John Parmentola: “How could Sea Levels Fall by 400 Feet During an Ice Age?” | Tom Nelson Pod #400

John Parmentola discusses a puzzle of how sea levels fell ~400 feet during ice ages and argues global annual solar input is nearly constant, implying compensating regional heating when the Arctic cools. Using Antarctic ice-core temperature proxies and orbital mechanics, he introduces a new “countervailing obliquity precession effect” (COPE): a biannual insolation asymmetry that increases tropical-zone energy deposition while Arctic summer insolation and melt potential decline, affecting the hydrological cycle, moisture transport, albedo, and glacial descent. He estimates the evaporation energy need (~10^26 J) and says COPE energy over millennia exceeds this. He cites satellite/top-of-atmosphere energy-balance analysis (~1 W/m² net gain) and notes tests: second-half-year precipitation bias, possible Arctic moisture-transport bias, and CO2 outgassing seasonality. Links to his preprint and related work are mentioned.

00:00 Sea Level Ice Age Mystery

09:33 Warming Before Glaciation

12:01 Evaporation Energy Math

13:28 Solar Input Basics

17:10 Why Insolation Stays Constant

20:54 Milankovitch Parameters Explained

26:45 Obliquity Heat Redistribution

29:08 Seasonal Zone Matrix

33:33 Arctic Insolation Then vs Now

40:05 Milankovitch Hypothesis Summary

40:56 Snow Ice Evidence

42:15 Orbit Month Swap

43:54 Hidden Insolation Split

46:12 Seasonal Energy Gap

48:48 Tropical Energy Build

50:15 COPE Defined

53:01 Satellite Signal Test

56:24 Past Interglacial Match

59:22 Summary And Wrap

01:01:08 Q And A Tests

01:05:51 Website And Preprint

01:06:30 Economic Growth Detour

01:11:21 Final Links Farewell

https://johnparmentola.com/

2019: The Great Mystery of Economic Growth”: https://youtu.be/sx-55BhuFks

John Parmentola: Estimating the Holocene Warm Period Termination | Tom Nelson Pod #96: https://youtu.be/6c3yW6s0shQ

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