OPEC’s effort to shore up world oil markets during the pandemic is facing a new threat — from the group’s own rising production. In the past few months, the resurgent coronavirus has increasingly frustrated the cartel’s attempt to defend crude prices through cutting its output. Oil futures have sunk below $40 a barrel in London to their lowest since May. But a fresh challenge is emerging from within the organization’s own ranks, just weeks before Saudi Arabia and other oil heavyweights meet to to draw up plans for the year ahead. OPEC production increased significantly last month, according to a Bloomberg survey. Libya, a member exempt from the pact to restrain production, is reviving exports as its political turmoil eases. Meanwhile, Iraq and Nigeria are once again reneging on pledges to rein in their shipments. Output […]