By Jyoti Thakur, Pratik Chakarborty
It’s an autumn morning at Mawmluh Cave, near Cherrapunji, in Meghalaya’s north-eastern hills. At the entrance, 27-year-old Milton Marak switches on his headlamp, and leads a group into the darkness.
There are no electric lights inside. Only the beams from visitors’ torches illuminate towering stalagmites, delicate soda straws and curtains of calcite hanging from the cave ceiling.
Marak was 18 when he first crawled into the Mawmluh Cave with nothing but a borrowed torch. Trained over two years, he knows the 7.2 kilometre cave well enough to navigate its passages without a map.
“We’ve deliberately kept the cave natural,” he says. “If we install lights, it becomes a showroom. The real experience is entering a naturally dark cave with only your own light.”
Marak adds that they could not rely on maps while guiding visitors. “We had to know every route by heart,” he says. Every visitor, while caving, is briefed to not touch the formations, litter, or carve their names into the cave walls. Only 25 people are allowed inside the Mawmluh cave each day. The rules, Marak says, exist for good reason.
Mawmluh is more than a tourist attraction for people in Meghalaya and scientists worldwide. Beneath Meghalaya’s rain-soaked limestone hills, the caves hold a remarkable archive of the planet’s climate history, one that scientists now fear is increasingly vulnerable.
Across Meghalaya’s limestone plateau, hundreds of such caves face growing pressure from two fronts: a changing climate is altering the rainfall and groundwater systems that shaped them over millennia, while decades of unregulated mining are slowly destroying geological formations that took millions of years to form.
As these subterranean ecosystems come under increasing pressure, scientists and local communities are looking for ways to protect them.
A library written in stone
To truly understand what’s at stake, it’s important to learn how these caves are formed.
Every drop of rain that filters through Meghalaya’s limestone hills carries dissolved minerals into the cave. Over thousands of years, those minerals accumulate layer by layer, forming stalagmites that preserve an uninterrupted chemical record of past rainfall, droughts and environmental change. Using uranium-thorium dating, researchers can determine precisely when each layer formed, while tiny variations in its chemistry reveal how the Indian summer monsoon changed through time.
“They are like books in a library,” says Sebastian Breitenbach, a paleoclimatologist and an associate professor at Northumbria University, who studies ancient climates using cave formations. “You just have to learn the language and then you can read the past.”
That record extends far beyond India’s borders.
A stalagmite from Mawmluh Cave preserves evidence of a major weakening of the Indian summer monsoon around 4,200 years ago, a climatic event associated with periods of drought and societal changes in parts of the world, including Indus Valley, Mesopotamia and Egypt. The cave’s speleothem was chosen as the geological marker for the beginning of the Meghalayan Age, which was formally recognised in 2018. Scientists say rainfall across Meghalaya is becoming more erratic. Wet seasons are shortening, while intense downpours are becoming more common. Instead of slowly filtering through limestone, large volumes of water now rush underground, carrying sediment that can damage delicate formations and alter the chemical conditions needed for stalagmites to continue growing.
“It’s ironic,” says Jaishree Sanwal Bhatt, a geologist at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bengaluru, who has spent two decades studying cave deposits across the Himalayas and Meghalaya. “The climate changes we study in these records are now putting those records at risk.”
Breitenbach points out the risk in terms of the stalagmites’ own survival: they need a minimum of steady infiltration to keep growing. If water infiltration were to stop completely, stalagmite growth would cease, creating what scientists call a “hiatus”, a permanent break in one of Earth’s most valuable climate archives.
Though, he quickly adds, Meghalaya’s monsoon still delivers enough rain to keep the caves “happy”. But the seasonality is shifting, and both Breitenbach and Bhatt warn that prolonged dry spells can be just as damaging to cave ecosystems as sudden floods, starving the insects, fish and crustaceans that depend entirely on stable underground water.
Mining the caves
While climate change is one aspect, the more immediate danger lies above ground.
Much of Meghalaya’s cave network runs through limestone hills that are also prized for cement production. Limestone quarrying can destroy caves outright by removing the rock that contains them, while coal mining alters underground water flow and introduces pollution into fragile ecosystems.
“I remember standing inside Mawmluh Cave and hearing blasting from a nearby limestone quarry,” Breitenbach recalls. “Not a great experience,” he says, adding that mining has already changed the hydrology of several cave systems. Coal dust, oil, plastic waste and sulphur washed into underground streams can alter mineral formation and threaten cave fish, crabs and other species found nowhere else.
