Here is a bizarre observation: Climate scientists claim they can explain every facet of the climate-weather system, yet they still don’t know why ice-ages occur. Isn’t that peculiar? They will arm-wave about orbital cycles (regular and specific changes in the earth’s orbital relationship to the sun) and CO2, while desperately hoping you won’t ask troubling questions, such as “Why do some orbital cycles produce ice-ages and interglacials (that is, the milder climates between ice ages), while others do nothing at all?” Or “Why should a climate system be selective in its response to orbital cycles?”

And that’s not the only problem for classical climate scientists because they have not even begun to explain the convoluted complexities of the ice-age cycle. And yet they will still claim a thorough understanding of both ancient and modern climate systems.

There were no answers to these problems—until now....

To begin, what are the missing pieces from this palaeoclimatic jigsaw puzzle?

Contrarian CO2 feedbacks

The first problem for CO2 supposedly controlling global temperatures during the Earth’s many ice-ages is that when CO2 concentrations were high the world cooled and when CO2 was low the world warmed. This counter-intuitive temperature response strongly suggests that CO2 was not the primary feedback agent.

Selective orbital cycles

The second problem for CO2 supposedly controlling ice-age temperatures is that interglacial warming periods are always initiated by increased Milankovitch insolation (i.e., increased sunlight because of Earth’s orbital cycles) in the Northern Hemisphere (NH), but never by sunlight increases in the Southern Hemisphere (SH).

If the feedback agent assisting this orbital sunlight forcing was a global gas (CO2), it would be logical for increased sunlight in either hemisphere to force interglacials. That, however, is not what happens. Interglacials are only ever NH sunlight events, a fact that strongly suggests that the true feedback agent for interglacial warming periods is regional rather than global. Something is happening in the northern hemisphere.

Missing orbital cycles

The third problem for CO2 as the factor controlling ice-age temperatures is the vexing fact that, during each roughly 100,000-year ice age, many orbital cycles will come and go, with many producing little or no temperature response. Why would the temperature response to predictable orbital cycles be selective? Again, this is an unlikely result if omnipresent CO2 was the primary feedback agent controlling global temperatures.

A weak feedback agent

The fourth problem for CO2 controlling ice-age temperatures is that CO2 is a very weak feedback agent. During an interglacial warming era, the CO2 feedback requires warming from decade-to-decade to feedback-force (that is, to bring about) warmer temperatures in the next decade. Unfortunately, the CO2 feedback is only 0.007 W/m2 per decade, which is less energy than a bee requires to fly.

The conundrum

This is a problem for those invested in the CO2 theory because of the fact that not every orbital cycle produces an ice-age or interglacial shows that the climate must need a feedback agent to assist Milankovitch orbital cycles. If orbital cycles were sufficiently powerful, the Earth would experience an ice age every 22,000 years—yet it doesn’t.*

To see the answer to this conundrum, a true scientist must shake off the shackles of CO2 indoctrination and look for other feedback possibilities. What we need is a feedback agent that is quite strong but is situated in the NH rather than the SH. Now, what on Earth could that be? How can a feedback agent be regional?

The obvious difference between the northern and southern hemispheres is that all the great landmasses reside in the NH and, during ice-ages, all the great ice sheets likewise reside in the NH. So, could the missing feedback agent be ice sheet albedo—that is, ice’s reflectivity?

Fresh snow on polar ice sheets can have a very high albedo, reaching up to 0.95 albedo, meaning that it reflects 95% of inbound sunlight back into space. This reflectivity can have a huge regional cooling effect on the climate. Indeed, this bright, white ice can reflect so much sunlight that it negates entirely some orbital cycles that, in theory, should bring more sunlight to earth. Thus, the reflection can reach hundreds of W/m2 when measured regionally, rather than the 0.007 W/m2 of CO2. Fig 1 demonstrates the result of this reflectivity.

Fig 1. A graph of sunlight strength (blue) vs Antarctic temperatures (red).

Each red peak represents an interglacial warming event, which occurs roughly every 100,000 years. The blue peaks represent orbital cycle sunlight maxima in the northern hemisphere. Note that some sunlight maxima produce no temperature response at all.

Sources: Laskar 2004 orbital cycles, Epica3 2007 temperature data.

These facts suggest that we may have discovered the true ice-age temperature feedback agent: It is albedo (reflectivity), rather than CO2.

However, if ice sheet albedo is such a strong feedback agent (keeping the earth cool no matter its orbital cycle vis-à-vis the sun), how can the climate system generate a sudden interglacial warming era? The simple answer is that ice-sheet albedo has a very prominent Achilles’ heel: Dust.

If dust gets onto ice sheets their albedo is reduced considerably, so they can absorb much more sunlight, causing them to melt very quickly. Surprising as it may seem, this is exactly what happens—every interglacial warming period is preceded by about 10,000 years of intense dust storms.

So, why are dust storms generated just before every interglacial warming era? The answer to this is even more enigmatic and esoteric. In fact, it is so counterintuitive that no indoctrinated climate scientist would ever dream up such a scenario. The unexpected answer to this problem is that CO2 is plant food, making it the most essential gas in the atmosphere. Without CO2, all life on Earth would perish. But due to oceanic absorption during ice-ages, CO2 concentrations eventually reach as low as 180 ppm, which is dangerously low for much of the world’s plant life, especially at higher altitudes.

The result of this low CO2 is that the Gobi Plateau in northern China turns into a true desert caused, not by a lack of rain, but by a lack of CO2—a CO2 desert. Without plant life, it becomes a vast shifting-sand desert that is whisked eastwards by strong prevailing winds, forming the Loess Plateau in China and coating the Laurentide and Eurasian ice sheets in dust. These dust storms last for some 10,000 years, allowing the increased sunlight during a new orbital cycle to be absorbed instead of reflected, melting the ice sheets, and heralding the warming of an interglacial period.

Thus, the delightful conclusion to this study, is that during ice-ages it is low CO2 concentrations, not high ones, that cause global warming.

Q.E.D.

Fig 2. A summary graph of all the factors that play a role in glacial modulation.

* Ice sheets (light blue and grey) grow, forcing temperature (red) to fall.

* CO₂ (yellow) reduces with temperature (red), due to oceanic absorption.

* As CO₂ reaches 180 ppm there are CO2 deserts and dust storms (purple).

* When the next orbital cycle (blue sine wave) comes along,

* …the dusty-ice sheets can melt and the world warms (red peaks).

The above analysis is extracted from Modulation of Ice-ages via Precession and Dust-Albedo Feedbacks.

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*This used to happen 1 million years ago, but it does not happen now. The change between orbitally induced ice-ages and feedback-induced ice-ages is another fascinating topic.

Image: The ice sheet on Greenland’s east coast by Hannes Grobe. CC BY-SA 2.5.

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