Quaternary Climate

The Quaternary Period refers to the last 2.6 million years of the Earth's history. While glaciation in Antarctica occurred earlier in the Cenozoic, the Quaternary Period refers to glacial cycles synced to Milankovitch Cycles, or orbital cycles, which affect that distribution of energy that the Earth receives either throughout the year or between the poles. The Quaternary is made up of two Epochs, the Pleistocene and the Holocene. The Holocene refers to the most recent interglacial (the last 11,700 years). All of the glacial cycles prior to the Holocene make up the Pleistocene.

Pleistocene

  1. The glacial cycles of the Pleistocene have been synced to orbital cycles, but a transition occurred about 1 million years ago, which is called the Mid-Pleistocene Transition. At that time, these cycles shifted from being synced obliquity to eccentricity.
  2. Early reconstructions of the glacial cycles showed that CO2 increases lagged behind increases in Antarctic temperatures. However, it turns out that increases in CO2 and temperature were nearly synchronous and global temperature increases followed increases in CO2. 
  3. CO2 levels at 420 ppm exceed any levels we've experienced in the entire Quaternary. The implications for the long-term changes in climate, especially sea level rise, are enormous.
  4. The Younger Dryas marks the transition to he Holocene, and it's an example of abrupt climate change. The probable causes are extremely interesting.

Holocene

  1. Marcott 2013 was an extremely influential reconstruction extending our understanding of global temperatures to the beginning of the Holocene. I wrote a couple posts explaining the value of the reconstruction and the evidence that it shows current warming to be truly exceptional.
  2. The GISP2 ice core reconstructs temperatures at the Greenland Summit for the last 50,000 years or so, but contrarians have misused this data in countless ways.
  3. Some graphs of the Holocene appear to be either made up entirely or modified to the point of being nearly unrecognizable.
  4. The second part of my review of Inconvenient Facts contains refutations of some of Gregory Wrightstone's counterfactual claims about the Holocene.

Common Era

  1. Some use Loehle 2007 (corrected in 2008) to suggest that the Medieval Warm Period was warmer than today, even though the time series ends in the 1930s.
  2. Some use solar reconstructions to suggest that the Medieval Warm Period was warmer than today, even though the Sun is a stable star, and solar variability is small.


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