Abstract There is substantial evidence on the associations between cold ambient temperature and adverse health effects. Less is known about the role of prolonged episodes of cold weather denoted as cold spells. This study assessed relations between cold spells and adverse health effects globally, and quantified and elaborated the associations between cold spells and sudden cardiac death (SCD) in northern Finland. Based on random-effects models in the meta-analyses of evidence from 9 studies around the world, cold spells were associated with increased mortality rates from all or all non-accidental causes (RR 1.10; 95% CI: 1.04–1.17), cardiovascular diseases (RR 1.11; 95% CI: 1.03–1.19), and respiratory diseases (RR 1.21; 95% CI: 0.97–1.51). Suggestive evidence of other health effects was identified. Investigating 51-years of coordinate-specific weather data at the home coordinates of autopsy-verified cases of SCD, conditional logistic regression in a case-crossover setting produced an estimate for the association between cold spells and the risk of SCD (OR 1.33; 95% CI: 1.00–1.78). A greater number of cold days preceding death increased the risk of SCD approximately 19% per day (OR 1.19; 95% CI: 1.07–1.32). The association between season-specific cold spells and SCD was strongest during autumn and winter, and lowest during spring and summer. The association was stronger for ischemic (OR 1.55; 95% CI: 1.12–2.13) than for non-ischemic SCD (OR 0.68; 95% CI: 0.32–1.45) (Q-statistic 3.85, p 0.05), confirmed by the autopsy finding. Among cases suffering ischemic SCD, the association seemed stronger in those without a prior diagnosis of ischemic heart disease than in those diagnosed during lifetime. The association seemed stronger with severe coronary stenosis (OR 1.60; 95% CI: 1.11–2.30), and weaker with moderate stenosis (OR 0.97; 95% CI: 0.37–2.55). The use of aspirin, β-blockers, and nitrates seemed to decrease the risk of ischemic SCD during cold spells. In conclusion, cold spells increased the risk of ischemic SCD, and patients without appropriate diagnosis and medications for ischemic heart disease seemed most susceptible. The results indicate that coronary stenosis plays a central role in the cold-related pathogenesis of SCD. Timely diagnosis and treatment of ischemic heart disease might reduce weather-related SCDs in a community. / Tiivistelmä Kylmän lämpötilan ja terveyshaittojen välisistä yhteyksistä on vahva tutkimusnäyttö. Vähemmän tiedetään pitkittyneiden kylmäjaksojen ja terveyshaittojen välisistä yhteyksistä. Tutkimuksessa arvioitiin kylmäjaksojen ja terveyshaittojen välisiä yhteyksiä globaalisti, ja määritettiin kylmäjaksojen ja sydänperäisen äkkikuoleman (SÄK) välisiä yhteyksiä Pohjois-Suomessa. Yhdeksän eri puolella maailmaa toteutetun tutkimuksen tulosten meta-analyysissa satunnaisvaikutusten malli osoitti yhteyden kylmäjaksojen ja kaikkien tai luonnollisien syiden (RR 1.10; 95% CI: 1.04–1.17), sydän- ja verisuonisairauksien (RR 1.11; 95% CI: 1.03–1.19), ja hengityselimistön sairauksien (RR 1.21; 95% CI: 0.97–1.51) kuolleisuuden välillä. Viitteellistä näyttöä havaittiin muista terveyshaitoista. Tutkittaessa 51-vuoden koordinaattikohtaista säätä case-crossover-asetelmassa oikeuslääketieteellisesti vahvistettujen SÄK-tapausten kotiosoitteissa, ehdollisen logistisen regression mukaan SÄK:n riski oli yhteydessä kuolemaa edeltävään kylmäjaksoon (OR 1.33; 95% CI: 1.00–1.78). Lisääntyvä kylmien päivien lukumäärä ennen kuolemaa lisäsi riskiä keskimäärin 19% päivää kohden (OR 1.19; 95% CI: 1.07–1.32). Yhteys kausikohtaisten kylmäjaksojen ja SÄK:n välillä oli vahvin syksyllä ja talvella, ja heikoin keväällä ja kesällä. Yhteys oli vahvempi kylmäjaksojen ja iskeemisen SÄK:n (OR 