Friday, March 18, 2016

NOAA Global Feb record - ENSO comparison.

The NOAA Land/Ocean index rose from 1.05°C in jan to 1.21°C in Feb, relative to 20th Cen average. Their report is here. At 0.16, this is a slightly smaller rise than GISS or TempLS, which both rose a little over 0.2°C. The total effect is smaller again, in that the NOAA global dropped from Dec to Jan. Still, it was easily the hottest month in the record. Again, I think the reason why NOAA is showing a little less rise is because it under-represents the Arctic, which was very warm.

As with GISS, I'll show the updated comparison with 1997/8. Again, it tracks closely, even with the dip in Jan and the peak in Feb. GISS was tracking in the range 0.4-0.5°C above 1997/8; NOAA is around 0.4. Both GISS and NOAA show a drop in March, back to about January levels. This seems less likely this time; with about half the month gone, the NCEP/NCAR index is still above Feb, although the early hot spell has subsided. Of course, much could still happen. Here is the plot:

I gave a collection of these plots that you can flick through here. I have updated it.


  1. As Tamino and others have pointed out, it appears what we are seeing is what you would expect from a large El Nino superimposed on the global warming trend.

    What does stand out however was the warmth in the Arctic. I would be interested in any comments as to why that was so.

  2. MarkG - Arctic Amplification has long been a prediction of AGW. As I understand it, this is mainly due to the numerous feedbacks present in the arctic that are not extensively found elsewhere; sea ice, snow cover, and water vapor.

    As the arctic warms there is less sea ice decreasing albedo and allowing more of the sun's energy to be absorbed. Likewise, as the arctic warms NH snow cover disappears earlier in the melt season and at higher latitudes than 'normal' also decreasing albedo and allowing more of the sun's energy to be absorbed. As for water vapor, the arctic can be best thought of as a desert. There is very little precipitation and the air simply is too cold to hold much moisture. Warm the arctic and you warm the air and increase the amount of water vapor it can hold.

    Water vapor is both a potent greenhouse gas and increasing atmospheric water vapor typically leads to more precipitation. The GHG nature of water vapor leads to additional warming, and the increase in precipitation has confounding effects - but in the long run (much like clouds) it appears to be a net positive feedback.

  3. I should have mentioned that since the sea water is relatively warm, -1.8C, if it has little or no ice cover its heat will warm the atmosphere and will be reflected in 2m surface temperatures. Put a thick lid of ice over the sea and winter temperatures can plummet to -30 or -40C. This is actually a negative feedback (that's a lot of heat from open water or thinly covered winter seas being directly radiated to space), but it shows up as warmer 2m surface temps.

  4. Kevin,
    Thanks much for this very clear explanation of an amplifier, a contributor to positive feedback. If not a denier, I am at least a dissenter, perplexed by the allegations that the increase in global temperature might greatly exceed that due to Arrhenius effects alone.

    My naive thought was that if our system wasn't more or less feedback neutral (sum of feedbacks neutral?) we would already have had a runaway.

    I suppose the response would be that sum of feedbacks may be neutral within the recent temperature ranges but that doe not preclude the possibility that imbalances may emerge with increased temperature.

    Hoping for indulgence of an innumerate reader trying to evolve a coherent, and realistic, understanding of what's happening, does my grasp of this seem reasonable to you? Is it similar to yours?

    1. Correct me but your understanding contains an unstated and incorrect assumption that all feedbacks are runaway. Some are, some are not.

      Water vapour in the atmosphere is a feedback but not a runaway one. An increase in temperature increases evaporation which means more water vapour in the air which increases the temperature but less than the initiating increase which means eventually the rise stops and equilibrium is reached even though there is plenty more water that could evaporate.

      A runaway feedback would be the melting of the ice sheets. Once a temperature is reached that melts the ice sufficiently to expose land surface the global albedo changes. This makes more heat be absorbed which raises the ambient temperature which makes the melting faster. Thus the feedback continues not decreases.

      Their are physical limits to all feedbacks so the starting of any particular one does not mean it continues indefinitely. For example once the ice sheet is all gone the temperature rise stops. Current estimates I think are that the melting of Greenland would take several centuries, add about 7m to sea level and add a few tenths of a K to the global mean temp.

