Robust but weak winter atmospheric circulation response to future Arctic sea ice loss.

The possibility that Arctic sea ice loss weakens mid-latitude westerlies, promoting more severe cold winters, has sparked more than a decade of scientific debate, with apparent support from observations but inconclusive modelling evidence. Here we show that sixteen models contributing to the Polar Amplification Model Intercomparison Project simulate a weakening of mid-latitude westerlies in response to projected Arctic sea ice loss. We develop an emergent constraint based on eddy feedback, which is 1.2 to 3 times too weak in the models, suggesting that the real-world weakening lies towards the higher end of the model simulations. Still, the modelled response to Arctic sea ice loss is weak: the North Atlantic Oscillation response is similar in magnitude and offsets the projected response to increased greenhouse gases, but would only account for around 10% of variations in individual years. We further find that relationships between Arctic sea ice and atmospheric circulation have weakened recently in observations and are no longer inconsistent with those in models.

Role of Atmospheric Indices in Describing Inshore Directional Wave Climate in the United Kingdom and Ireland.

Improved understanding of how our coasts will evolve over a range of time scales (years-decades) is critical for effective and sustainable management of coastal infrastructure. A robust knowledge of the spatial, directional and temporal variability of the inshore wave climate is required to predict future coastal evolution and hence vulnerability. However, the variability of the inshore directional wave climate has received little attention, and an improved understanding could drive development of skillful seasonal or decadal forecasts of coastal response. We examine inshore wave climate at 63 locations throughout the United Kingdom and Ireland (1980-2017) and show that 73% are directionally bimodal. We find that winter-averaged expressions of six leading atmospheric indices are strongly correlated (r = 0.60-0.87) with both total and directional winter wave power (peak spectral wave direction) at all studied sites. Regional inshore wave climate classification through hierarchical cluster analysis and stepwise multi-linear regression of directional wave correlations with atmospheric indices defined four spatially coherent regions. We show that combinations of indices have significant skill in predicting directional wave climates (R 2  = 0.45-0.8; p < 0.05). We demonstrate for the first time the significant explanatory power of leading winter-averaged atmospheric indices for directional wave climates, and show that leading seasonal forecasts of the NAO skillfully predict wave climate in some regions.

North Atlantic climate far more predictable than models imply.

Quantifying signals and uncertainties in climate models is essential for the detection, attribution, prediction and projection of climate change1-3. Although inter-model agreement is high for large-scale temperature signals, dynamical changes in atmospheric circulation are very uncertain4. This leads to low confidence in regional projections, especially for precipitation, over the coming decades5,6. The chaotic nature of the climate system7-9 may also mean that signal uncertainties are largely irreducible. However, climate projections are difficult to verify until further observations become available. Here we assess retrospective climate model predictions of the past six decades and show that decadal variations in North Atlantic winter climate are highly predictable, despite a lack of agreement between individual model simulations and the poor predictive ability of raw model outputs. Crucially, current models underestimate the predictable signal (the predictable fraction of the total variability) of the North Atlantic Oscillation (the leading mode of variability in North Atlantic atmospheric circulation) by an order of magnitude. Consequently, compared to perfect models, 100 times as many ensemble members are needed in current models to extract this signal, and its effects on the climate are underestimated relative to other factors. To address these limitations, we implement a two-stage post-processing technique. We first adjust the variance of the ensemble-mean North Atlantic Oscillation forecast to match the observed variance of the predictable signal. We then select and use only the ensemble members with a North Atlantic Oscillation sufficiently close to the variance-adjusted ensemble-mean forecast North Atlantic Oscillation. This approach greatly improves decadal predictions of winter climate for Europe and eastern North America. Predictions of Atlantic multidecadal variability are also improved, suggesting that the North Atlantic Oscillation is not driven solely by Atlantic multidecadal variability. Our results highlight the need to understand why the signal-to-noise ratio is too small in current climate models10, and the extent to which correcting this model error would reduce uncertainties in regional climate change projections on timescales beyond a decade.

Big telescope, big data: towards exascale with the Square Kilometre Array.

