South Peninsular India Shows Sharpest Drought Rise in 52-Year Study

South Peninsular India, the region that includes Tamil Nadu, has recorded the strongest long-term increase in drought-affected area among the country's four broad climatic zones, according to a 52-year analysis of daily rainfall and temperature data.

The study, titled 'Evolution of Climate Extremes Over the Indian Subcontinent Using a Revised CEI' and published in the International Journal of Climatology, examined records from 1971 to 2022. Its authors developed a revised India Climate Extremes Index (IndCEI) that combines seven indicators, covering heat, drought, dry spells and heavy rainfall.

Drought emerged as the clearest signal over the southern peninsula. Before the 1990s, less than 10% of the region was affected by drought for much of the period studied. After 2000, several years saw more than 40% of the region under drought conditions, with severe and persistent spells particularly evident through the 2010s and early 2020s.

A media note accompanying the research places Tamil Nadu, along with Odisha and Andhra Pradesh, among eastern coastal States where the drought-affected area grew by 20% to 30% during 2011–2021 compared with the 1980s.

To assess drought, the researchers used the Standardised Precipitation-Evapotranspiration Index (SPEI), which factors in both precipitation and potential evapotranspiration. Unlike a rainfall-only measure, it captures how rising temperatures affect water availability.

The findings also indicate a growing heat burden over southern India. The area experiencing high maximum-temperature extremes has expanded in South Peninsular India, especially since the 2010s. The researchers link this rise in heat exposure to declining rainfall, urban heat-island effects and wider climate change impacts.

The Heat Index, which combines temperature and humidity to gauge heat stress, has also risen steadily over the region. The study attributes part of this intensification to climbing minimum temperatures and high humidity tied to the region's proximity to the Bay of Bengal, with urbanisation and warmer sea-surface temperatures identified as factors that could amplify heat stress.

Consecutive dry days, however, did not show a significant long-term increase over South Peninsular India. The researchers recorded strong year-to-year variability, including a prominent peak in 2002, but the overall trend was nearly flat. They cautioned that using May–October for this indicator may have dampened the long-term trend by including pre- and post-monsoon months.

The study was conducted by scientists from the National Centre for Medium Range Weather Forecasting, the India Meteorological Department and Atria University, using IMD's 1° × 1° gridded rainfall and temperature datasets for 1971–2022.

The researchers said the results underline the need for region-specific adaptation, particularly drought resilience in southern India. The accompanying media note calls for a cross-sectoral response spanning agriculture, water management, health and infrastructure, along with finer-scale monitoring to identify localised climate extremes.