    2. J. Ferguson, the mathematician who hosts this blog has provided a comprehensive explanation :

      However, if you really are "innumerate" then you will find that hard to follow, so here's something simpler.

      First of all consider audio amplifiers. As the name suggests these are positive feedback devices. You have probably had the unpleasant experience of runaway feedback when someone speaks too loudly into a microphone and a horrible screeching sound ensues over the public address system. The fact that this is rare is in indication that positive feedback is by no means always runaway.

      In the case of climate let's suppose that a forcing leads to an increase of 1 degree. Then let's also assume that the resulting increase in evaporation from oceans leads to a further IMMEDIATE increase of 0.5 degree (positive feedback parameter of a half). This in turn gives a further rise of a half of 0.5, namely a quarter of a degree. That extra quarter of a degree leads to yet more evaporation and a further temperature increase equal to a half of a quarter degree, namely one eighth. This continues ad infinitum, so we end up with a total feedback due to increased water vapour of:

      Half + quarter + eighth + sixteenth + etc ad infinitum. Now, even if you are innumerate, you can, with the aid of a calculator or a spreadsheet application, keep adding terms to this sum for as long as you care and you will never get beyond a total feedback of 1 degree. You will never see runaway feedback, despite the claims of my Noble Lord, the Viscount Monckton of Brenchley.

  5. J ferguson, "My naive thought was that if our system wasn't more or less feedback neutral (sum of feedbacks neutral?) we would already have had a runaway."

    If I understand you properly, I don't think I can agree. The earth's climate has changed in the past with pretty well understood regularity. The energy changes that have caused these past cycles is relatively small - telling us the earth is actually quite sensitive to small changes. Climate history doesn't tell us that feedbacks are neutral, just that they aren't large enough to cause the system to go into a runaway condition.

    Feedbacks don't have to be large or have an instantaneous visible impact yet they will still have an effect. Especially when dealing with human lifetimes it may not be possible to clearly see the impacts; have you kept track of when your tulips first bloom in the spring or when the first migratory bird arrives? With many of these phenological traits we see evidence of change over decades. It is similar for temperatures in general. Can any of us notice an average increase of 1 degree over our lifetimes - given the daily and seasonal variations may be 50 times as great?

    Yet when taken over decades or a century or two, or longer these small increases can add up to significant impacts. The difference between 'Hothouse Earth' and an ice age is only a couple of percent change in global average temperature in one direction or the other. I.e., increase our global temperature by 5C and we'll be in hothouse earth conditions, reduce our global temps by 5C and we'll be in an ice age.

    Typically we know what drives the earth into these periods - orbital parameters. And typically these orbital changes take 10s of thousands or 100s of thousands of years to complete a cycle. What we're witnessing today isn't due to orbital changes and it's happening on timescales far, far shorter than any orbital cycle. Still, few serious climate scientists believe we're in danger of sending the earth into a runaway condition a la Venus.

  6. Thank you each for the help you've given me above. I think I understand now where I was going wrong. I apologize for diverting you from likely more interesting discussions, but I asked my questions here because the issues seem better understood by the numerate, and not so well by the others. I've been reading here for about a year and find the things I do understand trustworthy. Thank you again, and Nick, as well, for an informative site.

    1. Fergy, read this

  7. Nick, I'm not quite sure if your operation is permitted because you assume, that the ElNinos 1997/1998 and 2015/2016 had the same impact on the global temperatures. This is a postulate and you show no evidence for it. A new paper ( Hu et al. 2016) show a tool that can very good distinguish the types of ElNinos. Using it ( in roughly 1st order: 2 SST series) you see that the 1997 ElNino was a strictly EP-type and the 2010 was a strictly CP (Modoki) type. The ongoing ElNino is a duplex-type, CP AND EP. The influence on the global temperatures can be very different, due to the greater involved area stronger now than 1998, IMO.

    1. Frank,
      "because you assume"
      I don't think I'm assuming anything much. It's just an observation of how they are tracking to date. I think you are right that the future may be different, and that, like 2010, the warmth may peak about now and then decline rather earlier than 1998. That's on the basis of your hybrid suggestion, which seems plausible.

  8. My 2016 annual average forecast of 0.92C is now looking a bit on the low side. I did think that was likely the case but not by quite so much.

