Inter-model Robustness of the Forced Change of the ENSO-Indian Summer Monsoon Teleconnection

Abstract Concerning the robustness of the forced response of the ENSO - Indian monsoon teleconnection, three periods can be distinguished. (1) In the late 20th century, the change is insignificant in most models, which does not permit a statement on robustness in this period. This is in stark contrast with earlier claims of a weakening teleconnection allegedly detected from observational data. (2) Furthermore, we find it typical under global warming in the first part of the 21st century that the teleconnection is strengthening or non-decreasing. This considerable robustness is owed to an increasing ENSO variability as well as coupling strength. (3) In the end of the 21st century, however, under strong forcing, the teleconnection change is not robustly modelled: the ENSO variability change is not projected robustly across models, either wrt. the start or the rate of the ENSO variance decline, competing this time with an increase of the coupling strength.