India’s climate is turning hotter and drier, with large parts of north India changing from temperate to arid steppe and from hot and tropical Savannah to temperate, hot-summer, between 1961 and 2020, a 70-year analysis of rainfall and temperature changes conducted by researchers at the Indian Meteorological Department (IMD) has found.
The study titled: Identifying the climate zone shifts of Indian meteorological subdivisions: insights from historical records, by Ananya Karmakar, Rajib Chattopadhyay, Pulak Guhathakurta, K S Hosalikar and Mrutyunjay Mohapatra of the India Meteorological Department and the Indian Institute of Tropical Meteorology, Pune, is published in MAUSAM, IMD’s peer-reviewed journal, this month. The study had set out to investigate historical records of shifts in climate zone modulation across Indian meteorological subdivisions, aiming to uncover the underlying drivers and patterns that have shaped India’s climate landscape by examining historical data, including meteorological observations, proxy records, and historical accounts. This modulation is mainly associated with the increasing trend in temperature and decreasing trend in rainfall,” the study has noted.
“Two significant findings came out of this analysis — over the historical period 1951–2020, the major change in the climate zone is the shift to the drier region, i.e. temperate to arid steppe and hot and tropical Savannah to temperate hot summer for the North West and North East homogeneous regions, respectively. The percentage area transformed to the drier region is nearly 7% in both homogeneous regions. Climate zones are defined by temperature and rainfall, and the researchers redrew India’s climate map for successive 30-year periods (epochs), the standard span over which climate is measured, from 1951–1980 to 1991–2020, using IMD’s own observations. The study noted that between 1961–1990, along the coast, the tropical monsoon zone, the country’s wettest, with heavy seasonal rain, has extended further across the Konkan, Goa, coastal Karnataka and Kerala.
“For the Peninsular India homogeneous region, the climate zones shift towards the wetter zone, from Arid steppe hot to Tropical savannah by 15% due to a mainly increasing trend of rainfall in recent epochs,” the study also noted. “But interior Maharashtra, including Marathwada and west Vidarbha, which lay mostly in the tropical savannah zone, which is warm throughout the year with a long dry season, but by 1991–2020 they had moved into the hot semi-arid zone, which is hot with low rainfall, a change the authors attribute mainly to rising daytime and night-time temperatures,” lead study author Ananya Karmakar said.