Unlike optical telescopes, radio interferometers do not image the sky directly but require specialized image formation algorithms. For the Square Kilometre Array (SKA), the computational requirements of this image formation are extremely demanding due to the huge data rates produced by the telescope. This processing will be performed by the SKA Science Data Processor facilities and a network of SKA Regional Centres, which must not only deal with SKA-scale data volumes but also with stringent science-driven image fidelity requirements. This article is part of a discussion meeting issue 'Numerical algorithms for high-performance computational science'.

A radio ridge connecting two galaxy clusters in a filament of the cosmic web.

Galaxy clusters are the most massive gravitationally bound structures in the Universe. They grow by accreting smaller structures in a merging process that produces shocks and turbulence in the intracluster gas. We observed a ridge of radio emission connecting the merging galaxy clusters Abell 0399 and Abell 0401 with the Low-Frequency Array (LOFAR) telescope network at 140 megahertz. This emission requires a population of relativistic electrons and a magnetic field located in a filament between the two galaxy clusters. We performed simulations to show that a volume-filling distribution of weak shocks may reaccelerate a preexisting population of relativistic particles, producing emission at radio wavelengths that illuminates the magnetic ridge.

Maternal vitamin D and E intakes during early pregnancy are associated with airway epithelial cell responses in neonates.

BACKGROUND: Antenatal factors including maternal diet may predispose to airway disease, possibly by impacting on fetal airway development. OBJECTIVE: This cohort study tested the hypothesis that maternal vitamin D and E status in early pregnancy is associated with airway epithelial cell (AEC) responses in new born infants and examined constitutive and TNFα/IL-1ß, house dust mite (HDM) extract or lipopolysaccharide (LPS)-stimulated neonatal AEC responses in vitro. METHODS: Maternal dietary vitamin D and E intakes (plasma 25[OH]D3 or α-tocopherol) were characterized at 10-12 weeks gestation. Neonatal nasal AECs were collected soon after birth and cultured to tertiary passage. Constitutive and stimulated - TNFα/IL-1ß, HDM extract or LPS - secretory responses (VEGF, RANTES, MCP-1, IL-17A, IFN-γ, GM-CSF, eotaxin, MIP1-α, MIP1-ß, ICAM, IL-6, IL-8, IL-10, TNF) in 139 AEC cultures were quantified. RESULTS: AEC mediator release was greater following TNF-α/IL-1ß, HDM or LPS stimulation compared to constitutive release. Increased maternal dietary vitamin D was associated with significant increases in IL-10 release by AEC after stimulation with TNF-α/IL-1ß (P = 0.024) or HDM (P = 0.049). Maternal plasma α-tocopherol at 10-12 weeks gestation was positively associated with MIP1α (Spearman's rho 0.242, P = 0.009) and IL-3 (ρ 0.189, P = 0.043) responses after TNF-α/IL-1ß stimulation and negatively associated with TNF (ρ -0.404, P = 0.011) and MIP1ß (ρ -0.322, P = 0.046) responses after LPS stimulation. DISCUSSION: Neonatal AECs respond to pro-inflammatory and allergenic stimuli in vitro demonstrating their potential to function as components of the innate immune response. Our findings suggest that associations exist between maternal micronutrient intake during early pregnancy and aspects of stimulated neonatal airway epithelial cell secretory function that may in turn impact on the development of asthma and/or allergic rhinitis in later life.

Possible impacts of a future grand solar minimum on climate: Stratospheric and global circulation changes.

A future decline in solar activity would not offset projected global warmingA future decline in solar activity could have larger regional effects in winterTop-down mechanism contributes to Northern Hemisphere regional response.

Inhibitory effects of Montelukast on mediator release by nasal epithelial cells from asthmatic subjects with or without allergic rhinitis.

