Something Was Messing With Earth’s Axis. Guess Who?

Milutin Milankovitch
Orbital Variations
Changes in orbital eccentricity affect the Earth-sun distance. Currently, a difference of only 3 percent (5 million kilometers) exists between closest approach (perihelion), which occurs on or about January 3, and furthest departure (aphelion), which occurs on or about July 4. This difference in distance amounts to about a 6 percent increase in incoming solar radiation (insolation) from July to January. The shape of the Earth’s orbit changes from being elliptical (high eccentricity) to being nearly circular (low eccentricity) in a cycle that takes between 90,000 and 100,000 years. When the orbit is highly elliptical, the amount of insolation received at perihelion would be on the order of 20 to 30 percent greater than at aphelion, resulting in a substantially different climate from what we experience today.

earthobservatory.nasa.gov/features/Milankovitch/milankovitch_2.php

Now, some of the same scientists have identified another factor that’s had the same kind of effect: colossal quantities of water pumped out of the ground for crops and households.

“Wow,” Ki-Weon Seo, who led the research behind the latest discovery, recalled thinking when his calculations showed a strong link between groundwater extraction and the drifting of Earth’s axis. It was a “big surprise,” said Seo, a geophysicist at Seoul National University.

Water experts have long warned of the consequences of groundwater overuse, particularly as water from underground aquifers becomes an increasingly vital resource in drought-stressed areas like the American West. When water is pumped out of the ground but not replenished, the land can sink, damaging homes and infrastructure and also shrinking the amount of underground space that can hold water thereafter.