The effects of climate change are pervasive, from biodiversity loss to extreme weather events, rising sea levels, wildfires and human mass migration. With each year that passes, we learn more about our impact on the environment – some of which are more surprising than others.Joining the list is one of the most seismic findings to date: scientists have recently discovered that our greenhouse gas emissions are changing how Earth spins.The consequence? Earth’s days are getting longer, which could dramatically affect how we keep time in the coming years.“It’s fascinating that we, as humans, with the record change in the climate we’ve caused over the past 100 years, can impact the whole Earth like that,” says Prof Benedikt Soja, a scientist at ETH Zürich who helped uncover the troubling trend.“This could be larger than any previously dominant effect on our planet’s rotation.”We’re all familiar with the greenhouse effect: as we emit gases such as carbon dioxide, Earth’s atmosphere traps more heat, causing global temperatures to rise.Last year, the temperature around the world was 1.18°C above the 20th-century average, bringing us closer to the 1.5°C limit set in 2015 as the upper-bound target for avoiding the worst effects of climate change.In 2022, glaciers in Switzerland suffered a record melt – Credit: Getty ImagesA major consequence of this warming is the melting of vast ice regions at the North and South Poles. Switzerland has lost 10 per cent of its glacial mass in the past two years. Antarctica loses 150 billion tonnes of ice annually, while Greenland loses 270 billion tonnes.While many are (rightfully) concerned about how this melting affects coastal regions, Soja and his team asked a different question: how does this huge redistribution of mass affect Earth on a larger scale? And in a recent study published in the journal Proceedings of the National Academy of Sciences of the USA (PNAS), they answered that question.“As the ice melts, Earth’s mass is being redistributed from the polar regions to the oceans,” Soja says. “This means that Earth has become more oblate, flattened even, with mass further away from the axis of rotation.”Earth, like any rotating body, obeys the law of conservation of momentum, which can be briefly explained like this: momentum must be conserved; momentum depends on the moment of inertia and the speed of rotation; if mass moves further from the axis of rotation, the moment of inertia increases.As such, to maintain momentum as the ice melts, Earth’s rotation slows down, making our days longer.This concept, Soja explains, is similar to a figure skater performing a spin. When spinning with their arms outstretched, their spin slows, but when they pull their arms in it speeds up.The effect that altering the distance between mass and the axis of rotation can have is seen when a figure skater uses their arms to change the speed of their spinThe study found that from 1900 to 2000, the climat
Mer. Dic 25th, 2024
