Climate change is turning northern farmlands into nitrogen pollution hotspots (earth.com)

For as long as researchers have tracked it, China’s worst cropland nitrogen pollution has occurred in the humid south. Heavy rain, dense river networks, and fertilizer runoff flowing directly into the water have created a well-known and well-studied problem. A new modeling study suggests that the pattern is about to change. As the climate shifts, the country’s emerging pollution hotspots could migrate away from the humid south and into the arid and semi-arid regions of the north. The research comes from a team led by Professor Yongqiu Xia at the Institute of Soil Science, Chinese Academy of Sciences. Rainfall drove pollution in the south Nitrogen that crops fail to absorb does not simply vanish. It accumulates in the soil until rain washes it into rivers, lakes, and reservoirs downstream. Southern China’s heavier rainfall and dense network of waterways have made the region the country’s long-standing hotspot for this type of pollution. The north, by contrast, has largely escaped the problem. Less rain meant less runoff and, therefore, less nitrogen reaching rivers – or so researchers thought. Climate change shifts the balance That north-south divide was never a law of nature. It reflected a balance, and that balance can shift. Rising...