Studying the last 50 years of growth of a stalagmite from a cave in Meghalaya - known for getting the most rain on Earth - can unlock secrets about climate change and could help better predict monsoon patterns, droughts and floods in India, scientists say.
Each year, monsoon rains between June and September provide water to roughly 1.5 billion people in India.
Changes in monsoon strength and the timing of its onset or withdrawal can trigger either drought or flooding, with devastating consequences, highlighting the need for effective ways to predict and prepare for rainfall variations.
Earth scientists at Vanderbilt University at Tennessee in the US found that stalagmites from the Mawmluh Cave, Meghalaya, and the surrounding region indicate the recurrence of intense, multi-year droughts in India over the last several thousand years.
In fact, stalagmite records from monsoon regions are vital to understanding past variability in the global climate system and the underlying reasons for this variability.
"Counter-intuitively, air and water circulation in caves can cause, and even favour, stalagmite growth in the dry season, leading to unexpected effects in paleoclimate records," said Elli Ronay, a doctoral student at the University's Department of Earth and Environmental Sciences.
In the study, published in the journal Scientific Reports, the team found an unexpected connection between winter (dry season) rainfall amounts in northeast India and climatic conditions in the Pacific Ocean.
Winter rainfall following weak monsoon years in India can alleviate water stress for farmers.
This distant link between land and ocean records could aid in predicting dry season rainfall amounts in northeast India, researchers said.
These new results advocate for caution when interpreting stalagmite records from regions characterised by strong seasonality like the monsoon.
The researchers also noted that potentially powerful information about annual rainfall variability in northeast India has gone unnoticed in stalagmite records thus far.
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