Berinder and Karin are half hidden beneath their loads, only their legs visible as they pull onwards and upwards. Our porter team is a ragged line of colour, weaving in and out of mounds of rock and ice, disappearing and then reappearing. On all sides, ice climbs upwards in shards and shattered pyramids while frozen pillars tenuously support huge boulders.

The largest glacier in Asia, Gangotri is the prime feeder of water to India’s holy Ganges river and plays host to our team as we move further into a sacred Himalayan zone and towards the source of one of the greatest waterways on the planet, which Hindus know as the “Mother River”.

Our team is laced along a fractured kilometre of angled path. Behind me, bundled up against the cold, is Debra Tan, director of Hong Kong-based non-profit organisation China Water Risk. City resident and mountain lover, she is willing herself upwards to investigate one of the pressing issues of our times. The water-from-kitchen-tap culture of our cities spawns a comfortable apathy, but here the plight of water is crystal clear.

It is Berinder – unsmiling and tiny, in his pink woollen hat – who I track amid this maze of ice and stone. Having volun­teer­ed to take a double load of supplies for the entirety of this almost month-long journey from Gangotri town, in the Indian state of Uttarakhand, close to the Tibet border, he pirou­ettes under a crippling load, and the admiration I have for these porters – philosophers and fine-boned titans rolled into one – only increases. It is their sinuous power and knowledge of these mountains that can carry a journey (or unravel it), and they will be lifelines and compatriots in the weeks to come.

Gangotri is one of four dhams, places of pilgrimage for Hindus, and the faithful renew its vitality in annual migra­tions. Ill dressed, they wobble their way up with courage, grace and sometimes naiveté, while swamis tread barefoot, wrapped only in cottons, caps and a reverential gaze. The Ganges and Lord Shiva are worshipped with whatever zeal remains after the great journeys undertaken to get to this part of northern India.

If the Ganges thrives, India thrives and if the Ganges dies, India dies

Shuddering sounds and vibrations rumble non-stop through the moraine beneath us as crevasses open up and yawn. Massive vertical shards of ice cleave off under the sun, into the Bhagirathi River.

In Hindu mythology, the Bhagirathi is considered the source stream of the Ganges, but hydrology tells us that its other headstream, the Alaknanda, is more voluminous.

Destination: Uttarakhand

It is said that the Akash Ganga (“sky river”), the Milky Way as described in mythology, was persuaded to wash away the sins of mortals by King Bhagirathi. She descended into the locks of Lord Shiva, the first yogi, and broke into several river channels at Gangotri (ganga being the river, and utri meaning “descended”).

“If the Ganges thrives, India thrives and if the Ganges dies, India dies,” runs a popular refrain.

We’re in one of the most densely peak-ridden regions of the Himalayas and melting ice from here flows south onto the Indo-Gangetic Plain, a basin that encompasses nearly 42 per cent of the Indian population. When the Ganges finally discharges, after flowing for 2,525km, into the Bay of Bengal, it is a soup of industrial and human waste. Rivers across the globe have been similarly abused, but few to the extent of the Ganges.

Morning comes to Tapovan camp, 4,463 metres above sea level, and the northeastern wall of one of the mountain­eering world’s great peaks, Shivling, is lit up by the sun. “Camps” here are areas favoured by expeditions and climb­ing groups for their fresh water and wind breaks. Further west, languishing in cold blue shadow, is revered Meru, and one of many tributary glaciers that we have come to survey.

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Our kitchen tent comes to life, with Karma vocally shift­­ing between muttered mantras in Tibetan and bellowed Bollywood classics in Hindi while scurrying noises and vague complaints escape the porters’ tent.

Purun and I stand waiting for the sun to touch us and Karma’s potent cups of tea, complete with freshly grated ginger, cloves and cinnamon. Purun, Karma and I have travelled together in the mountains before, and with them mornings are pleasingly devoid of chatter.

Our team is a wonderful stew of characters: along with Purun, Karma and Tan is languid local guide Saurabh and a team of five porters, including Berinder (he of the pink hat), who has become like an appendage, shadowing me, admonish­ing me, and watching ... always watching.

Southwards we push, up and further onto the Gangotri, to another of the tributary glaciers, the Kirti, and to a camp that lies at 4,800 metres.

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Saurabh warns us of a “small descent that will take a little time” to negotiate, his voice ever so slightly raised, and this “small descent” is revealed as a dirt path that pitches into a dark line cleaved in the glacier below. Dust and sand rain down as the porters take the path with their huge loads and some mantras. Even they pray at such points. Tan’s wide eyes betray her trepidation as shale, dust, sand and rocks – landslides in the making – rocket down the slope, leaving little plumes in their wake.

Kalè, kalè,” whispers Karma – “Slowly, slowly.” One slip and gravity will do the rest. We are not roped to one another, as we have agreed that our chances are better if we catch a fall rather than drag down others on these paths.

Kirti camp is in a small river basin into which winds cannot quite corkscrew. We will camp here for three nights while I make daily glacier forays with Saurabh and Berinder in tow.The porters lose themselves in their billowing tent and games of cards, the epic voice of legendary Indian singer Lata Mangeshkar issuing from a mobile phone.

