Hindcasting climate shifts in the Pacific

From the Helmholtz Centre for Ocean Research Kiel (GEOMAR)

The potential for successful climate predictions

Hindcast experiments capture long-term climate fluctuations

This shows observed and predicted temperature changes in the Pacific during the 90s. Credit: Graphics: C. Kersten, GEOMAR.

Will there be rather warm or cold winters in Germany in the coming years? We may have a long way to go before reliable forecasts of this kind can be achieved. However, marine scientists, under the auspices of the GEOMAR Helmholtz Centre for Ocean Research Kiel, recently managed to successfully hindcast climate shifts in the Pacific. These shifts also have a profound effect on the average global surface air temperature of the Earth. The most recent shift in the 1990s is one of the reasons that the Earth’s temperature has not risen further since 1998. The study, published in the online edition of Journal of Climate, shows the potential for long-term climate predictions.

What happened in the years 1976/77 and 1998/99 in the Pacific was so unusual that scientists spoke of abrupt climate changes. They referred to a sudden warming of the tropical Pacific in the mid-1970s and rapid cooling in the late 1990s. Both events turned the world’s climate topsy-turvy and are clearly reflected in the average temperature of the Earth. Today we know that the cause is the interaction between ocean and atmosphere. Is it possible to successfully predict such climate shifts? This is the question that scientists, under the auspices of the GEOMAR Helmholtz Centre for Ocean Research Kiel, pursued. Using a coupled model of the ocean and the atmosphere, they were able to successfully replicate these events.

“The ocean plays a crucial role in our climate system, especially when it comes to fluctuations over several years or decades,” explains Prof. Mojib Latif, co-author of the study. “The chances of correctly predicting such variations are much better than the weather for the next few weeks, because the climate is far less chaotic than the rapidly changing weather conditions,” said Latif. This is due to the slow changes in ocean currents which affect climate parameters such as air temperature and precipitation. “The fluctuations of the currents bring order to the weather chaos”.

The researchers used a climate model, a so-called coupled ocean-atmosphere model, which they forced with the observed wind data of the last decades. For the abrupt changes during the 1970s and 1990s they calculated predictions which began a few months prior to the beginning of the observed climate shifts. The average of all predictions for both abrupt changes shows good agreement with the observed climate development in the Pacific. “The winds change the ocean currents which in turn affect the climate. In our study, we were able to identify and realistically reproduce the key processes for the two abrupt climate shifts,” says Prof. Latif. “We have taken a major step forward in terms of short-term climate forecasting, especially with regard to the development of global warming. However, we are still miles away from any reliable answers to the question whether the coming winter in Germany will be rather warm or cold”. Prof. Latif cautions against too much optimism regarding short-term regional climate predictions: “Since the reliability of those predictions is still at about 50%, you might as well flip a coin”.

###

Original publication:

Ding, H., R. J. Greatbatch, M. Latif, W. Park and R. Gerdes, 2013: Hindcast of the 1976/77 and 1998/99 climate shifts in the Pacific. J. Climate, http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00626.1

Links:

http://www.geomar.de GEOMAR Helmholtz Centre for Ocean Research Kiel

Images:

Under http://www.geomar.de/n1447 figures are available for download.

About these ads

45 thoughts on “Hindcasting climate shifts in the Pacific

  1. “The researchers used a climate model, a so-called coupled ocean-atmosphere model, which they forced with the observed wind data of the last decades. For the abrupt changes during the 1970s and 1990s they calculated predictions which began a few months prior to the beginning of the observed climate shifts. The average of all predictions for both abrupt changes shows good agreement with the observed climate development in the Pacific. “The winds change the ocean currents which in turn affect the climate. In our study, we were able to identify and realistically reproduce the key processes for the two abrupt climate shifts,”

    Does the model tell them how to predict when the wind patterns shift? Does it tell them whether the wind patterns and the current changes were causally related or both caused by something else?

    Another quibble–how does the researcher know that the climate is less chaotic than the weather? If the researcher is making long term predictions, the frequency of the measured “chaos” must also be longer. So if his assertion is correct, I guess that means the researcher can predict the next ice age and the next emergence from the ice age because those could not possible be “chaotic” phenomenon because they are climate??

