A framework for research linking weather, climate and COVID-19

Early studies of weather, seasonality, and environmental influences on COVID-19 have yielded inconsistent and confusing results. To provide policy-makers and the public with meaningful and actionable environmentally-informed COVID-19 risk estimates, the research community must meet robust methodological and communication standards.

Past pandemics and climate variability across the Mediterranean

The influence that meteorological, climatological and environmental factors had on historical disease outbreaks is often speculated upon, but little investigated. Here, we explore potential associations between pandemic disease and climate over the last 2,500 years in Mediterranean history, focusing on ancient disease outbreaks and the Justinianic plague in particular. We underscore variation in the quality, quantity and interpretation of written evidence and proxy information from natural archives, the comlexity of identifying and disentangling past climatological and environmental drivers, and the need to integrate diverse methodologies to discern past climate-disease linkages and leverage historical experiences to prepare for the rapid expansion of novel pathogenic diseases. Although the difficulties entailed in establishing historical climate-pandemic linkages persist to the present, this is a research area as urgent as it is complex and historical perspectives are desperately needed.

Impact of ambient temperature on mental health in Bern, Switzerland: a time-series study

Background

Previous studies suggest that people with mental disorders are more vulnerable to increased ambient temperatures (AT). In Switzerland, neuropsychiatric diseases contribute up to 35.1% of the total burden of disease. This burden could possibly increase in the future under current climate change scenarios, if no appropriate public health measures were implemented. However, there is lack of evidence on the impact of AT on mental health in Switzerland.

Objective

This study aimed to investigate the short-term association between AT and mental health hospitalizations in Bern, Switzerland.

Methods

From 1973 to 2010, we collected individual data on daily hospitalizations for mental disorders (71,931) from the University Hospital of Psychiatry and Psychotherapy in Bern. We used population-weighted daily mean AT for the canton of Bern derived from the 2.2-km gridded weather data provided by MeteoSwiss. We applied conditional Poisson regression with distributed lag linear models to assess the association and to account for delayed effects up to 3 days after the exposure. We conducted stratified analysis and by age, sex and diagnosis.

Results

The overall risk of hospitalizations increased linearly by 3.0% (95% CI: 0.0%, 6.0%) for every 10C°C-increase in mean daily AT. No differences in risk estimates were found across sex (3.0% in males (95% CI: 0%, 7.0%) and 4.0% in females (95% CI: 0%, 8.0%)) and age groups (≥ 45 years old: 4.0% (95% CI: 0%, 9.0%) and <45 years old: 3.0% (95% CI 0%, 7%)). Larger association estimates were found for schizophrenia (10.0%; 95% CI 4%, 16%), while no association was found for substance abuse (0.0%; 95% CI -7.0%, 6.0%).

Conclusions

Our preliminary findings suggest that increasing AT are associated with an increased risk in hospitalizations due to mental disorders in Bern. Specific public health policies should be urgently implemented in order to protect this vulnerable population sub-group from the challenges of climate change.

Key messages

Increased ambient temperatures are associated with an increased risk in hospitalizations due to mental health disorders. Specific health policies should be implement to protect mental health patients from the challenges of climate change.

Mediterranean circulation perturbations over the last five centuries: Relevance to past Eastern Mediterranean Transient-type events

The Eastern Mediterranean Transient (EMT) occurred in the Aegean Sea from 1988 to 1995 and is the most significant intermediate-to-deep Mediterranean overturning perturbation reported by instrumental records. The EMT was likely caused by accumulation of high salinity waters in the Levantine and enhanced heat loss in the Aegean Sea, coupled with surface water freshening in the Sicily Channel. It is still unknown whether similar transients occurred in the past and, if so, what their forcing processes were. In this study, sediments from the Sicily Channel document surface water freshening (SCFR) at 1910 ± 12, 1812 ± 18, 1725 ± 25 and 1580 ± 30 CE. A regional ocean hindcast links SCFR to enhanced deep-water production and in turn to strengthened Mediterranean thermohaline circulation. Independent evidence collected in the Aegean Sea supports this reconstruction, showing that enhanced bottom water ventilation in the Eastern Mediterranean was associated with each SCFR event. Comparison between the records and multi-decadal atmospheric circulation patterns and climatic external forcings indicates that Mediterranean circulation destabilisation occurs during positive North Atlantic Oscillation (NAO) and negative Atlantic Multidecadal Oscillation (AMO) phases, reduced solar activity and strong tropical volcanic eruptions. They may have recurrently produced favourable deep-water formation conditions, both increasing salinity and reducing temperature on multi-decadal time scales.

Detrended partial-cross-correlation analysis: a new method for analyzing correlations in complex system

In this paper, a new method, detrended partial-cross-correlation analysis (DPCCA), is proposed. Based on detrended cross-correlation analysis (DCCA), this method is improved by including partial-correlation technique, which can be applied to quantify the relations of two non-stationary signals (with influences of other signals removed) on different time scales. We illustrate the advantages of this method by performing two numerical tests. Test I shows the advantages of DPCCA in handling non-stationary signals, while Test II reveals the "intrinsic" relations between two considered time series with potential influences of other unconsidered signals removed. To further show the utility of DPCCA in natural complex systems, we provide new evidence on the winter-time Pacific Decadal Oscillation (PDO) and the winter-time Nino3 Sea Surface Temperature Anomaly (Nino3-SSTA) affecting the Summer Rainfall over the middle-lower reaches of the Yangtze River (SRYR). By applying DPCCA, better significant correlations between SRYR and Nino3-SSTA on time scales of 6 ~ 8 years are found over the period 1951 ~ 2012, while significant correlations between SRYR and PDO on time scales of 35 years arise. With these physically explainable results, we have confidence that DPCCA is an useful method in addressing complex systems.

Extreme climate of the global troposphere and stratosphere in 1940–42 related to El Niño

Although the El Niño/Southern Oscillation phenomenon is the most prominent mode of climate variability and affects weather and climate in large parts of the world, its effects on Europe and the high-latitude stratosphere are controversial. Using historical observations and reconstruction techniques, we analyse the anomalous state of the troposphere and stratosphere in the Northern Hemisphere from 1940 to 1942 that occurred during a strong and long-lasting El Niño event. Exceptionally low surface temperatures in Europe and the north Pacific Ocean coincided with high temperatures in Alaska. In the lower stratosphere, our reconstructions show high temperatures over northern Eurasia and the north Pacific Ocean, and a weak polar vortex. In addition, there is observational evidence for frequent stratospheric warmings and high column ozone at Arctic and mid-latitude sites. We compare our historical data for the period 1940-42 with more recent data and a 650-year climate model simulation. We conclude that the observed anomalies constitute a recurring extreme state of the global troposphere-stratosphere system in northern winter that is related to strong El Niño events.