Natural fluctuation ink: NOAA and NASA have different climate analyses. Who you gonna believe?

This week, as has gone on for quite awhile this time each year, separate offices within the two US agencies best known for monitoring our planet - the National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration - released their summary numbers on climate in 2011, specifically its warmth. Their differences are the kind that are addressed in the phrase "a distinction without a difference." They are different but it doesn't matter. But still. News agencies often choose one or the other.

A look through the scattering of stories finds US climate scientists saying 2011 was, globally, the 11th warmest on record. No wait! Some outlets go with 9th warmest. The reason there is not one voice of authority of course lies in the advantage of having independent groups monitor important things. NOAA has its crew at the National Climate Data Center, which is surely more official than NASA's team of climate scholars in Manhattan at the Goddard Institute for Space Studies. Not that it's maverick or anything like that, but the impression is that NASA's GISS assigned to itself, decades or more ago as a responsible thing to do, the constant scrutiny of world meteorological data to create a long term climate record. At NOAA and the NCDC, that's no option

or whim. It is the job explicitly assigned by high decree. And at NOAA things are very top-down and disciplined, yes sir and ma'am. The good suits for the bigshots are uniforms like they're in the military. NASA, the slightly looser goosier agency, says 9th warmest-ever, straight-laced NOAA says 11th-warmest. So what? The difference is easy to understand given the tiny changes in temperature year to year - meaning it is hard to assess exactly what has happened. Fine grained differences in how the data get smooshed together produce slightly different results. For one thing, as I recall, GISS takes a more adventurous (but plausible) way of filling in gaps in sparsely-instrumented places including the Arctic.

Most of the few US press outlets that paid attention is going with NASA's GISS. For sure, #9 is a newsier figure than #11. Not that the NASA-GISS's figure is not defensible, but if I were at NOAA where the  the sign outside its Asheville, North Caroline facility says it's the national center for climate data, I'd be miffed that NASA gets climate priority in some eyes.

And for the record the world's third-best known global thermometer reading, from the UK's MET office,  already said last week that its accounting puts 2011 at #11, same as NOAA.

The real news is that last year had a strong La Nina condition in the Pacific, which experts say cools the planet. It was the warmest La Nina year on record, but managed to drop the year under the long term trend line. And with La Nina expected to fade over coming months, the Met office expects 2012 to be a contender for hottest ever. Ditto, one presumes, at NASA and NOAA. All three agree that the number, despite jitter-bugging one year to the next, is due to rise dramatically in coming decades. The other news is that whatever the exact temperature, 2011 had a lot of weird weather and related catastrophes.

Stories:

• AP - Seth Borenstein: World not quite as hot in 2011 ; ranks 11th warmest ; Borenstein's story stands out for choosing the NOAA yardstick. He also stresses for his mostly-US readers that Americans had temperatures not far above the long-term average, with '11 merely 23rd warmest overall on the record since 1880. But the UK had the second warmest year ever, and Spain the warmest (as did some US cities including drought-hit Austin, Texas.) He mentions NASA's "slightly different" figure and its global assignment of temperature to #9. This seems the right call.
• Universe Today - Nancy Atkinson: NASA Finds 2011 Ninth-Warmest Year on Record ;
• NBC - 2011 is 9th Warmest Years on Record: NASA ;
• USA Today - Doyle Rice: La Nina cooled the globe in 2011 ; Wise move Mr. Rice. Don't put a number in the headline and put both of them in the second graf, equally prominently. The story gives a tagline credit to AP.
• Washington Post / Capital Weather Gang blog - Jason Samenow: Extreme weather 2011: warmest La Nina year on record, around 10th warmest overall ; Another equal-handed handling of the double-voiced federal analysis. Also, perfect selection of illus (reproduced above right), which lets readers decide for themselves whether to compare apples to apples or not.

Grist for the Mill: NOAA NCDC Press Release/Analysis ; NASA GISS Press Release ; Data Analysis Page ; UK Met Office Press Release ;

- Charlie Petit