Germany concludes underground coal mine fire in Thuringia may be impossible to extinguish

German authorities say an underground fire smouldering beneath a former lignite mining area in Thuringia may be effectively impossible to extinguish, after the blaze, which originated as a wildfire, burned its way beneath the surface.

While flames are now barely visible above ground, officials say the fire continues to burn underground within old lignite deposits, and could persist for years given the difficulty of reaching and suppressing combustion occurring beneath layers of soil and rock.

Underground coal and lignite fires are a recognised environmental challenge in regions with a history of mining, as such fires can be extremely difficult to fully extinguish once they take hold within exposed or abandoned coal seams, sometimes persisting for long periods and periodically resurfacing.

The fire's origin as a surface wildfire that then spread into the underground lignite area illustrates how conditions such as dry vegetation and extreme heat can interact with legacy industrial sites to create longer-lasting environmental hazards.

Authorities have not detailed the specific firefighting measures being deployed, nor have they given a timeline for how long the underground fire might continue to burn, beyond noting the possibility that it could persist for years.

Environmental and safety officials in the region are expected to continue monitoring the site, given the potential for the fire to affect air quality, soil conditions or resurface unexpectedly in the area.

The incident adds to concerns among environmental researchers about the compounding effects of increasingly severe wildfire conditions on legacy industrial and mining sites across parts of Europe.