Human-caused climate change very likely increased the severity of heat waves that plagued India, Pakistan, Europe, East Africa, East Asia, and Australia in 2015 and helped make it the warmest year on record, according to new research published today in a special edition of the Bulletin of the American Meteorological Society.  The fifth edition of Explaining Extreme Events from a Climate Perspective presents 25 peer-reviewed research papers that examine episodes of extreme weather of 2015 over five continents and two oceans. It features the research of 116 scientists from 18 countries analyzing both historical observations and changing trends along with model results to determine whether and how climate change may have influenced the event.