Asian monsoons in the future

17.5 Summary

Future anthropogenic changes in GHGs, aerosols, and land use/land cover will inevitably alter the climate in Asia. As global warming leads to greater warming over land than over the oceans, the continental land-sea temperature contrast will become larger in the summer and smaller in the winter. Based on this prediction, a simple conclusion is that the Asian summer monsoon will be stronger and the winter monsoon will be weaker in the future. However, model results are not so straightforward and do not fit easily into such a simple view. For the south Asian summer monsoon, models suggest a northward shift of the lower tropospheric monsoon wind system with a weakening of the westerly flow over the northern Indian Ocean. However, atmospheric moisture buildup due to increased temperature will result in larger moisture flux and more precipitation over India. Changes in the winter monsoon will have different consequences from region to region. East Asia will have a weakened north-westerly cold surge, while southeast Asia could experience a stronger north-east monsoon. The projections of these regional climate changes, however, may still be highly model dependent, and should be considered carefully as there are large differences among models in projecting changes in wintertime precipitation, including even the direction of changes.