Rainfall Becomes Increasingly Variable as Climate Warms IAP Classification of precipitation change regimes based on changes in the precipitation mean state and variability. Shading indicates the ratio of change in precipitation variability and mean precipitation. Newswise — Climate models predict that rainfall variability over wet regions globally will be greatly enhanced by global warming, causing wide swings between dry and wet conditions, according to a joint study by the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences (CAS) and the Met Office, the UK's national meteorological service. This study was published in Science Advances on July 28 th 2021. Rainfall plays an important part of our daily life. More leads to floods, less to drought. It has been realized decades earlier that global warming drives increased rainfall on average. How this increase is delivered in time matters enormously. A 2-3% increase of annual precipitation uniformly spreading out of the year does not mean much, but if it falls out in a week or a day, it will cause havoc.