Water loss may be changing the Earth's wobble

According to a report in Science, researchers have determined that water on land, which includes soil moisture levels, underground aquifers, lakes, rivers and other water-holding surfaces, has been declining. In fact, the water has gone down by “trillions of metric tons” within at least the last 20 years, which is believed to be having an impact on the Earth’s wobble.

Much of the blame for the water losses has been placed on the rising temperatures across the globe. As I mentioned in previous articles, drought conditions have been a major concern across the U.S. and the rest of the world.

The study that was released in late March claims that over the last 20 years, the amount of water that is stored on land, also known as terrestrial water, has shown a dramatic decline, especially in recent years. This research has been based on soil moisture data from satellites, sea levels and observations of the Earth’s poles.

The article in Science also revealed that the Earth has experienced a “dramatic shift” in its axis since the turn of the century. Their observations concluded that there has been a change in the wobble of approximately 45 centimeters in the last 20 years. Scientists have determined that the massive loss of soil moisture, over 1,600 gigatons, across the planet has been the primary cause of the shift, rather than changes in the Earth’s core or the loss of ice.

Since the early 1900s, scientists have been monitoring the wobble of our planet. This phenomenon is a gradual, cyclical motion of the Earth’s axis of rotation. It’s very similar to how a spinning top wobbles and is estimated to take approximately 26,000 years to complete a full circle. The wobble of our planet is primarily caused by the gravitational pull of the sun and the moon on the Earth. This effect causes the Earth to bulge at the equator, which has an impact on the planet’s rotation.

Shifts in the Earth’s wobble can also be influenced by large-scale movements of mass. For example, after the end of the last Ice Age, the rapid loss of ice sheets resulted in these wobble shifts from the redistribution of mass from the melting ice. During the peak of the last ice age, it’s estimated that glaciers covered about 32% of the land on Earth, resulting in a very heavy load, perhaps trillions of tons. As the glaciers melted, the mass on land changed, resulting in the redistribution of the mass, which had an effect on the wobble. The recent study concluded that changes in water on the land, especially soil moisture, have had a similar effect. In some cases, the effect was likely to be bigger.

The wobble of the Earth is part of a long-term cycle that can affect our seasons. The change in the angle of our axis (tilt) and orbit will influence our climate over tens of thousands to hundreds of thousands of years. They are known as the Milankovitch Cycles, named after a Serbian scientist, Milutin Milankovitch, who theorized that changes in the Earth’s position to the sun are responsible for long-term changes in climate, such as ice ages.

Over long periods of time, the wobble, also known as axial precession, can make seasonal contrasts more extreme in one hemisphere, but less extreme in the other. According to an article in NOAA, the summers in the Southern Hemisphere are hotter, while they are more moderate in the Northern Hemisphere. However, based on the theory, in about 13,000 years, the progression of the wobble will likely cause the conditions in both hemispheres to flip as our hemisphere will become even more extreme.

In terms of our local weather, our precipitation totals to date are falling further behind normal in Coeur d’Alene and the rest of the Inland Northwest. At Cliff’s station, the April rainfall total is just over .40 inches. The Spokane International Airport is close to 0.40 inches for April. There may be some showers and thunderstorms later this week, but we’re likely going to fall short of the 1.77-inch normal for April.

More showers are expected to fall across the region in early May. However, there is a strong high-pressure ridge that is trying to situate itself over the western U.S. We still expect to be close to the 2.37-inch normal precipitation for May as moisture is forecast to briefly pick up over the next four to six weeks.

Our seasonal total to date is nearly 7.60 inches of rain and melted snow in Coeur d’Alene. The normal precipitation is about 9.30 inches. Last year, we were slightly above the seasonal normal with 9.56 inches. As we’ve been mentioning, it’s still looking like a dry summer season, but not as dry as the one in 2024.

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Contact Randy Mann at randy@longrangeweather.com.