by Higgenbotham » Tue Jan 06, 2026 12:37 pm
dominant milankovitch cycle
AI Overview
The dominant Milankovitch cycle driving ice ages has shifted over time, with the ~41,000-year obliquity (axial tilt) cycle dominant for much of the last 2.5 million years, but the ~100,000-year eccentricity (orbital shape) cycle became dominant in the last 800,000 years, influencing glacial periods.
While all three cycles (eccentricity, obliquity, precession) affect incoming solar radiation, the 100,000-year eccentricity cycle, linked with precession (~20,000 years), now paces major ice ages, despite the 41,000-year tilt cycle still playing a role.
Key Milankovitch Cycles
Eccentricity (Orbit Shape): Changes Earth's orbit from nearly circular to slightly elliptical over ~100,000 and ~400,000-year cycles, affecting total solar energy received.
Obliquity (Axial Tilt): Varies Earth's axial tilt (related to seasons) every ~41,000 years, altering summer/winter intensity.
Precession (Axial Wobble): Earth's slow wobble changes the timing of seasons relative to its orbit, with cycles around ~19,000-26,000 years (often simplified to ~20,000 years).
Dominance Over Time
Before ~800,000 years ago: The ~41,000-year obliquity cycle seemed to pace ice ages.
Last 800,000 years: The ~100,000-year eccentricity cycle became the primary driver for glacial-interglacial cycles, often working with precession.
Why the Shift? (The 100,000-Year Problem)
While the 41,000-year tilt cycle is strong, the ~100,000-year eccentricity cycle's dominance for the last million years, despite its weaker direct effect, is known as the "100,000-year problem".
The interplay of these cycles, particularly how eccentricity modulates precession's influence on high-latitude summer insolation, drives the larger ice age patterns, notes Skeptical Science.
There might be something similar happening with the generational cycles. The 80 year cycle has been dominant. The most recent crisis concluded in 1945. After nearly 20 years of extend and pretend, it appears the current crisis may just be getting started.
[quote]
dominant milankovitch cycle
AI Overview
The dominant Milankovitch cycle driving ice ages has shifted over time, with the ~41,000-year obliquity (axial tilt) cycle dominant for much of the last 2.5 million years, but the ~100,000-year eccentricity (orbital shape) cycle became dominant in the last 800,000 years, influencing glacial periods.
While all three cycles (eccentricity, obliquity, precession) affect incoming solar radiation, the 100,000-year eccentricity cycle, linked with precession (~20,000 years), now paces major ice ages, despite the 41,000-year tilt cycle still playing a role.
Key Milankovitch Cycles
Eccentricity (Orbit Shape): Changes Earth's orbit from nearly circular to slightly elliptical over ~100,000 and ~400,000-year cycles, affecting total solar energy received.
Obliquity (Axial Tilt): Varies Earth's axial tilt (related to seasons) every ~41,000 years, altering summer/winter intensity.
Precession (Axial Wobble): Earth's slow wobble changes the timing of seasons relative to its orbit, with cycles around ~19,000-26,000 years (often simplified to ~20,000 years).
Dominance Over Time
Before ~800,000 years ago: The ~41,000-year obliquity cycle seemed to pace ice ages.
Last 800,000 years: The ~100,000-year eccentricity cycle became the primary driver for glacial-interglacial cycles, often working with precession.
Why the Shift? (The 100,000-Year Problem)
While the 41,000-year tilt cycle is strong, the ~100,000-year eccentricity cycle's dominance for the last million years, despite its weaker direct effect, is known as the "100,000-year problem".
The interplay of these cycles, particularly how eccentricity modulates precession's influence on high-latitude summer insolation, drives the larger ice age patterns, notes Skeptical Science. [/quote]
There might be something similar happening with the generational cycles. The 80 year cycle has been dominant. The most recent crisis concluded in 1945. After nearly 20 years of extend and pretend, it appears the current crisis may just be getting started.