Climate change-triggered glacial melting could increase the speed of the Earth’s rotation and even shift the planet’s axis, according to new research published this week. Changes in the speed in which the Earth spins could be significant enough to impact sunrise and sunset times, as the length of the days on our planet are determined by rotational speed, reports Live Science. Research has long indicated that the rotation speed of the Earth has changed over time, even without the modern influence of man-made climate change.
It’s long been understood that gravitational influences on the Earth, namely the pull of the moon and the sun, slow the Earth’s rotation over time and on a predictable scale. However, we’re now learning that other factors, such as melting of ice caps triggered by climate change, can speed up and/or slow down the planet’s rotation as well.
Earlier research into the climate change-triggered glacial melting demonstrated that such melting caused the world’s seas to rise substantially in the 20th century. The Earth’s seas rose an estimated 1.5 to 2 mm per year in the last century. The theory was that this change should have caused an axis shift and increased the Earth’s rotation, too. The issue of climate change related glacier melt causing changes in the Earth’s rotation is even more profound in the 21st century. Scientists are now saying that a massive section of the West Antarctic ice sheet has reached a tipping point. Collapse is now “inevitable,” the forthcoming event, triggered by climate change, is expected to eventually raise sea levels more than one meter.
The reason for this expected climate change-triggered increase in the speed of the Earth’s rotational speed has to do with the shape of the planet. When climate change causes the polar ice caps to melt, the previously-compressed rock beneath “rebound,” which makes the entire Earth more spherical. Theoretically, this should increase the tilt of the Earth’s axis and therefore the rotational speed, too.
Despite the hypothesis, earlier research could not find any evidence that the melting glaciers, triggered by the climate change of the 20th century, changed the rotation speed or axial tilt of the Earth as expected. The discrepancy in theory and observation became known as “Munk’s Enigma” in 2002.
The new research published this month seems to have solved Munk’s Enigma and proven that melting ice, caused by climate change, is truly affecting Earth’s axis and rotational speed. The head of the study, Jerry X. Mitrovica, a geophysicist at Harvard University, explained that not only is climate change contributing to highly-visible changes on planet Earth, climate change is also changing our planet in more difficult to observe ways.
“The rise of sea level and the melting of glaciers during the 20th century is confirmed not only by some of the most dramatic changes in the Earth system — for example, catastrophic flooding events, droughts [and] heat waves — but also in some of the most subtle — incredibly small changes in Earth’s rotation rate.”
The scientists that contributed to the study, which was published in its entirety in the scientific journal Science Advances, noted that Munk’s Enigma had some significant contributing factors. First and foremost, the glacial melting caused by climate change in the 20th century was roughly 30 percent less than previously assumed. This factor alone would have reduced the predicted changes to the Earth’s rotation speed and axial changes.
In addition, the previous research team was using calculations based on out-of-date models of the Earth’s internal composition, which meant that their figures regarding how much the glaciers would deform rock and influence rotation were incorrect. The impact of the mantle and core on slowing the Earth’s rotation were also underestimated.
Ultimately, this team of scientists were able to determine that climate change is impacting the speed of the Earth’s rotation and the tilt of its axis by way of glacial melt and rising sea levels. It wasn’t the theory that was incorrect, it was the underlying data that was skewed.
“What we believe in regard to melting of glaciers in the 20th century is completely consistent with changes in Earth’s rotation [as] measured by satellites and astronomical methods. This consistency was elusive for a few years, but now the enigma is resolved. Human-induced climate change is of such pressing importance to society that the responsibility on scientists to get things right is enormous. By resolving Munk’s enigma, we further strengthen the already-strong argument that we are impacting climate.”
The release of this new study comes at a time when climate change has been on the collective mind of the world. This week, there was an historic climate change conference and agreement in Paris, France. The agreement, which was approved and agreed-upon by 195 nations on December 12, is the first of its kind, and has been heralded by world leaders from President Obama to Pope Francis as a “turning point” for battling man-made climate change.
[Image Courtesy Of Joe Raedle/Getty Images]