Shifting climate and associated ecological impacts in the Indian subcontinent: Present and future outlook

Abstract

Anthropogenic climate change accelerates the decline of global biodiversity and disrupts ecosystem functioning, forcing terrestrial and aquatic species to change their ranges, phenology, physiology, and morphology. In our study, we have employed univariate and a newly-defined vector-algebra-derived multivariate estimate of the velocity of climate change (VoCC) derived from near-surface temperature and total precipitation to present the historical (1980-2005) and projected (2020-2097) shifts in the climate space over the Indian subcontinent. The multivariate VoCC was further used to derive climatic divergence (stress) and residence time of nine representative protected areas (PAs). VoCC is a versatile metric that approximates the “required” migration speeds for the species. Our results from observations (CRU, ERA5) and model simulations (CMIP5, Regional Earth System Model) show that regions with relatively flatter terrain, such as Deserts, Semi-Arid, Deccan Peninsula and Gangetic Plains, displayed the highest historical velocities in the range of 2-15 km/yr, which are also projected to increase in the future period to range of 4-20 km/yr. The estimates of multivariate velocities were generally higher than the univariate velocities, leading to a better representation of shifts in real climate space. The high-resolution regional earth system model, ROM, performed better than the global circulations models in producing realistic VoCCs. The climatic stress (diverging vectors closer to 180 degrees) was higher for the Trans-Himalayas, Himalayas, Gangetic Plains, and parts of the Deccan Peninsula, and it is projected to increase in the near and mid future. The PAs with the shortest residence times were found to be Sundarbans (63 years), Ranthambore (32 years) and Ramgarh Vishdhari (9 years), illustrating a severe challenge for conservationists under changing climate. Our results present the importance of employing multivariate velocities to simulate more realistic estimates of shifting climate and added benefits of measures of climatic divergence and stress on biodiversity.