At 6am, oil workers gather at Bergen heliport on the jagged west coast of Norway, don orange survival suits and prepare for the one-hour chopper flight 200km across the North Sea that will take them to their next two-week tour of duty. The trip is enlivened only marginally by tinny local news on the headphones.

But eventually the gas flare of the Statfjord oil rig looms into view. Along with flames from other platforms, it forms an arc of fire that runs north to the Norwegian Sea and crosses the Arctic Circle into the Barents Sea – each one a burning testament to the $273bn (£140bn, €211bn) wealth accumulated by the Nordic country of 4m as a result of its undersea resources.