ALBERT

Description: Increasing optical depth poleward of 45° is a robust response to warming in global climate models. Much of this cloud optical depth increase has been hypothesized to be due to transitions from ice-dominated to liquid-dominated mixed-phase cloud. In this study, the importance of liquid-ice partitioning for the optical depth feedback is quantified for 19 CMIP5 models. All models show a monotonic partitioning of ice and liquid as a function of temperature, but the temperature at which ice and liquid are equally mixed (the glaciation temperature) varies by as much as 40K across models. Models that have a higher glaciation temperature are found to have a smaller climatological liquid water path (LWP) and condensed water path, and experience a larger increase in LWP as the climate warms. The ice-liquid partitioning curve of each model may be used to calculate the response of LWP to warming. It is found that the re-partitioning between ice and liquid in a warming climate contributes at least 20% to 80% of the increase in LWP as the climate warms, depending on model. Inter-model differences in the climatological partitioning between ice and liquid are estimated to contribute at least 20% to the inter-model spread in the high-latitude LWP response in the mixed-phase region poleward of 45°S. It is hypothesized that a more thorough evaluation and constraint of GCM mixed-phase cloud parameterizations, and validation of the total condensate and ice-liquid apportionment against observations will yield a substantial reduction in model uncertainty in the high-latitude cloud response to warming.

Description: The Kingston Peak Formation is a Cryogenian sedimentary succession that crops out in the Death Valley area, California. It is widely accepted to record pre-glacial conditions (KP1), followed by two glaciations of pan-global extent, the older Sturtian (KP2 to KP3) and younger Marinoan glaciation (KP4). In the type area (the Kingston Range), detailed facies analysis of the Sturtian succession reveals that a basal diamictite unit and an upper boulder conglomerate were deposited by proglacial subaqueous sediment gravity flows. An olistostrome unit punctuating the succession is interpreted to result from tectonically-induced downslope mobilisation during isostatic rebound, triggered by significant ice-meltback. Focussing on strata onlapping the olistostrome, this paper provides insight into the processes of glacial re-advance following an intra-Sturtian glacial minimum. The first 50 m of strata above the olistostrome are thinly-bedded turbidites that are devoid of lonestones. A trend toward thicker graded beds upsection, in concert with the gradual appearance and then abundance of lonestones, testifies to the influence of ice rafting and to the resumption of a direct ice sheet influence upon sedimentation. Stratigraphic organisation into thickening and coarsening upward bedsets over a multi-metre scale reveals a subaqueous gravity flow-dominated succession composed of a spectrum of high to low density turbidites, with thick graded boulder-conglomerates at intervals. The finer-grained facies assemblage is heterolithic: current ripple cross-laminated sandstones intercalated with shales that bear delicate granule to pebble-sized dropstones in abundance. Intervals of dropstone-bearing and dropstone-free strata are attributable to dynamic oscillation of the ice margin in the hinterland. Integrating palaeocurrent data with observations from neighbouring outcrop belts allow a detailed palaeogeographic map of the eastern Death Valley area to be compiled for the first time. This article is protected by copyright. All rights reserved.

Description: Humans and their social institutions have a strong impact on the design and operation of our water resource systems, whether in response to flooding, drought, or just normally occurring events that include allocating water to different water users. Humans are a part of most water resource systems that modelers are asked to study. If modelers were able to predict human behavior under various hydrologic scenarios, and how that behavior affects the performance of our water resource systems, we would be better able to manage them and perhaps derive additional benefits from them. Di Baldassarre, et al. (2013a, 2013b, 2015) and Sivapalan et al. (2012), have suggested a modeling approach that couples the hydrologic and social components of water resource systems in order to better understand such interactions between these components. Their dynamic modeling approach coupling the social and hydrologic components of an urban flood model motivates the discussion in this paper on how their modeling approach might be extended to estimate possible human responses resulting from their perceptions of the effectiveness of a range of flood management and mitigation measures. But even with such extensions this writer is somewhat pessimistic as to the eventual ability of any mathematical models to predict even the probabilities of possible human or social actions without the direct participation of stakeholders. It is such stakeholders whose behavior and decisions will impact how we design and operate our water resource systems and will influence how well these systems will meet various economic and social objectives. This article is protected by copyright. All rights reserved.

