Unique CCNY study of extreme Indian rainfall upends conventional wisdom
City College of New York
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How extreme rainfall days within India change with the El Nino-La Nina cycle. Blue shades mean extreme rain is more likely, and brown shades mean less likely, during El Nino summers compared to La Nina summers.
view moreCredit: Spencer Hill/CCNU
New research led by City College of New York scientist Spencer A. Hill challenges generations-old beliefs about how El Niño events influence rainfall during the Indian summer monsoon. Entitled “More extreme Indian monsoon rainfall in El Niño summers,” the study appears in the journal Science.
“Our key finding is that you tend to get more days with extreme amounts of rainfall within India, not less, in El Niño summers. An El Niño event means that ocean surface temperatures in the eastern equatorial Pacific Ocean are warmer than usual,” said Hill, assistant professor, in CCNY’s Department of Earth and Atmospheric Sciences. “This finding was unexpected, because it has been known for over a century that El Niños do precisely the opposite, meaning they promote drought, for total rainfall summed over the rainy season, June through September.”
Hill, whose affiliations include the CUNY Graduate Center Departments of Earth and Environmental Sciences and of Physics, as well as Columbia University’s Lamont-Doherty Earth Observatory, however pointed out that these changes are not distributed uniformly within India. “The increases in extreme daily rainfall under El Niño compared to La Niña are concentrated in central India and in the southwestern coastal band, whereas in the southeast and northwest the signal is opposite, meaning daily extreme rainfall is less likely in El Niño summers,” he noted.
Highlighting the importance of the study, Hill said that extreme rain events come every summer, destroying infrastructure and killing people through flooding and landslides. The World Bank estimates that some 80 million people live in extreme poverty in the world’s most populous country of more than 1.45 billion. “Better predictions of when and where extreme rainfall events are likely to occur give society better chances to prepare, such as perhaps by earlier and better warnings or pre-mobilizing aid.”
And this novel work will continue beyond this study thanks to a new three-year $408,862 grant awarded to Hill this fall by the National Science Foundation [NSF]. “In this new NSF grant we will investigate how and why the type of storms responsible for much of this extreme rainfall, called monsoon low-pressure systems, change depending on whether there are El Niño or La Niña conditions,” said Hill.
Journal
Science
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
More extreme Indian monsoon rainfall in El Niño summers
Article Publication Date
18-Sep-2025
El Niño spurs extreme daily rain events despite drier monsoons in India
Summary author: Walter Beckwith
Although El Niño suppresses overall monsoon season rainfall across India, a new study finds that it also, counterintuitively, sharply increases the likelihood of extreme daily downpours in the country’s wetter regions. The findings suggest that the processes that drive this intensification may play an important role in driving extreme rainfall variability under climate change in other tropical locations. It’s long been known that the El Niño-Southern Oscillation (ENSO) exerts a powerful influence on India’s summer monsoon rains. During El Niño years, warmer Pacific waters trigger unusual patterns of rising and sinking air, producing a large-scale suppression of seasonal rainfall across the Indian subcontinent. In India’s typically drier regions, this results in fewer rainy days and weaker showers, compounding their dryness. However, in the nation’s climatologically wetter zones, which also experience less frequent rainfall during El Niño events, observations suggest that the storms that do occur tend to be markedly more intense. This contrasting pattern underscores El Niño’s complex and regionally varied impact on India’s monsoon rains. Yet, despite this, ENSOs’ influence on the Indian summer monsoon, and the physical mechanisms driving these patterns, remain largely unexplored. To address this gap, Spencer Hill and colleagues measured extreme daily rainfall using a cutoff accumulation metric, which captures how often very heavy rain occurs relative to average conditions. Applying this to over a century of high-resolution Indian rainfall observational data (1901–2020), Hill et al. found that while light and moderate rain become less frequent during El Niño, the probability of very heavy downpours rises steeply in India’s wetter regions, with extreme rainfall events becoming more than 50% likelier in some cases, which can result in potentially hazardous conditions. Moreover, unlike El Niño’s weakening influence on India’s average summer rainfall over recent decades, its impact on extremes has remained comparatively steady over time, though with some regional shifts. According to the authors, this intensification is linked to changes in atmospheric buoyancy and low-pressure system tracks.
Journal
Science
Article Title
More extreme Indian monsoon rainfall in El Niño summers
Article Publication Date
18-Sep-2025
Make People Accountable For Punjab Flood
– OpEd
Flooding in Punjab, India. Photo Credit: Tasnim News Agency
September 19, 2025
By Sudhansu R Das
The devastating flood in Punjab has killed more than 55 people and destroyed farmland, livestock and houses in nearly 2000 villages. The worst flood in the last four decades has impacted nearly four lakh people and the loss is estimated at Rs 13000 crores.
The actual loss is too huge if it values life, livelihood, mental trauma, destitution, loss of hope, confidence, cost of repair and relief amount etc. The flood has displaced more than 2.5 lakh people and destroyed roads, bridges, railway lines, offices, schools, hospitals and dairy farms etc; it has uprooted thousands of trees and washed away houses and economic assets. Vast agriculture fields with paddy, cotton and sugarcane were destroyed just before the harvest. Repairing the economy and social life in Punjab is impossible unless the root causes of flood are addressed.
