It used to be that you could measure confidence in the container-shipping industry by the ever-increasing scale of the carriers’ vessels and the size of their ship orders.

These days, the hulking megaships that serve the world’s biggest trade routes look more than ever like monuments to brash corporate planning and projections built out of hopes rather than reality.

From slowing global trade to rising fuel prices to capacity increasingly out of step with demand, container-shipping operators are facing new challenges over the next two years, hurting prospects for a recovery after nearly a decade of moving in fits and starts toward stability.

Shipments of boxes stuffed with clothing, electronics, manufacturing parts and a broad range of consumer goods across the oceans are the backbone of global trade. But the cost of moving them could go up sharply as regulations calling for cleaner—and more expensive—ship fuels kick in next year.

Estimates are that shipping companies will try to pass on to cargo owners about $10 billion a year in combined additional expenses from the new fuel requirements, but they will almost certainly have to absorb some of those costs to keep customers on board.