Assessment of the variation on maximum daily heat index in Ninh Binh city

This study was based on heat index (HI) to determine risk thresholds for warning heat stress to communities in Ninh Binh City. The study used correlation evaluation and regression equations, meteorological data for the period 1991 - 2021, and Vietnam climate change scenario data to calculate the maximum daily heat index (HImax) scenario for the country in the period 2024 - 2054. The results showed that, in the future, the trend of HImax will increase by 0.100 °C per year under the RCP 4.5 scenario (Medium Low greenhouse gases concentration scenario) and 0.105 °C per year under the RCP 8.5 scenario (High greenhouse gases concentration scenarios). The number of HImax days at dangerous levels will increase by about 1 day per year with both RCP 4.5 and RCP 8.5 scenarios. In particular, the number of HImax days at extreme danger levels, with the risk of causing stroke, in the period 2024 - 2054 appeared more than before, especially in the period 1941 - 2054, the trend increased sharply. In some last years of this period, the number of HImax days will be extremely dangerous up to 20 - 30 days.