Scientists reported Wednesday that 2015 was the hottest year in the historical record by far, breaking a mark set only the year before — a burst of heat that has continued into the new year and is roiling weather patterns all over the world.
The American agencies released figures on Wednesday showing that 2015 was the warmest year in a global record that began, in their data, in 1880. British scientists released figures showing 2015 as the warmest in a record dating to 1850. The Japan Meteorological Agency had already released preliminary results showing 2015 as the warmest year in a record beginning in 1891.
The intense warmth of 2015 contributed to a heat wave in India last spring that turns out to have been the second-worst in that country’s history, killing an estimated 2,500 people. The long-term global warming trend has exacted a severe toll from extreme heat, with eight of the world’s 10 deadliest heat waves occurring since 1997.