Understanding multi-decadal global warming rate changes

Posted: June 14, 2017 by oldbrew in climate, Cycles, Natural Variation, Ocean dynamics
Tags: ,

Credit: sciencedaily.com

Maybe a glimmer of recognition for natural warming from the oceans here, while still believing that alleged man-made effects on air temperatures are somehow warming the water in a cyclical fashion. Could there be a hint of strained logic here? Phys.org reports.

Despite persistently increasing greenhouse gas emissions throughout the 20th and early 21st centuries, the globally averaged surface temperature has shown distinct multi-decadal fluctuations since 1900, including two weak global warming slowdowns in the mid-20th century and early 21st century and two strong global warming accelerations in the early and late 20th century.

The multi-decadal global warming rate changes are primarily attributed to multiple ocean surface temperature changes, according to research by Institute of Atmospheric Physics and Australian Bureau of Meteorology.


It is the net impact of multiple ocean surface temperature changes, rather than a single ocean basin change, that plays a main driver for the multi-decadal global warming accelerations and slowdowns.

Understanding and quantifying the respective role of individual ocean basin in the multi-decadal global warming accelerations and slowdowns, under the forcing of the sustained increase in atmospheric greenhouse gas concentrations, could help achieve a more accurate estimate of the future global warming rate to better meet the global warming target of the Paris Accords—no more than 1.5ºC above pre-industrial levels by 2100.

The new finding of the importance of multiple ocean surface temperature changes to the multi-decadal global warming accelerations and slowdowns is supported by a set of computer modeling experiments, in which observed sea surface temperature changes are specified in individual ocean basins, separately. The results are published in Nature Climate Change.

Continued here.

Comments
  1. Richard111 says:

    “”under the forcing of the sustained increase in atmospheric greenhouse gas concentrations””

    I’m sorry, I fell over here. I am still unable to find any good explanation for “greenhouse gasses”.

    All current science for heat transfer is easily understandable and shows radiative gasses in the atmosphere cannot trap heat. Radiative gasses in the atmosphere can at best slightly reduce the rate of surface cooling. This is not a warming.

    Solar influence on ocean temperatures shows good relationship with historical ice records. Present solar activity implies a cooling period developing. It remains to be seen how long this cooling period will last. Any effect on present agriculture will have a bad effect on population in the near future.

  2. oldbrew says:

    ‘It is the net impact of multiple ocean surface temperature changes, rather than a single ocean basin change, that plays a main driver for the multi-decadal global warming accelerations and slowdowns.’

    They’ve admitted natural slowdowns, and natural variation in general. Some small progress maybe. On the other hand it could be preparing the ground for excuses if/when warming fails to happen.

    Also: ‘Our results identify multiple ocean surface temperature change as a major driver for global mean surface temperature changes on multi-decadal timescales.’

    ‘Major driver’ is getting close to marginalising non-natural effects.

  3. oldbrew says:

    From the report – up down up (like ~30 year oceanic cycles) – no correlation with CO2 steady increase:

    The surface temperature changes in multiple oceans determine the global warming rate changes. Credit: Gang Huang

    Read more at: http://phys.org/news/2017-06-multi-decadal-global.html
    _ _ _

    OCEAN COOLING RESUMES
    Date: 14/06/17 Ron Clutz, Science Matters

    http://www.thegwpf.com/ocean-cooling-resumes/

  4. JohnM says:

    “The multi-decadal global warming rate changes are primarily attributed to multiple ocean surface temperature changes, according to research by Institute of Atmospheric Physics and Australian Bureau of Meteorology. ”
    So far so good .. and unusually sensible from the Bureau of Meteorology.
    “Understanding and quantifying the respective role of individual ocean basin in the multi-decadal global warming accelerations and slowdowns, under the forcing of the sustained increase in atmospheric greenhouse gas concentrations, could help achieve a more accurate estimate of the future global warming rate to better meet the global warming target of the Paris Accords—no more than 1.5ºC above pre-industrial levels by 2100.”
    And their credibility disappears in a single sentence. The obvious question to ask them is why the ocean basin changes couldn’t be responsible for the small change in temperature that gets blamed on mankind. (The ENSO pattern can certainlyaccount for the global temperature pattern from 1950 to 1987 but it looks like other factors came into play after 1987.)
    You don’t think that the Bureau of Meteorology would lose funding and lose credibility if it made the obvious statement that it should make – it looks like changes in oceanic basins might account for most of the warming and mankind really isn’t to blame.

  5. oldbrew says:

    Multi-Decadal Trends of Global Surface Temperature: A Broken Line with Alternating ~30 yr Linear Segments?
    https://www.researchgate.net/publication/257923926_Multi-Decadal_Trends_of_Global_Surface_Temperature_A_Broken_Line_with_Alternating_30_yr_Linear_Segments

    H/T Michele Casati

    We investigate global temperature data produced by the Climate Research Unit at the University of East Anglia (CRU) and the Berkeley Earth Surface Temperature consortium (BEST). We first fit the 1850-2010 data with polynomials of degrees 1 to 9. A significant ~60-yr oscillation is accounted for as soon as degree 4 is reached. This oscillation is even better modeled as a broken line, more precisely a series of ~30-yr long linear segments, with slope breaks (singularities) in ~1904, ~1940, and ~1974 (±3 yr), and a possible recent occurrence at the turn of the 20th century. Oceanic indices PDO (Pacific Decadal Oscillation) and AMO (Atlantic Multidecadal Oscillation) have undergone major changes (respectively of sign and slope) roughly at the same times as the temperature slope breaks. This can be interpreted with a system of oceanic non-linear coupled oscillators with abrupt mode shifts. Thus, the Earth’s climate may have entered a new mode (a new ~30-yr episode) near the turn of the 20th century: no further temperature increase, a dominantly negative PDO index and a decreasing AMO index might be expected for the next decade or two.
    – – –
    ‘New mode…no further temperature increase’ = climate pause?

  6. oldbrew says:

    From the ‘multi-decadal’ paper (above):

    ‘Given the respective masses, impedances and time constants
    involved, it is reasonable to argue that the oceanic system
    forces the atmospheric system on these time scales rather than
    the opposite.’

    ‘Man-made greenhouse gas’ propagandists take note: ‘the oceanic system forces the atmospheric system’.

    The tail does not wag the dog 🙂
    – – –
    Jiggery-pokery alert (from the same paper):

    ‘We point out the puzzling fact that an earlier CRU
    global temperature dataset, HadCRUT3GL, displayed the
    alternating segments better than the latest version CRUTem4vGL
    (Figures 4(a) vs (b))’

    Puzzling indeed :/

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