GEOLOGY

Detailed explanation-1: -The answer is that the 100, 000-year orbital cycle modulates the effects of the precession cycle. The 100, 000-year cycle deals with the eccentricity of Earth’s orbit-meaning the extent to which it deviates from a circle.

Detailed explanation-2: -BERKELEY, CA–Recent ice ages–ten periods of glaciation in the past million years–are caused by changes in the tilt of the Earth’s orbit, according to research published in the July 11 issue of Science magazine.

Detailed explanation-3: -A likely reason could be a phenomenon called Milankovitch cycles–cyclic changes in Earth’s orbit and orientation toward the Sun that affect the amount of energy Earth absorbs. That, scientists agree, has been the main natural driver of alternating warm and cold periods for millions of years.

Detailed explanation-4: -Over thousands of years, the amount of sunshine reaching Earth changes by quite a lot, particularly in the northern latitudes, the area near and around the North Pole. When less sunlight reaches the northern latitudes, temperatures drop and more water freezes into ice, starting an ice age.

Detailed explanation-5: -Currently, Earth’s eccentricity is near its least elliptic (most circular) and is very slowly decreasing, in a cycle that spans about 100, 000 years. The total change in global annual insolation due to the eccentricity cycle is very small.