anna Armstrong

Beschreibung: Nature Geoscience 7, 340 (2014). doi:10.1038/ngeo2138 Authors: Jessica L. Neu, Thomas Flury, Gloria L. Manney, Michelle L. Santee, Nathaniel J. Livesey & John Worden The downward transport of stratospheric ozone is an important natural source of tropospheric ozone, particularly in the upper troposphere, where changes in ozone have their largest radiative effect. Stratospheric circulation is projected to intensify over the coming century, which could lead to an increase in the flux of ozone from the stratosphere to the troposphere. However, large uncertainties in the stratospheric contribution to trends and variability in tropospheric ozone levels make it difficult to reliably project future changes in tropospheric ozone. Here, we use satellite measurements of stratospheric water vapour and tropospheric ozone levels collected between 2005 and 2010 to assess the effect of changes in stratospheric circulation, driven by El Niño/Southern Oscillation and the stratospheric Quasi-Biennial Oscillation, on tropospheric ozone levels. We find that interannual variations in the strength of the stratospheric circulation of around 40%—comparable to the mean change in stratospheric circulation projected this century—lead to changes in tropospheric ozone levels in the northern mid-latitudes of around 2%, approximately half of the interannual variability. Assuming that the observed response of tropospheric ozone levels to interannual variations in circulation is a good predictor of its equilibrium response, we suggest that the projected intensification of the stratospheric circulation over the coming century could lead to small but important increases in tropospheric ozone levels.

Beschreibung: Nature Geoscience 7, 328 (2014). doi:10.1038/ngeo2161 Author: Amy Whitchurch

Beschreibung: Nature Geoscience 7, 355 (2014). doi:10.1038/ngeo2143 Authors: Jay J. Ague & Stefan Nicolescu The balance between the subduction of carbonate mineral-bearing rocks into Earth’s mantle and the return of CO2 to the atmosphere by volcanic and metamorphic degassing is critical to the carbon cycle. Carbon is thought to be released from subducted rocks mostly by simple devolatilization reactions. However, these reactions will also retain large amounts of carbon within the subducting slab and have difficulty in accounting for the mass of CO2 emitted from volcanic arcs. Carbon release may therefore occur via fluid-induced dissolution of calcium carbonate. Here we use carbonate δ18O and δ13C systematics, combined with analyses of rock and fluid inclusion mineralogy and geochemistry, to investigate the alteration of the exhumed Eocene Cycladic subduction complex on the Syros and Tinos islands, Greece. We find that in marble rocks adjacent to two fluid conduits that were active during subduction, the abundance of calcium carbonate drastically decreases approaching the conduits, whereas silicate minerals increase. Up to 60–90% of the CO2 was released from the rocks—far greater than expected via simple devolatilization reactions. The δ18O of the carbonate minerals is 5–10 lighter than is typical for metamorphosed carbonate rocks, implying that isotopically light oxygen was transported by fluid infiltration from the surroundings. We suggest that fluid-mediated carbonate mineral removal, accompanied by silicate mineral precipitation, provides a mechanism for the release of enormous amounts of CO2 from subduction zones.

Beschreibung: Nature Geoscience 7, 345 (2014). doi:10.1038/ngeo2141 Authors: Diego G. Miralles, Adriaan J. Teuling, Chiel C. van Heerwaarden & Jordi Vilà-Guerau de Arellano The recent European mega-heatwaves of 2003 and 2010 broke temperature records across Europe. Although events of this magnitude were unprecedented from a historical perspective, they are expected to become common by the end of the century. However, our understanding of extreme heatwave events is limited and their representation in climate models remains imperfect. Here we investigate the physical processes underlying recent mega-heatwaves using satellite and balloon measurements of land and atmospheric conditions from the summers of 2003 in France and 2010 in Russia, in combination with a soil–water–atmosphere model. We find that, in both events, persistent atmospheric pressure patterns induced land–atmosphere feedbacks that led to extreme temperatures. During daytime, heat was supplied by large-scale horizontal advection, warming of an increasingly desiccated land surface and enhanced entrainment of warm air into the atmospheric boundary layer. Overnight, the heat generated during the day was preserved in an anomalous kilometres-deep atmospheric layer located several hundred metres above the surface, available to re-enter the atmospheric boundary layer during the next diurnal cycle. This resulted in a progressive accumulation of heat over several days, which enhanced soil desiccation and led to further escalation in air temperatures. Our findings suggest that the extreme temperatures in mega-heatwaves can be explained by the combined multi-day memory of the land surface and the atmospheric boundary layer.

