The role of CO2 decline for the onset of Northern Hemisphere glaciation

The Pliocene–Pleistocene Transition (PPT), from around 3.2 to 2.5 million years ago (Ma), represented a major shift in the climate system and was characterized by a gradual cooling trend and the appearance of large continental ice sheets over northern Eurasia and North America. Paleo evidence indicates that the PPT was accompanied and possibly caused by a decrease in atmospheric CO2, but the temporal resolution of CO2 reconstructions is low for this period of time and uncertainties remain large. Therefore, instead of applying existent CO2 reconstructions we solved an ‘inverse’ problem by finding a schematic CO2 concentration scenario that allows us to simulate the temporal evolution of key climate characteristics in agreement with paleoclimate records. To this end, we performed an ensemble of transient simulations with an Earth system model of intermediate complexity from which we derived a best guess transient CO2 scenario for the interval from 3.2 to 2.4 Ma that gives the best fit between the simulated and reconstructed benthic δ18O and global sea surface temperature evolution. Our data-constrained CO2 scenarios are consistent with recent CO2 reconstructions and suggest a gradual CO2 decline from 375–425 to 275–300 ppm, between 3.2 and 2.4 Ma. In addition to a gradual decline, the best fit to paleoclimate data requires the existence of pronounced CO2 variability coherent with the 41-kyr (1 kyr = 1000 years) obliquity cycle. In our simulations the long-term CO2 decline is accompanied by a relatively abrupt intensification of Northern Hemisphere glaciation at around 2.7 Ma. This is the result of a threshold behaviour of the ice sheets response to gradual CO2 decrease and orbital forcing. The simulated Northern Hemisphere ice sheets during the early Pleistocene glacial cycles reach a maximum volume equivalent to a sea level drop of about 40 m. Both ice volume and benthic δ18O are dominated by 41-kyr cyclicity. Our simulations suggest that before 2.7 Ma Greenland was ice free during summer insolation maxima and only partly ice covered during periods of minimum summer insolation. A fully glaciated Greenland comparable to its present-day ice volume is modelled only during glacial maxima after 2.7 Ma and more continuously after 2.5 Ma

Mid-depth South Atlantic Ocean circulation and chemical stratification during MIS-10 to 12: implications for atmospheric CO₂

A detailed record of benthic foraminifera carbon isotopes from the intermediate-depth South East Atlantic margin shows little glacial-interglacial variability between MIS-12 to MIS-10, suggesting that Northern Atlantic deepwaters consistently penetrated to at least 30° S. Millennial-scale increases in either the mass or flux of northern-sourced deepwaters over the core site occurred alongside reductions in Lower North Atlantic Deep Water recorded in North Atlantic sediment cores and show that the lower and intermediate limb of the Atlantic deepwater convective cell oscillated in anti-phase during previous glacial periods. In addition, a 500 yr resolution record of the Cape Basin intermediate-deep δ13C gradient shows that a reduction in deep Southern Ocean ventilation at the end of MIS-11 was consistent with a modelled CO2 drawdown of ~21–30 ppm. Further increases in the Southern Ocean chemical divide during the transition into MIS-10 were completed before minimum CO2 levels were reached, suggesting that other mechanisms such as alkalinity changes were responsible for the remaining ~45 ppm drawdown

A review of potential impacts of climate change on coffee cultivation and mycotoxigenic fungi

