Nigeria boasts sub-Saharan Africa’s biggest energy industry and flared about 15bn cubic metres of gas last year, about one-tenth of the global total. But 150m Nigerians share roughly as much electricity as the 3m inhabitants of Wales.

As world leaders prepare to gather in Copenhagen of next month’s climate change summit, the Niger delta’s flares serve as reminders of the difficulties of their task.

Gas flares have wreaked environmental damage and pitted militants and activists against the government and oil companies