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On a partly sunlit day in May 2024, when I eventually reached the Khumbu Glacier after six days of trekking, I was struck by the number of people staying there. The trek was part of a science journalism Climate Boot Camp in the Everest region, organised by the Nepal Forum of Science Journalists (NFSJ), bringing together 10 South Asian journalists.
The base camp didn’t look like merely a temporary staging point for a handful of climbers preparing for an extraordinary ascent to the world’s tallest mountain.
The scene was strikingly different from the remoteness I had imagined. Tents were scattered across a large part of the glacier, forming what looked less like a temporary mountaineering outpost and more like a bustling high-altitude tourist settlement.
I, like most of my fellow trekkers in our group, kept wondering what impact could such a persistent and telling human presence and the resultant human activities, ranging from cooking and heating to urinating and defecating, have on the glacier?
Thankfully, those impressions have now acquired a striking scientific dimension. While I was surprised to see people beyond my expectations staying at the camp, I could not have known that a scientific study, sometime soon, would put surprising numbers against some of the questions that arose in my mind back then.
A new study in Regional Environmental Change by Springer Nature, after examining the human footprint at Everest Base Camp (EBC) and its possible contribution to local glacier melt, has analysed how human activity at the base camp impacts the Khumbu Glacier.
Using field data from the spring 2023 climbing season, the study examined the energy released through the use of liquefied petroleum gas (LPG), kerosene, and petrol for cooking, heating, and electricity, as well as the heat generated by human urinary discharge.
The numbers which the researchers have arrived at, are astonishing.
Over roughly 50 days, the study found that about 1,600 tents at EBC consumed 824 LPG canisters, 18,935 litres of kerosene and 5,130 litres of gasoline for cooking, heating and power generation.
Adding the heat associated with human urinary discharge, they calculated a total release of about 849,174 megajoules of thermal energy. The equivalent amount of heat which would be sufficient to melt approximately 2,492 tons of glacier ice and snow.
The researchers estimated that climbers and support staff can generate more than 6,000 litres of urine a day at high altitude, much of which is released directly onto the Khumbu Glacier. According to their calculations, heat contained in the urine alone has the energy equivalent to melting roughly 154 tonnes of ice over a season.
There was another part of my experience on the trail that the study has, however, missed to examine — the growing numbers of mules and yaks. During my trek to and from the base camp, I could repeatedly see long trains of mules clattering along the trail, often kicking up thick clouds of dust, their hooves striking the path in a distinctive way and their bells punctuating the mountain silence.
If the heat from human urine can be quantified in relation to glacier melt, what about the growing numbers of animals accompanying the expanding flow of trekkers and supplies? After all, their urine is also released into the same fragile high-altitude environment.
In any case, the presence of these animals in such large numbers along the trail was hard to miss and I asked one of our guides, Phu Chhettar Sherpa, if there were more mules and yaks on the trail now than before, or if it had always been this way. He told me that only until two or three years he would see just a few mules on the trail though yaks’ numbers have not changed much. “But now, there are too many mules.”
His explanation was straightforward. Now the region is thronged more so by tourists, “who often fail to muster up the stamina for trekking.” Serious trekkers, Sherpa said, generally preferred to walk. Earlier, he went on to say, mules were way lesser in number and were only used to carry supplies or somebody who became exhausted or unwell and could no longer continue comfortably on foot.
“Tourists from India mostly use mules to get to EBC,” he told me. More Indians, he said, are coming now, “and therefore more mules are being used.”
The new study on human footprint at EBC makes an important point impossible to ignore. Compared with the enormous volume of ice being lost to global warming — a consequence of decades of fossil-fuel-driven industrialisation and development, disproportionately driven by wealthier countries — the few thousand tonnes of potential melt associated with human activity at EBC are hardly comparable.
The climber or tourist, therefore, is certainly not the villain, nor is their activity the principal culprit. For example, a 2026 study in The Cryosphere found that historical warming has already committed the Khumbu Glacier to substantial mass loss this century.
Under an intermediate emissions scenario, the researchers project around 70 per cent glacier-mass loss by 2100 from warming alone, although increased precipitation could partially offset that loss under some scenarios. Under a high-emissions pathway, that compensation largely disappears.
But the finding certainly exposes a deeper contradiction. As we warm the planet at a global scale, we are also making some of its most fragile places increasingly comfortable for ourselves. The glacier is not merely being visited. It is being furnished, heated and fuelled. In the most literal sense, it is used as living space.
While trekking towards the world’s highest mountain before we had flown from Kathmandu to Lukla in a small fixed-wing aircraft — and when we walked down after a few days — I found myself thinking what if they decide to lay a road here.
It was an odd thought to have in a landscape which demands silence and the slow rhythm of walking. But somewhere along the trail, I began imagining if a road comes up from one of the valleys below, climbing higher and higher, perhaps eventually reaching EBC. Or as close to EBC as the terrain would permit.
This thought didn’t come out of the blue. Coming from the other side of the Himalayan arc in India, I have seen this obsession of mountains being machined through to make roads and tunnels, even in places where a road can look unnecessary, visually jarring and ecologically absurd. Contested fiercely on environmental grounds, the Char Dham highway project in the Himalayan state of Uttarakhand which connects the state’s four major pilgrimage centres, was executed despite triggering years of environmental litigation.
In my home region, Kashmir, where ecological sensitivity has frequently prompted concern over the scale and nature of infrastructure development in recent years, a plan for carving out a road worth Rs 3,500 crore to the Amarnath Cave, has alarmed the locals. Their concerns go beyond ecology. The Amarnath Cave, at about 3,880 metres, lies in the upper Lidder Valley, a remarkably fragile glaciated landscape that feeds the Lidder stream, an important tributary of the Jhelum river as also the Sindh stream, another tributary of the Jhelum.
A road is often marketed as a sign of development by ruling dispensations across South Asia. It is often a harbinger of connectivity, commerce, access and tourism. But in fragile mountain landscapes, the consequential effects of a road can come during and after its construction. Road construction in fragile mountainous environments often entails excavation, blasting, dumping and slope cutting.
And once a road is laid, it brings people, vehicles, goods, waste and more and more construction. Building infrastructure and settlements within ecologically sensitive mountain environments has repeatedly shown in recent years the consequences such development can bring, with the August 26 floods in Nepal providing the latest evidence.
On the Everest trail, it is the difficult trek which makes the journey beautiful, memorable and meaningful. And it is precisely that difficulty that seems to have protected the places along the Everest trail, at least to some extent.
Imagine what a road to EBC, or somewhere closer it would unleash.
When our hosts at the Nepal Forum of Science Journalists brought journalists and scientists together in Kathmandu after the boot camp, I strongly urged our Nepali friends to use their academic and intellectual heft to nip in the bud any move, or even proposal, to build a road to the EBC or push road access anywhere closer to it.
They agreed that this was something worth guarding against. Last year’s disaster in the Bhote Koshi River, followed by this year’s far more devastating tragedy in the same river system, must have strengthened that resolve even further.
I wish the Everest region, and other ecologically fragile regions around the globe, best of ecological health!