Coffee is one of the most traded commodities in the world. It plays a significant role in the global economy, employing over 125 million people. However, it is possible that this vital crop is threatened by changing climate conditions and fungal infections. This paper reviews how suitable areas for coffee cultivation and the toxigenic fungi species of Aspergillus, Penicillium, and Fusarium will be affected due to climate change. By combining climate models with species distribution models, a number of studies have investigated the future distribution of coffee cultivation. Studies predict that suitable coffee cultivation area could drop by ~50% under representation concentration pathway (RCP) 6.0 by 2050 for both Arabica and Robusta. These findings agree with other studies which also see an altitudinal migration of suitable cultivation areas to cooler regions, but limited scope for latitudinal migration owing to coffee’s inability to tolerate seasonal temperature changes. Increased temperatures will see an overall increase in mycotoxin production such as aflatoxins, particularly in mycotoxigenic fungi (e.g., Aspergillus flavus) more suited to higher temperatures. Arabica and Robusta’s limited ability to relocate means both species will be grown in less suitable climates, increasing plant stress and making coffee more susceptible to fungal infection and mycotoxins. Information regarding climate change parameters with respect to mycotoxin concentrations in real coffee samples is provided and how the changed climate affects mycotoxins in non-coffee systems is discussed. In a few areas where relocating farms is possible, mycotoxin contamination may decrease due to the “parasites lost” phenomenon. More research is needed to include the effect of mycotoxins on coffee under various climate change scenarios, as currently there is a significant knowledge gap, and only generalisations can be made. Future modelling of coffee cultivation, which includes the influence of atmospheric carbon dioxide fertilisation and forest management, is also required; however, all indications show that climate change will have an extremely negative effect on future coffee production worldwide in terms of both a loss of suitable cultivation areas and an increase in mycotoxin contamination.This research received external funding from the Natural Environment Research Council London DTP (NE/L002485/1).info:eu-repo/semantics/publishedVersio

Regulation of the ESC transcriptome by nuclear long non-coding RNAs

Long noncoding (lnc)RNAs have recently emerged as key regulators of gene expression. Here, we performed high-depth poly(A)+ RNA sequencing across multiple clonal populations of mouse embryonic stem cells (ESCs) and neural progenitor cells (NPCs) to comprehensively identify differentially regulated lncRNAs. We establish a biologically robust profile of lncRNA expression in these two cell types and further confirm that the majority of these lncRNAs are enriched in the nucleus. Applying weighted gene co-expression network analysis, we define a group of lncRNAs that are tightly associated with the pluripotent state of ESCs. Among these, we show that acute depletion of PAT-14 using antisense oligonucleotides impacts the differentiation- and development-associated gene expression program of ESCs. Furthermore, we demonstrate that Firre, a lncRNA highly enriched in the nucleoplasm and previously reported to mediate chromosomal contacts in ESCs, controls a network of genes related to RNA processing. Together, we provide a comprehensive, up-to-date and high resolution compilation of lncRNA expression in ESCs and NPCs and show that nuclear lncRNAs are tightly integrated into the regulation of ESC gene expression

What drives interannual variation in tree ring oxygen isotopes in the Amazon?

Oxygen isotope ratios in tree rings (δ18OTR) from northern Bolivia record local precipitation δ18O and correlate strongly with Amazon basin-wide rainfall. While this is encouraging evidence that δ18OTR can be used for palaeoclimate reconstructions, it remains unclear whether variation in δ18OTR is truly driven by within-basin processes, thus recording Amazon climate directly, or if the isotope signal may already be imprinted on incoming vapour, perhaps reflecting a pan-tropical climate signal. We use atmospheric back-trajectories combined with satellite observations of precipitation, together with water vapour transport analysis to show that δ18OTR in Bolivia are indeed controlled by basin-intrinsic processes, with rainout over the basin the most important factor. Furthermore, interannual variation in basin-wide precipitation and atmospheric circulation are both shown to affect δ18OTR. These findings suggest δ18OTR can be reliably used to reconstruct Amazon precipitation, and have implications for the interpretation of other palaeoproxy records from the Amazon basin

The inherent instability of leveed seafloor channels

New analytical models demonstrate that under 2 aggradational flow conditions seafloor channel-levee systems are inherently unstable; both channel area and stability necessarily decrease at long timescales. In time such systems must avulse purely through internal (autogenic) forcing. Although autogenic instabilities likely arise over long enough time for additional allogenic forcing to be expected, channel-levee sensitivity to variations in flow character depends on the prior degree of system evolution. Recalibrated modern Amazon Fan avulsion timings are consistent with this model, challenging accepted interpretations of avulsion triggering

Phase Angle and Bio-Impedance Values during the First Year after Delivery in Women with Previous Excessive Gestational Weight Gain: Innovative Data from the Belgian INTER-ACT Study