A small blue stream tinkles ever downwards. Later, having crawled down into a cave, with Saurabh somewhere above, waiting, I’m suspended inches above a glacial stream, icy water that will become the Ganges later today or perhaps tomorrow.

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Berinder is ahead and struggling. His body heaves as we diagonally traverse Gangotri, continuing east towards another tributary glacier. Karin, the head porter, takes Berinder’s extra load without ceremony, just a simple nod to his colleague’s travails.

The jagged belt that we cross is a lethal, ever-shifting body of ice and crevasses, the only pathways the ones that Karin sniffs out. Every step requires a variation in pace and the placing of feet.

Arriving at Nandanvan camp, Purun says simply, “The quiet time is leaving.” The sky is in dark flux and the nearby Bhagirathi Peaks seem to funnel winds down upon us.

North of our camp lies the layered rainbow of moraine and stone of the Chaturangi “four colours” Glacier. Every tributary glacier we’ve encountered has bled its tones into the larger Gangotri and all have their own tonal range and accents. Local guides can often tell which glaciers are bleeding most heavily simply by looking at the greater Gangotri ice flow to see which colours dominate.

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Winter is draping each day in more of its insulating curtains; life and movement are ebbing. Blue sheep move down in small groups from their high perches, setting off little landslides as they go, and even the foxes, which have been yipping and whining at night, are silenced.

Berinder has had his morning tea and stands like a shy gunslinger, hands at the side, ready. He wants to get moving as today we make an incursion east into the Chaturangi Glacier valley.

After packed lunches of chocolate, biscuits, raisins and tea (the power of tea cannot be overstated; it uncoils the muscles and brain, and reconstitutes the spirit), Berinder bolts off, eager to sate the demons that seem to come to him when sedentary. Saurabh glides after him.

Below us, red stone and green pools of glacial water pock the surface of the glacier. The pools are supraglacial lakes and can be far wider and deeper than one might suspect. Retain­ing more of the sun’s heat, they further warm the glacier.

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Above us, to the right, is Bhagirathi 2 and its 6,512-metre summit. Sacred peaks, rivers and the great arbours are con­sidered living entities in these parts. Practicality and the world of deities are remarkably complementary – a remnant from a time when the mountains belonged to the animists. For locals, there is little contradiction in fusing facts and beliefs. Beliefs inform life and, in many cases, locals will point to their own ways as being more sustainable and intuitive.

The air changes suddenly and completely – as it frequently does in the mountains – and there is the tang of snow in the winds racing down from the Kalindi Pass, to the east. The air carries with it the unmistakable sharpness of lands above, where temperatures remain low.

Saurabh sniffs at the sky with an arched neck, nodding; a storm is on the way. He heads on alone to assess conditions ahead in the valley. Berinder and I will have some tea, chocolate and almonds while we await his return.

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After a while, Berinder’s familiar look of furtive impati­ence returns. The storm continues to pile into the valley and now the sky is more grey than blue. We lie on our stomachs chewing on nuts, watching the tiny figure of Saurabh hurtling upwards along a little pathway. Then he disappears.

Berinder is itching to follow; there is a little English, a lot of Nepali, shakes of the head and some deep nods from him. I relent and we scurry after Saurabh.

The valley we pass down into and then out of is one of the reasons we have come. It is a hidden, rivulet-lined sheet of concave ice that plunges towards the Chaturangi Glacier, behind us. As a tributary glacier it is a vital witness to what ails the mountains.

As we reach a vertical ropeway, a permanent fixture, the last of the sun is eaten up by a surging cloud bank, and above appears Saurabh, smiling as he rappels down to us in easy springs.

He shakes his head at the notion of continuing further.

“Two storms are coming together,” he says. Another cloud front is being whipped up behind us as it moves towards the storm ahead. From somewhere comes a rumble that shakes the world.

The snow arrives and so, too, does our tea, from Karma’s busy kettle, as bodies snuggle up in tents.

Sight lines shrink from dozens of kilometres to just metres and flakes the size of leaves blow diagonally as the storm that barrelled down from the greater Gangotri Glacier takes our entire camp into its embrace.

Inevitably, conversation turns to the health of the mountains. One cannot spend time within these bastions without being wracked with worry about the intense changes being wrought by distant forces. With cups of tea in hand, we imagine what fate holds in store for the great bodies of ice.

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Tomorrow, we will descend from the mountains and pass those epic stones and disintegrating bodies of ice that we gazed on 26 days ago.

If estimates suggesting that 30 metres a year disappear are true, then about two metres of ice will have liquefied since our ascent.

Berinder sips his tea and shows only a hint of a smile.

Within their own colourful tent, the yips and squeals of the other porters can be heard even above the heaving storm. For now, they are content being content.

Jeff Fuchs is an explorer, mountaineer, writer and tea expert. He was the first Westerner to trek the entire Yunnan-Tibet Ancient Tea and Horse Road, an expedition spanning nearly 6,500km and lasting eight months.