Europe's hottest summer on record may have killed more than 50,000 people across 30 European countries, researchers have found, as they called on governments to reduce the use of fossil fuels. Scientists from Imperial College London and the London School of Hygiene and Tropical Medicine examined excess heat deaths in 854 cities in Europe from June 1 to August 31 this year, comparing it to data for the same period dating back to the year 2000.