The Indus Waters Treaty in a Warming World

In December 2025, Pakistan raised concerns over what it termed “unusual, abrupt variations” in the flow of the Indus waters, particularly in the Chenab River. Islamabad alleged that sudden changes in discharge patterns—without prior intimation—were affecting downstream availability, rekindling familiar anxieties around water security and upstream control. While such accusations are not new in the India–Pakistan water discourse, the timing is significant. These concerns come at a moment when climate volatility is reshaping river hydrology across South Asia, and when the Indus Waters Treaty (IWT) itself stands in abeyance following the Pahalgam terror attacks in April 2025.

Signed in 1960 under the aegis of the World Bank, the IWT was crafted in a post-Partition world marked by displacement, food insecurity, and the imperative of political stability. That it has survived wars, diplomatic breakdowns, and decades of hostility is often cited as evidence of its success. Nonetheless, resilience should not be confused with relevance. As climate change begins to disrupt river flows in ways that neither India nor Pakistan can fully control, episodic disputes over “sudden variations” risk becoming the new normal rather than the exception.

Can a treaty designed for a stable, predictable hydrological world continue to govern one that is increasingly volatile, climate-driven, and uncertain?

This raises a more fundamental question: can a treaty designed for a stable, predictable hydrological world continue to govern one that is increasingly volatile, climate-driven, and uncertain?

India today finds itself at the confluence of mounting water stress, rising population pressures, and accelerating climate change. Its annual water demand already exceeds 700 billion cubic metres (BCM), with agriculture accounting for the largest share. By 2030, this demand is projected to double to approximately 1,500 BCM. Yet India’s ability to meet this demand is constrained not only by internal inefficiencies and over-extraction of groundwater, but also by the structural limitations imposed by the IWT.

Under the IWT, Pakistan enjoys control over nearly 80 percent of the Indus system’s waters through exclusive rights over the three western rivers, despite 40 percent of the basin’s catchment area lying within Indian territory. This asymmetry, while politically expedient in 1960, sits uneasily with present-day realities—particularly as climate change introduces sharp intra-seasonal fluctuations in river flows, the very kind now being flagged by Pakistan.

The destabilising effects of climate change further compound this imbalance. The Hindu Kush-Himalayan (HKH) region, often described as the world’s ‘Third Pole’, is warming at nearly twice the global average. By 2100, Himalayan glaciers could lose up to 75 percent of their volume. Even by 2030, studies suggest that the Indus River Basin could experience water deficits of up to 50 percent during critical periods. For India, where per capita water availability has already fallen below 1,500 cubic metres, such volatility has profound implications for food security, energy generation, and long-term economic growth. NITI Aayog estimates that unchecked water scarcity could reduce India’s Gross Domestic Product (GDP) by up to 6 percent by 2050.

By 2100, Himalayan glaciers could lose up to 75 percent of their volume.

It is in this context that the IWT must be reimagined—not as a static water-sharing arrangement frozen in Cold War geopolitics, but as a dynamic, climate-resilient security framework. The central challenge is no longer simply about upstream versus downstream control, but whether existing institutional arrangements can manage climate-induced variability without escalating political tensions.

Recognising the Climate Imperative 

Any serious attempts to modernise the IWT must begin by recognising climate change as the primary driver of emerging water insecurity in the Indus basin. Accelerated glacial retreat, erratic precipitation, and altered snowfall patterns are already translating into extreme hydrological events. The 2014 Kashmir floods, for instance, were directly linked to climate variability compounded by unplanned urbanisation.

Yet the treaty remains silent on climate risks. Negotiated in an era that viewed water-sharing through a rigid, zero-sum lens, the IWT assumed hydrological stability—a premise that no longer holds. Meanwhile, India’s growing water stress is reflected in its unsustainable reliance on groundwater. As the world’s largest groundwater extractor, India withdraws nearly 251 BCM annually, accounting for a quarter of global extraction. In Punjab and Haryana, groundwater levels are falling by 0.3 to 1 metre each year. Enhanced access to surface water, enabled through a recalibrated Indus framework, could ease this pressure and support more sustainable agricultural practices.

International water law increasingly supports such an approach. The United Nations (UN) Watercourses Convention (2014) emphasises “equitable and reasonable utilisation,” explicitly requiring climatic, hydrological, and ecological considerations to inform transboundary water governance. This offers India a strong normative basis to argue that the IWT must evolve in line with contemporary realities.

Building a Climate-Sensitive Data Framework 

Another structural weakness of the IWT lies in its reliance on historical hydrological averages. By anchoring allocations to past flows, the treaty ignores the growing variability introduced by glacial melt and shifting monsoon patterns. The existing data-sharing mechanisms—largely seasonal and flood-focused—are insufficient in capturing rapid, climate-driven fluctuations, the very issue now being flagged by Pakistan.

India must advocate for a data-rich, climate-sensitive monitoring framework that incorporates glacial melt dynamics, snowpack variability, and precipitation trends across the HKH region. Real-time satellite monitoring, high-resolution hydrological modelling, and climate projections should underpin future allocation decisions.

Other river basins offer instructive examples. The Rhine Basin has embraced adaptive management through joint monitoring and scenario planning, while the Mekong Agreement incorporates periodic reviews to reflect evolving environmental and social conditions. The Indus framework, by contrast, remains tethered to assumptions from the mid-20th century.

From Static Division to Adaptive Governance 

Perhaps the IWT’s most serious limitation is its rigidity. It contains no provisions for periodic review, no triggers for revision, and no mechanisms to respond to extraordinary climate-induced events. In a future marked by frequent hydrological shocks, this rigidity risks transforming routine flow variations into diplomatic flashpoints.

Modern transboundary agreements prioritise flexibility. The Mekong Agreement mandates regular reassessments, while the Rhine regime integrates climate projections into governance. Even within India, parliamentary committees have recommended reviewing water-sharing arrangements every 5–10 years to incorporate new data and emerging risks.

For India, rethinking the IWT is no longer just a diplomatic option—it is a strategic necessity for water security, economic resilience, and climate adaptation in an increasingly uncertain world.

For the Indus, this would mean establishing a standing review mechanism supported by climate scientists, hydrologists, and economists—ensuring that governance evolves alongside the basin itself.

Towards a 21st-Century Framework 

India must now lead the effort to reimagine the IWT along three lines: recalibrating allocations based on equitable, climate-adjusted needs; building a robust, shared climate data architecture; and embedding adaptive governance with built-in review mechanisms.

The Indus system sustains millions across South Asia, and unless its governing framework evolves, disputes over “unusual variations” are bound to become more frequent, more politicised, and more destabilising. For India, rethinking the IWT is no longer just a diplomatic option—it is a strategic necessity for water security, economic resilience, and climate adaptation in an increasingly uncertain world.

Aparna Roy is a Fellow and Lead Climate Change and Energy at the Centre for New Economic Diplomacy (CNED) at the Observer Research Foundation.

Radhey Wadhwa is a Research Intern at the Observer Research Foundation.

• Water
• Climate Change
• India
• climate change
• Climate resilience
• equitable water utilisation
• Groundwater extraction
• Himalayan glaciers
• hydrological variability
• Indus River Basin
• Indus Water Treaty
• Transboundary water governance
• Water security

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