Pacific and Indian Oceans show decoupling in climate relationship

A study published in Nature Communications indicates that the long-standing relationship between Pacific atmospheric circulation and tropical Indian Ocean temperatures has been disrupted in recent decades. This shift represents an unprecedented change in the climate system.

Historically, the Pacific Walker circulation—a system of air movement driven by surface temperature differences in the Pacific—has influenced the Indian Ocean via an atmospheric bridge. During events like El Niño, this circulation weakens, and the effects are transmitted across the ocean. However, since the 1950s, the tropical Indian Ocean has been warming by approximately 0.1 degrees Celsius per decade due to greenhouse gas emissions, while the Pacific Walker circulation has strengthened since the 1980s. This divergence has decoupled the two systems, making it more difficult for scientists to rely on Pacific patterns to predict Indian Ocean climate trends.