The events at Lake Nyos, in Cameroon, Africa, in 1986 are terrifying, as the sudden release of tons of carbon dioxide asphyxiated the local population. Some died in their sleep, others as they investigated the noise of the gaseous eruption and resultant cloud. They simply collapsed.
But on the evening of Aug. 21, 1986, farmers living near the lake heard rumbling. At the same time, a frothy spray shot hundreds of feet out of the lake, and a white cloud collected over the water. From the ground, the cloud grew to 328 feet (100 meters) tall and flowed across the land. When farmers near the lake left their houses to investigate the noise, they lost consciousness.
The heavy cloud sunk into a valley, which channeled it into settlements. People in the affected areas collapsed in their tracks — at home, on roads or in the field — losing consciousness or dying in a few breaths. In Nyos and Kam, the first villages hit by the cloud, everyone but four inhabitants on high ground died.
And a similar situation may exist at Lake Kivu, threatening millions, as reported by The Observer.
Now a slow motion version of a similar problem involving currently sequestered carbon may be present in eastern Siberia. NewScientist‘s Eli Kintisch reports (15 August 2015, paywall):
The trees at Hellhole – the moniker sticks – were burned a decade ago and could provide an important clue in the debate over the impact of Arctic fire (see diagram). There is no question that warmer temperatures, drier conditions and, possibly, an uptick in lightning are catalysing a rise in blazes across the Arctic. This summer over 9 million hectares of forest in Alaska and Canada have burnt – a record – drawing thousands of firefighters to help.
Fires devour the organic layer of leaf litter and shrubs on the floor of boreal forests and tundra alike. As this layer offers insulation during the summer, burned sites could see an increase in the depth of the soil that thaws in summer, before refreezing in winter. More thawed soil could mean more microbial respiration of ancient Arctic carbon into the atmosphere, eventually turning the boreal forest from a carbon sink into a source.
Not the immediate deaths of millions, as at the lakes – but a large potential addition to the climate change crisis. But will it happen?
McKenzie Kuhn, a recent college graduate, checks one of a series of funnel-shaped bubble traps she set in the [Siberian] pools days ago. In the anoxic conditions found in the soil beneath the ponds, microbes can create methane, a potent greenhouse gas. The team is now trying to measure emissions from the ponds and determine if they come from the carbon locked in the permafrost.
Back in Cherskiy, preliminary lab tests of the gases emitted by the soils below Hellhole’s ponds show surprisingly high amounts of methane. So by destabilising the soil and creating microponds, the scientists hypothesise, fire may be creating a new fuse on the Arctic carbon bomb.
A great deal of methane, another component of climate change, is currently sequestered in the form of methane hydrates, methane frozen inside of ice. As the globe warms, there are concerns that these could melt, adding to our woes. They are found in the depths of the oceans as well as in permafrost. CommonDreams contributes this report:
Warning that a dramatic “burp” or “pulse” of methane from beneath the fragile permafrost of the Arctic caused by continued global warming would set off a “climate catastrophe,” a new study says that the continued melting is also an economic “time bomb” that could cost the global economy $60 trillion.
Billions upon billions of tons of methane remain stored in the permafrost throughout the Arctic regions, but specific concern has been placed on the enormous reserves that sit locked beneath the East Siberian Arctic Shelf. Scientists have repeatedly warned that if these deposits—many frozen in the form of methane hydrates—were released, they would trigger massive feedback loops and dramatically increase the rate of global warming.
The new study confirms these established fears, but also looks at the potential social and economic costs that would follow.
