Ozone Depletion and the Changing Face of Disaster Risk

A geographer's view on stratospheric change, atmospheric hazards, and lessons from the 2026 Nepal floods 

Most of us encounter the ozone layer only as a distant fact from a school textbook — a thin shield some 15 to 35 kilometres above our heads that quietly absorbs the sun's harshest ultraviolet rays. It rarely makes headlines the way an earthquake or a flood does. Yet the story of ozone depletion is, at its core, a story about disaster: about what happens when an invisible protective layer thins, and how that thinning ripples outward into human health, agriculture, ecosystems, and — as recent Himalayan events suggest — the wider architecture of atmospheric and cryospheric hazards that geographers now have to reckon with.

This piece tries to do two things. First, to explain, in plain terms, what ozone depletion actually is and why it still matters four decades after the Antarctic "ozone hole" was first identified. Second, to place it honestly within the broader disaster landscape — neither exaggerating its role nor dismissing it — using the catastrophic Nepal-Tibet flood of August 2026 as a live case study in how atmospheric science and disaster geography increasingly intersect.

The Ozone Layer: A Quick Refresher

Stratospheric ozone (O₃) forms naturally when ultraviolet radiation splits oxygen molecules apart, and the resulting atoms recombine into ozone. This layer absorbs roughly 97 to 99 percent of the sun's UV-B radiation, the band most damaging to living tissue. Without it, DNA damage, crop failure, and disrupted marine food chains would be routine rather than exceptional.

The depletion problem began with human ingenuity turned against itself. 

Chlorofluorocarbons (CFCs), once prized as stable, non-toxic compounds for refrigerants and aerosol propellants, turned out to be anything but stable once they reached the stratosphere. Sunlight breaks them apart, releasing chlorine atoms that catalytically destroy ozone — a single chlorine atom can knock out tens of thousands of ozone molecules before it is finally removed from the atmosphere. Over Antarctica, unique polar stratospheric clouds and a persistent winter vortex intensify this chemistry each spring, producing the seasonal "ozone hole" first documented by Farman et al. in 1985.
Why This Still Counts as a Disaster Issue
It is tempting to treat ozone depletion as a solved problem — after all, the Montreal Protocol of 1987 is often cited as the most successful environmental treaty in history, and the World Meteorological Organization and UNEP's most recent scientific assessment confirms that the ozone layer is on a path to recovery, with the Antarctic hole expected to return to 1980 levels by around mid-century (World Meteorological Organization & United Nations Environment Programme, 2022). That is genuinely good news, and it deserves to be told as such rather than buried under alarm.

But "recovering" is not "recovered," and the hazards associated with ozone depletion have not disappeared:

Human health. 

Elevated UV-B exposure remains linked to higher incidence of skin cancers, cataracts, and immune suppression in populations at high altitude or high latitude — a fact of direct relevance to hill and mountain communities in Maharashtra's Sahyadri region and the wider Himalayan arc, where thinner atmosphere already means higher ambient UV.

Agriculture and food security.

 UV-B stress reduces yields in UV-sensitive crops such as soybean and rice at the seedling stage, and it degrades the nutritional quality of leafy vegetables — a slow-onset disaster in the sense used by disaster-risk scholars, where damage accumulates gradually rather than striking in a single event.

Marine ecosystems. 

Phytoplankton, the base of the ocean food web and a major carbon sink, show measurable productivity declines under elevated UV-B, with downstream effects on fisheries that coastal disaster-management planning rarely accounts for.

Atmospheric circulation. 

This is the least intuitive but perhaps most consequential link. Solomon et al. (2016) demonstrated that the healing Antarctic ozone layer is already beginning to influence Southern Hemisphere jet-stream position and surface climate patterns, because stratospheric ozone loss itself had been driving a poleward shift in circulation. In other words, ozone depletion is not a story confined to the stratosphere; it reaches down and reshapes the wind and pressure systems that steer storms, rainfall belts, and heatwaves at the surface.

Where Ozone Depletion and Climate Change Diverge — and Meet

A geographer teaching this topic has a duty to be precise about one thing students and general readers frequently conflate: ozone depletion and global warming are different phenomena with different chemistry, even though they share a common origin in industrial emissions and a common treaty history.

Ozone depletion is driven by chlorine- and bromine-releasing compounds attacking stratospheric ozone. Global warming is driven by the accumulation of greenhouse gases — carbon dioxide, methane, and, notably, many of the same CFCs and their replacement HFCs — trapping outgoing infrared radiation in the troposphere. The Himalayan glacier retreat behind recent disasters in Nepal is a climate-warming story first and foremost, not an ozone-depletion story.

Where the two genuinely intersect is instructive rather than alarmist: many ozone-depleting substances are also potent greenhouse gases, so the Montreal Protocol has delivered a substantial, well-documented climate co-benefit alongside its ozone benefit (IPCC, 2021). And, as noted above, stratospheric ozone change itself alters circulation patterns that influence surface weather. Treating ozone and climate as entirely separate silos, as older textbooks sometimes still do, undersells how interconnected the stratosphere and troposphere really are.

