Global oil and gas prices have spiked as the conflict in the Middle East halts energy exports from the region. The strait of Hormuz has been in effect closed since the war began, causing fears of a global economic crisis. About a fifth of the world’s oil is shipped through the narrow passage of water, but, according to reports, traffic has dropped by about 80%, with little sign of return. How long until we feel the effects? Nosheen Iqbal speaks to John Collingridge, the Guardian’s head of business.