In the past decade, we’ve been hearing news of all sorts (official or not) about the Earth changing its North rotational pole. Now, NASA’s JPL (Jet Propulsion Laboratory) researchers have found that the move actually changed its direction, and that we (ahem)… we may be the cause.
Planets, Earth included, aren’t perfect spheres – they have various shapes, mountains and valleys, and have a constant rotation around their own axis. But you already know that since kindergarden.
Now, what’s different about Earth in the past decade or so, is the changing symmetry, which makes the spin axis to start moving.
After making a mathematical model of the Earth, JPL’s Surendra Adhikari discovered that there are two causes to our planet’s recent pole change: water.
Actually, it’s no wonder, if you start thinking further. The melting of the Greenland and West Antarctic ice sheets and humans pumping water across regions change the global distribution of water stored on land, and guess what that’s related to: climate change.
Since 1899, the year scientists started monitoring Earth’s spin axis, the pole was heading toward Hudson Bay, Canada, with a speed of seven centimeters a year. This was linked to th eloss of the Laurentide ice sheet, which covered Canada and most of Northern US during the last ice age (1.8 million years ago until about 11,700 years ago).
Now, the spin axis has shifted its path, moving along the Greenwich Meridian at a speed of 14 centimeters per year. This, as Adhikari says, has been attributed to the melting of the Greenland ice sheet.
But ice sheets are not entirely to blame for this shift. NASA’s Gravity Recovery and Climate Experiment satellite (GRACE) uncovered clues of another factor: the storage of water on land, in particular, across Eurasia. By pumping it and by climate change, humans have caused imbalances in the water stored on the ground.
Adhikari has also discovered that the poles don’t move in a straight line, but wobble from east to west, tracing a since curve with each decade. “Here, for the first time ever, we have presented a plausible physical mechanism for this,” he said.
These findings strengthen the belief that humans have become the most powerful force of nature on Earth, and the ways that humanity is taking through its decisions will affect the entire planet in the long run. Some have even suggested we should consider ourselves in a new geologic epoch – the Anthropocene (an age of humans and machines). This proposal will be reviewed later this year by scientists.
pictures (c) Caltech/NASA JPL