Is the Sun Setting in the Wrong Place?

In yesterday's post Suburban Sunset, @mepatriot, in a comment, asked the question "Are you noting anything unusual about the setting and/or rising sun locations?" and made the comment that some people were indicating it has changed. Knowing that the location of the sun setting changes throughout the year, I responded back that people may be noticing the sun shifting southward since the summer solstice has passed.

Later I started looking around the internet for indications the sun was setting in a different location. Sure enough, there are a number of postings using photo's taken from different times of the year to "prove" the sun is setting further north than before. One poster used the fact that while sitting in his chair he now had to turn his head to see the sunset as proof the sun was setting in the wrong location. Maybe he should should just reposition his chair back to the original position. The one common theme through these posts is that the tilt of the earth's axis is changing.

To a small extent they are correct, the angle of the earth's tilt is changing. However, this isn't a new thing and has been going on for millions of years. The earth doesn't actually rotate on an axis as much as it wobbles. In the 1920's Milutin Milankovitch hypothesized that the rotation and orbit of the earth changed in a predictable manner. The earth's orbit forms an ellipse around the sun rather than a circle and the shape of that ellipse changes over time. At the same time, the tilt of the earth is also changing, varying from 21.5° to 24.5°. Currently it's about 23.5°. The third method of changing is similar to a top winding down during which the top wobbles and the axis of rotation moves in a circular pattern. Each of these changes impacts the amount of solar radiation we receive on earth and thus our climate.

Like any hypothesis, there needed to be proof of it's accuracy. As a result, Milankovitch's theory was ignored for about 50 years until it was proven using deep sea sediment cores. The sediment cores were used to gather climate data over the past 450,000 years. When the climate data was compared to Milankovitch's work, his theory was proven.

The earth's tilt, called obliquity, changes over a period of 41,000 years, making it's way from 21.5° to 24.5° and back. As the angle increases, the northern hemisphere is more directly exposed to the sun in the summer and less exposed in the winter while the southern hemisphere is just the opposite. The result of this is hotter summers and colder winters.

More recently research from LSU by Kristine DeLong indicates the intertropical convergence zone (ITCZ) is also impacted by the tilt of the earth. The ITCZ is responsible for a large amount of heat and water vapor movement around the world. It's the area near the equator where the northern and southern hemispheres come together. The ITCZ is also the location of some of earth's largest storms, hurricanes and typhoons. Delong was able to correlate 282,000 years of data on the ITCZ to Milankovitch's 41,000 year cycle of the tilt of the earth.

All this sound familiar? Hotter summers, colder winters, tropical storm changes? The man made global warming crowd all blame these phenomena on increased levels of carbon dioxide in the atmosphere. Science says there's another potential explanation.