On 26 August 2026, part of a mountain in the Himalayas began to move. High on Langtang Lirung near the Nepal,Tibet border, an enormous mass of glacier ice and rock broke away and plunged more than a thousand metres into the valley below. The force was so great that the event was initially mistaken by some for an earthquake.
But the collapse did not end where it began. As millions of tonnes of ice and rock accelerated downhill, they gathered sediment, debris and water. An avalanche became a debris flow. The flow entered the river system and continued downstream at extraordinary speed, carrying destruction toward communities and infrastructure many kilometres from the original collapse.
Within minutes, the geography of the valley had changed.
The glacier collapsed. The mountain gave way. Ice and rock became a debris flow. A river became a wall of mud.
The human tragedy was immediate. But the catastrophe also raises a larger question: what happens when climate change begins to alter not simply our weather, but the physical landscape itself?
：source: Reuters Graphics
When the Frozen World Begins to Thaw
The question matters because the Himalayas are undergoing profound change.
Atmospheric carbon dioxide has risen from about 278 parts per million before industrialisation to more than 423 ppm today, a concentration unprecedented in at least two million years. The consequences of this accumulation of greenhouse gases are now visible across the planet. Glaciers are retreating worldwide, Greenland and Antarctica are losing ice, permafrost is thawing, oceans are warming and sea levels are rising.
The Himalayas are part of this planetary transformation.
Between 1990 and 2020, glaciers across the Hindu Kush Himalayan region lost about 12 percent of their area and approximately 9 percent of their estimated ice reserves. But disappearing ice is only the most visible consequence.
Ice also helps hold mountains together.
At high elevations, permafrost penetrates cracks and fissures in bedrock, helping stabilise steep mountain faces. As temperatures rise, this frozen “glue” begins to thaw, water penetrates fractures, hanging glaciers retreat and lose support, and rock faces that developed under one climatic regime increasingly confront another.
Scientists are still reconstructing precisely what produced the August 26 failure. Recent investigations point to long-term glacier movement, unusually warm spring and summer conditions, increased meltwater and degradation of high-altitude permafrost as factors likely to have weakened the ice-rock contact zone.
Climate change need not push the first rock down the mountain to have transformed the conditions that made the mountain vulnerable.
And that is where the Nepal catastrophe begins to tell us something much larger.
A Changing Geography of Risk
For most of human history, geography has provided a certain degree of permanence. Mountains remained mountains, rivers occupied broadly recognisable corridors, frozen ground remained frozen and coastlines moved slowly enough for communities to learn where floods occurred, which slopes were dangerous and where water could normally be found. Much of modern civilisation was built upon those assumptions.
Climate change is beginning to disturb them.
A warmer atmosphere can hold more moisture, increasing the potential for extreme rainfall, while higher temperatures accelerate glacier retreat and permafrost thaw. Heat and prolonged drought dry forests, vegetation and soils; rising seas alter coastlines; and changing precipitation affects rivers, reservoirs and water supplies.
More importantly, these changes do not remain neatly separated from one another.
A glacier failure can become an avalanche, the avalanche a debris flow and the debris flow a flood. Extreme rainfall can destabilise a slope, the resulting landslide can block a river, and the eventual failure of that temporary barrier can devastate communities downstream. Drought and heat can dry vegetation and intensify wildfire conditions; fire can then strip a slope of vegetation and alter its soils, leaving the same landscape more vulnerable to flooding and debris flows when rain eventually returns.
Climate change is therefore doing more than increasing individual hazards. It is changing the physical relationships among them.
This is what I call the changing geography of climate risk: a world in which the places where hazards originate, the pathways through which they travel and the people and infrastructure exposed to them are being altered by a changing climate.
The Himalayas provide a dramatic example. But they are not alone.
From Too Much Water to Too Little
China provides an immediate illustration of the other face of this changing geography. While the Himalayan catastrophe began in frozen terrain high above the Nepal–Tibet border, other parts of China have recently confronted extraordinary amounts of water. Torrential rainfall associated with tropical systems has produced flooding, landslides and mass evacuations, demonstrating how quickly rainfall can move from meteorological event to geological hazard and then to human emergency.
The significance lies not simply in the amount of rain. It lies in the chain of consequences. Water saturates soil; slopes become unstable; landslides damage homes and roads; rivers overflow; transport networks are interrupted; and communities that may lie far from the centre of a storm find themselves inside its expanding geography of risk.
Travel westward from China to Europe, however, and the problem can appear almost reversed.
