60,000 suicides in India linked to climate crisis

A Journal of People report

High and rapidly rising suicide rate in India have been linked to crop damage due to increasing temperature trends over the last 30 years, finds a new study.

One fifth of the world’s suicides happen in India, typically at more than 130,000 deaths a year. With more than half of the country’s population employed in agriculture, crop failures due to increasing temperatures have been suspected to be behind the increasing trend in suicides in the past three decades. Nearly all parts of India are experiencing rising temperatures due to climate change.

Political measures introduced to combat this have included a $1.3-billion climate-based crop insurance scheme. But such measures have lacked solid evidence to back them up.

Now researchers have found that suicide rates are higher in years where temperatures are warmer during the growing season. This is when the crops are most sensitive to temperature, and more likely to fail if it is too hot. A total of 59,000 suicides have been linked to these above-average temperatures over the past 30 years, finds the study. The study report has been published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

The study report “Crop-damaging temperatures increase suicide rates in India” said:

“This analysis of India, where one fifth of the world’s suicides occur, demonstrates that the climate, particularly temperature, has strong influence over a growing suicide epidemic.”

With 47 years of suicide records and climate data, the study shows:

“High temperatures increase suicide rates, but only during India’s growing season, when heat also reduces crop yields.”

Tamma Carleton of the University of California, Berkeley, writes in the study report:

The study “results are consistent with widely cited theories of economic suicide in India. Moreover, these findings have important implications for future climate change”

The study estimates that warming temperature trends over the last three decades have already been responsible for over 59,000 suicides throughout India.

“Despite lack of substantiation, public debate in India has centered around one possible cause of rapidly rising suicide rates: increasing variability of agricultural income,” writes Tamma Carleton.

“Drought and heat feature prominently in these claims; climate events are argued to damage crop yields, deepening farmers’ debt burdens and inducing some to commit suicide in response.”

Carleton analyzed suicide records and climate data from each of India’s 32 states and union territories to identify the trend. For each day when temperatures rose above an average of 20C in the growing season, there was an additional 67 deaths across India.

“India alone is predicted to experience an average temperature increase of up to 3C by 2050. Without investments in adaptation, my findings suggest that this warming will be accompanied by a rising number of lives lost to self-harm,” Carleton concludes.

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The study report said:

More than three quarters of the world’s suicides occur in developing countries, yet little is known about the drivers of suicidal behavior in poor populations.

The study centered India, where one fifth of global suicides occur and suicide rates have doubled since 1980.

Using nationally comprehensive panel data over 47 years, I demonstrate that fluctuations in climate, particularly temperature, significantly influence suicide rates. For temperatures above 20 °C, a 1 °C increase in a single day’s temperature causes ∼70 suicides, on average. This effect occurs only during India’s agricultural growing season, when heat also lowers crop yields. I find no evidence that acclimatization, rising incomes, or other unobserved drivers of adaptation are occurring. I estimate that warming over the last 30 years is responsible for 59,300 suicides in India, accounting for 6.8% of the total upward trend. These results deliver large-scale quantitative evidence linking climate and agricultural income to self-harm in a developing country.

It said:

“Each year, over 130,000 lives are lost to self-harm in Indi. The causes of these deaths are poorly understood; drivers of suicidal behavior remain disputed across scientific disciplines, and nearly all evidence comes from developed country contexts. Despite lack of substantiation, public debate in India has centered around one possible cause of rapidly rising suicide rates: increasing variability of agricultural income. Drought and heat feature prominently in these claims; climate events are argued to damage crop yields, deepening farmers’ debt burdens and inducing some to commit suicide in response. With more than half of India’s working population employed in agriculture, one third lying below the international poverty line, and nearly all experiencing rising temperatures due to anthropogenic climate change, these arguments appear plausible. However, the relationship between economic shocks and suicide is controversial, and, in India, the effect of income-damaging climate variation on suicide rates is unknown. Although the national government has recently announced a $1.3 billion climate-based crop insurance scheme motivated as suicide prevention policy, evidence to support such an intervention is lacking. Existing work has found that agricultural yields in India rely heavily on growing season temperature and precipitation, but it is unclear to what extent, if any, this sensitivity to climate influences suicide rates.”

It said:

“Previous studies of income variability affecting suicide in India are anecdotal or qualitative, and none attempt to identify and synthesize quantitative relationships between climate, crops, and suicides.”

To fill this knowledge gap, the researcher used a data set from India’s National Crime Records Bureau (NCRB), which contains the universe of reported suicides in the country from 1967 to 2013.  The researcher paired these data with information on agricultural crop yields and high-resolution climate data to identify the effect of climatic shifts on suicide rates, and to test whether agricultural yields are a mechanism through which these effects materialize.”

The analysis, the scientist said, “is most directly applicable to India, it also contributes to building a broader understanding of the effect of climate on suicide throughout the developing world.”

The scientists analyzed the relationship between annual suicide rates, measured for each of India’s all the states and union territories, cumulative exposure to temperature and rainfall, regional time trends in suicide rates.

Under the researcher’s estimation strategy, two key empirical concerns remain: the functional form of the relationship between suicide rates and climate variables has minimal precedent in existing literature.

# Temperature during India’s main agricultural growing season has a strong positive effect on annual suicide rates. For days above 20 °C, a 1 °C increase in a single day’s temperature during the growing season increases annual suicides by 0.008 per 100,000 people, causing an additional 67 deaths, on average across India; this amounts to a 3.5% increase in the suicide rate per. In contrast, temperatures in the non-growing season have no identifiable impact on suicide rates.

# Four states that have been at the center of India’s public debates regarding agricultural influences on suicide (Maharashtra, Karnataka, Tamil Nadu, and Andhra Pradesh) not only have severe suicide responses to temperature, but also exhibit large negative impacts of temperature on yield.

# Across all four tests, no evidence of any type of adaptive behavior was found. In hotter locations, I detect higher than average sensitivity to temperature was detected. Temperature sensitivity in wealthier locations is indistinguishable from that in poor locations.

# Temperature sensitivity of suicide has remained remarkably stable over time, despite India’s robust economic growth and dramatic improvements in agricultural yields over this period.

# No evidence of adaptive behavior in the context of temperature damages to suicide rates in India.

The scientist found:

Variations in temperature during India’s main growing season exert substantial influence over suicide rates.

The researcher found:

By 2013, temperature trends are responsible for over 4,000 additional deaths annually across India, accounting for ∼3% of annual suicides. Across all states and all years since 1980, a cumulative total of 59,300 suicides can be attributed to warming, accounting for 6.8% of the national upward trend in suicide rates over this time period.

The study report said:

Without investments in adaptation, my findings suggest that this warming will be accompanied by a rising number of lives lost to self-harm.

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