Archives par mot-clé : Milankovitch

The inter-glacial cycle is not a 100,000-year cycle, it is a shorter cycle with missing beats

by M.O. Jonas, 2022, WorldJ.Adv.ResReviews


Review Article
World Journal of Advanced Research and Reviews, 2022, 13(03), 388–392
Article DOI: 10.30574/wjarr.2022.13.3.0259
Publication history:
Received on 18 February 2022; revised on 20 March 2022; accepted on 22 March 2022
Abstract:
The “100,000-year problem” refers to an apparent unexplained change in the frequency of inter-glacial periods which occurred about a million years ago. Before that, inter-glacial periods seemed to occur about every 41,000 years, in line with the obliquity Milankovich cycle. But after that, they seemed to occur about every 100,000 years, in line with the orbital inclination Milankovich cycle. Examination of the data shows that there never was a 41,000-year cycle, and that there is no 100,000-year cycle, but that the most influential cycle is the approx 21,000-year precession cycle which is the major factor in the cycles of insolation at higher latitudes. Insolation at 65N is generally regarded as the most significant of these. Inspection of the data shows that every glacial termination (start of an inter-glacial period) began at a time when insolation at 65N increased from a low point in its cycle. That not every such cycle triggered a new inter-glacial period underlines the chaotic non-linear nature of Earth’s climate. Until about a million years ago, this cycle occasionally “missed a beat”, making the inter-glacial frequency average about 41,000 years. After that, the cycle started missing more “beats”, making the inter-glacial frequency average about 100,000 years. There never was an actual 41,000-year or 100,000-year inter-glacial cycle.
Keywords:
Climate; Glacial Termination; Inter-Glacial; Milankovich Cycle; Non-Linear; Precession
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Scientists discover link between climate change and biological evolution of phytoplankton

by Rutgers University, Dec 2, 2021 in WUWT


New Brunswick, N.J. (Dec. 1, 2021) – Using artificial intelligence techniques, an international team that included Rutgers-New Brunswick researchers have traced the evolution of coccolithophores, an ocean-dwelling phytoplankton group, over 2.8 million years.

Their findings, published this week in the journal Nature, reveal new evidence that evolutionary cycles in a marine phytoplankton group are related to changes in tropical seasonality, shedding light on the link between biological evolution and climate change.

Coccolithophores are abundant single-celled organisms that surround themselves with microscopic plates made of calcium carbonate, called coccoliths. Due to their photosynthetic activity, mineral production and widespread abundance throughout the world’s oceans, coccolithophores play an important role in the carbon cycle.

Scientists have long thought that climate changes’ effects on plants, animals and other organisms occur in cycles, which are reversed when each cycle is completed, thus erasing any small evolutionary changes during each cycle. In contrast, evolutionary changes, as known from the fossil record, are non-cyclic trends that occur over millions of years.