While world attention is focused on climate change and extreme weather, U.S. researchers say another global change underway must be addressed: acidification. The combustion of fossil fuels, smelting of ores, mining of coal and metal ores and the application of nitrogen fertilizer to soils are all driving down the pH of the Earth\'s air, water and the soil at rates faster than Earth\'s natural systems can buffer, posing threats to both land and sea life, they said. Janet Herman of the Department of Environmental Sciences at University of Virginia in Charlottesville and her colleague Karen Rice of the U.S. Geological Survey presented their review of environmental acidification at the annual meeting of the Geological Society of America in Charlotte, N.C. \"It\'s a bigger picture than most of us know,\" Herman said in a society release Tuesday. Acidification is both a local and global problem, Herman and Rice said, since it can be as close as a nearby stream contaminated by mine tailings or as far-reaching as the world\'s oceans, made more acidic as they absorb higher concentrations of carbon dioxide from the burning of fossil fuels. Normally, acids in the environment are buffered by alkaline compounds released by the weathering of minerals in rocks, but the rate of acidification by human activities has outstripped the weathering rate and buffering capacity of the planet, Herman said.