Over decades, Punjab, the food bowl of India has become the victim of a development illusion. There has been an infrastructure project mess in the state for the last many decades. Roads, bridges, highways in vulnerable areas, dams, flyovers, urban infrastructure projects were made beyond the actual need of people; there was no scientific environmental appraisal of those projects which aggravated the impact of the flood. Unless the people behind those unscientific projects are caught, those people will return with more harmful projects in future.
The state needs state specific infrastructure projects for inclusive growth but not the overdose of it. Besides, the Indian society should be reformed to produce quality public representatives who can address the root causes of natural calamities across the country. The citizens’ intellectual capacity, patriotism and skills have no meaning unless the citizens have the moral courage to stand for good cause; moral and physical courage build a nation and it will rebuild Punjab. A home is a home and no foreign country can be better than one’s own home.
Punjab has already witnessed the flood havoc in 2004, 2008, 2010, 2013, 2019 and in 2023; it has done little to address the root causes of flood and invited the most devastating flood this year. It is like pushing the state into the edge of a cliff. “Encroachments through settlements close to rivers and rivulets have been happening for years. Successive governments have failed to control them,” said Mr S.K. Saluja, former chief engineer with the Ranjit Sagar and Shahpurkandi dam projects, ” the construction works done in an unscientific way also obstruct water flow; rampant sand mining in riverbeds is a huge problem in Punjab,” he added. Human greed has overshadowed all logic, reasons and religious preaching in Punjab. “The impact of climate change is evident,” said Surender Paul, scientist and IMD director at Chandigarh. The people who are responsible for the environmental degradation should be accountable for this human tragedy which unfolds every five years.
“The Flood Preparedness Guidebook 2024,” prepared by the Punjab’s water resources department after the devastating flood of 2023 documented that the construction of concrete structures obstruct the natural drainage routes. The document cited the instance of a railway bridge that became a big problem for a village located near the Sutlej. A waterway was built under the bridge for water drainage, gathering silt and blocking the water flow in the river Sutlej which later flooded the nearby villages. The booklet also cited how a road bridge situated on the river Beas has obstructed the flow of river and broke the river bank during the 2023 flood. The document has mentioned the unscientific construction of new elevated highways and expressways which have blocked the rain water flow to the rivers and flooded the villages nearby. Not listening to the advice of the experts and not taking measures as per the findings in “The Flood Preparedness Guidelines 2024” is a criminal negligence. If the state fails to make people accountable for the deaths and destruction of the 2025 Punjab flood, it will be another criminal negligence. Inaction will adversely affect the economy, society, culture and people of the state. Any attempt to mess things up with blame games and promises will add to the problem. If people in power do not take adequate measures to safeguard human life, livelihood, economy, social life, culture and religion while building infrastructure projects, they should quit; because the economic loss is too huge in comparison to the financial gains from many of those unscientific infrastructure projects. There is too much population pressure on urban areas due to a large-scale migration of rural people to urban areas. It results in errant urban growth which has obstructed the rain water flow; encroachment of river banks and conversion of open land into concrete structures and deforestation etc. Farmers in Punjab have built pipe outlets, houses, temporary ramps and roads on the river banks and on flood plains which have weakened the strength and stability of the embankment. People who constructed those life threatening structures bribed the officials for permission to build those structures. Corruption can kill people and devastate the economy, society and religion at a massive scale.
Water rich Punjab had a thriving agriculture sector. Green revolution in the mid 60s increased the yield of rice and paddy but it depleted water resources and destroyed crop diversity; the cost of farming has increased due to chemical fertilizers, pesticides and weedicides etc. In the later period mono crop practices wiped out much of the crop diversity and made small farms unviable and big farm activity too costly. The recent flood has destroyed both big and small farms when the demand for export of food has boomed due to hunger and starvation across the world. Today, more than 50% people in the world are not getting adequate food and nutrition due to wrong agriculture practices, environmental degradation and over exploitation of natural resources like water, energy, mineral and forest products.
Nature has gifted Punjab alluvial fertile agriculture land on flood plain. Mismanagement of flood plains is one of the main causes of flood and loss of farm income. Today concrete structures have replaced much of the floodplains; salinity and alkalinity have reduced the fertility of the three major flood plains which form 77% of the total land area of Punjab. The nature gift has become a curse due to poor management of rivers, fertile floodplains, forest and natural drainage system. Punjab should learn to respect the rivers as living mothers.
Over decades, Punjab has immensely contributed to India’s economy, culture, defense and sports. Punjabis are enterprising and bold people who venture out and establish their business across the country and abroad. They have made India proud in various fields of activities. What Punjab needs today is immediate relief from the Central and state governments. The entire country should stand by Punjab at this moment of crisis. More than the relief Punjab needs experts who know the social, cultural and economic life of Punjab to rebuild the state. Let religious reformers, social workers, intellectuals, youth and good leaders come together to address the root causes of flood and other socio-economic problems of Punjab.
Sudhansu R Das is a sustainable micro-economic activities analyst.
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