Volcanic eruptions and greenhouse gases disrupt 400-year Indian-Pacific ocean climate link

September 13, 2026 at 05:15 PM2 min

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A new study finds that major volcanic eruptions temporarily weakened the climate connection between the tropical Indian and Pacific oceans between 1810 and 1850. Human-caused greenhouse gas emissions are now driving an even more unusual breakdown in that relationship. The findings, based on paleoclimate records and model simulations, were published in Nature Communications.

Key Facts

The study was published in Nature Communications under the title "Coupling of Pacific and Indian Ocean variability disrupted by 19th century volcanism."
Between 1810 and 1850, the relationship between the two ocean basins changed significantly, linked to a series of major tropical volcanic eruptions.
Researchers at the Woods Hole Oceanographic Institution combined paleoclimate evidence with climate model simulations to examine the ocean link back to the early 1600s.
Since the 1980s, the Indian Ocean has increasingly behaved differently from what would be expected based on Pacific conditions, a change linked to climate warming.

Volcanic Disruption

Paleoclimate evidence shows the Indian and Pacific oceans remained closely connected through most of the past 400 years. Between 1810 and 1850, the relationship between the two ocean basins changed significantly. Researchers linked that disruption to a series of major tropical volcanic eruptions, which appear to have weakened the Pacific Ocean's usual influence over climate conditions in the Indian Ocean. Computer simulations covering the past thousand years supported that interpretation. The strength of the disruption depended on both the size of the volcanic eruptions and the background climate conditions that existed at the time.

Recent Weakening

Climate conditions across the Indian Ocean often respond to changes occurring in the Pacific Ocean, shaping broad patterns of rainfall, temperature, and atmospheric circulation across the tropics. Since the 1980s, scientists have noticed that this relationship has weakened. The Indian Ocean has increasingly behaved differently from what would normally be expected based on conditions in the Pacific, a change that researchers have linked to climate warming. Reliable instrumental climate records cover less than a century, making it difficult to determine whether the recent change is truly unusual or part of a longer natural cycle. To look further back in time, the WHOI team turned to tropical paleoclimate records preserved in corals, tree rings, and stalagmites, reconstructing Indian and Pacific Ocean climate conditions back to the early 1600s.