A third practical concern is the melting of permafrost due to climate change. Degradation of this permafrost is leading to major ground surface subsidence and pounding. The ground is literally melting away in many regions of the Arctic. The locations of towns and communities that have been inhabited for centuries are now in jeopardy. A condition known as drunken tree syndrome is being caused by this melting. Ground water and river runoffs are being negatively impacted as well. Although warming conditions might increase uptake for photosynthetic organisms in some places, scientists are concerned that melting permafrost will also release large amounts of carbon locked in permafrost. Higher temperatures increase soil decomposition and if soil decomposition becomes higher than net primary production, global atmospheric carbon dioxide will in turn increase. Atmospheric sinks in the water table are also being reduced as the permafrost melts and decreases the height of the water table in the Arctic.