"Globally, 2016 edged out 1998 by +0.02 C to become the warmest year in the 38-year satellite temperature record," notes Dr. John Christy, director of the Earth System Science Center in a press release from The University of Alabama in Huntsville. Christy adds, "Because the margin of error is about 0.10 C, this would technically be a statistical tie, with a higher probability that 2016 was warmer than 1998. The main difference was the extra warmth in the Northern Hemisphere in 2016 compared to 1998." Globally, the atmopshere in 2016 was +0.505 C° warmer than the 30 year average (1981-2010) whereas 1998 was +0.484 C° warmer than that average.
Given that the satellite data trend tends to be lower than the trends based on thermometer readings from around the globe it is likely that other groups will also be declaring 2016 to be the warmest year in their records stretching back to the late 19th century. I'll report their results when they become available.
Global Temperature Report: December 2016
Global climate trend since Nov. 16, 1978: +0.12 C per decade
December temperatures (preliminary)
Global composite temp.: +0.24 C (about 0.43 degrees Fahrenheit) above 30-year average for December.
Northern Hemisphere: +0.19 C (about 0.34 degrees Fahrenheit) above 30-year average for December.
Southern Hemisphere: +0.30 C (about 0.54 degrees Fahrenheit) above 30-year average for December.
Tropics: +0.21 C (about 0.38 degrees Fahrenheit) above 30-year average for December.
"The question is, does 2016's record warmth mean anything scientifically?" Christy said in the press release. "I suppose the answer is, not really. Both 1998 and 2016 are anomalies, outliers, and in both cases we have an easily identifiable cause for that anomaly: A powerful El Niño Pacific Ocean warming event. While El Niños are natural climatic events, they also are transient. In the study of climate, we are more concerned with accurately identifying long-term temperature trends than we are with short-term spikes and dips, especially when those spikes and dips have easily identified natural causes.
"Some records catch our attention because we usually struggle to cope with rare events. For example, the Sept.-Nov. record heat and dryness in the southeastern U.S. (now a thing of the past) will be remembered more than the probability that 2016 edged 1998 in global temperatures. So, from the long-term perspective, 2016's record may be less noteworthy than where the month-to-month temperature settles out between warming and cooling events."