Sunil Amrith

Stephanie Mitchell/Harvard University

Q&A: The epic tale of the scientists who unraveled the mystery of the monsoon

This year, India’s monsoon rains—critical to the country’s harvest and water supply—were below average for the 13th time in 18 years. And alarm spreads when those annual rains don’t come between June and September, says Sunil Amrith, a historian at Harvard University who has just released a new book documenting the long quest to understand one of Asia’s most important weather patterns.

Amrith became fascinated by the history of monsoon science while studying migration among coastal communities in South Asia. Now, he unfolds that history in Unruly Waters: How Rains, Rivers, Coasts, And Seas Have Shaped Asia’s History. He also explores how the quest to control water—whether to fend off floods or avoid the ravages of drought—has shaped the history of India and other Asian nations. Kirkus Reviews calls the book, published last week by Basic Books, a “lively history” that highlights the “obscure heroes” who developed modern meteorology and built irrigation projects, canals, and dams.

ScienceInsider recently spoke with Amrith about his research, concerns about how climate change and human activities are affecting India’s water supply, and his own experiences with the monsoon. This interview has been edited for clarity and brevity.

Q: Why did you decide to write about the monsoon and water?

A: I was spending a lot of time in coastal areas in India and South Asia studying migration and, like many scholars, I sort of took the monsoon for granted. It’s simply seen as a backdrop. The cliché is that India is always just one bad monsoon away from disaster. But as I learned about the people who had tried to figure out what makes the monsoon tick and why it varies from year to year, I realized we hadn’t explored all of the implications. [The monsoon] is connected to so many things—food, floods, dams, climate change, sustainability. It turned out to be a much bigger book than I imagined.

Q: Who among the early monsoon researchers stood out for you?

A: I was especially drawn to one character, Henry Blanford, who became the first head of the India Meteorological Department [in 1875]. In some sense, he was an amateur. He was trained as a geologist and learned on the job about meteorology. But he really was the person who set up this massive infrastructure for monitoring rain and weather in India. Scientists still rely on it. And he was one of the first to recognize some of the [large-scale patterns] related to the monsoon, even though he didn’t really have the data needed to understand it all. He was writing to his colleagues across the British Empire, getting information. He was one of the first to observe the synchronicity of drought around large parts of the world. We know now that is associated with the El Niño-La Niña oscillation.

Q: You write that Blanford, who was British, was unusual in training and supporting his Indian colleagues.

A: He does stand apart from the typical view of colonial scientists being very exclusive and hierarchical. He was a relatively open person, keen to train Indian meteorologists. We have a rare view of Blanford because one of his Indian deputies [Lala Ruchi Ram Sahni] wrote a memoir. One rarely gets that kind of access. Most of the time, the Indian scientists [in the colonial era] are in the shadows—we don’t we know what they did. But by the 1930s, more and more of the senior officials in the meteorological service are Indian, even before India became independent [in 1947].

Q: You make the case that efforts to harness and engineer water have deeply shaped the history of India and other South Asian nations.

A: Yes. They often faced either too little or too much water. Sometimes you have both at the same time—flooding in [wet regions], drought in places that are among the most arid in the world. Eventually, [in India] you see the emergence of this idea that the nation needs to be liberated from climate.In areas where rainfall was seen as unreliable, [dams and other] big infrastructure projects were built. Groundwater pumping becomes a major source of water [for irrigation].

As a result, [India’s] geography of water has become completely inverted. For centuries, the agricultural heart of the country was the area that received the most rainfall. Now, the areas that were historically the driest have become among the most productive agricultural lands. But the groundwater is being severely depleted. The question is whether this is sustainable. What was seen as an agricultural miracle is now seen as fragile.

Q: You recently published an opinion piece in The New York Times about a new push by India and China to build hundreds of dams in the Himalayas, both to produce power and store water. You have some strong views about those plans.

A: I think the historical record shows that relying on large-scale projects and purely technical and engineering solutions is a mistake and raises new risks. Dams epitomize that, and the dams in the Himalayas are particularly worrying. Until the 1980s, it was not viable to dam the rivers that far upstream in the mountains. That’s changed, and the risks are enormous. This is a seismically active zone, and the downstream consequences of a dam collapse would be serious. There are ecological risks. And because these rivers cross national boundaries, there is the risk of strategic and political conflict. We need to pay more attention to smaller local projects … and to broader social, political, and ecological concerns.

Q: You have also urged more attention to how climate change and shifts in the monsoon could affect water supplies.

A: That’s right. You have melting glaciers, for instance. And there is an increasing body of work on how the monsoon is changing, and the factors driving those changes. It’s not just global warming, but a whole set of local and regional factors. Planetary warming is interacting with aerosol emissions and land use changes to make the monsoon very unpredictable.

Q: The arrival of the monsoon is a big event in parts of Asia. What is your most memorable monsoon?

A: I grew up in Singapore, but spent a lot of time in India as a child, and the arrival of the monsoon is remarkable. You can see why it is celebrated in art, cinema, and poetry. I remember being in India when I was writing the book, in 2015 or 2016, just waiting after months and months of unrelenting heat. Watching the weather forecasters tracking it. Then, you could just see the clouds start marching in. Finally, the rains began. It was spectacular.