Phase angle (PhA) is a body composition parameter that measures changes in the amount and quality of soft tissue. Few studies have explored PhA in pregnancy or postpartum. The aim of this study was to explore the PhA during the first year postpartum in a Belgian cohort using data from the control group of the INTER-ACT study, an intervention trial targeting those with excess gestational weight gain. A secondary aim was to examine associations between PhA and potential explanatory variables. Women aged ≥18 with excessive weight gain in a singleton pregnancy and without a chronic disease were eligible. Data collection included anthropometry as well as demographic and lifestyle questionnaires at 6 weeks, 6 months and 12 months postpartum. Body composition, including PhA, was measured with the Tanita MC780SMA device. Data was analysed using correlation and mixed model analyses. A total of 509 participants (median age 31.2) were included. The median PhA at 6 weeks postpartum was 5.8°. Higher PhA values were seen in multiparous women (p = 0.02) but there was no association with any other lifestyle or demographic factors. PhA values were positively associated with muscle mass and BMI (r = 0.13, p = 0.004 and r = 0.18, p &lt; 0.001) at 6 weeks postpartum. PhA increased slightly in the 12 months postpartum, which was related to a decrease in fat percentage (p = 0.004). Further research in the pregnant/postpartum population is needed to elucidate any links with perinatal or future health outcomes.</jats:p

Abrupt intrinsic and extrinsic responses of southwestern Iberian vegetation to millennial-scale variability over the past 28 ka

We present new high-resolution pollen records combined with palaeoceanographic proxies from the same samples in deep-sea cores SHAK06-5K and MD01-2444 on the southwestern Iberian Margin, documenting regional vegetation responses to orbital and millennial-scale climate changes over the last 28 ka. The chronology of these records is based on high-resolution radiocarbon dates of monospecific samples of the planktonic foraminifera Globigerina bulloides, measured from SHAK06-5K and MD01-2444 and aligned using an automated stratigraphical alignment method. Changes in temperate and steppe vegetation during Marine Isotope Stage 2 are closely coupled with sea surface temperature (SST) and global ice-volume changes. The peak expansion of thermophilous woodland between ~10.1 and 8.4 cal ka bp lags behind the boreal summer insolation maximum by ~2 ka, possibly arising from residual high-latitude ice-sheets into the Holocene. Rapid changes in pollen percentages are coeval with abrupt transitions in SSTs, precipitation and winter temperature at the onset and end of Heinrich Stadial 2, the ice-rafted debris event and end of Heinrich Stadial 1, and the onset of the Younger Dryas, suggesting extrinsically forced southwestern Iberian ecosystem changes by abrupt North Atlantic climate events. In contrast, the abrupt decline in thermophilous elements at ~7.8 cal ka bp indicates an intrinsically mediated abrupt vegetation response to the gradually declining boreal insolation, potentially resulting from the crossing of a seasonality of precipitation threshold

Мировоззрение М.В. Ломоносова. К 300-летию со дня рождения великого ученого

Fundamental factors of the formation of scientific and philosophical world view of the great Russian scientist and thinker M.V. Lomonosov (1711-1765) are exposed. Correlation between scientific and philosophical reasoning in his creation work is analysed. His contribution to developing the national philosophy is shown.В статье раскрыты основополагающие факторы формирования научного и философского мировоззрения великого русского ученого и мыслителя М.В. Ломоносова (1711-1765), проанализирована взаимосвязь естественнонаучного и философского мышления в его творчестве, показан его вклад в развитие отечественной философской мысли

An assistive and research framework methodology for ships’ upkeep and repair organisational learning performance

The Omani Dockyard (OD) requires the development of a research methodology, which encompasses an assistive framework to maintain the research boundary to support a research framework. A research framework is developed to understand the behaviour of variables. A deductive/quantitative – survey questionnaire is employed in the main research to statistically understand the ‘mindsets/opinions’ of a large population and an inductive/qualitative – semi-structured interview using selected senior managers for the total research. Another questionnaire was used to critically learn from the agreement of the senior managers if the proposed contributions were in line with the ships’ upkeep and repair ‘organisational performance’. The initial and most definitive requirement is also to understand the strength of independent and mediation constructs applicability for the enhancement of performance. The problem is in the area of ‘enhancement of organisational learning on knowledge and competencies’ to underpin ships’ upkeep and repair support performance for better availability of operational ships. This research methodology was designed for a ‘major piece of research’ involving a doctorate dissertation in ships’ support performance. The conclusion and recommendation for a ‘major piece of research’ formulated the framework/model to underpin performance. This study concentrates on the research methodology that was used for ships’ upkeep and repair performance of the Omani dockyard with a compressive description of the total results, which can be generalized for other studies