Current emissions of SO2 and NO x have caused regional scale acidification of the atmosphere and sensitive ecosystems in North America and Europe. Over the next several decades, Europe and North America will not experience major increases in the emissions of SO2 and NO x. However, environmental effects in Europe and North America will still continue, and in some cases, will get worse due to the delayed acidification of aquatic and terrestrial ecosystems. Over the next several decades, Asia, Africa, and South America will probably experience major increases in SO2 and NO x emissions to the atmosphere. Given the reality of population growth in these areas and the potential for industrial expansion, future emissions of SO2 and NO x could greatly exceed current emissions to the global atmosphere. Some of the consequences to the environment of the increased emissions are well known from our current knowledge. However, given the magnitude of the potential change in emissions, other effects are possible.