Beschreibung: Nature Geoscience 7, 371 (2014). doi:10.1038/ngeo2121 Authors: Shuichi Kodaira, Gou Fujie, Mikiya Yamashita, Takeshi Sato, Tsutomu Takahashi & Narumi Takahashi A long-standing question about the dynamics of mid-ocean spreading centres is whether mantle upwelling is passive or active. During passive upwelling, the motion of the overlying plate would be expected to drive mantle flow. In contrast, during active upwelling, decompression melting of the mantle beneath the spreading axis would result in a low-density melt that creates local buoyancy, forcing mantle convection and driving plate motion. Seismic images of older parts of the Pacific Plate reveal dipping reflectors in the lower crust that could be shear zones created by active mantle flow, but there is little seismological evidence to indicate that mantle flow drags the plate. Here we use active-source seismic data to image the Pacific Plate that was created at a palaeo-spreading centre in the northwest Pacific Ocean. We identify very high P-wave velocities of 8.5–8.6 km s−1 and strong seismic anisotropy of 8.5–9.8% in the uppermost mantle, immediately below the lower-crustal dipping reflectors. We suggest that such strong seismic anisotropy, caused by the alignment of olivine crystals in response to mantle flow, could have been generated if mantle flow was much faster than plate motion. We conclude that both the lower-crustal dipping reflectors and the anisotropy were formed by a drag force at the Moho caused by rapid mantle flow, providing direct evidence for active mantle flow at a spreading centre.

Beschreibung: Nature Geoscience 7, 382 (2014). doi:10.1038/ngeo2139 Authors: Zhongwu Ma, Ellen Gray, Ellen Thomas, Brandon Murphy, James Zachos & Adina Paytan

Beschreibung: The case for sustainable management strategies is strengthened by the threats climate change poses to the private sector — companies face up to the challenge. Nature Climate Change 4 301 doi: 10.1038/nclimate2238

Beschreibung: The proposed 'cost assessment cycle' is a framework for the integrated cost assessment of natural hazards. Nature Climate Change 4 303 doi: 10.1038/nclimate2182

Beschreibung: Nature Climate Change 4 303 doi: 10.1038/nclimate2202

Beschreibung: Rewarding smallholders for sequestering carbon in agricultural land can improve food security while mitigating climate change. Verification of carbon offsets in food-insecure regions is possible and achievable through rigorously controlled monitoring. Nature Climate Change 4 309 doi: 10.1038/nclimate2209

Beschreibung: Climate change, alongside numerous other pressures, is having unprecedented effects on water resources both globally and locally. Retailers need to implement a range of adaptation measures to ensure the sustainability of supply chains. Nature Climate Change 4 314 doi: 10.1038/nclimate2211

Beschreibung: As global population continues to grow, managing the relationships between water, food and energy is becoming increasingly critical. Businesses need to react to the challenge and be mindful of the important role they play in implementing solutions. Nature Climate Change 4 316 doi: 10.1038/nclimate2220

Beschreibung: The growing scarcity of freshwater due to rising water demands and a changing climate is increasingly seen as a major risk for the global economy. Consumer awareness, private sector initiatives, governmental regulation and targeted investments are urgently needed to move towards sustainable water use. Nature Climate Change 4 318 doi: 10.1038/nclimate2214

Beschreibung: Colombia's sustainable cattle ranching programme restores degraded land while boosting livestock production and making farmland more resilient to climate change. Nature Climate Change 4 321 doi: 10.1038/nclimate2215

Beschreibung: The rooftop solar industry in the United States is experiencing rapid growth. Anna Petherick reports on its progress. Nature Climate Change 4 324 doi: 10.1038/nclimate2213

Beschreibung: Nature Climate Change 4 326 doi: 10.1038/nclimate2230

Beschreibung: Nature Climate Change 4 326 doi: 10.1038/nclimate2231

Beschreibung: Nature Climate Change 4 326 doi: 10.1038/nclimate2232

Beschreibung: Nature Climate Change 4 326 doi: 10.1038/nclimate2233

Beschreibung: Over short periods of time, it can be difficult to isolate sea-level increase in observations as it is hidden by natural shifts in rainfall quantities over ocean and land, which cause temporary drops in the global sea-level curve. Now research shows how to detect the signal, even in short records, by estimating these variations. Nature Climate Change 4 327 doi: 10.1038/nclimate2205

Beschreibung: Nature Climate Change 4 326 doi: 10.1038/nclimate2234

Beschreibung: Temperature reconstructions of the past millennium rely heavily on Northern Hemisphere data. Now a Southern Hemisphere temperature reconstruction is available and sheds light on the complexity of the interhemispheric temperature relationship. Nature Climate Change 4 328 doi: 10.1038/nclimate2219

