Berlin - Climate researchers are warning that Europeans should prepare for the return of "Lucifer", saying the hellishly named heat wave that hit parts of the continent this summer could become a regular occurrence due to man-made climate change.Hotter-than-usual temperatures in the Mediterranean region resulted in higher hospital admissions, numerous forest fires and widespread economic losses between June and August. Peak heat struck Italy and the Balkans for three days in early August, when temperatures remained above 30°C even at night."We found clear evidence of human influence on this summer's record warmth - both in the overall summer temperatures and in the heat wave dubbed Lucifer," said Geert Jan van Oldenborgh, a senior researcher at the Royal Netherlands Meteorological Institute.Van Oldenborgh is part of the World Weather Attribution team that published a study on Wednesday, concluding that greenhouse gas emissions linked to human activity have increased the chances of such heat waves four-to-tenfold compared to the early 1900s.The team's use of actual temperature measurements and computer simulations is widely accepted among scientists as a means of determining whether climate change plays a role in extreme events."The analysis applies state of the art techniques that have withstood rigorous peer-review in many previous studies," said Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre.The World Weather Attribution team said its study indicates that summers like in 2017 could become the norm in the Euro-Mediterranean region by 2050 if greenhouse gas emissions continue to rise.Van Aalst, whose centre provides research to national Red Cross or Red Crescent agencies around the world, said the new study should be a wake-up call to policymakers about the need to prepare for hotter summers.While the average person in developed countries might enjoy a few days of strong sunshine - especially if they can cool off at the beach - elderly people, infants and those who are chronically ill will suffer, he said."Climate change is already having a significant impact on the risks we face today, and we should do what we can to keep that risk from rising out of control."