Tuesday 3rd November 8.00pm
The documentary series examining freak occurrences in the natural world concludes. In 1986, a mysterious natural disaster claimed the lives of nearly 2,000 people at a lake in Cameroon. Scientists initially believed an underwater volcanic eruption was to blame, until the evidence pointed them towards an astonishing new scientific phenomenon.
On 21 August 1986, disaster struck a remote corner of north-west Cameroon. Nearly 2,000 people dropped dead by Lake Nyos without any obvious signs of injury or struggle. The following day, news of the staggering scale of the tragedy reached the outside world.
Father Anthony Bangsi, a missionary in the village of Subum, recalls the awful event. He was a witness to the aftermath of the terrifying incident that virtually wiped out an entire village. Neither Anthony nor any of the locals could explain what happened at Lake Nyos.
American lake expert George Kling was one of the first outsiders on the scene. There was some evidence to suggest that a volcanic eruption under the lake was to blame for the incident. Bodies were burnt and people recalled smelling volcanic gases like sulphur in the air. However, Kling could find no proof of lava flows, fire fountains or any traces of volcanic gases. Moreover, the temperature of the lake was actually cooler than normal. Kling concluded that a volcano could not be responsible for the tragedy. What, then, was the cause?
Officials turned to Icelandic volcanologist Haraldur Sigurdsson, who had investigated a similar incident in Cameroon two years earlier. In 1984, Sigurdsson was dispatched to the volcanic Lake Monoun to probe 37 very similar deaths. As in the disaster at Nyos, the victims died in one night without any sign of a struggle. Sigurdsson was asked to confirm that an eruption was to blame, but his tests also showed no evidence of volcanic activity.
A sample taken from the bottom of Lake Monoun provided a possible answer. The water was found to contain large amounts of carbon dioxide, a natural gas that, in sufficient quantities, can kill through suffocation. Sigurdsson formulated a hypothesis called ‘lake overturn’. He postulated that an unprecedented natural disaster could occur when a large concentration of CO2 stored in a lake erupts to the surface.
However, Sigurdsson’s theory was deemed too controversial as nothing like it had ever happened before. It was ignored by his fellow scientists, and his suggestion that other lakes in the region be checked for high levels of CO2 was rejected by the Cameroon government. This mistake led to the massive loss of life at Lake Nyos two years later.
Back at Nyos, George Kling decided that Sigurdsson’s theory could be right. His own investigation found large quantities of CO2 in the deep water of the lake. He concluded that this natural gas erupted in a toxic cloud that poisoned three lakeside villages. This cloud would have been invisible, silent and odourless, rendering it the perfect killer.
The theory was supported by the discovery that the burns on the victims’ bodies were in fact inflicted by frostbite from the cold carbon dioxide and not from hot volcanic gases. Kling also found research from the US Air Force that proved exposure to CO2 can lead to hallucinations where victims imagine they smell sulphur. These extraordinary revelations paved the way for new safeguards to prevent any repeat of the tragic accident at Lake Nyos.