Indo-Pacific Rainfall

The rapid warming of the Indo-Pacific Ocean is altering rainfall patterns in Earth’s equatorial band.

The warm pool of water in the eastern Indian Ocean and western Pacific has doubled within the past decade. The sweltering and size of the tepid marine pool are accelerating.

The expansion and intensification of warmth is altering the hydrodynamic feature called the Madden-Julian Oscillation (MJO), which is characterized by rain clouds that move over the tropical ocean, ranging from the Seychelle Islands (off the east coast of Africa) into the western Pacific Ocean, influencing everything from monsoons in India to heat waves and flooding in the United States.

The US National Oceanic and Atmospheric Administration (NOAA): “Though the entire Indo-Pacific Ocean has warmed, the warmest waters are over the west Pacific, creating a temperature contrast that drives moisture from the Indian Ocean to the west, enhancing cloud formation. This has changed the life cycle of the MJO.”

Continued warming of the Indo-Pacific will further warp the MJO and intensify changes in global rainfall patterns.


Rainfall diagram courtesy of M. Koll Roxy.

M.K. Roxy et al, “Twofold expansion of the Indo-Pacific warm pool warps the MJO life cycle,” Nature (27 November 2019).

NOAA Headquarters, “Indo-Pacific Ocean warming is changing global rainfall patterns,” (28 November 2019).