Impacts of climate change on the association between extreme weather events and waterborne illness

Work Package I and 2. The results of the study show positive relationships between weather conditions and raw water quality, but associations with treated drinking water were much fewer. No correlations identified between raw / treated water quality and outbreaks of gastroenteritis, except for colour of treated water and increased number of outbreaks for 0-4 year old children. Extreme precipitation did not trigger an increase in gastroenteritis outbreaks. Our study shows that the biggest waterworks in Norway currently have treatment capacity to handle weather events and prevent waterborne disease. However, with aging distribution systems and more extreme weather conditions in the future, this can change. Modelling future climate scenarios is a requirement to be able to prepare for and handle the potential for increased treatment capacity. Impact of future climate scenarioes. Climate change will lead to frequent extreme weather conditions in Norway. More extreme precipitation and increased drainage are associated with higher concentrations of indicator bacteria, colour and turbidity in raw water of Norwegian waterworks, which potentially leads to a deterioration of drinking water quality. With continued climate change, we expect higher concentrations of water quality indicators for raw water by the end of the century due to the expected increase in precipitation. We also estimate an increase in E. coli bacterial concentration in winter in the west and east, and a decrease in intestinal enterococci bacterial concentration in the summer in the north. Possible higher future maximum temperatures may increase the concentrations of water quality indicators in the winter and spring, and reduce concentrations during the summer. Combining these results with further studies on treatment effects and microbial risk assessment is necessary to ensure adequate treatment capacity for the raw water in the future. Work package 3 In this study, we used national monitoring data to first describe the spatial and temporal distribution of Campylobacter in Norway, Sweden, Finland and Denmark in relation to a variety of climatic conditions and secondly to predict the effect of future climate change on campylobacteriosis in the Nordic countries. We modelled data (on reported cases on Campylobacter at the municipal level for all four countries, 2000-2015) against temperature and precipitation in a multivariate model. The results of the models developed in this study correlate with published evidence of a Campylobacter climate association and confirm that precipitation is particularly an important climatic determinant of disease. The models predicted that future climate change could lead to large increases in the prevalence of Campylobacter throughout Scandinavia. Some regions are likely to be more vulnerable than others, and emphasize a need to focus on effective public health and climate change adaptation strategies. In other European countries where the season and the geographical distribution of Campylobacter are determined by the same factors as in Scandinavia, there is also a strong effect on the incidence of campylobacteriosis. Again, the authorities at the local level should be aware of this with regard to assessing the impact on particularly vulnerable areas. Work Package 4 Based on climate forecasts for the Møre and Romsdal region, we expect almost no changes in today's level concentrations of E. coli in Brusdalsvatnet (main drinking water source for Ålesund) in the next 45 years. We also expect gradual temperature rise to occur at the water intake point from the base year levels in 2015 through the four seasons. In addition, we estimate shorter spring circulation and longer autumn circulation periods in the sea in the future as an effect of the temperature rise. The four seasons are very significant in determining the variables in the concentrations of coliform bacteria and E. coli in raw water and the effect of the autumn season is clearer. This may be due to circulation in the sea during this season, which allows micro-particles on the raw water surface of the sea to reach the water intake depth. Artificial intelligence models and zero-blown models have high potential for identifying key environmental and water quality variables that determine the concentrations of faecal indicator organisms in drinking water resources.

Prosjektet har ført til økt kompetanse på sammenhenger mellom vær,drikkevannskvalitet og helse, og økt samarbeid på tvers av institusjoner og fagfelter. For alle prosjektdeltakere er resultatene fra prosjektet nyttige i kontakt med brukere som trenger informasjon for å kunne tilpasse seg både dagens klima og framtidige klimaendringer.

Climate change will lead to higher temperatures, increased precipitation and runoff and more frequent extreme weather events in Norway. Aging drinking water treatment and distribution systems and sewage systems will be particularly vulnerable to flooding, leading to potential deterioration in the quality of drinking water. Many infectious microorganisms are sensitive to climatic conditions. These factors together will increase the risk and burden of waterborne illnesses. In Norway, little is known about how climate change will affect the safety of drinking water and, thus, waterborne illness and potential needs for adaptation. We will enhance the current understanding of the association between climate, and water quality or waterborne illness by taking advantage of the high quality epidemiological, hydrological and meteorological registries and databases that are available in the Nordic countries but are not often linked. In addition, we will perform quantitative microbiological risk assessment to assess the microbial infection risk and disease burdens associated with climate change impact on water supplies. Our project will be structured as an interdisciplinary collaboration that will bring together top national organizations and actors with extensive experience in the fields of public health, infectious diseases epidemiology, microbiology, hydrology, meteorology, infectious diseases modeling and statistics. The outcome of the project will provide crucial information for understanding the impact of climate change on drinking water safety. This will be central to minimize the risk and reduce harmful effects on the health of the society and waterborne illness burden. Specifically, our results will contribute to identify the priority areas for the recently established Norwegian Centre for Climate Services to disseminate data and generate climate and hydrological indicators to assess the potential negative effects related to drinking water and waterborne illness.