    As a means to provide a lower bound forecast based on the year so far I've found the difference between the average of the last 10 months and the average of the first two months of every year in the record. The largest negative difference is -0.292 in 1958, I understand a strong El Nino year.

    Applying that as an upper bound on the post-El Nino temperature drop through the year, the 2-month average = 1.245 so lower bound on 10-month average = 1.245 - 0.292 = 0.953. Combined 12-month average = 1.002.

    That means it will take a record-breaking intra-annual temperature drop to avoid an annual anomaly of >= 1ºC.

    1. Oh, should say this is for GISS, not NOAA.

    2. My bet for 2016 was +0.94K (GISS), based on an analysis of 1996-1998 vs 2014-2016, with 2016 being the fcst ... obviously. While I would probably go a bit higher now (especially considering March, which, as far as the GFS forecast is concerned, suggests +1.28 +/- 0.1K for GISS, which in turn is the same value GFS was suggesting for GISS last month), I won't rule out an annual anomaly <1K. It's literally all about Antarctica. If the Antarctic region (60S-90S) behaves like last year, we will almost certainly see a larger temperature drop than in any other (post-) strong El Nino year. Thing is, Antarctica turned cold two weeks earlier than last year already .. well under way to continue the trend of extremely cold SH summer anomalies (despite sea ice extent anomalies hovering around normal/zero this year). Usually Antarctica should be warmer post-El Nino, but TBH I wouldn't be surprised if we see another record-breaker down south this year ...

    3. Hi Karsten,

      Can't rule out under 1K - the record has to be broken at some point, and arguably the sample size isn't very big. It's 136 years but only 2nd years of El Ninos and those influenced by well-timed volcanic eruptions are really eligible to cause larger temperature drops, so probably about 90% of years aren't relevant. In fact, looking at the details I suspect it will be closer to the record than most El Nino events. Nonetheless, I think it's a reasonable indicative lower bound - say a likely level.

      I can't see a large Antarctic contribution to dropping temperature though. January and February were both below average in 60S-90S so it seems unlikely it could fall far enough from here to be a big factor. As it happens that record 1958 intra-annual drop had a large Antarctic contribution - a drop of 1.15K (Mar-Dec vs. Jan-Feb) according to Climate Explorer averaging, which is the largest on record for this region and translates globally to 0.08K of the 0.292K, taking into account surface area. However, January and February were both above average in 1958. I've plotted here what the 2016 Mar-Dec average anomaly would have to look like in context of other years to have the same effect. That cannot be realistic and the graph suggests we're far more likely to see warmer Antarctic anomalies - a regression to the mean from the rather severe lows of 2015 - than significantly cooler.

      On the other hand/pole the Arctic (60N-90N) saw huge record anomalies in January and February by about 1.5K. The last time there was anything like that, relatively speaking, was 1981 and that year also experienced a record Arctic intra-annual change (Mar-Dec vs. Jan-Feb) of -2.2K, which translates to -0.15K for the global average. It's reasonable to expect something like that again, so I wouldn't be surprised if we at least approached the 1958 global intra-annual drop record.

      A warm March doesn't change the statistics much, but if April remains around 1.1-1.2K the historical record suggests an annual anomaly under 1K would be very unlikely.

    4. Hi PaulS,

      thanks for the plot. I don't think we're gonna see a regression to the mean. Something has happened to the circumpolar circulation that's causing Antarctic winter T anomalies to nosedive (btw, I meant to write "trend of extremely cold SH winter anomalies" in the previous posting). Since external forcing alone (GHG+O3 as opposing forces now) can't do it, PDV related teleconnections are a contender. However, regressing temperatures on PDV doesn't really support this idea. Fun fact, March 2016 was exactly as cold as March 2015 in GFS in 60S-90S. April 2016 currently colder than April 2015 with sea ice is growing very fast, pushing the ice anomalies well into positive terrain again. No sign of change to what happened in 2016. This means -0.1K globally between April and September if things stay that way.

      Another -0.1K comes from the Arctic region in summer when anomalies are literally bound to be zero between mid-May and mid-Sept. This will bring anomalies further down in comparison to 1998 (when the Arctic wasn't particularly warm in winter). Hence I'd be surprised if we stay as much ahead of 1998 as we are right now (with March 2016 at +1.28 +/-0.1K in GISS based on GFS and NCEP).

