This is the conclusion of a new study published in the Proceedings of the National Academy of Science, by a team of scientists at the International Pacific Research Center, University of Hawaii at Manoa.
Professor Bin Wang and his colleagues analysed 30 years of climate data to observe trends and patterns in monsoon rainfall with the raise in global temperatures. Currently, it has been thought that under the influence of anthropogenic global warming, the summer monsoon circulation should become weaker.
The study, however, estimates that intense rainfall caused by the cooling of the eastern Pacific, which began in 1998, has increased by 9.8% compared to previously estimated by climate change models 2.6%.
The scientists state that the this is due to long-term changes in ocean surface temperatures caused by the natural swings in Interdecadal Pacific Oscillation or mega-El Niño-Southern Oscillation, and the Atlantic Multidecadal Oscillation.
Wang is certain that in order to make accurate predictions of future monsoon rainfall, the whole climate system should be understood much better and the contribution of greenhouse gas emissions should be carefully estimated.