New Study: ‘CO2 is only a bit-player in the drama of world climate’

My science paper on the modulation of ice aces and interglacials has been published, at last. It is an interesting study that demonstrates that CO2 is only a bit-player in the drama of world climate, while the main characters are ice, dust and albedo.


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Why do ice ages occur? Surprisingly, even after many decades of paleoclimatic research we simply do not know for sure. Most scientists will agree that ice age cycles have something to do with precession: the slow wobble of the axis of the Earth. The ancient Egyptians and Greeks knew of precession and called it the Great Year, because it gives warm and cool seasons over its approximate 23,000-year cycle. But there is a problem with invoking the Great Year as the regulator of ice ages, because we should really get an interglacial warming every 23,000 years or so. And we don’t – they only happen every fourth or fifth Great Year.

But why should the global climate give a selective response to orbital warming and cooling? (Called ‘forcing’ in the climate trade.) This is one of the great unknowns of modern science. Many suggestions have been made, from interstellar dust blocking sunlight to the weight of the ice sheets depressing the lithosphere and warming the ice. And yet all of these theories share one thing in common – they stretch credulity. The only thing that is certain, is that the science is not settled in this area of climate research.

But a new peer-reviewed theory by independent researcher Ralph Ellis may have unlocked this perennial conundrum of paleoclimatology.*1 And considering the myriad implications that flow from this theory, its mechanism is nevertheless very simple to understand. What we need is a selective feedback system that can act either in concert with or in opposition to, the warming and cooling provided by the ~23,000-year Great Year. At present it is claimed that this feedback agent is CO2, because CO2 is a warming agent and its concentrations do indeed rise and fall with the ice ages. But there is a big problem with this assertion, because when CO2 concentrations reach a minimum in the depths of the ice age, the world warms. And when CO2 concentrations reach a maximum during the warm interglacial period, the world cools. And yet this is the very opposite of what should happen if CO2 was the primary warming feedback agent.

This is where the new theory by Ralph Ellis shifts the paradigm, and the primary character in this new climatic drama is albedo – the reflectivity of the Earth. Obviously polar ice sheets are highly reflective, they have a high albedo, and reflect up to 90% of the incident sunlight during the all-important northern summer. The cooling effect from this high albedo allows the polar ice sheets to slowly grow, year after year, and slowly reflect more and more incident sunlight in the process. And this ice-albedo reflection mechanism is so strong, it can even resist the next Great Summer when northern sunlight (insolation) is once again at a maximum, which is why some Great Summers produce no global warming whatsoever.

Modulation of ice ages via precession and dust-albedo feedbacks.

A graph of insolation strength at 65oN (blue) vs Antarctic temperatures (red).

A graph of insolation strength at 65oN (blue) vs Antarctic temperatures (red). Each red peak represents an interglacial warming, which occur roughly every 100,000 years. The blue peaks represent Great Summers in the northern hemisphere. Note that not every Great Summer produces an interglacial global warming. Sources: Laskar 2004 orbital cycles, Epica3 2007 temperature data.

Science Direct

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Comments (9)

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    Al Shelton


    What about obliquity?? 
    Has that been factored in?

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      If you hit “Science Direct”, there you’ll find obliquity and eccentricity considered. 

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    Great article. Nice work, Ralph.

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    “CO2 is only a bit-player in the drama of world climate” ? … Pfffttt … CO2 is not a player at all .. NO gas is a “player” … This article is stupid.

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      John West


      So, Squidly, you don’t think plants need CO2?

      If you’d take the time to read the full paper you’d see that the role CO2 plays in this hypothesis is the opposite of what the climate alarmists have been espousing. CO2 hoarding by cold oceans results in a CO2 shortage that in turn results in increased desertification. This results in increased dust deposits on ice fields/glaciers which increases their albedo thus increasing their rate of melting. This ushers in an interglacial.

      I think it’s an eloquent explanation. It fits the data well and fills in the gaps of understanding of how Milankovitch cycles and interglacials are coupled. Milankovitch cycles have long been thought of as the “root cause” but with something missing in our understanding due to the lack of direct correlation. This fixes that problem. I’ll certainly be reading the paper again and giving it more thought but my first impression is that we may now understand the glacial cycle like never before.

      I don’t know but you might want to be getting used to seeing “Milankovitch-Ellis”.

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    >>CO2 is only a bit-player. This article is stupid.

    This is not an article, it is a 19-page peer-review science paper.  

    And if you think that CO2 plays no role at all in climate, you will need to present some evidence.  This paper cannot rule out CO2 being a warming agent, but what it does demonstrate is that its role is far smaller than that of albedo.  In which case, the role of CO2 has probably been greatly exaggerated.

    And if you think the proposal is ‘stupid’ you should explain why, otherwise, the comment reflects back upon yourself.

    The full paper.
    Modulation of ice ages via precession and dust-albedo feedbacks.

    Ralph Ellis

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    Well presented and very thought provoking . Destroys the myth that CO2 is a primary
    warming feedback agent . But it doesn’t matter because Al Gore has informed everyone who listens to him that the science is settled . No further study required ,no more inflated climate model projections ,no IPCC , no NOAA puffed and polished numbers
    just start writing checks . On the other hand real science is all about ongoing analysis, rigorous debate ,and a humble acknowledgement that there is far more to learn instead of trying to shut down discussion to pursue a business agenda .
    The big bad climate wolves are losing so now they have moved on to their final phase .
    Attempt to silence and threaten those who already accept climate changes , acknowledge it has directionally warmed for over 10 thousand years and humans have some impact .

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    Lois Johnson


    Actually James Croll was the first to publish on the effect of solar cycles on Earth’s climate in 1875. He also determined that something more than the sun’s output was necessary to initiate an Ice Age – which he determined was albedo.

    • Avatar

      ralph ellis


      >>James Croll

      The fact that ice sheet abedo can enhance an ice age has indeed been known for a long time, but the problem has always been how an interglacial happens. Especially when they only happen ever four or five Milankovitch Great Summer cycles. And the answer is CO2 reductions, plant die-back, Co2 deserts and dust.

      As I have said to many academics, most of the pieces of this jigsaw were already on the table. But nobody has placed them together into a cohesive and meaningful picture before. This is a first.


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