  2. doesn’t ocean coupling mean climate is chaotic? why do modelers assert by hand waving that chaos averages out, and long term (any scale for that matter) climate is not chaotic?

  3. Anthony,
    Whole bunch of words in this have been changed to orange with double underlining. They are all links that lead to commercial sites rather than what one would think they lead to. Not your style, my supposition being that wordpress is inserting these opportunistically. Not impressed (though I recognize this may simply be the price of keeping your costs down).

    • @davidmhoffer

      “Whole bunch of words in this have been changed to orange with double underlining. They are all links that lead to commercial sites rather than what one would think they lead to. “

      Nope, I just checked the page code, no such thing exists. You’ve got some adware/malware on your machine my friend. – Anthony

  4. “Since the reliability of those predictions is still at about 50%, you might as well flip a coin”.

    Ah, the famous Met Office method.

  5. In the late 70s the jets became more zonal and the climate zones began to drift poleward leading to a reduction in global cloudiness.

    Warming El Ninos gained dominance over cooling La Ninas over and above the effect of the positive phase of the Pacific Multidecadal Oscillation in the background.

    In the early 2000s the whole pattern went into reverse.

    The only change that occurred in correlation with both climate shifts was the level of solar activity.

    In the late 70s the run of active cycles 21 to 23 began, Around 2000 it ended with the imminent arrival of weak cycle 24.

    Any link to our omissions is completely swamped by the natural solar and oceanic influences.

  6. That chart is so small it is hard to read. Regardless, I do not see anywhere in it where the warm water is supposed to be hiding. Can anyone else find it?

  7. Friends:

    The above article reports that Prof. Latif has said

    We have taken a major step forward in terms of short-term climate forecasting, especially with regard to the development of global warming.

    Oh, dear. NO!
    A demonstrated ability to hindcast says NOTHING about an ability to forecast.

    The philosophical reason for this is that there is only one past but there are an infinite number of possible futures.

    The practical demonstration of this is that a variety of models can be constructed which hindcast the behaviour of a stock market, but there is no way to decide which – if any – of them provides a correct forecast.

    Forecasting skill is only demonstrated and assessed by comparing a series of forecasts to the resulting outcomes in reality.

    I am astonished that any scientist would say what Prof. Latif is reported to have said.

    Richard

  8. “The winds change the ocean currents which in turn affect the climate.”

    That supports my proposition that something other than the oceans initiates the process. The oceanic response is merely an out of phase (and variable) modulating response to the initial forcing element.

    For a long time it was proposed that our emissions were causing the changes in the atmospheric circulation.

    Various reports suggested that our emissions were causing the more zonal jets.

    That proposition was falsified from 2000 when emissions rose strongly but the jets became more meridional.

    It has to be solar effects on the upper atmosphere. For example it cannot be a mere coincidence that the recent extreme negative polar oscillations happened during a period of less active sun. Negative polar oscillations involve more meridional jets.

    All the observations fit the proposition that somehow the sun is the cause.

  9. You’ve got some adware/malware on your machine my friend. – Anthony
    >>>>>>>>>>>>

    Sigh, you are correct. Killed it already. Oddly, I had about 9 browser tabs going and the only one which was affected was WUWT. Jumped to a conclusion based on that, apologies.

    Almost three years without any malware getting past me. Grumble, grumble, I hate those guys.

  10. Hindcast experiments capture long-term climate fluctuations…

    I’d be more inclined to say they hind casted one short (10year) half of a sine wave….
    if so, that’s not impressive at all

    I could be wrong!

  11. Hindcasting is a reasonable filter. However, even if your hindcast is correct, you can get the right answer for the wrong reasons, and you still have no predictive power.

  12. Hi Henry.

    I don’t know why the sun does what it does or what it will do next.

    I only think I know how it affects the global air circulation out of all proportion to the tiny changes in TSI.

  13. WTH?? Where is their forecast? Does their forecast not indicate impending GLOOM AND DOOM so because of PC choose not to show it?

  14. lts nice to see they are waking up to the fact that its the winds that drive the ocean surface currents. lt has to do as l can not see how the ice sheets over Europe would of formed in the last ice age otherwise. As for forcasting if the winters will be getting colder over Europe. What l would be looking out for are increasing signs of winter and snow cover setting in early over northern Russia. So as to build up a big pool of cold air ready to invade Europe when the weather patterns are right. Also a jet stream that goes zonal and tracks to the south as we move towards winter over Europe would be a other sign. So as to let blocking highs set up to the NE North or NW of Europe, and allowing the cold air to flow from the Arctic and Russia.

