Will climate change increase or decrease suicide rates?
Anthropogenic climate change is likely to impact human well-being in a variety of ways. Some previous studies have found a positive relationship between temperature and suicide rates, suggesting that one potential impact may be an increase in suicide rates. In this study we report an investigation of temperature and suicide in New Zealand over the period 1988–2007. Days that were hotter than average for a particular location and time of year were associated with higher suicide rates (estimated effect: 1.8% increase per °C). Paradoxically, warmer geographical locations were associated with lower suicide rates when controlling for demographic differences. This intriguing conflict between the effects of temporal and geographical variation in temperature echoes the findings of several prior studies. The possibility that the effect of warmer temperatures may vary depending on the time of exposure makes it difficult to predict how suicide rates will change in a warming world.