Developing climate extreme indicators for EpiOutlook, a climate-informed subseasonal-to-seasonal forecast platform for epidemiological risks

EpiOutlook is an epidemiological indicator platform currently under development as part of the IDAlert project, a research consortium taking a OneHealth approach to understanding the impacts of climate change on the emergence and spread of infectious diseases in Europe and Bangladesh. The aim of the platform is to provide short-term early warning indicators of epidemiological risks, including those related to extreme weather and climate-sensitive infectious diseases (CSIDs). Currently, one climatic extreme indicator is operational for use in EpiOutlook which relates to drought, and makes use of the Standardised Precipitation-Evapotranspiration Index. Here, we propose two new climate extreme indicators currently under development, one related to heat and a second related to flood risk. We make use of fine-scale climate data (0.25x0.25) to categorise grid cells by the two proposed indicators (heat and flooding), which can then be extrapolated to the scale of interest. The impacts of extreme heat on health are well documented (e.g., extreme low and high temperatures and humidity leading to more adverse health outcomes), particularly for vulnerable groups such as pregnant women and children. Less well established are specific temperature ranges which puts people at risk to the highest number of climate-related health risks including CSIDs. We propose making use of our current CSID indicators (malaria, tick-borne diseases, leishmaniasis, Vibrio spp., West Nile Virus and Aedes-borne diseases), all of which consider the impacts of temperature and humidity. We aim to categorise temperature and humidity ranges which create ideal conditions for the highest number of CSIDs, weighed against the non-communicable disease impacts such as heat stress/stroke and adverse pregnancy outcomes, to provide a comprehensive spatial and temporal outlook for the effects of heat on health. Flooding is a major climatic risk in Europe, leading to destruction of property and livelihoods and infectious disease risk. We aim to develop a simple categorisation of flood risk via fluvial and pluvial flooding over Europe, incorporating several elements of the traditional water balance model, but producing an output which will be more interpretable by a wider range of end users. Risk will be assessed based on precipitation, elevation, land cover, potential evapotranspiration/soil moisture, groundwater recharge rate, proximity to a river, and river runoff/flow. Coastal flooding will not be considered at this stage, due to different flooding mechanisms, and instead proximity to a coastline will be seen as preventative as a source of drainage. Flood risk will be validated using flood data, and if the categorisation is proved accurate in representing flood risk, the occurrence of a flood in the preceding years will be considered in the categorisation. We aim to use the results from the flood indicator to provide valuable input to a leptospirosis indicator, a water-borne disease which is closely related to flooding. We believe that these indicators will provide easy to interpret quantification of climate extremes which relate to health in Europe, useful for public health decision-makers to make necessary adjustments to the current and near future risks posed by climate change.