Multiple Threshold Effects for Temperature and Mortality

Heat waves and cold fronts have become frequent of late, and have caused serious disruptions around the world, especially in the mid- and high-latitudes. In future, human beings are likely to face more serious, frequent and long-lasting extreme climate events, with consequent greater damage to human life. This paper uses the multiple panel threshold model to test whether there are threshold effects between temperature and mortality, using a panel of 78 major cities in 22 OECD countries for 1990-2008. From the empirical analysis, we find that the relationship between temperature and mortality has three threshold effects, namely 15.21℉ (-9.33℃), 46.97℉ (8.32℃), and 87.53℉ (30.85℃). If the temperature is below 15.21℉ (-9.33℃), the magnitude of the temperature effect below 15.21℉ (-9.33℃) is greater than the effect between 15.21℉ (-9.33₀C) and 46.97℉ (8.32₀C). When the temperature exceeds 87.53℉ (30.85℃), higher temperature leads to higher mortality rate. Based on the estimated coefficients of mean temperatures in four regimes, we separate 78 cities into five areas with latitudes below 30°, 31°-40°, 41°-50°, and 61°-70°, and predict the impacts of future climate change on mortality for 2021-2040, 2041-2060, and 2061-2100. In summer, climate is predicted to increase mortality rates for 2021-2040, 2041-2060, and 2061-2100. For latitudes 41°-50° and 51°-60°, the increased mortality rate is much larger than for other latitudes. In winter, the increased magnitude induced by climate change is found to be greater than in summer