Sentences with phrase «obliquity cycle»

And why does the 41kyr obliquity cycle dominate most of the time?

During the past several million years, astronomical cycles are dominated by 405 kyr, 125 kyr, and 95 kyr eccentricity cycles, 40.9 kyr obliquity cycles, and 23.6 kyr, 22.3 kyr, and 19.1 kyr precession cycles19, 49.

Ekholm also discusses the orbital obliquity cycle and its influence, presenting some interesting calculations a la his buddy Arrhenius, but he sees it as secondary to CO2 / temperature feedbacks.

For example, in the Upper Carboniferous (~ 300 million years ago), the ~ 41,000 yr obliquity cycle would have taken about 33,000 years (see e.g., here)

In a recent paper, paleoclimatic data shows that the tropical monsoon cycle responds very reliably to the ups and downs of Milankovitch insolation forcing on one of the shorter time scales (either 23kyr 65N forcing swings or the 41kyr obliquity cycle, I forget which), but the ice sheets and sea level and global temperature do not respond directly to those insolation forcings.

During the Early Triassic, Milankovitch cycles were dominated by 405 kyr, 125 kyr, and 95 kyr eccentricity cycles, 33 kyr obliquity cycles, and 21 kyr, 20 kyr, and 17 kyr precession cycles19, 31,49.

Huybers & Wunsch (2005, Nature, 434, 491) and Huybers (Quaternary Science Reviews, 26, 37) have convincingly shown that even during the late Pleistocene, the timing of deglaciations is strongly correlated to the obliquity cycle.

This procedure is sometimes derided as «wiggle matching,» and I have literally seen it done in a way that the obliquity cycle is overlain with delta -18-O and peaks are moved to match the obliquity peaks.

The obliquity cycle creates our seasons.

Ekholm cites work on the «obliquity cycle» performed by J. Croll and by J.N. Stockwell, and allows that, although CO2 is the «principal cause» of the ending of the Ice Age, obliquity changes may have provided a «material» contribution.

This is surely due to the changes of earth's obliquity, since changes in the amplitude of the climate signal correspond to changes in the amplitude of the obliquity cycle (Lisiecki & Raymo 2007, Quaternary Science Reviews, 26, 56).

An example of this might be the «mid Pleistocene revolution» 1 million years ago, 2/3 of the way through the current glacial period, where the timing of interglacials changed from 41,000 year spacing aligned with the obliquity cycle to an approximately 100,000 year spacing involving apparently a more complex interaction between precession and eccentricity.