Friday, June 19, 2015

Hottest May on record at NOAA. Has the "pause" gone for good?

Sou | 10:10 AM Go to the first of 8 comments. Add a comment
NOAA has released the global analysis for May 2015. It reports that May was the hottest on record, beating the 2014 record by 0.08°C. NOAA has May higher than GISTemp, but that doesn't mean a whole lot.  For one thing it's only one month. For another, GISTemp does change as it receives reports from around the world. Not all data comes in at the same time.

Here is a chart with both GISTemp and NOAA data. The chart includes 2015 year to date average, which might or might not drop as the year progresses.

Data sources: NOAA and NASA GISS

You'll notice that the Y axis is shifting higher. If it stays hot this year, any "hiatus" looks as if it will be nothing but a memory soon, with all the other hiati, sorry, I mean hiatuses of the past.

Here's the percentiles map from NOAA, for the period from March to May 2015. Most places are hot, with large areas showing the record warmest:

March–May 2015 Blended Land & Sea Surface Temperature Anomalies in °C. Source: NOAA

I've pointed to a cool spot in the Arctic, because Stefan Rahmstorf tweeted about it. He was referring to his recent paper in Nature Climate Change which is in the May issue. (It was first published online in March.) That paper was discussing the observed cold spot in the North Atlantic and the slowing of the Atlantic Meridional Overturning Circulation (AMOC). You can read more about that here.


  1. The new Sea Surface Temperature [SST] data-set used for the NOAA/NCEI "May 2015 Global Surface Temperature Data Transition", ERSST 4.0.0, "is the same as that used in Karl et al.(2015)." NOAA/NCEI
    Karl(2015)'s land-based data set will be 'transitioned-in' by early 2016.

    GISS's SST will switch to ERSST v4 next month, for the June 2015 data.
    And "the collection of land station data used in [Karl(2015)] includes many more sources than GHCN v3.3.0 and will probably be incorporated into a future GHCN v4." GISS

    This comment precedes your blogpost. It was started elsewhere, but couldn't be finished....

    1. This comment was initially written for Greg Laden's 18June article on NOAA and CONUS. It was meant to fill a gap in Internet coverage of Karl(2015), concerning when its findings would be incorporated into the everyday NOAA and NASA data sets. Laptop trouble intervened.

      I'd also like to address my own use of quotation marks. Unlike a paraphrase, some authoratative-ness survives. And, Google will take the reader back to the source.

  2. I know you put it in quotes, but there never was a pause without statistical "inference" that would earn an "F" in every stats class in the world. If you are going to cherrypick you need to control for it or you will get false positives every time.

    It's a complete statistical sin that this ever became an issue to discuss in the first place.

  3. The pause is dead, long live the hiatus! Let that be a lesson to those who allow the media to make up science.

    Yes, that Northern Atlantic cold spot is a real standout, isn't it?

    1. And the thing is that the "cold spot" is only there because a body of water that is itself warmer in absolute terms has moved to that point on the planet where it is colder than the water that was there previously.

      The "cold spot" is an anomaly measure that doesn't explain that the water is actually warmer than it used to be - but it just moved to a place where the ambient temperature is still greater than the temperature to which it warmed.

      Just watch the deniers get this wrong too...

    2. OK, that was tautological. It's late here...

    3. Yeah, but there is always a pause. Its just how short a period you need for short term noise to mask the long term trend that varies. The 1998 pause is gone, so the 2005 pause is now 'a la mode', or is that one gone now too? Yay for the 2014 pause, that one should be here for a while.


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