T he conflict in the Middle East has claimed Opec as the latest casualty of war. The United Arab Emirates’ shock exit from the oil cartel on Tuesday after 60 years is expected to weaken the alliance, which under the leadership of Saudi Arabia has helped to soothe volatility in the global oil market for decades. Global oil prices reached the highest level in four years on Thursday, rising above $126 a barrel. But as the region grapples with the continuing conflict, a fresh war may be brewing in the international oil markets, which could lead to greater market volatility for years to come. For now, the UAE’s intention to ignore Opec production quotas and pump as much crude as it wants is notional, owing to Iran’s blockade on the strait of Hormuz. So too is Riyadh’s ability to weaponise its vast oil reserves in response. But in a postwar standoff between the two Gulf oil heavyweights, there lies the real risk of a price war in which global energy markets could plunge, with unpredictable economic consequences.…