Satellite-derived global temperature data shows 2016 was half a degree Celsius warmer than the 30-year average, which is not statistically different than the incredibly warm year of 1998.
2016 is in a statistical tie with 1998 for the warmest year in the 38-year satellite record, according to satellite data from the University of Alabama-Huntsville (UAH).
“We estimate that 2016 would have had to be 0.10 C warmer than 1998 to be significantly different at the 95% confidence level. Both 2016 and 1998 were strong El Nino years,” wrote Dr. Roy Spencer, a climate scientist who runs the UAH dataset with Dr. John Christy.
“The resulting 2016 annual average global temperature anomaly is +0.50 deg. C, which is (a statistically insignificant) 0.02 deg. C warmer than 1998 at +0.48 deg. C,” Spencer wrote.
For months, climate scientists have been saying 2016 would be the hottest year on record, beating out 2015 and 2014. An incredibly strong El Nino warming event boosted global average temperature at the beginning of the year.
NASA scientists found the first six months of 2016 set records for warmth, with the average global temperature for that period hitting 1.3 degrees Celsius above the late 1800s.
“While the El Ni√±o event in the tropical Pacific this winter gave a boost to global temperatures from October onwards, it is the underlying trend which is producing these record numbers,” Gavin Schmidt, director of the Goddard Institute for Space Studies, said in a July statement.
In October, Schmidt predicted 2016 would be the warmest on record. He said it would be about “1.25¬∫C above late 19th C.”
NASA takes readings from weather stations, ships and buoys that go through numerous adjustments to correct for “biases” in measurements. UAH satellite data looks at the bulk atmosphere. Satellite data is adjusted as well, but in different ways and not as often.
“Contrary to some reports, the satellite measurements are not calibrated in any way with the global surface-based thermometer records of temperature,” Spencer wrote. “They instead use their own on-board precision redundant platinum resistance thermometers (PRTs) calibrated to a laboratory reference standard before launch.”
UAH satellite data shows global average temperature for December 2016 was 0.24 degrees Celsius above the 30-year average. That’s down substantially from November, which hit 0.45 degrees Celsius above normal.
Scientists predict 2017 will be cooler than 2016, driven in part by a weak La Nina cooling event.