cooled atop the churning lava, like the skin on a pan of custard, it contracted and twisted, leaving some parts higher and thicker than others: the first mountains were created.
But the earth is never still. This solid ground, this apparently permanent land is imperceptibly shifting. Over the billions of years, the planet’s bubbling-custard turbulence has shattered the crust into scattered fragments, or sent its many islands crashing together to form huge continents. Several of these vast, coalesced supercontinents have merged and separated, each time creating an entirely reconfigured planet – the most recent and best known of these is Pangaea (‘all-earth’), which formed 300 million years ago before splitting up. Each time the drifting plates of crust have crashed into each other, the collision sends one edge above the other, creating a mountain. When the plates have drifted apart, the wrinkles are pulled smoother and the mountains sink. So some mountains on the planet are on the up, like the still-growing Himalayas, and others are dropping.
Mountains can also appear suddenly, through the process that gave birth to the original land masses, volcanism. Every so often, a bubble of molten rock spews out of a crack between the plates, and piles up on the surface of the land or seabed, creating a new mountain. Kilimanjaro in Tanzania and Kinabalu in Borneo appeared in this way.
When mountains first arise, they are sharp and jagged like the Himalayas, but over time, they round down as their surfaces erode, crumbling gradually away through glacial or river flows, or in the sudden slips of a landslide. Exposure to the air, wind, sun, munching microorganisms, and rain, also wear away mountain rocks in a process called ‘weathering’, which locks away carbon dioxide from the air as it reacts with dissolved minerals in the rocks.
Mountains are unusual because they have multiple climates. Usually, in order to experience a different temperature or weather system, you need to travel hundreds of kilometres north or south, but heading just a hundred metres up or down a mountain can have a similar effect. That’s because the air molecules in our atmosphere are not evenly spread out – they are far denser in a blanket near the ground. The higher you rise, the fewer molecules there are in the air to radiate back the sun’s heat, so it’s colder. That’s why mountains – even those on the equator, like Mount Kenya – have snow and ice on the top. When the altitude is combined with latitude, such as in Antarctica, the entire range can be hidden under deep snow and ice.
This change in climate produces interesting island-like ecosystems, with some species found only on specific altitude-defined spots on certain mountains where they have been isolated from their cousins for thousands of years.
The relative coldness up a mountain also generates the world’s largest source of fresh water, as moisture-laden air condenses against the peaks, relinquishing its load as rain or snow. And much of this remains where it accumulates, in mountain caches. For perspective, consider this: 97.5% of the Earth’s water is ocean or salty groundwater; of the remainder, just 0.01% is held in the clouds and rain, 0.08% is in all the world’s lakes, rivers and wetlands, 0.75% is in groundwater, while 1.66% is in glaciers and snow-packs. That means well over half of the world’s fresh water is stored in glaciers.
That’s how it was in the Holocene. But, as humans heat the planet in the Anthropocene, mountains are changing dramatically. Species seeking their usual living temperatures are climbing up the slopes at an average rate of twelve metres a decade, driven by global warming – they will need to migrate an estimated one hundred metres upslope for every 0.5°C of temperature rise.1 Clearly this is easier for animals than plants, but they too are moving – European vascular plants have shifted an average 2.7 metres uphill in the past seven years, for example.2 Other species have been marooned on peaks because their previous ranges have been occupied by human settlements or become farmland. Once at the top, though, there’s nowhere further to go, and thousands of species risk extinction, particularly those living on tropical mountains. Conservationists are now carrying out ‘managed relocation’ of species to places with a more a suitable climate, in the hope of saving them. In some cases, climate migrations have been beneficial, allowing people to cultivate fruit and vegetables higher up a mountain. But elsewhere, disease-carrying mosquitoes are now living at higher elevations where people with no immunity are being infected, with deadly consequences.
Of most concern to humans is the loss of ice. On average, glaciers have become fourteen metres thinner since 1970.3 Almost every single glacier looked at by the World Glacier Monitoring Service since 2000 has retreated, including all of the European ones, most of the tropical ones from the Himalayas through Africa to the Andes, and south to the mountains of New Zealand.
Humans have always worshipped mountains as gods or the home of gods, they have built temples high on their slopes and made pilgrimages to their peaks. In the Anthropocene, we are subjugating these geological marvels, turning them darker, drier and more homogeneous, stripping them of their unique flora and fauna, even decapitating them for the minerals inside. We are changing the shapes of Earth’s mountains – when they lose their protective snow, the exposed parts crumble away. Mountains including the Matterhorn in Switzerland are disintegrating.
Humans are still enthralled by the highest peaks, but the trails they make now to these heavenly reaches are more likely to be marked by litter than prayer stones. Nevertheless, even as we desecrate them, we depend more than ever on mountains for our fresh water.
In this chapter, I look at how the changes we are making to our mountains are affecting the people who live on them, and how humans are trying to recreate Holocene mountain conditions in the Anthropocene.
Temples rise above mudbrick houses and castles. Prayer flags flutter from every roof and woollen cloaked men and women with brightly coloured waist-sashes stand in the street gossiping. I’m in northern India’s remote Trans-Himalaya, in the the ancient kingdom of Ladakh. Consisting entirely of mountains, this, the highest inhabited region on Earth, is home to an 80% Tantric Buddhist population, settled by pilgrims and traders travelling the ancient Silk Route between Tibet and India or Iran.
In Stakmo village, farmers are preparing for harvest. Two men sit, chatting in sing-song tones against a dry-stone wall, sharpening their scythes with a blade pressed between their knees. An old woman with long, ribbon-woven plaits leads a donkey and calf over to her whitewashed mud-brick house. In the field behind, a yak munches alfalfa and swishes its horse-like tail. Bright marigolds nod crazily around a single apricot tree, and there is a barely perceptible tinkle of wind chimes. The scene feels timeless.
And yet, much has changed, the villagers tell me. ‘By mid-September, we would wake up with completely frozen moustaches,’ says Tashi, a 76-year-old farmer, who wears a woollen hat and large, pink-tinted sunglasses. Buddhist prayer beads hang around his neck and his dark sun-crinkled face is cleanish-shaven. I’m above 4,000 metres (13,000 feet), but nevertheless, it is not cold enough to freeze moustaches – from the clear, cloudless sky, the sun beams down intensely, as it does for more than 300 days of the year, and it’s burning my European face. The roof of the world is heating up.
Wedged between Pakistan, Afghanistan and China (or, more accurately, Tibet), Ladakh was a latecomer to the Indian state of Jammu and Kashmir and remains a contested territory. At night the Indian and Pakistani border patrols take potshots at each other; the Chinese come and paint Indian rocks red and the Indians respond by painting Chinese boulders green. But Stakmo feels very far from such nationalistic posturing. The villagers are more concerned with the ancient and essential task of coaxing food from the mountains’ mustard-coloured desert soils. Global warming is at play here, disrupting Ladakhi lives more effectively than any international land squabbles. Humanity is heating the region so fast that the mountains are changing colour before people’s eyes: from white to tobacco as the glaciers disappear. And with them, Ladakh’s only reliable water source.
In
