For many weeks this summer, a group of farmers from Tamil Nadu, the southern Indian state ravaged by one of its worst droughts in over a century, has been vociferously protesting in New Delhi. Almost always clad in green and sometimes holding human skulls or dead rats, they have been attempting to lobby the Narendra Modi government for a relief package, including a farm-loan waiver.

“Due to water crisis and drought in the state, farmers are under a huge financial burden,” P Ayyakkannu, the protest’s leader, told NDTV last month. “We are almost destroyed. We don’t care if we die protesting here.”

Yet, Ayyakkannu and his group are among the more resilient ones.

Across India’s hinterland, intemperate climate during key agricultural seasons has been driving thousands of Indian farmers into despair—and suicide. In the last three decades alone, rising temperatures, and their impact on crop yields, have been responsible for an estimated 59,000 farmer suicides, according to a new study by Tamma A Carleton, a researcher at the University of California, Berkeley.

Carleton, who paired data from India’s National Crime Records Bureau between 1967 and 2013 with crop yields and climate patterns, found that temperature variations during the growing season mirrored a rise in suicides. For instance, a 1 degree Celsius (°C) increase in temperature, on days warmer than 20°C, could cause 67 additional suicides on average nationwide. “In contrast, temperatures in the non-growing season have no identifiable impact on suicide rates,” Carleton wrote in a recent paper (pdf) in the Proceedings of the National Academy of Sciences journal.

“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,” she added.

Broadly, Carleton’s explanation is that increasing heat damages crops, which puts pressure on agriculture-dependent households, eventually driving some farmers to suicide. Census data from 2013 revealed that 52% of Indian households that survive on agriculture are indebted, with an average outstanding loan of Rs47,000. Moreover, around 60% of the total land under cultivation—48% for food crops and 68% for non-food crops—lacks irrigation facilities and is solely reliant on rain. So when the rains fail, the impact is catastrophic.

Although government after government has tried to resuscitate the farm sector, no intervention has been able to snap the relationship between rising temperatures and suicides over 47 years, Carleton found. “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,” she wrote.

With the possibility of a 3°C increase in India’s average temperature by 2050, thousands more could end up taking their own lives, unless interventions are made quickly, the research indicates. “Without investments in adaptation,” Carleton said, “my findings suggest that this warming will be accompanied by a rising number of lives lost to self-harm.”