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Effects of wood chip amendments on the revegetation performance of plant species on eroded marly terrains in a Mediterranean mountainous climate (Southern Alps, France)

This paper presents the results of two experiments of revegetation techniques in context of water erosion and mountainous Mediterranean climate. We studied the interest of a wood chip amendment, applied on soil surface (mulch), and its interaction with plant development. The use of different plant species and the monitoring on three growing seasons (with climatic variations) allow us to specify the interest of wood chip mulch to improve revegetation especially in erosion and drought conditions.

The link between marine sediment records and changes in Holocene Saharan landscape: simulating the dust cycle

We demonstrate for the first time the direct link between dust accumulation in marine sediment cores and Saharan land surface by simulating the mid-Holocene and pre-industrial dust cycle as a function of Saharan land surface cover and atmosphere-ocean conditions using the coupled atmosphere-aerosol model ECHAM6-HAM2.1. Mid-Holocene surface characteristics, including vegetation cover and lake surface area, are derived from proxy data and simulations.

Combined fluvial and pluvial urban flood hazard analysis: concept development and application to Can Tho city, Mekong Delta, Vietnam

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-16-941-2016
13 April 2016

Many urban areas experience both fluvial and pluvial floods, thus this study aims to analyse fluvial and pluvial flood hazards as well as combined pluvial and fluvial flood hazards. This combined fluvial-pluvial flood hazard analysis is performed in a tropical environment for Can Tho city in the Mekong Delta. The final results are probabilistic hazard maps, showing the maximum inundation caused by floods of different magnitudes along with an uncertainty estimation.

Non-deforestation fire vs. fossil fuel combustion: the source of CO2 emissions affects the global carbon cycle and climate responses

We simulated both fire pulses and stable fire regimes and found the resulting climatic impacts to be irreconcilable with equivalent amounts of CO2 emissions produced by fossil fuel combustion. Consequently, side-by-side comparisons of fire and fossil fuel CO2 emissions—implicitly implying that they have similar effects—should be avoided. Our study calls for the explicit representation of fire in climate models in order to improve our understanding of its impacts in the Earth system.

Early warning signals of tipping points in periodically forced systems

We find early warnings of abrupt changes in complex dynamical systems such as the climate where the usual early warning indicators do not work. In particular, these are systems that are periodically forced, for example by the annual cycle of solar insolation. We show these indicators are good theoretically in a general setting then apply them to a specific system, that of the Arctic sea ice, which has been conjectured to be close to such a tipping point. We do not find evidence of it.

Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2015

We examine changes in SO2 and NO2 over the world’s most polluted regions during the first decade of Aura OMI observations. Over the eastern US, both NO2 and SO2 levels decreased by 40% and 80%, respectively. OMI confirmed large reductions in SO2 over eastern Europe’s largest coal power plants. The North China Plain has the world’s most severe SO2 pollution, but a decreasing trend been observed since 2011, with a 50% reduction in 2012-2014. India’s SO2 and NO2 levels are growing at a fast pace.

OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2015">Read more

Statistical analysis of magnetotail fast flows and related magnetic disturbances

This study presents an investigation on the occurrence of fast flows in the magnetotail using the complete available data set of the THEMIS spacecraft for the years 2007 to 2015. First, basic statistical findings concerning velocity distributions, occurrence rates, group structures and key features of 16 000 events are presented using Superposed Epoch and Minimum Variance Analysis techniques.

Kinetic isotope effects of ¹³CH₃D + OH and ¹³CH₃D + OH from 278 to 313 K

We present experimental kinetic isotope effects (KIE) for the OH oxidation of CH₃D and ¹³CH₃D and their temperature dependence. Our determination of the ¹³CH₃D+OH KIE is novel and we find no “clumped” isotope effect within the experimental uncertainty.

A multiproxy approach to understanding the “enhanced” flux of organic matter through the oxygen-deficient waters of the Arabian Sea

Drifting sediment traps were deployed in the oxygen-deficient waters of the Arabian Sea, where the sinking flux is less attenuated than in more oxic waters. Six mechanisms that might explain this “enhanced flux” were evaluated using literature and data. In the upper 500m, evidence was found supporting an oxygen effect and/or changes in the efficiency of the microbial loop, including the addition of chemoautotrophic carbon to the sinking flux.

Ideas and perspectives: Holocene thermokarst sediments of the Yedoma permafrost region do not increase the northern peatland carbon pool

We investigate the properties of soils and sediments in a particular and ancient Siberian permafrost landscape. We critically examine statements from a recent study that specific permafrost landforms affected by thawed permafrost (alases) in this region contain very large quantities of peat that previous studies had failed to include because of data set biases. We conclude that there is no evidence to suggest biases in existing data sets or that alas deposits increase the northern peatland pool.

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