Role of blue and green spaces in mitigating heat stress and providing biodiversity co-benefits in Indias cities

Cities and urbanizing spaces combine heat stress from both heat island effect due to the built environment as well as global warming. India with its high rate of urbanization is no exception. However, many Indian cities have blue and green spaces with various levels of protection from land-use and land-cover change. Blue and green spaces (BGS) are potentially nature-based solutions for mitigating heat stress through evaporation and transpiration besides sequestering carbon and as a habitat for urban biodiversity. The effectiveness of BGS in mitigating heat stress depends on size, shape, weather, and climate variables, especially humidity. We use satellite derived land surface temperature (LST) to quantify and map negative temperature anomalies (cooling) with respect to spatial average across the city in years with different levels of summer temperature, especially due to El Nino. We analyse the diverse types of blue and green spaces in three metropolitan cities in India and classify them in terms of biodiversity value (using e-bird data and other published sources). Cooling more than few degrees Celsius with respect to city wide averages from blue and green infrastructure has been observed and is much higher if compared to nearby built areas. The geometry and landscape ecology of existing urban blue and green infrastructure can help inform future planning for blue and green spaces as adaptation in a warming urban environment.