Description: The Kingston Peak Formation is an archetypal Cryogenian succession that crops out across the Death Valley region of eastern California. Above pre-glacial strata (KP1), two distinct glacial phases have been recognized and are interpreted to be allied to the panglacial Sturtian (KP2 and KP3) and Marinoan (KP4) icehouse events. The thickest and most extensive unit, KP3, forms the entire exposed section at Sperry Wash. At this locality, ice-distal turbidites are succeeded in turn by ice-medial and ice-proximal facies, comprising a spectrum of ice-rafted debris-bearing turbidites, debrites and shales. These are overlain by ice-marginal grounding-line fan deposits interbedded with glacitectonically deformed heterolithics, supporting local advance to an ice-contact position. The succession records accumulation within a glacier-fed subaqueous shelf, wherein the clear progradational signature is driven by ice advance towards the south-east. Evolution of the subaqueous complex is five-fold, comprising: (i) ice-distal outwash; (ii) build-out of ice-medial depositional lobes; (iii) ice-proximal deposition and increased calving; (iv) resumed ice-margin advance; and (v) growth of ice-contact grounding line fan. This sequence is unique in the Death Valley region for recording the first evidence of advance to ice-marginal and ice-contact settings, thereby enabling the location of the glacier terminus to be documented for the first time. This article is protected by copyright. All rights reserved.

Description: The Vorogovka Basin records the establishment and infilling of a rift-related basin during Cryogenian time. Its infill records the whole spectrum of continental clastic and carbonate shelfal to deep marine systems. Initiation of the Vorogovka trough as a sedimentary basin was accompanied by subsidence and the accumulation of diamictites and conglomerates, of probable glacial affinity. The accumulation of Sturtian-age diamictites and the unsorted gravelstones resting on a metamorphic basement was coeval with rifting. Based on a facies analysis, it is shown that the Vorogovka trough demonstrates the evolution of a basin characterized initially by a half-graben with glaciofluvial deposits, and with a shelf shallow-marine shelf passing into a slope at the passive continental margin side. Episodic re(activation) of trough bounding faults can be illustrated on the basis of palaeocurrent analysis of fluvial-deltaic plain deposits, in deep-water fans and in shelfal, tide-related sediments. The final stage in basin evolution was characterized by the establishment of carbonate systems of probable microbial affinity and mixed tidal siliciclastic–carbonate sediments in the outer shelf. The phases of subsidence and palaeogeographic evolution proposed herein provide the basis for correlation between Cryogenian sediments of the Vorogovka basin with those on other continents. This article is protected by copyright. All rights reserved.

