An analysis of data from various rain gauge stations across north-east India shows a decreasing pattern in rainfall since 19731.
Mawsynram and Cherrapunji, places which receive the highest rainfall in the region, have recorded a decrease in average rainfall in recent decades. Cherrapunji, earlier the wettest place on Earth, showed a larger decrease thus shifting the distinction to Mawsynram.
Changes in sea-surface temperature and land-use patterns contributed considerably to such a dip in rainfall, the researchers report.
Rainfall study in northeast India had so far focused on only one or two cities for a shorter period. To broadly understand rainfall patterns in this region, scientists measured daily and continuous rainfall at 16 stations across seven states of north-east India between 1901 and 2019.
The team, including researchers from the Indian Institute of Technology in Kharagpur and Indian Institute of Tropical Meteorology in Pune, found that most stations showed the largest decreasing trend in rainfall in summer and the lowest in winter with a clear reduction in rainfall at most stations since the late 1970s.
The reduction in winter rainfall is statistically significant at North Lakhimpur, Pasighat and Shillong.
Population growth and human activities such as agriculture have caused deforestation and reduction in ice and snow in northeast India. This has increased water bodies, and urban and built-up lands between 2001 and 2018.
Such changes in land-use patterns, coupled with variations in temperature in the Indian Ocean and Arabian Sea, remarkably contributed to a decreasing trend in rainfall, suggesting a link between human activities and climate change.
1. Kuttippurath, J. et al. Observed rainfall changes in the past century (1901–2019) over the wettest place on Earth. Environ. Res. Lett. 16, 024018 (2021)