Despite the 2014 National Green Tribunal ban, illegal rat-hole mining continues across Meghalaya, with the state government registering more than 1,000 cases since the prohibition. The scale of enforcement failures was underscored earlier this year, when an explosion at an illegal mine in East Jaintia Hills killed 27 miners and injured nine.
Bhatt describes mining as an irreversible threat. Unlike forests, she says, cave formations cannot regenerate once they are destroyed. Because Meghalaya’s caves form almost entirely within limestone, quarrying for cement can remove the rock the cave was carved from, collapsing passages and destroying formations that took tens of thousands of years to grow. Even where caves appear intact, disrupted groundwater can permanently alter the processes that created them.
Importantly, those caves are also home to extraordinary life.
Inside Mawmluh, lost in complete darkness and submerged in freezing cold water, Marak points his head torch at transparent freshwater shrimp, white crabs, spiders, cave crickets and worms that have adapted to perpetual darkness. Their lack of pigmentation reflects an ecosystem that evolved completely in the absence of sunlight.
Across Meghalaya, researchers continue to discover species found nowhere else, including what is believed to be the world’s largest cave-dwelling fish. During a 2019 expedition, state researchers discovered Neolissochilus pnar, measuring nearly a foot and a half in length and weighing roughly ten times more than any other known species.
Brian D. Kharpran, regarded as India’s first speleologist, has spent three decades documenting more than 1,700 of Meghalaya’s estimated 2,000 caves with his team at the Meghalaya Adventures’ Association (MAA) that he founded in 1990 to explore the subterranean world of the state. He contends that even so-called “scientific mining” requires the removal of forests, hills, and limestone landscapes, making it fundamentally destructive.
In 2007 he filed a Public Interest Litigation (PIL) in the Supreme Court seeking protection from limestone quarrying, cement production and coal mining. It was dismissed more than a year later without explanation. He believes “powerful political” and “economic interests” blocked it.
Moreover, most land in Meghalaya is privately or community-owned rather than government-controlled, leaving authorities with limited power to stop mining even where they want to.
The village steps in
In the absence of strong regulation, many villages are trying a different approach, not by closing caves to people, but by giving local communities a reason to protect them.
Quenty Mary Jallong, 24, recently completed a nature guide training programme under the MAA. Her village has known about its cave for generations, but only the entrance had ever been explored safely.
“I wanted to learn what lies inside,” she says, adding that she hopes to work with her village council to develop the cave as a community-managed tourist destination. The goal is not mass tourism but carefully managed visits that create jobs, while discouraging future quarrying.
“Jobs are very difficult to find in our village,” she says. “Most opportunities would require leaving the village. But I would rather help create opportunities here, within my own community.”
A similar vision motivates Wanpylnbiang, 22, who had to leave school after Class 12 because his family could not afford higher education. He works part-time in a shop, but hopes responsible tourism can create livelihoods that allow young people to remain in their villages.
While exploring local caves prior to joining the training programme, he discovered fossils, bats, and a wild snail, which piqued his interest in the underground world. Today, he believes that conservation and employment can coexist if the council backs their vision for responsible tourism.
Much of that vision stems from Kharpran’s initiative through MAA of training approximately 100 local youth as certified cave guides and collaborating with village councils to promote responsible cave tourism over the last three decades. Kharpran advocates for the opening of only a few caves to visitors, while ecologically sensitive caves remain protected.
‘Conservation must be guided by science’
Kharpran says Meghalaya’s unique system of land ownership makes community stewardship essential, because conservation cannot be achieved through government regulation alone. “Unless locals benefit from cave protection, mining will be an appealing alternative,” he adds.
Scientists welcome these efforts but caution that local initiatives cannot shoulder the burden alone. “Ecotourism is important, but conservation must also be guided by science,” Bhatt says. Communities lack the tools for long-term monitoring and no control over mining permissions, which are decided at higher government levels.
Protecting caves, Bhatt says, of global scientific importance, requires stronger mining regulations, scientifically defined buffer zones around sensitive cave systems, sustained monitoring and closer collaboration between researchers, policymakers and local communities.
Inside the Mawmluh Cave, Marak watches another group disappear into the darkness, their headlamps flickering against walls that have recorded thousands of years of climatic past. “Earlier, we had very few visitors,” he says. “Today, hundreds of people come every year to experience the cave. That has made me realise how important it is to preserve it [the caves] so future generations can experience it too.”
This article is republished from Mongabay under a Creative Commons license. Read the original article here.