Climate change alters the Indian Ocean Dipole and weakens its North Atlantic teleconnection

Abstract

An important source of long range forecast skill for the North Atlantic Oscillation (NAO) comes from predictability of tropical rainfall. While the El Niño Southern Oscillation (ENSO) is a better-known driver of the NAO, the Indian Ocean Dipole (IOD) also has an influence, particularly when ENSO is inactive. Given future projected changes to ENSO and the IOD, it is important to understand how the IOD–NAO teleconnection may evolve. Here we use climate model simulations to investigate the IOD and its NAO teleconnection. We find that the IOD itself changes considerably under climate change, with a weakening of the present-day anticorrelation between the dipole nodes and a westward shift in the IOD pattern. While historical model simulations reproduce the IOD–NAO teleconnection pathway seen in observational analyses, the teleconnection is projected to weaken in future, with the weakening linked to the westward IOD shift.