2016 may be warmest year on record: study

The year 2016 was warmest in the 38-year satellite temperature record, edging out 1998 by a mere 0.02 degrees Celsius.
However, since the margin of error is about 0.10 degrees Celsius, this would technically be a statistical tie, with a higher probability that 2016 was warmer than 1998, researchers said.
The main difference was the extra warmth in the Northern Hemisphere in 2016 compared to 1998.
"Both 1998 and 2016 are anomalies, outliers, and in both cases we have an easily identifiable cause for that anomaly: A powerful El Nino Pacific Ocean warming event," said John Christy, director of the Earth System Science Centre at The University of Alabama in the US.

"While El Ninos 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," he said.
Compared to seasonal norms, the warmest average temperature anomaly on Earth in December was in south central China, near the town of Qamdo.

December temperatures there averaged 3.91 degrees Celsius warmer than seasonal norms. The coolest average temperature on Earth in December was near the town of Buffalo Narrows in Canada. December temperatures there averaged 4.13 degrees Celsius cooler than seasonal norms.

Researchers used data gathered by advanced microwave sounding units on National Oceanic and Atmospheric Administration (NOAA) and NASA satellites to get accurate temperature readings for almost all regions of the Earth.
This includes remote desert, ocean and rain forest areas where reliable climate data are not otherwise available.
The satellite-based instruments measure the temperature of the atmosphere from the surface up to an altitude of about eight kilometres above sea level.
Once the monthly temperature data are collected and processed, they are placed in a "public" computer file for immediate access by atmospheric scientists in the US and abroad.