New Delhi, June 11 (UNI) A new study has sounded the alarm on the intensifying threat of extreme heatwaves in Indian cities. Urban areas like Mumbai, Delhi, Chennai, Hyderabad, Surat, Thane, Patna, and Bhubaneswar are projected to see a two-fold increase in heatwave days by 2030, according to the study by IPE Global and Esri India.