Description: Sedimentological insights underpin many of the important recent advances in understanding of Earth system behaviour in the Neoproterozoic Era. This article reviews three main areas: (i) chemical proxies and their preservation, with emphasis on carbonate facies; (ii) glacial and post-glacial facies, including their age constraints; III) sedimentary evidence for biotic innovations and responses. Chemostratigraphy plays an important role in ordering Neoproterozoic events and defining disturbances to the carbon cycle. There is increasing attention being paid to assessing the role of diagenetic origination or modification of chemostratigraphic signals. Alongside this, new criteria for identifying primary dolomite and precursor metastable phases such as ikaite have been developed. In respect of oxygenation, geochemical proxies substantiate the concept of a Neoproterozoic Oxygenation Event as a very gradual transition, the ocean being at any one time a heterogeneous assemblage of ferruginous, sulphidic and oxic conditions, with some evidence of increasing deep-sea oxidation through the Ediacaran Period. Techniques such as Fe-speciation need to be supplemented with proxies sensitive to suboxic conditions. More generally, it is predicted that petrographically constrained microanalytical studies will also become more important in reconstructing palaeoenvironmental conditions. The global distribution of Neoproterozoic glacial deposits combined with palaeomagnetic evidence supports the concept of panglaciations in which ice sheets reached sea-level in the tropics. Advances in radiometric dating have demonstrated the synchronous onset of global (Sturtian) glaciation at 717 Ma and the demise of a second (Marinoan) glaciation at 635 Ma and plausibly indicate long durations for each (55 Ma for Sturtian and 5 to 15 My for Marinoan). However, a compilation of radiometric dates indicates ambiguities indicating the need for further improvements to the radiometric and Sr-isotope database to understand events within the Sturtian time frame, the timing of onset of Marinoan glaciations, and age and synchroneity of individual negative δ 13 C anomalies. Sturtian deposits are typically thick, rift-related successions containing a range of environments influenced or dominated by dynamic glaciers, as well as ice-free marine intervals. Marinoan glacial deposits, by contrast, tend to be thin and continental. During the latter interval, oxygen isotope systematics of sulphate demonstrate that atmospheric CO 2 was high as predicted by Snowball Earth theory, and that sedimentation was influenced by orbital forcing. The Sturtian record, by comparison, needs to be searched for evidence of cold-climate hiatuses on the one hand and orbital forcing on the other. Cap carbonate formation appears to have coincided with rising sea-levels following panglaciations. Snowball theory considers that they formed rapidly in the postglacial greenhouse, but an alternative model of slower formation with clastic sediment starvation during transgression may prove to be consistent with new data and models showing extensive glacier terminations on land. For all facies, but especially caps, the use of microanalytical techniques and holistic studies of petrogenesis are future priorities. There are important discrepancies between molecular clock predictions of early metazoan origination and the hard evidence from the sedimentary records which largely depend on local exceptional preservation by early diagenesis. A variety of life survived panglaciation, and there is little evidence that glaciations directly caused oxygenation or stimulated evolution. This article is protected by copyright. All rights reserved.

Description: Invasive species threaten global biodiversity, agriculture, food security and ecosystem function. Pest risk analysis is key to biosecurity efforts, but is hampered by incomplete knowledge of invasive species distributions. We use statistical species distribution models to estimate presence probabilities for 1,739 crop pests and pathogens globally, and test model predictions for unobserved occurrences in China against observations abstracted from the Chinese literature. We show that large numbers of currently unobserved invasive species of agriculture are probably already present around the world, particularly in China, India and the former USSR. Abstract Invasive species threaten global biodiversity, food security and ecosystem function. Such incursions present challenges to agriculture where invasive species cause significant crop damage and require major economic investment to control production losses. Pest risk analysis (PRA) is key to prioritize agricultural biosecurity efforts, but is hampered by incomplete knowledge of current crop pest and pathogen distributions. Here, we develop predictive models of current pest distributions and test these models using new observations at subnational resolution. We apply generalized linear models (GLM) to estimate presence probabilities for 1,739 crop pests in the CABI pest distribution database. We test model predictions for 100 unobserved pest occurrences in the People's Republic of China (PRC), against observations of these pests abstracted from the Chinese literature. This resource has hitherto been omitted from databases on global pest distributions. Finally, we predict occurrences of all unobserved pests globally. Presence probability increases with host presence, presence in neighbouring regions, per capita GDP and global prevalence. Presence probability decreases with mean distance from coast and known host number per pest. The models are good predictors of pest presence in provinces of the PRC, with area under the ROC curve (AUC) values of 0.75–0.76. Large numbers of currently unobserved, but probably present pests (defined here as unreported pests with a predicted presence probability 〉0.75), are predicted in China, India, southern Brazil and some countries of the former USSR. We show that GLMs can predict presences of pseudoabsent pests at subnational resolution. The Chinese literature has been largely inaccessible to Western academia but contains important information that can support PRA. Prior studies have often assumed that unreported pests in a global distribution database represent a true absence. Our analysis provides a method for quantifying pseudoabsences to enable improved PRA and species distribution modelling.