A Case Study in Cascading Atmospheric Risk: Nepal, August 2026

On 26 August 2026, a section of glacier on Langtang Lirung, in Nepal's Langtang National Park, collapsed without warning. What followed was not a conventional flood but a cascading mass-movement disaster: an ice-rock avalanche entrained enormous volumes of debris as it thundered down the valley at speeds approaching 190 kilometres per hour, temporarily damming the Bhote Koshi/Trishuli river system before bursting through and surging across the Nepal-China border (Britannica, 2026). Early seismic readings were initially misread as a moderate earthquake; only later did USGS and GFZ analysis of long-period seismic waves confirm a glacier collapse rather than tectonic rupture (Al Jazeera, 2026).
The human toll was severe. Preliminary figures from Nepal's National Disaster Risk Reduction and Management Authority put the confirmed death toll above 350 across Nepal and China, with over a thousand people initially reported missing, including foreign trekkers caught in the Langtang corridor (Nature India, 2026). Infrastructure losses were extensive: roughly 430 megawatts of hydropower capacity, close to an eighth of Nepal's installed capacity, was damaged, along with bridges and highways along the valley (Nature India, 2026).

Why does this matter for a discussion of ozone depletion? Not because the two are causally linked — they are not — but because the Nepal event illustrates a pattern that ozone science shares: the danger of monitoring systems built for yesterday's hazard rather than today's. Nepal's flood-warning sensors were calibrated for slow-building monsoon floods, not the sudden dry-weather glacier collapse that actually occurred, and upstream stations were destroyed before alerts could reach downstream communities (Nature India, 2026). Similarly, ozone monitoring in the 1970s was not designed to catch a hole opening over Antarctica until satellite and ground data were cross-checked years apart. Both cases are reminders that atmospheric and cryospheric systems can shift in ways existing instrumentation is not built to detect quickly enough — a lesson directly relevant to disaster-risk-reduction planning in India's own Himalayan and sub-Himalayan catchments, including basins geographers in Maharashtra study by proxy through glacial-lake and river-basin research methods.

It is also worth noting that this was Nepal's third major glacial-region flood event in as many years — a smaller Humla GLOF in May 2025, the Bhote Koshi flood of July 2025 that swept away the Nepal-China Friendship Bridge, and now the August 2026 Langtang collapse (Britannica, 2026; Nature India, 2026). Whatever the precise trigger in each case, the frequency itself is the finding: high-mountain Asia's cryosphere is destabilising faster than existing early-warning infrastructure can track, a trend consistent with the broader atmospheric warming documented in the IPCC's Sixth Assessment Report (IPCC, 2021).

What This Means for Disaster Geography Going Forward

Three practical points emerge from reading ozone science and Himalayan disaster reporting side by side.
 

First, slow-onset atmospheric change deserves the same planning attention as sudden-onset disasters. Ozone depletion did its damage silently for a decade before satellites confirmed it; glacier destabilisation in Nepal proceeded for years before the August 2026 collapse made it visible to the world.
 

Second, treaty-based international cooperation works, imperfectly but measurably. The Montreal Protocol remains the clearest evidence available that coordinated global action on atmospheric chemistry can reverse course within a human lifetime (United Nations Environment Programme, 2023). That precedent is worth invoking whenever climate negotiators are told that nothing large-scale can be achieved.
 

Third, and most relevant to teaching geography in India, disaster curricula benefit from treating the atmosphere as one connected system rather than a set of separate chapters — ozone in one unit, climate change in another, glacial hazards in a third. Students who understand how stratospheric chemistry, tropospheric warming, and cryospheric collapse interact are better equipped to interpret the next unexpected event, wherever in the mountain arc it occurs.

References
Al Jazeera. (2026, August 27). Nepal-Tibet floods: What is a glacial collapse, how common is it? https://www.aljazeera.com/features/2026/8/27/nepal-tibet-floods-what-is-a-glacial-collapse-how-common-is-it
Britannica. (2026, September). Nepal floods of 2026. Encyclopaedia Britannica. https://www.britannica.com/event/Nepal-floods-of-2026
Farman, J. C., Gardiner, B. G., & Shanklin, J. D. (1985). Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction. Nature, 315(6016), 207–210. https://doi.org/10.1038/315207a0
Intergovernmental Panel on Climate Change. (2021). Climate change 2021: The physical science basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.
Nature India. (2026, August). Early warning could have saved hundreds of lives in Nepal floods. https://www.nature.com/articles/d44151-026-00167-w
Solomon, S., Ivy, D. J., Kinnison, D., Mills, M. J., Neely, R. R., & Schmidt, A. (2016). Emergence of healing in the Antarctic ozone layer. Science, 353(6296), 269–274. https://doi.org/10.1126/science.aae0061
United Nations Environment Programme. (2023). Montreal Protocol on Substances that Deplete the Ozone Layer. https://ozone.unep.org/treaties/montreal-protocol
World Meteorological Organization & United Nations Environment Programme. (2022). Scientific assessment of ozone depletion: 2022. WMO.

Dr. Namdev V. Telore is a Professor of Geography at Raja Shripatrao Bhagwantrao Mahavidyalaya, Aundh, Satara, affiliated with Shivaji University, Kolhapur. His research interests include geomorphology, watershed management, and remote sensing/GIS applications in disaster and drought assessment.https://vidwan.inflibnet.ac.in/profile/159877