NEW YORK – One of the few remaining bulwarks propping up the US coal industry is languishing.

Prices for steelmaking coal, which has sustained miners as exports decline and power plants forsake the fuel, are down 22% since May as concerns about the global economy weigh on demand for steel.

That has US miners treading water as their shares sink. Peabody Energy  and Arch Coal are expanding production of metallurgical coal to offset falling prices, and both say those efforts will have little impact on earnings. The moves reflect the challenges facing an industry that has few options to drive growth in a world that’s turning away from the fuel.

“If you’re in the coal business, these are the times that try you,” Randy Atkins, chairman of Ramaco Resources, said on a conference call Wednesday. “The thermal coal market has pretty much dropped off the shelf. Even met coal benchmark prices that have held pretty steady at reasonably strong levels over the past year have now dropped.”

Ramaco, which produces met coal almost exclusively, attributes falling prices to uncertainties in the Chinese market, especially over import restrictions.

Peabody, the biggest US coal company, says the issues in the met coal market are broader. Prices have “eased largely due to the global concerns around trade and economic growth,” CEO Glenn Kellow said during the St. Louis-based company’s second-quarter earnings call last month.

He expects met coal production to increase in the second half, but lower prices mean Peabody’s adjusted earnings before interest, taxes, depreciation and amortization will be in line with the $481.9-million reported for the first half.

Arch, the No. 2 producer, will boost met coal output as much as 29% in the second half, potentially reaching four-million tons. However, the financial contribution this quarter from those operations will be comparable to the second quarter, as “increased shipping volumes are projected to be counterbalanced by lower index-based pricing,” Arch president Paul Lang said during the St. Louis-based company’s second-quarter earnings call.

Weak pricing prompted Contura Energy  to trim its 2019 shipment forecast for met coal by about 5.2%, “rather than being overly aggressive in selling at low returns into the buyer’s market,” CEO David Stetson said on a conference call Wednesday. “It’s prudent to be more conservative given the softness we experienced at the end use markets, most notably Europe and South America.”

Investors have watched shares follow met coal prices downward. Peabody has lost almost a quarter of its value since the end of the second quarter, while Ramaco and Contura are both down by more than a third.

Prices are unlikely to stay low forever because demand is tied to steel production, which isn’t going away. Global investment in met coal production is low, Ramaco executives said, which will help support prices as demand increases.

And the silver lining is that prices may be close to a bottom, according to Daniel Scott, an analyst with Clarksons Platou Securities. While he doesn’t expect steel demand to increase significantly in the near term, especially in China, inventory levels at mills are below average. That could drive sales and provide some stability to the market.

“While we think pricing could continue to move slightly lower from today’s levels, we expect it to find a floor soon,” he said in a research note.