Thursday, January 4, 2018

December NCEP/NCAR global anomaly up 0.075°C from November

In the Moyhu NCEP/NCAR index, the monthly reanalysis anomaly average rose from 0.253°C in November to 0.328°C in December, 2017, making it a mid-range month for 2017. The temperature did not oscillate as much as in some recent months.

The main cool spots were Canada and E Siberia, NW Africa (Algeria) and Antarctica. East Europe and NW Russia were warm, and also Alaska and a band through the Rockies, S Calif. There was a notable warm spot in the seas around New Zealand.

The annual averfage for 2017 was 0.376°C. This puts it behind 2016 (0.531) but ahead of 2015 (0.330) and 2014 (0.190).


  1. Professor Curry is predicting 2018 will not be a top-5 warmest year. As of today's BOM update, the La Niña appears weaker than it did last month, and is still forecast to be short in duration. So about the only way she can be right would be a decidedly negative PDO and another La Niña in the last half of 2018. The chillers are on hard times, and they're a bit sensitive.

    1. Maybe she's banking on Agung blowing its top in the next couple of months?

      We can look at historical short-term variability patterns purely statistically in order to get some idea of where 2018 might go. First isolating comparative years - those following a substantial (in this case I've specified <-0.08C) drop in the prior year (e.g. 2017 versus 2016 looks like it's going to be about -0.1C drop in GISS, similar in other datasets), which picks out post El Nino years while also possibly including standalone La Ninas, internal variability from other causes and years influenced by volcanic activity.

      Looking at Berkeley Land+Ocean going back to 1850 most such years are warmer than the previous and there are only three instances of such "secondary drop years" which show a fall larger than -0.1C, none larger than -0.12C. Two of those appear to be associated with volcanic forcing events in the 1850s and in 1902. The other is 1917, following what appears to be a very strong El Nino event peaking in 1915.

      Further isolating comparative years by requiring, as we see now, La Nina-like conditions at the end of the previous year (September-December average Nino3.4 in ERSSTv5 <-0.8C after detrending using CMIP5mean) reduces the sample size to 13 and there is roughly an even spread between warmer and cooler changes. Those two volcanic-influenced years are no longer involved and 1917 shows clearly the largest second year drop at -0.11C. However, the Nino3.4 average associated with 1917 is substantially more negative than that for 2018 (i.e. 2017 September-December average) - in fact the most negative in the entire ERSSTv5 record - which suggests any further temperature drop for 2018 versus 2017 is unlikely to be that large. Which would seem to place a lower limit at about 0.78C for 2018 GISS anomaly.

      The best case I can make for something beyond that (and I do actually think it may be a reasonable case) is looking at the Nino1+2 record, which can be considered a good indicator of tropical Eastern Pacific variability, which is being recognised as very important for the global picture (e.g. this recent paper). Nino1+2 has been in freefall over the past several months and the 2017 September-December average after detrending is among the lowest on record. Looking at December on its own, it's only beaten to the bottom by 1872 and 2007. This is suggestive of a return to "hiatus"-like Pacific conditions. There was also a spike in Nino1+2 in early 2017, which may mean 2017 temperatures were being temporarily boosted and 2018 has further to fall.

      So what happens if 2018 sees a return to "hiatus"-like conditions? We can perhaps use 2008 as a good comparison year given the similarly low Nino1+2 figure. Adding on a 0.2C/decade forced trend gets us to 0.72C in the GISS record, which would still be just about a top 5 year. Of course, given data uncertainties and potential for freak months, going below that couldn't be ruled out. However, 2008 was also preceded by stronger negative Nino3.4 activity than at present, which suggests it's more likely a lower limit.

      Well, that's more than I intended to write.

    2. I saw that paper yesterday. I will just say for my amateur self, I started hammering on the Eastern Pacific over at CargoCult Etc. about 6 years ago. My AMO bashing is also Eastern Pacific cheerleading. It's the big dog of ocean cycles, and you know it when it bites you as I got nailed by a huge German Shepard a few weeks ago. Ouch. Anyway, Niño 3.4 just took a big drop, which it did about this same time in December. That freezer event failed to sustain, so we'll see about this one. But so far the equator off Peru just keeps fluctuating cold and warm, and that propagates over to 3 and 4. Same for the PDO. JIASO is reporting very late for some reason, but NOAA PDO indicates it should be climbing. If so, the sort off cooling they need just isn't in the cards.

    3. My prediction for GISS 2018 rises from 0.82+-0.13 to 0.86+-0.12 due to the higher Dec17 temp, substantial rises the prediction for DJF18. There is a confusing ENSO trend in MEI adding some uncertainty.
      But GISS 2018 not in the top-5 warmest years at the end seams at least as unlikely now as 2018 breaking the 2016 record.

    4. Thanks, Uli
      I'll put up a new thread for review of 2017 and prospects for 2018. I've jus put up one with graphs of years to 2017; the prospects thread will be in a day or two.

  2. JRA-55 has completed year 2017 now.
    Regarding global 2 m temps, Dec was 0.456 C, up by 0.097 C from Nov, and 2017 became the second warmest year. The top three ranking looks like this (all data on the 1981-2010 base)
    2016 0.570 C
    2017 0.440 C
    2015 0.382 C

    JCH, I don't think that 2018 will be cooler than 2014, but probably near 2015 and 2017..

  3. I found the following changes in global temperature anomalies from November to December 2017 (deg C):
    +0.04 RSS TLT
    +0.05 UAH TLT
    +0.09 CFSR Sfc (WxBELL)
    +0.10 CFSR Sfc (UM CCI)
    +0.10 ERAI Sfc (Copernicus)

    I plotted a graph of monthly temperature anomalies for these and the other major sources since 2014 here. To me the pattern is suggestive of another over-all flat trend at near current levels until the next major El Nino, which is likely to be many years away (and barring any major explosive volcanic eruptions similar to Pinatubo or Chichon). But my confidence in this type of El Nino based stair-step pattern is low because I can't really think of any mechanism(s) to cause it. I suspect there may be a temporary overall downward trend for a few month in early 2018 because of the weak La Nina pattern, but it is not likely to be substantial enough to affect the possible longer-term overall flat trend until the next El Nino.

  4. Nick, pretty soon it will be time for a thread on 2018 predictions. It would be fun to look at last years thread to what went right and what went wrong.

    1. JCH,
      Yes I'll do that. There will be a TempLS thread soon, so prediction can come next.

  5. OT but...
    Just wanted to say thanks Nick for your tireless efforts at wuwt. I'm censored now but I'm always pleased to see your patient, common-sense, informative posts in a sea of weird.

    1. Thanks, Tony. I miss your comments there. They were doing a lot of good.