AIMS: This study tested inhibitory effects of in vitro Montelukast treatment on nasal airway epithelial cells (AEC) cultured from asthmatic patients treated with Montelukast with and without concomitant allergic rhinitis. We further examined the effect of Montelukast withdrawal in these patients on cytokine release from cultured nasal AEC. METHODS: Nasal AEC were collected by brushings from subjects with a history of stable (no exacerbations or change in medication for ≥ 1 month) physician confirmed mild/moderate asthma whose asthma symptoms were documented to benefit from Montelukast treatment (NCT01230437). Release of the following mediators by nasal AEC were measured: IL-8, IL-6, IL-10, GM-CSF, RANTES, eotaxin and IFN-γ. Nasal AEC were cultured before and one week after withdrawal of their Montelukast treatment. RESULTS: Forty two asthmatics were recruited. Nasal AEC were successfully cultured in 17 at the first assessment, 14 at the second assessment and in 10 individuals at both assessments. Nasal AEC release was no different between asthmatics with or without allergic rhinitis. Montelukast significantly suppressed the release of IL-8 (p = 0.016), IL-6 (p = 0.006), RANTES (p = 0.002) and IFN-γ (p = 0.046), in a dose dependent manner in unstimulated cultures but not in those stimulated with IL-1/TNF. Withdrawal of Montelukast treatment, was associated with increased IL-8 and RANTES secretion in unstimulated nasal AEC cultured from subjects with asthma and allergic rhinitis but not with asthma alone. CONCLUSIONS: Montelukast treatment for asthma symptoms reversibly suppresses nasal AEC release of pro-inflammatory mediators (i.e. IL-8 and RANTES) but only in those cells cultured from subjects with concomitant allergic rhinitis.

High prevalence of skin symptoms among bakery workers.

BACKGROUND: Occupational skin disease is common and bakery workers are at increased risk of hand dermatitis. AIMS: To explore the frequency of, and to identify risk factors for, skin symptoms in a small bakery. METHODS: A cross-sectional survey of workers in a small bakery in Scotland, using a self-completed questionnaire regarding skin symptoms over the last 12 months. Additionally, data on self-reported atopy status, glove use and daily hand washing frequencies were obtained. Workers were classed as being at low, medium or high risk of occupational skin disease based on their job titles. RESULTS: The overall response rate was 85% (52 women, 41 men) with a mean age of 41 (range 17-72). Eleven per cent of bakers, confectioners and packers and 31% of cleaners, cooks and food production workers reported at least one skin symptom. Thirty-three per cent of symptomatic low-risk workers, 50% of symptomatic medium-risk workers and 75% of symptomatic high-risk workers stated their symptoms usually improved away from work. While washing hands more frequently than 20 times a day had an increased risk of skin symptoms, this was not significant [OR 3.5 (95% CI 0.9-13.2)]. CONCLUSIONS: There was a high prevalence of skin symptoms among these bakery workers which was more than double that previously reported in UK bakeries. Frequent washing of hands as a risk factor for skin symptoms may warrant further investigation in bakery workers.

Sodium metabisulphite induced airways disease in the fishing and fish-processing industry.

BACKGROUND: Sodium metabisulphite (SMBS) is recognized as a potential cause of airway irritation and possibly occupational asthma, but awareness of its use in the fishing and fish-processing industry is low. AIMS AND METHODS: To describe three cases of occupational airways disease due to SMBS exposure and to review the literature. RESULTS: Three patients, one trawlerman and two prawn processors, developed work-related airways disease due to exposure to SMBS, one with irritant-induced asthma with a positive-specific bronchial challenge associated with very high sulphur dioxide exposures, one with occupational asthma and one with vocal cord dysfunction and underlying asthma. Of the nine cases recorded in the literature, most were non-atopic and responses to specific bronchial challenge when undertaken showed an immediate response. Exposures to sulphur dioxide in these settings are very high, in excess of 30 ppm. CONCLUSION: SMBS should be regarded as a cause of occupational airways disease and its use in the fish and prawn-processing industry investigated further to better identify risks from exposure and handling of the agent in the workplace.

Removal of chlorofluorocarbons by increased mass exchange between the stratosphere and troposphere in a changing climate.

Chlorofluorocarbons (CFCs), along with bromine compounds, have been unequivocally identified as being responsible for most of the anthropogenic destruction of stratospheric ozone. With curbs on emissions of these substances, the recovery of the ozone layer will depend on their removal from the atmosphere. As CFCs have no significant tropospheric removal process, but are rapidly photolysed above the lower stratosphere, the timescale for their removal is set mainly by the rate at which air is transported from the troposphere into the stratosphere. Using a global climate model we predict that, in response to the projected changes in greenhouse-gas concentrations during the first half of the twenty-first century, this rate of mass exchange will increase by 3% per decade. This increase is due to more vigorous extra-tropical planetary waves emanating from the troposphere. We estimate that this increase in mass exchange will accelerate the removal of CFCs to an extent that recovery to levels currently predicted for 2050 and 2080 will occur 5 and 10 years earlier, respectively.