A third sources, the warming-enhanced decay of organic matter in forests and soils, especially in the middle and higher latitudes, is now being recognized as potentially significant.

第三个来源，特别是在中纬度和高纬度地区，森林和土壤中因气候变暖而加剧的有机物腐烂，现在被认为具有潜在的重大意义。