Description: Abstract Extreme temperatures have caused various damages to society around the world. In Brazil, an example of that is the impact of cold and heat waves on public health. In order to analyze the temporal and spatial variability of such events, this study applied a single criterion to identify cold and heat waves. The study collected data on the events from daily temperature records from 264 weather stations over 56 years (1961–2016). The following parameters were used to describe each event: frequency, duration, severity, and intensity. The results showed that in all the Brazilian regions the frequency of heat waves increased and that of cold waves decreased between the years 1961 and 2016. The number of heat waves per year, notably, was greater than that of cold waves, and the mean duration of heat waves was about 1 day longer than that of cold waves. Additionally, it was found that cold waves were more severe and intense in areas often reached by cold air masses with temperatures below zero in most of Southern Brazil. In terms of severity and intensity of heat waves, two different configurations were observed: they were more severe in the Southern region and more intense in the Midwestern region of the country, and not so expressive in the Northern and Northeastern regions. Those findings justify the need for continuous updating of public policies focused on sectors often affected by cold and heat. This article is protected by copyright. All rights reserved.

Description: The Sample Analysis at Mars (SAM) instrument suite aboard Curiosity has detected chlorinated organic compounds in martian sediment samples. The chlorine in these molecules is thought to derive from oxychlorine salts in martian sediments, but the carbon source remains under investigation. To constrain possible carbon sources, we investigated how the composition and concentration of oxychlorine phases in solid samples affects organic molecules released from the Tenax traps onboard SAM. We created Mars analogue soils by spiking olivine sand with calcium perchlorate, magnesium perchlorate, or ferric iron chloride, and analyzed the volatiles generated during pyrolysis-gas chromatography–mass spectrometry (pyrolysis-GC-MS) using commercial instruments operated under SAM-like conditions, with and without a Tenax trap. Benzoic acid, phthalic anhydride, high-molecular-weight aromatics, and chlorobenzenes are produced from the trap in response to volatiles released during Cl salt pyrolysis. Changes in composition or concentration of oxychlorine phases between samples could thus potentially produce an increase in chlorobenzene, as observed between samples from Rocknest and Cumberland. However, in our experiments benzoic acid, phthalic anhydride, and chlorobenzenes increase in proportion with the amount of HCl sent to the trap, while in Cumberland samples the chlorobenzene increase showed no corresponding increase in HCl. Based on our experiments, the Tenax trap is a possible source of the traces of chlorobenzene observed at Rocknest, John Klein, and Confidence Hills. The order-of-magnitude higher chlorobenzene abundances observed at Cumberland cannot be attributed to the Tenax trap. Furthermore, we found no evidence of significant trap degradation after hundreds of experiments with Cl salt-containing analogue soils.

Description: “Mafic Mound” is a distinctive and enigmatic feature 75 km across and 1 km high near the center of the vast South Pole-Aitken Basin (SPA). Using several modern data sets, we characterize the composition, morphology, and gravity signature of the structure in order to assess its origin. Mafic Mound is found to exhibit a perched circular depression and a homogeneous high-Ca pyroxene-bearing composition. Several formation hypotheses based on known lunar processes are evaluated, including the possibilities that Mafic Mound represents (1) uplifted mantle, (2) SPA-derived impact melt, (3) a basalt-filled impact crater, or (4) a volcanic construct. Individually, these common processes cannot fully reproduce the properties of Mafic Mound. Instead, we propose a hybrid origin in which Mafic Mound is an edifice formed by magmatic processes induced by the formation and evolution of SPA. This form of nonmare volcanism has not previously been documented on the Moon.