We have learned about how the tilt of the Earth’s axis affects the change of seasons. However, over a 40,000 year cycle, the intensity of seasons and ice ages are affected by the Milankovitch Cycles. This link provides a simple explanation of how these cycles work. The obliquity, or how tilted the axis is, changes every 40,000 years, affecting seasons. The more oblique, the more extreme the seasons. Now, which direction the axis points changes every 26,000 years. This actually changes which star is closest to the North Pole. Currently, this star is Polaris or the North Star. Combining this procession with obliquity changes when in the orbit Northern Hemisphere winter occurs. Since there is more land mass in the Northern Hemisphere, this has a large effect on ice ages. When the Northern Hemisphere winter occurs at the farthest point from the sun, less sunlight will reach any given point on Earth. This effect is compounded when the ubliquity is large, and then ice is able to grow over a large area of the Northern Hemisphere. How eccentric, or flat, the Earth’s orbit is changes on about a 100,000 year cycle, and can also increase or decrease the intensity of sunlight during Northern Hemisphere winters. On a much shorter scale, 11 years, sunspots also affect global temperature.
The changes in obliquity, precession, eccentricity and sunspots affect global temperature