  15. Given enough degrees of freedom, I can use that model to hindcast what I had for breakfast for the past week. In fairness, forecasting a mathematically chaotic system is best a problematic endeavor. Perhaps, in that fact is a reason to keep one’s pretended forecasting abilities to a near term. Alas, we see routine predictions of a century or so ahead.

  16. Climate is described by averages as well as extremes. It is also described by its global address in terms of latitude, longitude and altitude. All that is basic 5th grade geography. Therefore any “shift” from one range/average to another range/average in weather metrics within the outer bands of the extremes is not a climate shift. Rather it is a weather pattern shift. The only time there have been true shifts in climate is during major ice ages and interglacial ice advances.

    If this degradation of the definition of climate continues, you will be able to use the two words climate and weather interchangeably!

  17. Whenever they can predict it, it is chaotic. Oh, so now that they got a hindcast correct, it is Ocean current and not chaotic!

  18. …says Prof. Latif. “We have taken a major step forward in terms of short-term climate forecasting, especially with regard to the development of global warming.”
    then
    “Since the reliability of those predictions is still at about 50%, you might as well flip a coin”.
    ==============
    So, global warming is back in vogue now?

    It is getting to the point where I’m not sure what the latest crisis is, then again, I don’t depend on funding to run my shop.

  19. Stephen Wilde cooling.
    2) 100-130 -> stay the same.
    3) 130-up -> warming

    Remember that the energy reaching the Earth is the area under the Flux curve throughout recorded history [1600 until now]. The almost 2 years [2006-7] of zero Sun spots gave average Flux readings of 65.

    So it is clouds [ice clouds]. Note the giant ice rings that are showing up around the full Moon. An indication that the ice is expanding.

  20. Stephen Wilde cooling.
    2) 100-130 -> stay the same.
    3) 130-up -> warming

    Remember that the energy reaching the Earth is the area under the Flux curve throughout recorded history [1600 until now]. The almost 2 years [2006-7] of zero Sun spots gave average Flux readings of 65.

    So it is clouds [ice clouds]. Note the giant ice rings that are showing up around the full Moon. An indication that the ice is expanding.

  21. “We have taken a major step forward in terms of short-term climate forecasting, especially with regard to the development of global warming.”

    I think this is indeed an important step forward, diverting the focus from linking everything to CO2. They demonstrate on the short term that ocean oscillations that shift surface temperatures alter pressure systems and thus the climate. That is exactly what the the “Natural Variation Deniers” (credit Tallbloke for this term) ignore. Most models can now hindcast droughts when ocean surface temperatures are prescribed. For example La NIna conditions strengthen the Pacific High and the odds of a drought in the Southwest. The public is grossly unaware of how ocean oscillations cause extreme weather events like floods and droughts and Latif’s research need more attention. Similarly it was a colder North Atlantic that encouraged a blocking High that drove a minor hurricane into New York to become Superstorm Sandy. Their research can only bolster the claims that natural ocean oscillations cause extreme weather, not CO2.

    They should also be praised for admitting short term forecasting is still no better than a coin flip in contrast to CO2 advocates who advocate inevitable warming and inevitable catastrophes. Drawing more attention to the fact that “These shifts also have a profound effect on the average global surface air temperature of the Earth” is progress.

  22. The PDO has defined changes in atmospheric pressure across the Pacific Ocean. When these pressure changes occur it will lead to different winds. This is all well known so I’m not too sure there is anything new in this paper.

    I guess all they are claiming is a correlation between specific wind patterns and a climate shift. Could be true but not really all that helpful in understanding the underlying cause/s.

  23. Pamela Gray says:
    August 22, 2013 at 2:07 pm
    Climate is described by averages as well as extremes. It is also described by its global address in terms of latitude, longitude and altitude. All that is basic 5th grade geography. Therefore any “shift” from one range/average to another range/average in weather metrics within the outer bands of the extremes is not a climate shift. Rather it is a weather pattern shift. The only time there have been true shifts in climate is during major ice ages and interglacial ice advances.

