Links between suicide and changes in weather have existed since the 1880s when Italian physician Enrico Morselli compiled data from twenty-eight European countries and found higher rates of suicide in the summer months. He noted the regularity of suicide statistics was “too great for it to be attributed to chance of the human will.”
More recently, a heatwave in the UK during the summer of 1995 led to a 46.9% increase in suicide. Every 1-degree increase in mean temperature above 18C was associated with a 4–5% rise.
Similarly, a study explored death records and temperature variations in Finland from 1751 to 2008 and found that temperature variability explained more than 60% total variance up until the beginning of a national suicide prevention program.
Naturally, there are considerable difficulties in establishing direct causality. Several other factors also contribute to suicide, for example, socio-economic issues such as financial security and relationship stressors as well as previous mental health difficulties.
Such studies have suffered considerable obstacles in methodology such as varying social patterns and day length that had made a direct link to temperature difficult to establish.
However, 2018 research published in Nature aimed to tackle these specific difficulties. Researchers assembled and examined decades of temperature and suicide data as well as scanning over half a billion social media updates to look for negative language associated with mental well-being.
The study concluded that if a month is one degree Celsius warmer than average, the suicide rate will increase by 0.7% in the U.S and 2.1% in Mexico.
It is believed that up to 26,000 more deaths could occur in the US if warming continues at current rates, this is comparable to the impact of economic recessions, suicide prevention programmes or gun restriction laws.
This is different from the studies mentioned previously for two reasons.
Firstly, this paper makes a causative claim. Even when factoring in the influences of poverty, gender, weapons possession and other socio-economic issues, the study found a small, statistically significant correlation.
Secondly, it finds that this holds everywhere in the two countries studied, regardless of whether it is a hot town in Mexico or a cold town in the U.S.
It is important to note that the removal of bias altogether is incredibly troublesome, but this study has made considerable strides in controlling external variables.
Elsewhere, temperatures and weather extremes have more indirect effects on suicide rates. In communities where agriculture makes up the vast majority of income, links to suicide are strong.
India, for its part, has witnessed a dramatic rise in suicides. A recent report noted over 60,000 suicide cases in India over the last 30 years. Poor harvests as a result of climate vulnerability lead farmers to borrow money to replant, with a guarantee of repayment following the new harvest.
Climate fluctuations, however, can result in multiple failed years, creating a cycle of borrowing. Their inability to sustain a livelihood, combined with growing debt, leads many farmers to take their own life.
Many point to the changing climate as a key contributing factor in these deaths.
In a world where climate change dialogue has, rightly, become inescapable and the importance of mental health conversations is at an all-time high, it makes sense to continue researching the two together.
Climate change is rapidly becoming a burden on global health systems, not just from the physical injuries associated with environmental disasters but also the psychological toll on those on the frontline.
It is paramount that we continue to further our understanding of how climate change weighs on our psyche, otherwise, we will potentially face a mental health crisis.