The summer of 2026 brought extraordinary heat and drought across large parts of Europe. Major rivers including the Loire, Po, Rhine and Danube fell to exceptionally low levels, while dry vegetation and soils contributed to severe wildfire conditions. The consequences moved well beyond the environment: low river flows affected navigation and water supply, while shortages of cooling water and reduced hydropower generation placed pressure on energy systems.
France offers an especially striking example. The summer of 2026 was the hottest recorded there since national records began in 1900. Repeated heatwaves coincided with severe rainfall deficits, exceptional soil dryness and damaging wildfires.
Here again, the important story is not simply “heat” or “drought.” It is their interaction. Heat increases evaporation, drought removes moisture from soil and vegetation, dry vegetation becomes fuel for wildfire, diminished rivers affect transport and electricity generation, and the same climatic stress travels through agriculture, ecosystems, public health and the economy.
The geography of climate risk is therefore changing in apparently contradictory directions. In one place there may be destructive excesses of water; in another, a dangerous absence of it. The common denominator is a climate system accumulating additional energy and moisture and altering the environmental conditions around which societies organised themselves.
The pattern extends further. Across North America and parts of Europe, drought and record heat are placing forests under increasing stress, contributing not only to wildfire danger but also to forest dieback and vulnerability to pests and disease. Around the world's coastlines, rising seas and erosion are gradually shifting the boundary between land and water, while communities, ports and infrastructure remain where they were built.
What links these experiences is not geographical proximity. It is physical transformation.
The Future Has Arrived
The scientific evidence surrounding that transformation is becoming increasingly difficult to separate into isolated warning signs. The eleven years from 2015 to 2025 were the warmest eleven years in the observational record. Ocean heat content reached another record in 2025, while atmospheric greenhouse-gas concentrations remained at unprecedented levels.
Glaciers are retreating across the world's major mountain regions as the Greenland and Antarctic ice sheets continue losing mass. At the same time, changing heat and precipitation patterns are affecting forests, rivers, agricultural systems and human settlements thousands of kilometres from the frozen regions.
We are no longer looking at scattered signals. We are looking at a changing Earth system.
And therein lies perhaps the greatest difficulty.
Human civilisation is remarkably fixed in space. Political borders remain largely where they were drawn, while cities, roads, bridges, dams, ports and power stations remain where they were built. The maps, engineering standards and planning assumptions designed to protect them were developed largely from observations of the past.
But the physical environment around them is becoming less stationary. Water is appearing in unexpected quantities in some regions while disappearing for longer periods from others; frozen ground is thawing as glaciers retreat; prolonged heat is changing forests and landscapes; and rising seas are gradually shifting coastlines against settlements that cannot simply move with them.
The future has arrived—not as one climatic catastrophe, but as a transformation of the physical environment within which human civilisation operates.
When Resilience Must Come Before Disaster
This brings us to resilience.
For too long, resilience has been associated principally with surviving disaster, recovering and rebuilding. Those capacities remain essential, but they begin after something has already gone wrong.
That is no longer sufficient.
If yesterday's physical conditions cannot automatically be assumed tomorrow, rebuilding yesterday's infrastructure in yesterday's locations may simply reproduce tomorrow's vulnerability.
Resilience must therefore begin before disaster. It must mean observing environmental change, anticipating where risk is moving, adapting infrastructure and land use, protecting vulnerable communities and, where necessary, transforming how and where we build.
The conventional sequence has too often been: Disaster → Response → Recovery → Reconstruction.
The emerging climatic reality requires something different: Observe → Anticipate → Adapt → Protect → Transform.
The distinction is not semantic. It changes when societies act and what they prepare for.
The Himalayas make this particularly clear. A village does not need to stand beside a glacier to be exposed to glacial risk. It may lie tens of kilometres downstream, connected to the glacier by a slope, a river, a road or a hydropower system. The same principle applies elsewhere: a city does not need to burn to suffer the consequences of wildfire if fire damages its watershed; nor does an industrial centre need to experience drought directly if falling river levels interrupt the transport or energy systems upon which it depends.
The tragedy of Langtang Lirung therefore leaves us with a question far larger than what caused one mountain face to collapse.
It asks whether our understanding of risk is changing as rapidly as the physical world around us.
Climate change does not move political borders, but it is moving some of the physical boundaries upon which civilisation has depended: between ice and water, frozen and thawed ground, river and settlement, forest and fire zone, and habitable coast and encroaching sea.
If the geography of risk is changing, the geography of resilience must change with it.
When glaciers retreat, rivers exceed their historical boundaries, forests become more combustible and mountains begin to move, waiting for catastrophe before adapting is no longer resilience.
It is already too late.
By: Professor Mehri Madarshahi
Honorary Professor of The Institute of Public Policy (IPP) , South China University of Technology (SCUT)
