'Methane leak in Kazakhstan among the worst ever recorded' - Breaking news. An estimated 127,000 tonnes of gas have entered the atmosphere since an explosion caused a fire that lasted more than six months.
Buzachi Neft, the company that owns the well, denies that a "substantial quantity" of methane escaped. Methane is a much more potent greenhouse gas than carbon dioxide. Local authorities told the BBC that work is currently underway to seal the concrete pit in Mangistau.