Earth is in a pretty unique state of climate change at the moment, but for the past 1 million years, almost like clockwork, our planet has moved in and out of an ice age every 100,000 years. The only problem is, researchers have never really been able to figure out why. In fact, they’ve been so puzzled by the mysterious phenomenon, they’ve labelled it the ‘100,000 year problem’. But now a new study might finally have the solution.
New research suggests that our oceans might regularly suck more CO2 out of the atmosphere every 100,000 years, allowing the planet to get cold enough to trigger an ice age. The ‘100,000 year problem’ stems from the fact that around 1 million years ago, Earth started experiencing ice ages – vast ice sheets covering North America, Europe, and Asia – every 100,000 years.Before this point, which is known the mid-Pleistocene transition, our planet’s ice ages used to occur at intervals of every 40,000 years, which made a lot more sense to scientists. That’s because Earth’s angular tilt also wobbles in a 40,000 year cycle, which means every 40,000 years, the planet experiences colder than usual summer months because of the way it’s tilted towards the Sun.
That variation in Earth’s tilt made the 40,000 year ice ages make sense – but, until now, no one has been able to explain what happened at the mid-Pleistocene transition to overhaul this natural cycle and put our Earth on a 100,000-year schedule instead.
Now researchers have stumbled on a new planetary cycle, and suggest the shift could be a result of our oceans regularly sucking more CO2 out of the atmosphere. “We can think of the oceans as inhaling and exhaling carbon dioxide, so when the ice sheets are larger, the oceans have inhaled carbon dioxide from the atmosphere, making the planet colder,” explains lead researcher Carrie Lear from Cardiff University in Wales. “When the ice sheets are small, the oceans have exhaled carbon dioxide, so there is more in the atmosphere which makes the planet warmer.” Source: We might finally know the weird reason Earth experiences an ice age every 100,000 years