Wood Romances

CO2 Coalition's " Fact #14 " appears to be pretty trivial, and as best I can tell, it exists here to scare people into being afraid of a coming ice age. Over the last million years (since the Mid-Pleistocene Transition), glacial cycles have been about 100K years long, synced with orbital cycles. For most of each glacial cycle, the Earth is in a glacial period, with continental ice sheets extending into mid-latitudes, but for about 10K-15K years, the Earth experiences an "interglacial" period, when global temperatures increase and continental ice sheets retreat. Our current interglacial, the Holocene, has lasted about 11,700 years, and the major ice sheets are restricted to Greenland and Antarctica. None of this is particularly controversial or relevant to whether AGW is causing harm to human civilization. Now technically, the above graph shows the last 420K years of the current ice age. There are not multiple ice ages in the Quaternary. Even the interglacial per...

The View from Wesser Bald Nantahala National Forest, North Carolina Considerable research has been given to understanding the processes by which climate has changed to produce the glacial-interglacial cycles. Two studies have examined how climate warmed from the Last Glacial Maximum (LGM) to the Holocene Thermal Maximum (HTM). Shakun et al 2012[1] examined proxies from around the globe to construct a timeline of how and when warming occurred. Beginning with the LGM, the Milankovitch Cycles triggered a global warming of about 0.3 C. This initial warming caused CO2 to degas from the oceans about 17,500 years ago. CO2 in this case doesn’t cause the initial warming; it is a feedback that amplifies warming. “This early global warming occurs in two phases: a gradual increase between 21.5 and 19 kyr ago followed by a somewhat steeper increase between 19 and 17.5 kyr ago (Fig. 2a). The first increase is associated with mean warming of the northern mid to high latitudes, most prominently in Gre...

I recently read a fascinating study looking to understand why the “Mid-Pleistocene Transition” (MPT) happened about 1 million years ago. The MPT refers to the change where the glacial-interglacial cycles of the Pleistocene (the last 2.6 million years) changed from cycles of ~41,000 years to ~100,000 years. Both periodicities are synced to Milankovitch Cycles. During the early Pleistocene, the periodicity matches cycles in the earth’s obliquity, but after the MPT the glacial-interglacial cycles began to track more closely with variations in the earth’s orbital eccentricity. So the big question has been why the change? A recent paper by Willeit published in Science Advances [1] examined this by producing a model that was able to reproduce the MPT. In fact it accurately reproduced the maximum extent of the ice sheets as well as extent of sea level rise. It made use of the carbon cycle, volcanic activity, and changes in regolith cover. The model results indicate that continents had built u...