Moving with the Climate: An Outlook from the Indian Subcontinent

Abstract

Anthropogenic climate change accelerates the decline of global biodiversity, which in turn disrupts ecosystem functioning, forcing terrestrial and aquatic species to change their ranges, phenology, physiology, and morphology. Land use land cover changes, habitat fragmentation, and overexploitation also influence biodiversity synergistically with climate change. For the current study, we have used the univariate and multivariate estimates of the velocity of climate change (VoCC) to present the historical (1980-2005) and projected (2020-2097) shifts in the climate space over the Indian subcontinent and its biogeographic zones. VoCC is a versatile metric presenting the speed of a climatic isoline along the earth’s surface and approximates the “required” migration speeds for the species. Subsequently, multivariate estimates of VoCC were used to derive the climatic divergence and related climatic stress and determine the residence time of nine representative protected areas (PAs). The results from observations (CRU, ERA5) and model simulations (CMIP5, Regional Earth System Model) demonstrate that regions with relatively flatter terrain displayed the highest historical velocities in the range of 2-15 km/yr, which are also projected to increase in the future period to a 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 achieved better results than the global circulations models in producing more accurate VoCCs. The climatic stress (diverging vectors closer to 180 degrees) was higher for parts of north India and the Deccan Peninsula and 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 to conservationists under changing climate. Such climate change metrics can be modified to be more biologically relevant, incorporating species-specific biological data to deliver more precise estimates of migration rates of individual species in response to climate change.