Beschreibung: Faced with serious air pollution, China is aggressively reshaping its energy system, building on recent progress with renewables and on available supplies of gas. This should help contain global warming and provide new impetus to climate change negotiations. Nature Climate Change 4 306 doi: 10.1038/nclimate2197

Beschreibung: Nature Climate Change 4 302 doi: 10.1038/nclimate2201

Beschreibung: Management practices applied to existing types of land cover can influence the local climate as much as a conversion to a different type of plant cover. Nature Climate Change 4 330 doi: 10.1038/nclimate2221

Beschreibung: There has been a rapid growth in the use of natural gas and biofuels. This study evaluates energy technologies against climate targets and shows that the impact of technologies that result in the emission of both methane and carbon dioxide depends on their time of use. The changes in climate impacts over time are large, with several technologies that are widely considered mitigation options becoming unfavourable within two decades. Nature Climate Change 4 347 doi: 10.1038/nclimate2204

Beschreibung: It is widely recognized that cities must play a leading role in efforts to mitigate climate change. Building on previous inventory work, this study looks at options for reducing greenhouse gas emissions from major cities around the world. The strategies identified reflect the unique characteristics of different cities, such as their climate, industry, urbanized density and electricity supply. Nature Climate Change 4 343 doi: 10.1038/nclimate2160

Beschreibung: The international community's support for adaptation in developing countries has proliferated through numerous complementary funding mechanisms. A range of serious practical issues are emerging, however, as adaptation moves from theory and international negotiation to implementation. We identify three areas deserving greater scrutiny: in-country priorities, entry points and delivery systems, and provide recommendations for improving adaptation practice. These concerns, if not addressed, have the potential to hamper attempts at effective delivery and to increase the vulnerability of intended beneficiaries of the adaptation agenda. Nature Climate Change 4 339 doi: 10.1038/nclimate2199

Beschreibung: The impacts of extreme weather are being felt by us all and scientific research points to a likely worsening of weather patterns in the next decades. Therefore, it is imperative to think carefully about how we build the infrastructure of the future to increase the resilience of our societies. Nature Climate Change 4 311 doi: 10.1038/nclimate2217

Beschreibung: In recent years there has been a slowdown in sea-level rise, along with the slowdown in global surface temperatures. This study analyses sea-level data to separate long-term natural variability from anthropogenic influence on sea level. They find that correcting for natural variability shows recent sea-level rise has not slowed compared with earlier periods. Nature Climate Change 4 358 doi: 10.1038/nclimate2159

Beschreibung: Palaeoclimate temperature records are dominated by Northern Hemisphere reconstructions. This study introduces a new Southern Hemisphere millennial temperature reconstruction from terrestrial and oceanic proxy records. This highlights the asynchronicity of temperature fluctuations across the two hemispheres, which should be taken into consideration in climate models and projections. Nature Climate Change 4 362 doi: 10.1038/nclimate2174

Beschreibung: Prediction of seasonal Arctic sea-ice extent is of increased interest as the region opens up due to climate change. This work uses spring melt-pond area to forecast the Arctic sea-ice minimum in September. This proves accurate, as increasing melt-ponds reduce surface albedo, allowing more melt to occur, creating a positive feedback mechanism. Nature Climate Change 4 353 doi: 10.1038/nclimate2203

Beschreibung: Large ensemble climate modelling experiments demonstrate the large role natural variability plays in local climate on a multi-decadal timescale. Variability in local weather and climate influences individual beliefs about climate change. To the extent that support for climate mitigation policies is determined by citizens' local experiences, natural variability will strongly influence the timescale for implementation of such policies. Under a number of illustrative threshold criteria for both national and international climate action, we show that variability-driven uncertainty about local change, even in the face of a well-constrained estimate of global change, can potentially delay the time to policy implementation by decades. Because several decades of greenhouse gas emissions can have a large impact on long-term climate outcomes, there is substantial risk associated with climate policies driven by consensus among individuals who are strongly influenced by local weather conditions. Nature Climate Change 4 333 doi: 10.1038/nclimate2186

Beschreibung: Large parts of the circumpolar Arctic are grazed by reindeer but the effects of grazing pressure on ecological responses to climate change, and the associated climate feedbacks, remain unclear. Now, research using a long-term environmental manipulation experiment finds that although warming decreased the carbon sink of tundra experiencing light grazing pressure, it had no effect on tundra under high grazing pressure. Nature Climate Change 4 384 doi: 10.1038/nclimate2147

Beschreibung: The direct effects of land-cover change on surface climate are increasingly well understood, but fewer studies have investigated the consequences of the trend towards more intensive land management practices. Now, research investigating the biophysical effects of temperate land-management changes reveals a net warming effect of similar magnitude to that driven by changing land cover. Nature Climate Change 4 389 doi: 10.1038/nclimate2196