1.55; 95% CI: 1.12–2.13) kuin kylmäjaksojen ja ei-iskeemisen SÄK:n (OR 0.68; 95% CI: 0.32–1.45) välillä (Q-statistic 3.85, p 0.05). Iskeemisen SÄK:n kokeneilla yhteys vaikutti vahvemmalta tapauksilla joilla ei ollut aiempaa iskeemisen sydänsairauden diagnoosia, kuin tapauksilla jotka oli diagnosoitu elinaikana. Yhteys vaikutti vahvemmalta vaikea-asteisesta sepelvaltimostenoosia sairastavilla (OR 1.60; 95% CI: 1.11–2.30), kuin lievempi-asteisessa stenoosissa (OR 0.97; 95% CI: 0.37–2.55). Aspiriini, β-salpaajat, ja nitraatit vaikuttivat vähentävän iskeemisen SÄK:n riskiä kylmäjakson aikana. Yhteenvetona, kylmäjaksot lisäsivät iskeemisen SÄK:n riskiä, ja potilaat vailla iskeemisen sydänsairauden diagnoosia ja lääkityksiä vaikuttivat olevan alttiimpia kylmäjaksojen haittavaikutuksille. Tulokset viittaavat sepelvaltimostenoosin keskeiseen rooliin kylmään liittyvän SÄK:n patogeneesissä. Varhainen iskeemisen sydänsairauden diagnoosi ja siihen liittyvä sydäntä suojaava lääkitys voisivat vähentää säähän liittyviä SÄK:a.

Climate change poses a significant threat to bioenergy production, impacting plant’s phenology and physiological performance. Investigating the adaptation of bioenergy crops like Populus is crucial for sustaining production. Populus, known for its genetic variation and ease of study, offers insights into tree responses to climate change. My research, part of the Advancing Populus Pathways in the Southeast (APPS) project, focuses on various Populus genotypes across multiple growing seasons, exploring phenology under different management strategies. Planting Populus across two sites, namely Monroe and Pontotoc, allows for the examination of genotype responses to climate change factors, particularly in terms of phenology and productivity. Factors like parentage provenance and temperature fluctuations influence budburst timing. Additionally, management practices, such as coppicing, significantly affect budburst, with coppiced trees showing delayed timing (five to ten days) compared to non-coppiced ones. Cold spell damage during budbreak reveals vulnerability, with northern provenances exhibiting greater resilience. Understanding such events is vital for tailored management. Cold spells not only impact initial budbreak but also alter leaf phenology and canopy dynamics, affecting overall productivity. Genotypes exhibit varied responses to rising temperatures and CO2 levels, influenced by their parentage. Trees with northern provenance, for instance, display higher photosynthetic capacity, but may face thermal stress under certain temperature increases. Conversely, southern genotypes demonstrate moderate photosynthetic capacity, but showcase better adaptation to heat, offering potential for breeding resilient varieties. Leaf traits serve as proxies for biomass production and water use efficiency prediction, aiding in genotype screening. Mechanisms like self-shading and leaf movability influence responses to environmental changes. For instance, self-shading helps regulate leaf temperature, thereby enhancing photosynthetic performance, albeit with some trade-offs. Elevated CO2 levels enhance water use efficiency, but determining whole-tree water use efficiency requires integration of various methods. While leaf-level measurements correlate with whole-tree water use efficiency, an integrated approach, combining leaf-level gas exchange and isotopic measurements, shows promise. In conclusion, understanding Populus responses to climate change is crucial for sustainable bioenergy production in the southeastern United States. Insights into phenology, productivity, and adaptation mechanisms offer avenues for management and breeding strategies, ensuring resilience amidst shifting climates.

