Eastern Kentucky news outlets are reporting that Arch Coal will lay off 500 miners across the region. 

This is only the latest wave of layoffs in the coal industry, but so far, the largest. Earlier this month, Alpha Natural Resources announced it would close four Eastern Kentucky mines, but that only resulted in 150 total layoffs. There are numerous factors contributing to the current weak market for coal–the main ones are a warm winter, where people didn't use as much energy and record-low natural gas prices. With new federal pollution regulations on the horizon, power plants are finding it more cost-effective to cut back or abandon coal entirely.

And in the most recent data from the Energy Information Administration, coal's share of the nation's energy had dropped to only 34 percent.

UPDATE 2:13pm: In addition to the 500 layoffs planned in Kentucky, the Lexington Herald-Leader is reporting an additional 250 coal miners in West Virginia will be affected.

UPDATE 5:23 pm: Here's a link to Alpha's announcement. It quotes Arch CEO John Eaves:

Current market pressures and a challenging regulatory environment have pushed coal consumption in the United States to a 20-year low.  In response, we had previously streamlined capital spending, idled equipment and reduced shift work.  We now are taking further steps to enhance our competitive cost position in Appalachia, while increasingly shifting our portfolio in the region toward higher-margin metallurgical coal operations.  Despite the operational changes announced today, we are still able to serve customers here and abroad with the high level of quality they have come to expect from Arch.