Beschreibung: Understanding how climate change will impact whole ecosystems, rather than single species within them, remains challenging. Now, research into the direct and indirect impacts of climate on the functioning of Arctic terrestrial ecosystems reveals effects on tundra primary production, food-web structure and the strength of species interaction. Nature Climate Change 4 379 doi: 10.1038/nclimate2168

Beschreibung: Increasing concentrations of atmospheric particles are expected to impact Northern Hemisphere mid-latitude precipitation and temperature. This study finds that there is little evidence that aerosol concentrations affect land precipitation in the region, which they attribute to changes in observational techniques that increased measured values at the time aerosols were expected to suppress precipitation. Nature Climate Change 4 374 doi: 10.1038/nclimate2173

Beschreibung: Anthropogenic influence, due to greenhouse gases and aerosols, on the frequency and intensity of tropical cyclones is not well known. In this study, aerosols are shown to delay development, weaken intensity and cause early dissipation of storms, but also to increase precipitation across an enlarged rainband. Nature Climate Change 4 368 doi: 10.1038/nclimate2144

Beschreibung: Life-cycle assessment of biofuel carbon emissions does not usually take into account the potential for soil carbon loss resulting from crop residue removal. Now estimates of CO2 emissions due to corn residue removal across the US Corn Belt indicate that the emissions from soil carbon loss could push total emissions above the US legislative mandate. Nature Climate Change 4 398 doi: 10.1038/nclimate2187

Beschreibung: The response of terrestrial ecosystems to climate change remains a large source of uncertainty in the global carbon budget. Now results from a ten-year ecological manipulation experiment in the Mojave Desert provide direct evidence that CO2 fertilization can substantially increase ecosystem carbon storage in arid ecosystems. Nature Climate Change 4 394 doi: 10.1038/nclimate2184

Beschreibung: Weather events make the news but shouldn't be confused with climate change impacts. Nature Climate Change 4 75 doi: 10.1038/nclimate2131

Beschreibung: Nature Geoscience 7, 95 (2014). doi:10.1038/ngeo2043 Authors: Richard R. Forster, Jason E. Box, Michiel R. van den Broeke, Clément Miège, Evan W. Burgess, Jan H. van Angelen, Jan T. M. Lenaerts, Lora S. Koenig, John Paden, Cameron Lewis, S. Prasad Gogineni, Carl Leuschen & Joseph R. McConnell Mass loss from the Greenland ice sheet contributes significantly to present sea level rise. High meltwater runoff is responsible for half of Greenland’s mass loss. Surface melt has been spreading and intensifying in Greenland, with the highest ever surface area melt and runoff recorded in 2012. However, how surface melt water reaches the ocean, and how fast it does so, is poorly understood. Firn—partially compacted snow from previous years—potentially has the capacity to store significant amounts of melt water in liquid or frozen form, and thus delay its contribution to sea level. Here we present direct observations from ground and airborne radar, as well as ice cores, of liquid water within firn in the southern Greenland ice sheet. We find a substantial amount of water in this firn aquifer that persists throughout the winter, when snow accumulation and melt rates are high. This represents a previously unknown storage mode for water within the ice sheet. We estimate, using a regional climate model, aquifer area at about 70,000 km2 and the depth to the top of the water table as 5–50 m. The perennial firn aquifer could be important for estimates of ice sheet mass and energy budget.

Beschreibung: Nature Geoscience 7, 91 (2014). doi:10.1038/ngeo2046 Authors: Jin Liao, L. Gregory Huey, Zhen Liu, David J. Tanner, Chris A. Cantrell, John J. Orlando, Frank M. Flocke, Paul B. Shepson, Andrew J. Weinheimer, Samuel R. Hall, Kirk Ullmann, Harry J. Beine, Yuhang Wang, Ellery D. Ingall, Chelsea R. Stephens, Rebecca S. Hornbrook, Eric C. Apel, Daniel Riemer, Alan Fried, Roy L. Mauldin, James N. Smith, Ralf M. Staebler, J. Andrew Neuman & John B. Nowak Chlorine radicals can function as a strong atmospheric oxidant, particularly in polar regions, where levels of hydroxyl radicals are low. In the atmosphere, chlorine radicals expedite the degradation of methane and tropospheric ozone, and the oxidation of mercury to more toxic forms. Here we present direct measurements of molecular chlorine levels in the Arctic marine boundary layer in Barrow, Alaska, collected in the spring of 2009 over a six-week period using chemical ionization mass spectrometry. We report high levels of molecular chlorine, of up to 400 pptv. Concentrations peaked in the early morning and late afternoon, and fell to near-zero levels at night. Average daytime molecular chlorine levels were correlated with ozone concentrations, suggesting that sunlight and ozone are required for molecular chlorine formation. Using a time-dependent box model, we estimate that the chlorine radicals produced from the photolysis of molecular chlorine oxidized more methane than hydroxyl radicals, on average, and enhanced the abundance of short-lived peroxy radicals. Elevated hydroperoxyl radical levels, in turn, promoted the formation of hypobromous acid, which catalyses mercury oxidation and the breakdown of tropospheric ozone. We therefore suggest that molecular chlorine exerts a significant effect on the atmospheric chemistry of the Arctic.

