Describe the Milankovitch theory of climatic change by explaining how each of the three cycles alters the amount of solar energy reaching Earth

Question

What will be the ideal response?

Answer 1

ANSWER: The first cycle deals with changes in the shape (eccentricity) of Earth’s orbit as Earth revolves about the Sun. To go from less elliptical to more elliptical and back again takes about 100,000 years. The greater the eccentricity of the orbit (that is, the more eccentric the orbit), the greater the variation in solar energy received by Earth between its closest and farthest approach to the Sun. The second cycle takes into account the fact that, as Earth rotates on its axis, it wobbles like a spinning top. This wobble, known as the precession of Earth’s axis, occurs in a cycle of about 23,000 years. This affects the strength of seasonal variations in climate. The third cycle takes about 41,000 years to complete and relates to the changes in tilt (obliquity) of Earth as it orbits the Sun. Presently, Earth’s orbital tilt is 23.5°, but during the 41,000-year cycle the tilt varies from about 22° to 24.5°. The smaller the tilt, the less seasonal variation there is between summer and winter in middle and high latitudes. Thus, winters tend to be milder and summers cooler. During the warmer winters, more snow would probably fall in polar regions due to the air’s increased capacity for water vapor. And during the cooler summers, less snow would melt. As a consequence, the periods of smaller tilt would tend to promote the formation of glaciers in high latitudes.