Once upon a time – six months ago, another age – anyone who could say “crack spread” without laughing was assured a lucrative job as an oil trader. Back then, when crude oil was trading at $140 a barrel, the world looked Malthusian. The globe was running out of oil, civilisation was threatened by a violent scramble for scarce resources, and peak oil theorists – or POT heads – held the stage. Now the oil price has collapsed to just over $40 and everyone is swimming in the stuff. Curiously, for those who seek patterns in numbers, the crash comes exactly 10 years after the Asian financial crisis, when crude prices plumbed $10.

Few believe crude will fall that low again – although in theory it could. Demand has contracted so rapidly that it has depressed the spot price relative to future prices, creating what oil traders call a contango. This encourages oil companies and traders to hoard crude – onshore, or in super tankers out at sea. Because storage costs are so low, decent profits can then be made from holding the oil and delivering it forward at a higher price later. But if spare storage capacity were to run out, there would be a risk that physical oil would be dumped on to the market for immediate delivery, thereby forcing down the spot price even further.