I realize in listening to the podcast that there are a couple of minor technical errors that need to be addressed, as follows:
1. Where I spoke of cosmic rays in discussing the ozone layer I should have more specifically said gamma rays.
2. In discussing Milankovitch Cycles I erroneously referred to obliquity (degree of axial tilt) when I was actually discussing eccentricity (degree of non-circularity of Earth’s orbit). So, to clarify, eccentricity varies from minimal (75,000 Km out of perfectly circular) to maximal (9,000,080 Km out of circular) over a 100,000 year cycle. Eccentricity is principally caused by Jupiter’s gravitational influence, and it is the primary driver of climate on Earth. Obliquity factors in, varying from a minimum tilt (non-perpendicularity) of 22.1° to maximum tilt of 24.5° on a 41,000 year cycle. The third cycle is precession, operating on a 26,000 year cycle.
My apologies to any well informed listeners who may have found the discussion a little confusing at those points.
I realize in listening to the podcast that there are a couple of minor technical errors that need to be addressed, as follows:
1. Where I spoke of cosmic rays in discussing the ozone layer I should have more specifically said gamma rays.
2. In discussing Milankovitch Cycles I erroneously referred to obliquity (degree of axial tilt) when I was actually discussing eccentricity (degree of non-circularity of Earth’s orbit). So, to clarify, eccentricity varies from minimal (75,000 Km out of perfectly circular) to maximal (9,000,080 Km out of circular) over a 100,000 year cycle. Eccentricity is principally caused by Jupiter’s gravitational influence, and it is the primary driver of climate on Earth. Obliquity factors in, varying from a minimum tilt (non-perpendicularity) of 22.1° to maximum tilt of 24.5° on a 41,000 year cycle. The third cycle is precession, operating on a 26,000 year cycle.
My apologies to any well informed listeners who may have found the discussion a little confusing at those points.
Dave Plumb