Modulation of Ice Ages via Dust and Albedo

Image: The Importance of the Ice Age Today

Related: A Terrifying GIF Of An Ice Age Ripping Through The US

By Ralph Ellis

The first problem with ice ages is:
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 is not the primary feedback agent.

The second problem with ice ages is:
Ice ages are forced by increased Milankovitch insolation in the Northern Hemisphere (NH), but never by increased insolation in the Southern Hemisphere. If CO2 were the primary feedback agent interglacials could and would be forced by increased insolation in either hemisphere, but they are not. The fact that interglacials are only ever NH events, strongly suggests that surface albedo is the primary feedback agent (the great landmasses being in the NH), rather than CO2.

The third problem with ice ages is:
During an ice age, many NH Milankovitch maxima produce little or temperature response. Again, this would be unlikely if CO2 was the primary feedback agent, but it is to be expected if surface albedo was the primary feedback. High albedo ice sheets covered in fresh snow can and will reject the increased insolation from a NH Milankovitch maximum, resulting in little or no temperature response.
Unless, of course, the ice sheets are somehow covered in dust, thus reducing their albedo. Fortuitously, the northern ice sheets do indeed get covered in dust just before each and every interglacial. This is the topic of my ice age modulation paper – the counter-intuitive method of dust production, and its function as the primary feedback agent controlling interglacial warming.

The fourth problem with ice ages is:
The CO2 is a very weak feedback agent indeed. During an interglacial warming era, the CO2 feedback requires warming from decade to decade, to feedback-force temperatures into the next (warmer) decade. Unfortunately the CO2 feedback is only 0.007 W/m2 per decade, which is less energy than a bee requires to fly.
Conversely, reduced albedo ice sheets can absorb an extra 200 W/m2 every single annual year, when measured regionally. Clearly the albedo feedback is far stronger than the proposed CO2 feedback, and could indeed dissipate the vast northern ice sheets in about 6,000 years.

All of the above points strongly suggest that ice sheet albedo is the primary feedback agent modulating interglacials, rather than CO2.

Increased dust is caused by low CO2 concentrations, because CO2 is plant-food, and the most essential gas in the atmosphere. Thus low CO2 concentrations cause the death of all C3 vegetation at high altitude, causing CO2 deserts to form across the Gobi plateau. Dust from these CO2 deserts formed the huge dust deposits of the Loess Plateau, and also covered the northern ice sheets in dust – which lowered the albedo of the ice sheets and precipitated melting.

See the full peer-reviewed paper

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