ANCHORAGE, Alaska (AP) — A company operating one of the world’s largest zinc mines in Alaska says thawing permafrost linked to global warming has forced an expenditure of nearly $20 million on water storage and discharge management. Alaska’s Energy Desk reported Teck Resources Ltd. says permafrost thaw in the watershed surrounding the Red Dog Mine is releasing higher natural levels of dissolved minerals and other particles into streams. The Vancouver-based company says the release limited the mine’s ability to discharge its treated wastewater into a nearby creek, causing water to back up. Red Dog resumed discharging after constructing a new wastewater treatment system.