Breaking a 16-month trend of record warmth, September 2016 was the second warmest September on record, the National Oceanic and Atmospheric Administration said Tuesday. “September was 1.60 degrees F above the 20th-century average, missing last year’s record for the month by just 0.07 degrees,” the Commerce Department branch said in a press release. “For the year to date, the average global temperature was 1.78 degrees F above average, surpassing the heat record set in 2015 by 0.23 degrees.”
NOAA’s finding diverges from data released Monday by NASA’s Goddard Institute for Space Studies, which found that last month was the warmest September on record, though by only 0.004 degrees Celsius above September 2014.
There are a few reasons for the differing conclusions, NOAA climate scientist Jessica Blunden told GHG Daily by email. “While the two agencies use basically the same data, our analysis methods differ slightly. NASA, for example, interpolates temperatures over polar regions while NOAA does not. This may account for the slight differences you see,” said Blunden, who authored the NOAA report.
Both NASA and NOAA note that while monthly averages are interesting, they should not detract from the bigger picture. “The key thing to remember is that it really doesn’t matter whether the month is record warmest, tied as warmest, or second warmest, etc – it’s the overall trend of increasing global temperatures that matter,” Blunden said.
NASA made a similar point on Monday. “We continue to stress that while monthly rankings are newsworthy, they are not nearly as important as long-term trends,” GISS Director Gavin Schmidt said in the agency’s release.
When it comes to the longer term, NASA and NOAA are in agreement, Blunden said: “Both NOAA and NASA wholeheartedly agree that this year is record warm so far and will end up as warmest or very close to warmest in the modern record. And if La Nina in fact develops later this year and 2017 is not record warm, that in no way signifies that warming is not happening.”
