The Environment and Suicide – Why Suicidologists Should Support Climate Change Policies
When suicidologists consider how the environment may impact suicide, they typically focus on the social and economic environment and the interpersonal environment. For the former, Lester and Yang (1997) documented how factors such as the business cycle might impact suicide rates while, many years ago, Platt (1984) showed that unemployment increased suicide rates. As for the interpersonal environment, in articulating his interpersonal theory of suicide, Joiner (2005) argued that perceived burdensomeness and thwarted belonging were present in those who died by suicide, and Van Orden et al. (2010) reviewed research supporting the theory. But does the physical environment have an impact on suicide?
It is well documented that there is a seasonal variation in suicide rates. For example, Bando and Volpe (2014) found a seasonal pattern in São Paulo, Brazil, with a peak in late spring (November) and a trough during May–June (late autumn) for men, and a peak in January and a trough during June–July for women. Chris Cornell, a rock-and-roll musician from Seattle, died by suicide in May 2017, and Schwartz (2019) noted that Cornell's lyrics contain clear indicators of mixed depressive and seasonal imagery, suggesting that the yearly suicide risk becomes maximal when winter turns to spring and there emerges a mixed mood state. The seasonal variation in suicides could be a result of changes in patterns of social interaction at the end of winter or a result of meteorological changes. However, Moore et al. (2018) reported that the seasonal variation of suicides at the Tay Road Bridge in Scotland (for the period 1968–2017) was found even after controls for temperature and hours of sunshine.
Also illustrating the impact of the environment on suicide, there is evidence that naturally occurring variations in water supplies can impact suicidal behavior. For example, it was noted back in the 1970s that water supplies differ in the amount of naturally occurring lithium in the drinking water (a medication approved for treating patients with bipolar affective disorder). In a recent meta-analysis of 13 ecological studies and one cohort study testing this association, Barjasteh-Askari et al. (2020) found a significant preventive association for men (odds ratio [OR] = 0.54, p < .01) and a trend for women (OR = 0.70, p = 0.06).
There have been several research studies on the impact of natural disasters on suicide. Orui (2020) found an increase in male suicide rates after the earthquake in March 2011 in the east of Japan (in Miyagi prefecture) and also during the recovery phase. On the other hand, Chen et al. (2016) found a decrease in suicide rates after the 1999 earthquake in Taiwan in the affected regions as compared with the unaffected regions, while Rodrigo and colleagues (2009) found no impact on suicide rates in Sri Lanka after the tsunami in 2004. Kõlves et al. (2013) reviewed research on the impact of earthquakes, hurricanes and cyclones, tsunamis, floods, heat waves and droughts on suicide and, although they found evidence for an increase in suicide after natural disasters, they found several methodological problems with the research (such as a failure to control for economic changes).
Climate change appears to be increasing the occurrence of extremes in weather conditions. Richardson et al. (in press) monitored 8.5 million people in a sample of randomly selected rural regions of India from 2001 to 2013 where 9,456 suicides occurred out of 249,786 total deaths. Compared with normal growing seasons, the percentage of deaths from suicide increased by 18.7% in extremely wet growing seasons and by 3.6% in extremely dry growing seasons.
For many of these topics, there have not been enough studies to permit a meta-analysis of the results of the studies in order to examine the degree of consistency of the results. One exception to this is the study of the impact of air quality on suicide.
Pollutants in the Air
Those concerned with climate change are particularly worried about emissions and pollutants in the air we breathe. One of the environmental consequences of the Covid-19 pandemic in 2020 was the improvement in air quality. As people stayed home, airplane flights were cut drastically and factories were closed. The result was that dangerous emissions were reduced. Clearly, people with respiratory diseases experienced better health, but was there an impact on suicides? At the present time, it appears that the psychological consequences of the pandemic will be harmful to people's mental health and that suicide rates may rise as a result of the accompanying fear and anxiety, social isolation, and economic catastrophe. However, the improvement in air quality in major cities during the pandemic has drawn people's attention to the danger linked to the way in which our climate is changing.
Davoudi et al. (2020) conducted a meta-analysis of 12 studies on the association of air pollutants and suicide, published between 2010 and 2019, and found that concentrations of NO2, SO2, O3, and CO were all associated with an increased number of suicides in the next few days, as was particulate matter smaller than 10 μm (one millionth of a meter). Air pollution had a stronger impact on suicide for people aged ≤ 64 years, suicides occurring on summer days, and for violent methods of suicide, but there was no difference between men and women.
Changes in the climate have already brought about changes in the gases and pollutants in the air that have a deleterious impact on physical health. It would appear also, therefore, that climate change has impacted, and will continue to impact, mental health and suicidal behavior.
Ambient Temperature and Suicide
As noted earlier, many countries show a seasonal pattern in suicides with spring typically having the major peak and autumn a secondary peak (Lester, 1979). There have been many studies examining whether suicides vary with the daily local weather. For example, Bozsonyi et al. (2020) studied one region in Hungary with a high suicide rate from 1971 to 2013 and found that the daily hours of sunshine had an immediate and significant impact on suicides (leading to an increase in suicides), while daily changes in temperature had an impact on daily suicides over the following 2 days.
The temperature in regions of the world is changing as a result of climate change. Burke et al. (2018) investigated the potential impact of climate change by studying the United States (1968–2004) and Mexico (1990–2010) using monthly vital statistics data for American counties (n = 851,088 data points) and Mexican municipalities (n = 611,366 data points). They found that the relationship between the temperature changes in a region and the monthly number of suicides was roughly linear. An increase of 1oC in the monthly temperature was associated with a 0.86% increase in the monthly suicide rate in the United States and a 2.1% increase in the monthly suicide rate in Mexico. Burke et al. noted that more recent data from the Centers of Disease Control for the United States indicated a 1.3% increase in the monthly suicide rate in the United States. The only other country with available data was India, which indicated an even greater increase (but the percentage increase in India was not stated in the article).
Discussion
It has long been known that the environment in which we live has an impact on our physical health. It has become apparent in recent years that the environment may also have an impact on our mental health and on suicide. Climate change will have many impacts, including floods and droughts, with consequent displacement of people and damage to food supplies, increases in air pollution, and changes in temperature. These changes will affect living conditions and the physical health of people. The changes will also have an impact on mental health. For suicidologists and their organizations, the potential rise in suicides is troubling and should lead to our support for those arguing for climate change policies.
How might this be done? Apart from our support as individuals for organizations and leaders arguing for climate change policies, the organizations involved in suicidology and suicide prevention might consider making public position statements concerning the importance of policies for improving the climate and for reversing the harmful changes in the climate that have occurred in the past. The International Association for Suicide Prevention (IASP) and each of the national suicide prevention organizations in countries around the world should urge governments to promote policies for climate change, lending support to the growing demand for action on climate change.
David Lester, PhD, is Emeritus Professor of Psychology at Stockton University in Galloway, NJ, USA, and is a former president of the International Association for Suicide Prevention. He has published extensively on suicide, murder, and other issues in thanatology. His recent books include Katie's Diary and Preventing Suicide: Why We Don't and How We Might.
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