Here is more bad news for Delhiites. The Capital is now witnessing a rise in night-time temperature. And in worse news, the number of heat wave days has been showing an ascending trend, warns the Centre for Science and Environment (CSE).

“Climate records show that human-induced global warming had turned 2014 into the hottest year on record. Eight of the 10 warmest years in India were during the recent decade (2001-2010), making it the warmest decade on record with a decadal mean temperature anomaly of 0.49 degrees Celsius. Also, more heat waves are expected as temperatures globally have risen by an average 0.8 degrees in the past 100 years,” noted CSE climate researchers in a release issued on Thursday.

However, what has the city ‘hot under its collar’ is the fact that night-time temperatures too are rising, with Ahmedabad and Delhi recently reporting 39 and 36 degrees Celsius.

“The number of heat wave days may go up from about five to between 30 and 40 every year,” added CSE programme manager (climate change), Arjuna Srinidhi.

She noted that there is enough evidence of extreme weather events being on the rise.

Additionally, owing to the rising temperatures, ultra violet (UV) rays are also emerging as a serious health menace.

“Data from Pune-based Indian Institute of Tropical Meteorology (IITM) shows that in several cities, including Delhi, UV rays are above normal. The IITM set up a monitoring system in Delhi two weeks ago and found UV rays ranging between six and nine on the UV index, meaning medium to high health risk,” noted the CSE.

“Compared to 2010, heat wave conditions in 2015 so far have been of a shorter duration but with a higher toll. This could be due to the sudden change in temperatures after a prolonged wet February and March, that had kept the temperatures cool,” she said.

Heat wave is declared when the temperature is five degrees or more than the average temperature recorded on a particular day over the past three decades. Cities feel the brunt of elevated temperatures due to the magnified effect of paved surfaces and lack of tree cover or the “urban heat island effect”. Ms. Srinidhi added that the urban heat island effects makes ambient temperatures feel three to four degrees more than what they actually are.