Beschreibung: Nature Geoscience 7, 136 (2014). doi:10.1038/ngeo2066 Authors: Meiyun Lin, Larry W. Horowitz, Samuel J. Oltmans, Arlene M. Fiore & Songmiao Fan

Beschreibung: Nature Geoscience 7, 144 (2014). doi:10.1038/ngeo2045 Authors: Jean Lynch-Stieglitz, Matthew W. Schmidt, L. Gene Henry, William B. Curry, Luke C. Skinner, Stefan Mulitza, Rong Zhang & Ping Chang

Beschreibung: Nature Geoscience 7, 151 (2014). doi:10.1038/ngeo2062 Authors: Darwin R. Villagómez, Douglas R. Toomey, Dennis J. Geist, Emilie E. E. Hooft & Sean C. Solomon

Beschreibung: Nature Geoscience 7, 126 (2014). doi:10.1038/ngeo2041 Authors: Luca Caricchi, Catherine Annen, Jon Blundy, Guy Simpson & Virginie Pinel Super-eruptions are extremely rare events. Indeed, the global frequency of explosive volcanic eruptions is inversely proportional to the volume of magma released in a single event. The rate of magma supply, mechanical properties of the crust and magma, and tectonic regime are known to play a role in controlling eruption frequency and magnitude, but their relative contributions have not been quantified. Here we use a thermomechanical numerical model of magma injection into Earth’s crust and Monte Carlo simulations to explore the factors controlling the recurrence rates of eruptions of different magnitudes. We find that the rate of magma supply to the upper crust controls the volume of a single eruption. The time interval between magma injections into the subvolcanic reservoir, at a constant magma-supply rate, determines the duration of the magmatic activity that precedes eruptions. Our simulations reproduce the observed relationship between eruption volume and magma chamber residence times and replicate the observed correlation between erupted volumes and caldera dimensions. We also find that magma buoyancy is key to triggering super-eruptions, whereas pressurization associated with magma injection is responsible for relatively small and frequent eruptions. Our findings help improve our ability to decipher the long-term activity patterns of volcanic systems.

Beschreibung: Nature Climate Change 4 171 doi: 10.1038/nclimate2162

Beschreibung: It is time to acknowledge that global average temperatures are likely to rise above the 2 °C policy target and consider how that deeply troubling prospect should affect priorities for communicating and managing the risks of a dangerously warming climate. Nature Climate Change 4 164 doi: 10.1038/nclimate2148

Beschreibung: Damage from hurricanes is increasing in many coastal regions worldwide. Research now shows that large wind-turbine arrays can significantly diminish peak near-surface hurricane wind speeds and storm surge. The net cost of turbine arrays is less than that of today’s fossil-fuel electricity generation and also than that of sea walls used to avoid storm-surge damage. Nature Climate Change 4 195 doi: 10.1038/nclimate2120

Beschreibung: Observational data show a continued increase of hot extremes over land during the so-called global warming hiatus. This tendency is greater for the most extreme events and thus more relevant for impacts than changes in global mean temperature. Nature Climate Change 4 161 doi: 10.1038/nclimate2145

Beschreibung: We must not fall victim to decontextualized and ahistorical media accounting of climate trends. Nature Climate Change 4 156 doi: 10.1038/nclimate2156

Beschreibung: Nature Climate Change 4 171 doi: 10.1038/nclimate2164

Beschreibung: Nature Climate Change 4 171 doi: 10.1038/nclimate2166

Beschreibung: Economic development improves the conditions of human life, but at a cost to the natural environment. Research now estimates the relationship between economic development and the carbon intensity of human well-being—the ratio of anthropogenic carbon emissions to average life expectancy at birth—globally, over 40 years. Most of the countries studied, including African nations over recent decades, followed unsustainable paths of development. Nature Climate Change 4 186 doi: 10.1038/nclimate2110

Beschreibung: Nature Climate Change 4 228 doi: 10.1038/nclimate2151

Beschreibung: The slowdown in global average surface warming has recently been linked to sea surface cooling in the eastern Pacific Ocean. This work shows that strengthening trade winds caused a reduction in the 2012 global average surface air temperature of 0.1–0.2 °C. This may account for much of the warming hiatus and is a result of increased subsurface ocean heat uptake. Nature Climate Change 4 222 doi: 10.1038/nclimate2106

Beschreibung: Nature Geoscience 7, 169 (2014). doi:10.1038/ngeo2100 Author: Samuel Bowring The age of the oldest Jack Hills zircons — Earth's oldest minerals — is contentious. Atomic-scale mapping of the distribution of radiogenic isotopes within a Jack Hills zircon confirms that the oldest known continental crust formed just after the Earth–Moon system.

