A Lake Breathed Out and 1,746 People Died. It's Breathing Again.

On the evening of August 21, 1986, the people of the villages around Lake Nyos, in the hills of northwest Cameroon, went to sleep as usual.¹

Around nine at night, some of them heard a rumble from the direction of the lake.

Then, silently, the lake breathed out.

Lake Nyos sits in the crater of an old volcano. For centuries, carbon dioxide gas from deep in the earth had been seeping up into its bottom water and dissolving there, building up under the weight of the lake like gas in a sealed soda bottle.² That night, something disturbed it. Maybe a landslide. Maybe a sudden change in temperature. The water turned over, and an enormous amount of carbon dioxide burst out of the lake at once.³

Carbon dioxide is invisible. It has no smell. It is heavier than air. The cloud rolled down out of the crater and along the valleys like water, for miles, hugging the ground.⁴ It pushed the air out of every house and every field it touched.

People died in their sleep. Families died at their tables. Herders died with their cattle. In the morning, the survivors walked out of their houses into silence. No birds. No insects. No voices.

At least 1,746 people were dead. Around 3,500 cattle. Every living thing in some villages.⁵

Scientists later installed pipes in the lake to slowly release the gas from the bottom, so it could never build up like that again.⁶

The pipes work. The lake is safer now. That is what the reports say.

Dr. Samuel Nkeng had been measuring Lake Nyos for twenty years. He knew its moods. He knew its colors. After 1986, the lake had turned a rusty red for weeks, as iron from the bottom came to the surface. In the decades since, it had been a calm, beautiful blue.

He came back from a routine survey in March with a sensor logbook that made no sense.

The degassing pipes were working perfectly. But the readings from the bottom of the lake showed the gas building up again, faster than ever. Faster than any natural process should allow. And when he dropped a sensor down to measure it, the sensor was dragged sideways in the water, against the current, toward the old village side of the lake, as if something down there were pulling it.

His colleagues said it was a malfunction. He knew better. He had seen something else in the logbook. Something written in the margin in handwriting that was not his.

She is not done.

Two days later, a teenager from a village near the lake came to his field station with a school exercise book.

The boy's name was Tamfu. His grandmother had survived 1986 as a girl. She had been the only one in her house to wake up that night. She had found her mother and her three brothers lying still on their sleeping mats, and she had run out into a silent valley full of the dead.

She had kept the exercise book under her bed for forty years. It belonged to her older brother, who was twelve when he died. The last page was written in a neat school hand, the night of August 21, 1986.

Grandfather says the lake has a spirit. A woman who lives at the bottom. He says the old people of the village made a promise to her long ago. Never fish the deep water. Never take the stones from her shore. Never let her see that we have forgotten her.

The new men came this year with their machines and their boats. They took stones from the shore for the road. They fished the deep water. They laughed at the old promise.

Tonight the lake is very quiet. Grandfather is afraid. He says she is holding her breath.