By Jeff Masters
The top weather story of 2016: Earth had its warmest year on record (again)! While the final numbers are not officially tabulated, 2016 appears certain to be the warmest year in every major dataset scientists use to track global warmth.
The previous warmest year on record for Earth's surface was set in 2015, which in turn broke the record set in 2014. The three-year string of warmest years on record is the first time such an event has happened since record keeping began in 1880. One official record has already been announced: Earth's warmest year in the 38-year satellite-measured lower atmosphere temperature record was 2016, beating a record had stood since 1998, according to the University of Alabama-Huntsville.
The first seven months of 2016 all set new monthly records for global heat in the the National Oceanic and Atmospheric Administration (NOAA) database, giving the planet an unprecedented streak of 15 consecutive record-warm months. February 2016 had the warmest departure from average of month in recorded history and July 2016 was the warmest month in recorded history in absolute terms.
According to the World Meteorological Organization (WMO), 2016's global temperatures were approximately 1.2 C above pre-industrial levels. About 0.2 C of this warming was due to the strong El Niño event that ended in May 2016 and the remainder was due to the long-term warming of the planet from human-caused emissions of heat-trapping gases like carbon dioxide. Assuming that all nations who agreed to the Paris climate accord in 2015 fulfill their pledges, Earth is on track to see 2.3 C of warming over pre-industrial levels by 2050. This is above the "dangerous" 2 C level of warming considered likely to greatly increase the risk of hunger, thirst, disease, refugees and war.
Figure 1. Departure of the global surface temperature from average for the period January—November, for all years from 1880 to 2016. The year 2016 will easily beat 2015 as the warmest year on record. NOAA