Beschreibung: Nature Geoscience 7, 195 (2014). doi:10.1038/ngeo2084 Authors: Laura Klüpfel, Annette Piepenbrock, Andreas Kappler & Michael Sander Humic substances form through the degradation of microbial and plant precursors, and make up a significant fraction of natural organic matter in terrestrial and aquatic environments. Humic substances are redox-active and can act as terminal electron acceptors in anaerobic microbial respiration. Reduced humic substances may become re-oxidized during aeration of temporarily anoxic systems, such as wetlands, sediments and many soils. If the transfer of electrons from anaerobic respiration through humic substances to oxygen is sustained over many redox cycles, it may competitively suppress electron transfer to carbon dioxide, and thereby lower the formation of methane in temporarily anoxic systems. Here, we monitor changes in the redox states of four chemically distinct dissolved humic substances over successive cycles of reduction by the bacterium Shewanella oneidensis MR-1 and oxidation by oxygen, in a series of laboratory experiments. We show that electron transfer to and from these substances is fully reversible and sustainable over successive redox cycles. We suggest that redox cycling of humic substances may largely suppress methane production in temporarily anoxic systems.

Beschreibung: Nature Geoscience 7, 201 (2014). doi:10.1038/ngeo2070 Authors: Xiaole Sun & Alexandra V. Turchyn Carbon is removed from the Earth’s surface through the formation and burial of carbon-bearing rocks and minerals. The formation of calcium carbonate and its burial in marine sediments accounts for around 80% of the total carbon removed from the Earth’s surface. However, the fraction of calcium carbonate that precipitates in the oceans, versus that which precipitates authigenically in marine sediments, is unclear. Here, we compile measurements of the calcium concentration of pore fluids collected at 672 seafloor sites around the globe to calculate the global flux of calcium within marine sediments. We use these data, combined with alkalinity measurements of pore fluids, to quantify authigenic calcium carbonate precipitation. We estimate that the net calcium flux into marine sediments that can be ascribed to authigenic carbonate precipitation amounts to around 1×1012 mol yr−1. As such, we estimate that authigenic carbonate precipitation accounts for at least 10% of global carbonate accumulation. We show that much of the precipitation occurs along the eastern margins of ocean basins, where organic matter delivery to the sea floor is likely to be high. We suggest that authigenic calcium carbonate precipitation represents a non-negligible component of the global carbon cycle.

Beschreibung: There has been much debate about whether winter warming due to climate change will substantially decrease mortality in that season. Research now finds that cold severity no longer predicts the number of excess winter deaths in England and Wales. Nature Climate Change 4 173 doi: 10.1038/nclimate2146

Beschreibung: Nature Geoscience 7, 171 (2014). doi:10.1038/ngeo2085 Author: Martin Aberhan The end-Permian extinction decimated marine life on an unprecedented scale. However, an analysis of the lifestyles of the surviving genera shows that very little functional diversity was lost at the sea floor.

Beschreibung: Nature Geoscience 7, 163 (2014). doi:10.1038/ngeo2113 Author: Anna Armstrong

Beschreibung: Nature Geoscience 7, 165 (2014). doi:10.1038/ngeo2080 Author: Catherine E. Stickley Little is known about the presence of high-latitude sea ice before 2.6 million years ago. A reanalysis of marine sediments from the Arctic Ocean indicates an intermittent presence of perennial sea ice as early as 44 million years ago.

