New study finds variations in global warming trend are caused by oceans

Posted: May 15, 2018 by oldbrew in atmosphere, modelling, Natural Variation, Ocean dynamics, research, Temperature
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The headline from the source should perhaps mention that those ‘variations’ can include ‘no global warming trend’, or hiatus, as explained below.

New research has shown that natural variations in global mean temperature are always forced by changes in heat release and heat uptake by the oceans, in particular the heat release associated with evaporation, reports Phys.org.

Analysing data from six climate models that simulated future climate change scenarios for the last International Panel for Climate Change (IPCC) Report, which appeared in 2014, University of Southampton Professor Sybren Drijfhout has shown that in all cases variations in global mean temperature were correlated with variations in heat release by sensible and latent heat.

Writing in the journal Nature Scientific Reports, Professor Drijfhout says these variations are associated with heat transfer due to temperature differences between the surface ocean and the overlying air, and heat transfer associated with evaporation. The heat fluxes are also called the turbulent heat fluxes.

“The relation holds in all models and is independent of the time-scale of the variation in temperature”, says Professor Drijfhout, Chair in Physical Oceanography and Climate Physics at Southampton. “When the atmosphere gets extra warm it receives more heat from the ocean, when it is extra cool it receives less heat from the ocean, making it clear that the ocean is the driving force behind these variations.”

“The same relation can be observed in the observations, but because the data on surface heat fluxes is characterised by large uncertainties, reviewers urged me to drop the part associated with analysis of these data,” he adds.

Professor Drijfhout also explains he could only analyse six climate models because he needed to split natural temperature variations from the forced trend due to increased greenhouse gas concentrations. “You need the same model to repeat the same emission scenario a few times with slightly different initial conditions”, he argues. “In that case the natural variations will run out of phase, while the forced response is the same in each model run. This allows for a clear separation of the two.”

The relation between global mean temperature variations and total heat uptake appears to be more complex due to changes in absorbed solar radiation which are out of phase with the turbulent fluxes and the temperature response.

Before the ocean releases extra amounts of heat to the atmosphere, it is warmed by increased absorption of solar radiation. For a hiatus in global warming, or relatively cool period, the opposite occurs and more sunlight is reflected, cooling the ocean after which the atmosphere on its turn is cooled by less heat release from the ocean.

“The changes in solar radiation received at the Earth’s surface are clearly a trigger for these variations in global mean temperature,” says Professor Drijfhout, “but the mechanisms by which these changes occur are a bit more complex and depend on the time-scale of the changes.

“When the temperature variations only last a few years,” he continues. “The changes in absorbed solar radiation occur in the tropics, preferably the Pacific, and are associated with moving patterns of more or less clouds that are characteristic with El Niño, or its counterpart, La Niña.”

If the variations take longer, ten years or so, sea-ice becomes the dominant trigger, with more sea-ice reflecting more solar radiation and less sea-ice allowing for more absorption.

Continued here.

Comments
  1. Bitter@twisted says:

    “Natural cycles”
    Now who would have thought that?
    Hint: Sceptics.

  2. oldbrew says:

    “The changes in solar radiation received at the Earth’s surface are clearly a trigger for these variations in global mean temperature”

    There you have it.

  3. Brett Keane says:

    Would sound nice but he says ‘data from models’! No such thing is possible.

  4. Phoenix44 says:

    If the models show that, then the models have been constructed to do that.

    The models don’t do things on their own.

    I honestly wonder if half the scientists in the world actually understand what a model is and how hey work. Matt Ridley had a Twitter exchange last week with various climate scientists who claimed CO2 sensitivity in their models was an “emergent” property and a consequence of their assumptions!

    Models just do what they are told, and doing arithmetic you set up on assumptions you make CANNOT produce anything other than another assumption.

  5. Phoenix44 says:

    “…and NOT a consequence of their assumptions!”

  6. oldbrew says:

    in all cases variations in global mean temperature were correlated with variations in heat release

    Correlation with heat release sounds a lot more plausible than a claimed correlation with a trace gas comprising 0.04% of the atmosphere (or 0.01% if the change since around 1850 is taken as the key factor).

  7. oldbrew says:

    Estimating Solar Irradiance Since 850 CE
    J. L. Lean
    Space Science Division, Naval Research Laboratory, Washington, DC, USA
    Published online 20 APR 2018

    From the abstract:
    In the new estimates, solar irradiance cycle amplitudes in the Medieval Maximum are comparable to those in the Modern Maximum

    http://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2017EA000357

    From the intro:
    Solar irradiance is Earth’s primary energy input. It establishes the thermal and dynamical structure of the terrestrial environment and is the primary external cause of terrestrial variability. The specification of solar irradiance over multiple centuries is requisite input for numerical simulations of climate variability prior to the industrial epoch that provide a baseline against which to evaluate contemporary anthropogenic influences. [bold added]

  8. I got down to the “heat release” for evaporation in the article and gave up. Evaporation requires heat and for water it is about 5.5 times that of the heat to raise the temperature of an equivalent weight of water from 0C to 100C. It is condensation which leads to the formation of clouds that releases heat. In clouds this heat release is to a large extent radiate to space because the surface of water has an emissivity close to unity. Freezing the water droplets ti ice also releases heat but this is less than the heat for evaporation. The surface of ice has a lower emissivity than water. If in fact the “heat release” for evaporation is actually in the article then the author has little understanding of heat & mass transfer (which by the way is an engineering subject little understoos by physicists and certainly not at all be so-called climate scientists)

  9. nickreality65 says:

    The up/down/”back” radiation greenhouse gas energy loop of the radiative greenhouse effect theory is pencil on paper, a spreadsheet cell, a “what if” scenario and NOT a physical reality.

    Without this GHG energy loop, radiative greenhouse theory collapses.

    Without RGHE theory, man-caused climate change does not exist.

    And with a snap of the fingers and “Presto!!” the bazillion dollar global climate change fantasy is suddenly unemployed.

    Must be why nobody is allowed to talk about this possibility. Not newsworthy enough? Or too far outside the fake news narrative?

  10. Ned Nikolov says:

    If variations in global temperature are caused by the oceans, them what causes changes in the ocean temperature? The proposed random uptake & release of heat by oceans without an external forcing does not seem to make much physical sense. Would you agree?

  11. oldbrew says:

    Ned N – yes, the Phys.org report does cover it:

    Before the ocean releases extra amounts of heat to the atmosphere, it is warmed by increased absorption of solar radiation. For a hiatus in global warming, or relatively cool period, the opposite occurs and more sunlight is reflected, cooling the ocean after which the atmosphere on its turn is cooled by less heat release from the ocean.

    Read more at: http://phys.org/news/2018-05-variations-global-trend-oceans.html

    So… Sun > Oceans > Atmosphere — for ~70% of the Earth’s surface anyway.

    Also: “The changes in solar radiation received at the Earth’s surface are clearly a trigger for these variations in global mean temperature,” says Professor Drijfhout, “but the mechanisms by which these changes occur are a bit more complex and depend on the time-scale of the changes.”

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