      Given that GISS would stay above +1K based on 1998 expectations, both Arctic and Antarctic region have easily the potential to push it below the 1K threshold no later than June. Oct-Dec will certainly see the usual recovery from both polar ends, but La Nina (and potentially WACCy) will counter that recovery to an unknown degree. Everything still possible ;) I will say though, if Antarctica is going to do what I anticipate, it's time to find out what's really going on down there. After all, there is an interesting seasonal cycle noticeable in the 60S-90S T anomalies over the last few years (weaker tendency already over the last three decades) with SH autumn being colder.

    5. Yes, the Antarctic winters are weird. There is some recent research suggesting an increased negative greenhouse effect over Antarctica, e.g:

      I have my own conceptual model for this (probably not quite right) which goes: In the winter strong katabatic wind sucks the stratosphere all the way down to the high grounds of inner Antarctica, and AGW is cooling the stratosphere...

    6. Thanks Olof! Knew the abstract but missed the paper. Saved now :) Thing is, SH winter is the only season that actually produces GHG warming. So I venture to say, this isn't what's causing it. The magnitude of the current cooling is way too large to be explained by forcing either way anyways. Winds are the most likely reason. Your hypothesis sounds plausible ... somehow circumpolarly controlled.

  9. This ENSO comparison by Nick Stokes with the superposed mean lines is really interesting.

    Perhaps is another comparison a bit interesting too: that of the years in front of the two dominant El Ninos which started in 1997 resp. 2015:

    Here you can see two 5 years temp series starting in 1993 resp. 2011; the series are built out of the average of 5 surface records (GISS, NOAA, HadCRUT4, JMA, BEST) and 3 lower troposphere records (RSS, UAH5.6, UAH6.0beta5). All data is baselined at UAH level.

    Note the stunning similarity of the two series at some places, even if their trend differs by 1 °C... as if these El Ninos were preprogrammed events :-)

    Suddenly I remembered to have picked up somewhere on the Net an info about a huge El Nino which happened in 1877-1878.

    Using the BEST data, I found it really, and repeated the little exercise above:

    That old guy really was a huge one! This time however the series differ much more, whilst the trends are very similar.

    It seems from this example that El Ninos might not necessarily be driven by higher global temperature schemes, as this 1877/8 Nino grew within a colder context, in front of that rather harsh cooling period between 1880 and 1910.

    1. Bindidon,
      ENSO is potentially a deterministic forced behavior.

      With just a few factors and one assumption in defining a phase inversion, the ENSO index is stationary

      A multiple regression fit using the same factors over two non-overlapping 52 year training intervals yields the essentially the same time-series when extrapolated each way.

      It's just a matter of time before ENSO is fully decoded, the key being a biennial modulation

    2. Thanks whut. Your math is far above my knowledge.

      But your reply was not a response... I still miss some explanation about this 1877/8 Nino violence.

      Until now I had read that before the XXeth century the Nino/Nina phemomens had occured with the same frequency as actually but with lower amplitude.

    3. I don't think I've heard that before, other than as speculation or a hypothesis. As far as I'm aware there is no consensus or convergence of evidence on if/how the ENSO phenomenon itself might change in response to anthropogenic forcing. There is a common view that the effects of ENSO swings will intensify, in the sense that timing of droughts and floods in many parts of the world is linked to ENSO and the severity of such events will increase, but that wouldn't necessarily imply a change in the underlying phenomenon.

      Another thing is that Nino3.4 and some other El Nino indicators are SST anomalies. In common with much of the rest of the planet this region is expected to warm due to anthropogenic forcing. Therefore, as a matter of course Nino3.4 peaks will, absent accurate standardisation, generally be warmer now than in the past and will continue to get warmer in the future.

      We have to be somewhat careful about temperature data going back to 1877/88 - coverage was pretty terrible, with only intermittent and spatially inconsistent SST data in the all important tropical Pacific region. However, the data we do have, including independent land thermometer records does point to an unusually strong El Nino, with a good claim of being the strongest in the industrial era.

    4. I think the issue is that to determine what kind of impact that AGW will have on ENSO, you first have to understand what drives ENSO's behavior.

      I don't think scientists have a handle on the understanding because they still argue whether it has a large stochastic element.

      What I cooked up looks like a plausible model: