The Globe and Mail reports in its Wednesday edition that the OPEC oil cartel shrank again on Tuesday when the United Arab Emirates exited after nearly 60 years. The Globe's Eric Reguly writes that this departure of the seventh-largest oil producer is a setback for OPEC and Saudi Arabia, while benefiting U.S. President Donald Trump, who has criticized the group's price-setting power. The UAE is leaving on May 1, citing vague reasons. Its Energy Minister said the decision followed a review of the country's production policy and capacity, based on national interest. Mr. Reguly figures that was a polite way of saying: We don't like the Saudis telling us how much to produce. The UAE, like Saudi Arabia, is a key "swing producer" in OPEC, meaning it has the capacity to increase oil output when global demand rises. According to various reports, the UAE has sustainable production capacity of 4.85 million barrels a day, which is just short of Canada's output. But under OPEC's quota system, the UAE's production is capped at 3.4 million barrels -- 30 per cent below its capacity. That is a lot of money to leave on the table, especially in a country where oil exports account for almost a third of gross domestic product.