This study examined the effects of the January 2010 cold spell on mangrove utilizing coral reef fishes off the southeast coast of Florida, USA, in the vicinity of Biscayne National Park (BNP). An ongoing, fishery-independent mangrove visual survey documenting fish assemblages in BNP provided data from the years 1998 to 2014 for examination. Of particular interest were the presence, abundance, and size structure for five mangrove utilizing coral reef fishes: sergeant major (Abudefduf saxatilis), yellowfin mojarra (Gerres cinereus), schoolmaster snapper (Lutjanus apodus), gray snapper (Lutjanus griseus), and great barracuda (Sphyraena barracuda). These species were selected for analysis due to their economic and ecologic importance, their potential as environmental indicators, their connectedness to multiple habitats, and their abundance within the available data set. Data were collected using a modified visual ‘belt transect’ method, consisting of 60 m2 transects running parallel to the mangrove shorelines. Data for average length of fish were reconstructed to form standard normal distributions and the resulting lengths were assigned to various age-classes to create species-specific length-frequency distributions. Variations in presence and abundance were examined across three time periods (1998-2009; 2010-2011; 2012-2014), as well as comparisons of length-frequency distributions. Following the January 2010 cold spell, the presence and abundance values for the two years immediately following the event were significantly decreased compared to the years prior to the cold spell for most of the five species at either mainland (ML) or leeward key (LK) locations. Additionally, the presence and abundance estimates typically remained statistically decreased when compared against the remaining years in the available data set. The size structures for the majority of the five species at either location, however, were not consistently significantly different between the three time periods, as was hypothesized. Instead, the analyses showed mixed results, with the size structure typically shifting towards smaller individuals immediately following the event. These findings suggest that drops in water temperature resulting from cold spells are capable of directly impacting mangrove utilizing reef fish species, albeit to varying degrees depending on various factors, such as physiological tolerances, ecological life history strategies, and habitat requirements.

Background: Incidence of death and hospitalizations have been observed to depend on short-term changes in weather and to increase with extreme temperatures. This thesis aims to strengthen the scientific knowledge on the relationship between temperature and daily deaths, but also the relationship between temperature and daily hospital admissions. Methods: We constructed time series regression models using daily counts of death and daily weather from the Stockholm area incorporating adjustment for potential confounding factors, season, and long-term time trends. From these models, we established the short-term relationship with daily temperatures and the associated relative risks on daily deaths allowing for a delay between exposure and subsequent deaths. Daily hospital admissions and daily temperatures were analyzed correspondingly using data from Skåne. Results: Hot and cold temperatures significantly impact on mortality rates as well as rates of hospitalization in Sweden. We found an immediate heat effect on daily deaths, while the impacts of cold temperatures were delayed up to a week after exposure. Cold-related deaths are generally cardiovascular in nature, while deaths resulting from warm temperatures are cardiovascular, respiratory as well as non-cardiorespiratory in nature. The impacts following a heat wave appear to increase proportionally with the length of the extreme hot conditions. The results suggest that the population aged 45 years and older is the main group at elevated risk of death when exposed to high and low temperatures. Moreover, the results suggest that there are several factors of susceptibility on an individual basis that correspond to larger relative risk with high and/or low temperatures. Daily hospitalisations increased in particular among individuals with respiratory illnesses during extreme persistent heat, whereas high temperatures in general have little impact. In contrast, hospitalizations increased for up to two weeks following exposure to cold temperatures. Conclusions: The health impacts related to temperature are a serious concern and the attributed impacts are likely to increase to some extent in the future due to an ageing population. Public health preventive strategies should be developed to prevent health consequences related to heat waves and cold temperatures. Future studies should aim at identifying susceptible individuals with elevated death risk at hot and cold ambient temperature conditions.

Diss. (sammanfattning) Umeå : Umeå universitet, 2010.