    If this degradation of the definition of climate continues, you will be able to use the two words climate and weather interchangeably!

    ———–_——-_————-

    Unfortunatly , it has already happened. IMHO

    Think of the “Russian heatwave” blocking high as an example, or Extratropical storm Sandy?

    Seems everywhere you turn in today’s world the embelishhment of weather into climate is prevalent.

    Just my take…….

  24. And the next “climate step” will be?
    Hindcasting is a polite term, I too can predict who will win a 2012 election in 2013.
    Do these clowns have any reason to keep feeding at the public trough?

  25. So is there a cause to this effect that will allow us to predict the next one? Maybe a 60 year cycle.

  26. What’s new here is they are using winds (a proxy for pressure changes?) to force the model, and NOT CO2. CO2 has no say in all this. It’s just something that plants relish.

  27. The PDO/PNA is ABSOLUTELY the most important factor in natural climate change. It’s still very poorly understood. But it surely dominates(everything).

  28. taxed (August 22, 2013 at 12:31 pm)
    “lts nice to see they are waking up to the fact that its the winds that drive the ocean surface currents.”

    Amen. Hallelujah. Common sense begins to prevail.
    Dear God: Thank You.

    __
    jim Steele (August 22, 2013 at 4:36 pm)
    “I think this is indeed an important step forward, diverting the focus from linking everything to CO2. They demonstrate on the short term that ocean oscillations that shift surface temperatures alter pressure systems and thus the climate. That is exactly what the the “Natural Variation Deniers” (credit Tallbloke for this term) ignore.”

    Recently I found a paper that mentions CO2 ~360 times.
    What article holds the record for most mentions of CO2?

    Is there a correlation between number of mentions of CO2 and funding $$$?
    SOLAR TERRESTRIAL CLIMATE

    _______

  29. __

    Atlantic Hurricanes & the Sun

    __
    Also:
    I have an interesting story to tell in the coming months about TSI reconstructions.
    It’s a game-changer.

    Related reading:

    Soon, W.; & Legates, D.R. (2013). Solar irradiance modulation of equator-to-pole (Arctic) temperature gradients: empirical evidence for climate variation on multi-decadal timescales. Journal of Atmospheric and Solar-Terrestrial Physics 93, 45-56.

    http://people.duke.edu/~ns2002/pdf/soon_legate.pdf

  30. Vaughan says:
    August 22, 2013 at 11:29 pm
    __
    Atlantic Hurricanes & the Sun
    Also:
    I have an interesting story to tell in the coming months about TSI reconstructions.
    It’s a game-changer\========================================================================================
    Ny supercomputer forecasts that a WUWT resident solar specialist will dispute this up coming paper.

  31. The method described in their (carefully paywalled) paper either has some merit or not. If it has, I can see no reason why it could not be applied to current data to forecast Pacific temperatures for the next decade. The fact that they have not ventured that far is telling.

  32. I really wish I knew what a “hindcast” was / is.

    Does it mean a “best guess” about some past unknown extrapolated from known bodies of evidence? And if so, does that mean they came up with some kind of new “historical record” as they call it? Based on what evidence can they claim to have “successfully hindcast climate shifts in the Pacific.” (?) If they have verified their hindcast using known historical data, why didn’t they use that data? (sigh)

    As I recall, neither Epimetheus nor Prometheus made out too well – the one who was limited to afterthought eloping with Pandora, and the other gifted with foresight, doomed to liver problems.

    I wish they would stop trying to “predict” things. Just give us accurate historical records.

  33. There are very large amounts of money to be made predicting the weather from a few months to a couple of decades ahead. Now that the GCM climate models have completely failed to produce any worthwhile predictions, people are starting to look for other approaches to longer term weather forecasting.

    This is a good thing, and likely to produce advances in understanding mostly outside mainstream climate science, which is hopelessly mired in its GHGism..

  34. A hindcast is the same as a forecast, except a hindcast is for period when whatever is predicted, say temperature, is known. Whereas, a forecast is for a period when the value isn’t known, generally in the future.

    When done properly a hindcast is as valid as a forecast. Unfortunately, in climate science, hindcasting is just an exercise in tuning the fiddle factors, aerosols, etc.

Comments are closed.