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

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

Visitors’ and locals’ views of environmental management in Christchurch, New Zealand

The objective of the research presented in this report was to develop an understanding of visitors' and locals' views of environmental management in Christchurch. A total of 63 people were selected in a diverse, non-random sample with roughly equal proportions of men and women, and including 21 overseas visitors, 33 domestic visitors and 22 local people. Each subject sorted a pre selected set of structured photographs into nine piles, ranging from those that represented good environmental management to those that represented poor environmental management, to create their own Q sort. All Q sorts were factor analysed to identify three factors or views on environmental management. Subjects' attitudes, beliefs and expectations in making their selections were recorded in interviews and provide an additional basis for interpreting the three different factors. The themes distinctive to the factors, and the themes that are common to the factors, are discussed to develop some theoretical implications. Finally, a number of implications for policy are considered, in particular the need to retain a breadth of approaches to environmental management

Very low prevalence of IgE mediated wheat allergy and high levels of cross-sensitisation between grass and wheat in a UK birth cohort

BackgroundPatients often report adverse reactions to wheat. Interpretation of sensitization to wheat pollen and flour with/without sensitization to grass pollen is a clinical problem.AimWe set out to determine the prevalence of wheat allergy in a birth cohort (10/11 year olds) and investigate the usefulness of performing skin prick tests (SPT), specific IgE tests and component resolved diagnostics to wheat pollen and flour.MethodsThe Food Allergy and Intolerance Research (FAIR) birth cohort included babies born on the Isle of Wight (UK) between September 2001–August 2002 (n = 969). Children were followed up at 1, 2, 3 and 10/11 years. 588 children had SPTs to wheat pollen and grass during the 10 year follow-up. 294 children underwent further SPT to wheat flour and 246 had specific IgE testing to wheat and grass.ResultsEight children underwent oral food challenges (OFC). We diagnosed 0.48 % (4/827; 95 % CI 0–1 %) children with wheat allergy based on OFC. 16.3 % (96/588) were sensitized to grass pollen, 13.4 % (79/588) to wheat pollen; 78 % (75/96) sensitized to both. Only one child was sensitized to wheat flour and wheat pollen, but not grass pollen. For specific IgE, 15.0 % (37/246) and 36.2 % (89/246) were sensitized to wheat and grass pollen, with 40.5 % (36/89) sensitized to both. Of the 37 children sensitized to wheat, 3 (8.1 %) were sensitized to omega 5 gliadin, 1 (2.7 %) to wheat lipid transfer protein and 1 to wheat gliadin.ConclusionClinicians should be aware of the high level of cross-sensitization when performing tests to wheat and grass pollen i.e. sensitisation to wheat specific IgE and wheat pollen SPT should be assessed in the presence of grass pollen SPT and/or specific IgE

Centennial-scale evolution of Dansgaard-Oeschger events in the northeast Atlantic Ocean between 39.5 and 56.5 ka B.P

There is much uncertainty surrounding the mechanisms that forced the abrupt climate fluctuations found in many palaeoclimate records during Marine Isotope Stage (MIS)-3. One of the processes thought to be involved in these events is the Atlantic Meridional Overturning Circulation (MOC), which exhibited large changes in its dominant mode throughout the last glacial period. Giant piston core MD95-2006 from the northeast Atlantic Ocean records a suite of palaeoceanographic proxies related to the activity of both surface and deep water masses through a period of MIS-3 when abrupt climate fluctuations were extremely pronounced. A two-stage progression of surface water warming during interstadial warm events is proposed, with initial warming related to the northward advection of a thin warm surface layer within the North Atlantic Current, which only extended into deeper surface layers as the interstadial progressed. Benthic foraminifera isotope data also show millennial-scale oscillations but of a different structure to the abrupt surface water changes. These changes are argued to partly be related to the influence of low-salinity deepwater brines. The influence of deepwater brines over the site of MD95-2006 reached a maximum at times of rapid warming of surface waters. This observation supports the suggestion that brine formation may have helped to destabilize the accumulation of warm, saline surface waters at low latitudes, helping to force the MOC into a warm mode of operation. The contribution of deepwater brines relative to other mechanisms proposed to alter the state of the MOC needs to be examined further in future studies

Investigations on the Peach 4 Debrite, a Late Pleistocene Mass Movement on the Northwest British Continental Margin

The Peach 4 debrite is the most recent in a series of large scale Pleistocene MTDs within the Barra fan on the northwest British continental margin. Geophysical data indicate that Peach 4 was formed through a combination of blocky and muddy debris flows and affects an area of ~ 700 km2. BGS core sample 56 -10 36, located directly over the Peach 4 debrite, provides a minimum age of 14.68 ka cal BP for the last major failure. An upwards fining turbidite sequence in BGS core sample 56 -10 239 is associ-ated with increased As and S concentrations, indicators of diagenetic pyrite which forms under anoxic conditions. It is proposed that As and S concentrations may pro-vide a method of distinguishing between contourite and turbidite sedimentation, though further research is required

Increased auditory cortex neural response amplitude in adults with chronic unilateral conductive hearing impairment

Animal studies have demonstrated that unilateral hearing loss can induce changes in neural response amplitude of the mature central auditory system (CAS). However, there is limited physiological evidence of these neural gain changes in the auditory cortex of human adults. The present study investigated the impact of chronic, unilateral conductive hearing impairment on cortical auditory evoked potentials (CAEPs) recorded from 15 adults (21-65 years old) in response to a 1 kHz tone (80 ms duration) presented to the impaired ear via a bone conduction transducer. The amplitude and latency of the main CAEP components were compared to those obtained from normal hearing age-matched control participants. Both P1-N1 and N1-P2 amplitudes were significantly larger in the hearing impaired relative to the control participants. Differences between groups in the mean latencies of P1, N1, and P2 were not statistically significant. These results are the first to provide direct evidence of increased neural response amplitude in the adult human auditory cortex in the presence of unilateral conductive hearing loss. Importantly, the study shows that central gain changes are a direct result of deprivation of sound rather than cochlear or neural pathology

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

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

Mulga, a major tropical dry open forest of Australia: Recent insights to carbon and water fluxes

© 2016 IOP Publishing Ltd. Mulga, comprised of a complex of closely related Acacia spp., grades from a low open forest to tall shrublands in tropical and sub-tropical arid and semi-arid regions of Australia and experiences warm-to-hot annual temperatures and a pronounced dry season. This short synthesis of current knowledge briefly outlines the causes of the extreme variability in rainfall characteristic of much of central Australia, and then discusses the patterns and drivers of variability in carbon and water fluxes of a central Australian low open Mulga forest. Variation in phenology and the impact of differences in the amount and timing of precipitation on vegetation function are then discussed. We use field observations, with particular emphasis on eddy covariance data, coupled with modelling and remote sensing products to interpret inter-seasonal and inter-annual patterns in the behaviour of this ecosystem. We show that Mulga can vary between periods of near carbon neutrality to periods of being a significant sink or source for carbon, depending on both the amount and timing of rainfall. Further, we demonstrate that Mulga contributed significantly to the 2011 global land sink anomaly, a result ascribed to the exceptional rainfall of 2010/2011. Finally, we compare and contrast the hydraulic traits of three tree species growing close to the Mulga and show how each species uses different combinations of trait strategies (for example, sapwood density, xylem vessel implosion resistance, phenological guild, access to groundwater and Huber value) to co-exist in this semi-arid environment. Understanding the inter-annual variability in functional behaviour of this important arid-zone biome and mechanisms underlying species co-existence will increase our ability to predict trajectories of carbon and water balances for future changing climates