Beschreibung: Nature Geoscience 7, 190 (2014). doi:10.1038/ngeo2069 Authors: Marcos Y. Yoshinaga, Thomas Holler, Tobias Goldhammer, Gunter Wegener, John W. Pohlman, Benjamin Brunner, Marcel M. M. Kuypers, Kai-Uwe Hinrichs & Marcus Elvert Collectively, marine sediments comprise the largest reservoir of methane on Earth. The flux of methane from the sea bed to the overlying water column is mitigated by the sulphate-dependent anaerobic oxidation of methane by marine microbes within a discrete sedimentary horizon termed the sulphate–methane transition zone. According to conventional isotope systematics, the biological consumption of methane leaves a residue of methane enriched in 13C (refs , , ). However, in many instances the methane within sulphate–methane transition zones is depleted in 13C, consistent with the production of methane, and interpreted as evidence for the intertwined anaerobic oxidation and production of methane. Here, we report results from experiments in which we incubated cultures of microbial methane consumers with methane and low levels of sulphate, and monitored the stable isotope composition of the methane and dissolved inorganic carbon pools over time. Residual methane became progressively enriched in 13C at sulphate concentrations above 0.5 mM, and progressively depleted in 13C below this threshold. We attribute the shift to 13C depletion during the anaerobic oxidation of methane at low sulphate concentrations to the microbially mediated carbon isotope equilibration between methane and carbon dioxide. We suggest that this isotopic effect could help to explain the 13C-depletion of methane in subseafloor sulphate–methane transition zones.

Beschreibung: Natural variability can explain fluctuations in surface temperatures but can it account for the current slowdown in warming? Nature Climate Change 4 158 doi: 10.1038/nclimate2155

Beschreibung: Nature Climate Change 4 151 doi: 10.1038/nclimate2154

Beschreibung: The recent slowdown (or 'pause') in global surface temperature rise is a hot topic for climate scientists and the wider public. We discuss how climate scientists have tried to communicate the pause and suggest that 'many-to-many' communication offers a key opportunity to directly engage with the public. Nature Climate Change 4 154 doi: 10.1038/nclimate2150

Beschreibung: Climate change could be a game-changer for biodiversity conservation, potentially invalidating many established methods including those employed in vulnerability assessments. Now, a simulation study finds that extinction risk due to climate change can be predicted using measurable spatial and demographic variables. Interestingly, most of those variables identified as important are already used in species conservation assessment. Nature Climate Change 4 217 doi: 10.1038/nclimate2113

Beschreibung: The use of models for the prediction of future climate conditions is commonplace. This study investigates regional sea surface temperature biases across 22 climate models and finds that they are linked to the large circulation system in the Atlantic Ocean. Improvements to climate models will need to consider the impact of remote biases on regional processes. Nature Climate Change 4 201 doi: 10.1038/nclimate2118

Beschreibung: Nature Climate Change 4 171 doi: 10.1038/nclimate2165

Beschreibung: Nature Climate Change 4 171 doi: 10.1038/nclimate2163

Beschreibung: Although many species-level responses to climate warming have been documented, understanding of ecosystem-level stability under warming remains low. Now, a study using meta-analyses of temperature effects on metabolic rates, reeding rates and population sizes along with a mechanistic predator–prey model finds that warming stabilizes predator–prey dynamics but risks predator starvation. Nature Climate Change 4 206 doi: 10.1038/nclimate2134

Beschreibung: International trade is responsible for a large portion of carbon emissions transfers, mainly from developing to developed countries. Research now analyses different policies to address these transfers. The most promising option, both environmentally and economically, is for developed nations to offset trade-related emissions by financing clean development projects in developing countries. Nature Climate Change 4 177 doi: 10.1038/nclimate2102

Beschreibung: Nature Geoscience 7, 224 (2014). doi:10.1038/ngeo2074 Authors: M. Nishi, T. Irifune, J. Tsuchiya, Y. Tange, Y. Nishihara, K. Fujino & Y. Higo The presence of water strongly influences the structure, composition and dynamics of the Earth’s deep mantle. Hydrous magnesium-rich silicates play an important role in transporting water into the deep mantle when oceanic plates subduct as slabs. The highest-pressure form of such hydrous silicates, phase D, was reported to dissociate into an assemblage of nominally anhydrous phases plus water at pressures of about 44 GPa, equivalent to 1,250 km depth. In this way, free water would be released in the middle region of the lower mantle, which suggests that no water can reach the deeper regions of the lower mantle. Here we use in situ X-ray measurements in conjunction with a multi-anvil apparatus using sintered diamond anvils to show that hydrous phases are stable under lower mantle conditions up to 50 GPa. We found that phase D transforms to an assemblage with another hydrous silicate (MgSiH2O4), named phase H, at pressures above about 48 GPa. Our results suggest that phase H is the dominant hydrous silicate in descending slabs, and may be found at depths far deeper than 1,250 km. We conclude that a significant amount of water is retained in the descending slabs and may be delivered to the deepest part of the lower mantle.

