Global warming possibly linked to an enhanced risk of suicide: data from Italy, 1974-2003.

BACKGROUND The global increase in surface temperature (known as global warming) was found to impact on mortality through ill health, particularly among the elderly and in summer. This study sets out to explore the impact of global warming on suicide mortality, using data from Italy. METHODS Monthly data on suicide mortality and temperature were obtained for a 30-year period (from January 1974 to December 2003), and the relation between them was investigated using the Gaussian low-pass filter, linear correlation analysis and rank analysis. RESULTS For males, increasing anomalies in monthly average temperatures associated to a higher monthly suicide mean from May to August and, to a lower extent, in November and December. In January, on the other hand, increasing anomalies in monthly average temperatures appeared to be coupled to a lower number of suicides. For females, the links between temperature and suicides are less consistent than for males, and sometimes have a reverse sign, too. LIMITATIONS Data could not be analyzed according to age, since this information was not available across the whole time interval. The use of monthly data, instead of daily data (unavailable), is another major limitation of this study. CONCLUSIONS An improvement in the ability of communities to adjust to temperature changes by implementing public health interventions may play an important part in preserving the wellness of the general population, and also in limiting the worst consequences of suicidal behaviour.