Monday, October 7, 2013

Study finds global ocean warming has decelerated 50% over the past 50 years

The currently-favored excuse du jour for no statistically-significant global warming over the past 20 years is that the oceans "ate the man-made global warming." However, a 2012 paper published in Nature Climate Change torpedoes this notion, finding the global oceans started warming at least 135 years ago just after the Little Ice Age, on or before the historic voyage of the HMS Challenger in the 1870's. More importantly, the study finds that ocean warming has decelerated 50% over the past 50 years. 

If, as claimed, man-made greenhouse gases are causing the oceans to warm, the opposite would have been expected, namely an acceleration of ocean warming over the past 60 years, beginning in the ~1950's. The fact that the oceans were warming long before CO2 levels significantly increased, and at a higher rate before 50 years ago, clearly demonstrates ocean warming is a natural recovery from the Little Ice Age, and not due to man-made CO2.

The paper is corroborated by a recent paper finding the oceans have warmed only 0.09C over the past 55 years, a rate of 0.016C per decade, and a 34% deceleration from the rate of 0.024C per decade over the past 135 years found by this study.

Further, climate alarmists claim that the "missing heat" is hiding below 1,500 meters deep, but this paper finds the oceans have instead cooled below 1,500 meters over the past 135 years [see third figure below].

In addition, if man-made CO2 was warming the oceans, there should have been an acceleration of steric sea level rise over the past 50 years due to thermal expansion, but no acceleration of sea level rise has been found over the past 203 years.


New Comparison of Ocean Temperatures Reveals Rise over the Last Century; Ocean robots used in Scripps-led study that traces ocean warming to late 19th century

A new study contrasting ocean temperature readings of the 1870s with temperatures of the modern seas reveals an upward trend of global ocean warming spanning at least 100 years.




10 comments:

  1. "The 0.33 °C±0.14 average temperature difference from 0 to 700 m is twice the value observed globally in that depth range over the past 50 years."

    The answer is in the paper, if you read it:

    "The larger temperature change observed between the Challenger expedition and Argo Programme... seems to be associated with the longer timescale of a century or more."

    0.33 degrees over 13 decades is a 0.025 increase per decade.

    0.165 degrees over 5 decades is a 0.033 increase per decade.

    This doesn't seem to justify the statement that "global ocean warming has decelerated 50% over the past 50 years".

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    1. The statement "The 0.33 °C±0.14 average temperature difference from 0 to 700 m is twice the value observed globally in that depth range over the past 50 years." is by definition equivalent to saying ocean warming has decelerated 50% over the past 50 years.

      The reference cited in this paper for the warming over the past 50 years is Levitus 2009. A more recent update is Levitus 2012, which is the data I used in this post, and shows a warming of 0.09C over the past 55 years, or 0.016C per decade, a deceleration of 34%.

      Therefore, depending on the reference cited, ocean warming has decelerated 34-50% over the past 50-55 years.

      Whether it's 34 or 50% or something inbetween, it makes no difference to the fact that it contradicts the "ocean ate the man-made global warming" meme.

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    2. "The statement "The 0.33 °C±0.14 average temperature difference from 0 to 700 m is twice the value observed globally in that depth range over the past 50 years." is by definition equivalent to saying ocean warming has decelerated 50% over the past 50 years."

      This is simply incorrect: when you take the period of the two observations into account, the numbers show that warming has actually accelerated.

      The 0.33 increase is over a period of 13 decades, whereas the 0.168 increase from Levitus is over 5 decades.

      The oceans have warmed more per decade over the last 50 years than they did per decade since the Challenger expedition.

      To claim otherwise is a simple error of maths, a mistake.

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    3. "The reference cited in this paper for the warming over the past 50 years is Levitus 2009. A more recent update is Levitus 2012, which is the data I used in this post, and shows a warming of 0.09C over the past 55 years, or 0.016C per decade, a deceleration of 34%."

      Levitus 2012 actually gives a figure of 0.18 degrees for the equivalent 0-700m layer- the 0.09 figure is 0-2000m.

      http://www.agu.org/pubs/crossref/pip/2012GL051106.shtml

      0.18 over 5.5 decades is 0.033 per decade.

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    4. Ok you're correct for 0-700m depth

      .33/13 = .025
      .18/5 = .033

      ...an acceleration

      I was using 0-2000m depth change of 0.09C/55 years from Levitus 2012, but the Challenger data only goes to ~1800m apparently, so not a direct comparison, but the paper indicates significantly less warming with depth and even cooling over the past 135 years below ~1,500 m. Unfortunately, the paper doesn't indicate the temperature change of 0-1800m, but it does appear from what is provided that there has been a deceleration of warming from 0-2000m depth over the past ~50 years.

      for 0-2000 m depth

      0.09/5 = .018 from Levitus 2012

      a deceleration, but admittedly I shouldn't compare 0-700m data to 0-2000m data. Thanks for pointing out.

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    5. "...it does appear from what is provided that there has been a deceleration of warming from 0-2000m depth over the past ~50 years."

      I can't see anything in the paper to justify that statement.

      The paper gives a figure of 0.12 °C±0.07 at 914 m, which as you point out is not comparable with the Levitus figure for 0-2000m.

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    6. Yes, unfortunately the paper doesn't provide the Challenger temperature difference for the 0-1800m depth, which would have been reasonably close to 0-2000m. From eyeballing fig 3 and making some rough calculations for 0-1800-2000m depth I get almost exactly the same warming rate of 0.0163C/decade over the past 135 years vs. past 55 years, so I withdraw the claim of deceleration.

      Nonetheless, based on the information available there doesn't appear to be acceleration in the rate of warming 0-1800 or 0-2000m over the past 135 years and the rate appears to be be quite stable.

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    7. That is correct: the pressure corrected line shows zero warming at that depth.

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  2. http://wattsupwiththat.com/2013/10/21/radiative-forcing-radiative-feedbacks-and-radiative-imbalance-the-2013-wg1-ipcc-report-failed-to-properly-report-on-this-issue/#comment-1454603

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  3. http://joannenova.com.au/2013/09/ipcc-in-denial-just-so-excuses-use-mystery-ocean-heat-to-hide-their-failure/

    ReplyDelete