Beschreibung: Nature Geoscience 7, 214 (2014). doi:10.1038/ngeo2044 Authors: Sigrún Hreinsdóttir, Freysteinn Sigmundsson, Matthew J. Roberts, Halldór Björnsson, Ronni Grapenthin, Pórdur Arason, Thóra Árnadóttir, Jósef Hólmjárn, Halldór Geirsson, Richard A. Bennett, Magnús T. Gudmundsson, Björn Oddsson, Benedikt G. Ófeigsson, Thierry Villemin, Thorsteinn Jónsson, Erik Sturkell, Ármann Höskuldsson, Gudrún Larsen, Thor Thordarson & Bergrún Arna Óladóttir Magma flow during volcanic eruptions causes surface deformation that can be used to constrain the location, geometry and internal pressure evolution of the underlying magmatic source. The height of the volcanic plumes during explosive eruptions also varies with magma flow rate, in a nonlinear way. In May 2011, an explosive eruption at Grímsvötn Volcano, Iceland, erupted about 0.27 km3 dense-rock equivalent of basaltic magma in an eruption plume that was about 20 km high. Here we use Global Positioning System (GPS) and tilt data, measured before and during the eruption at Grímsvötn Volcano, to show that the rate of pressure change in an underlying magma chamber correlates with the height of the volcanic plume over the course of the eruption. We interpret ground deformation of the volcano, measured by geodesy, to result from a pressure drop within a magma chamber at about 1.7 km depth. We estimate the rate of magma discharge and the associated evolution of the plume height by differentiating the co-eruptive pressure drop with time. The time from the initiation of the pressure drop to the onset of the eruption was about 60 min, with about 25% of the total pressure change preceding the eruption. Near-real-time geodetic observations can thus be useful for both timely eruption warnings and for constraining the evolution of volcanic plumes.

Beschreibung: Nature Geoscience 7, 219 (2014). doi:10.1038/ngeo2075 Authors: John W. Valley, Aaron J. Cavosie, Takayuki Ushikubo, David A. Reinhard, Daniel F. Lawrence, David J. Larson, Peter H. Clifton, Thomas F. Kelly, Simon A. Wilde, Desmond E. Moser & Michael J. Spicuzza The only physical evidence from the earliest phases of Earth’s evolution comes from zircons, ancient mineral grains that can be dated using the U–Th–Pb geochronometer. Oxygen isotope ratios from such zircons have been used to infer when the hydrosphere and conditions habitable to life were established. Chemical homogenization of Earth’s crust and the existence of a magma ocean have not been dated directly, but must have occurred earlier. However, the accuracy of the U–Pb zircon ages can plausibly be biased by poorly understood processes of intracrystalline Pb mobility. Here we use atom-probe tomography to identify and map individual atoms in the oldest concordant grain from Earth, a 4.4-Gyr-old Hadean zircon with a high-temperature overgrowth that formed about 1 Gyr after the mineral’s core. Isolated nanoclusters, measuring about 10 nm and spaced 10–50 nm apart, are enriched in incompatible elements including radiogenic Pb with unusually high 207Pb/206Pb ratios. We demonstrate that the length scales of these clusters make U–Pb age biasing impossible, and that they formed during the later reheating event. Our tomography data thereby confirm that any mixing event of the silicate Earth must have occurred before 4.4 Gyr ago, consistent with magma ocean formation by an early moon-forming impact about 4.5 Gyr ago.

Beschreibung: Nature Climate Change 4 230 doi: 10.1038/nclimate2170

Beschreibung: Nature Climate Change 4 232 doi: 10.1038/nclimate2114

Beschreibung: Nature Climate Change 4 233 doi: 10.1038/nclimate2139

Beschreibung: Nature Climate Change 4 234 doi: 10.1038/nclimate2140

Beschreibung: Nature Climate Change 4 234 doi: 10.1038/nclimate2171

Beschreibung: Truly understanding climate-related disaster risk, and the management of that risk, can inform effective action on climate adaptation and the loss and damage mechanism, the main vehicle under the UN Climate Convention for dealing with climate-related effects, including residual impacts after adaptation. Nature Climate Change 4 235 doi: 10.1038/nclimate2137

Beschreibung: Effective mitigation of climate change requires investment flows to be redirected from high- to low-carbon technologies. However, especially in developing countries, low-carbon investments often suffer from high risks. More research is needed to address these risks and allow sound policy decisions to be made. Nature Climate Change 4 237 doi: 10.1038/nclimate2112

Beschreibung: Nature Climate Change 4 240 doi: 10.1038/nclimate2185

Beschreibung: When it comes to investments, the smart bet may be on clean energy and low-carbon infrastructure. Sonja van Renssen looks at the causes and implications of divestment from fossil fuels. Nature Climate Change 4 241 doi: 10.1038/nclimate2175

Beschreibung: Nature Climate Change 4 243 doi: 10.1038/nclimate2188

Beschreibung: Nature Climate Change 4 243 doi: 10.1038/nclimate2189