The 100,000 year problem

This mysterious phenomena, dubbed the '100,000 year problem', has been occurring for the past million years or so and leads to vast ice sheets covering North America, Europe and Asia. Up until now, scientists have been unable to explain why this happens. Our planet's ice ages used to occur at intervals of every 40,000 years, which made sense to scientists as the Earth's seasons vary in a predictable way, with colder summers occurring at these intervals. However there was a point, about a million years ago, called the 'Mid-Pleistocene Transition', in which the ice age intervals changed from every 40,000 years to every 100,000 years. New research published today in the journal Geology has suggested the oceans may be responsible for this change, specifically in the way that they suck carbon dioxide (CO₂) out of the atmosphere. By studying the chemical make-up of tiny fossils on the ocean floor, the team discovered that there was more CO₂ stored in the deep ocean during the ice age periods at regular intervals every 100,000 years. This suggests that extra carbon dioxide was being pulled from the atmosphere and into the oceans at this time, subsequently lowering the temperature on Earth and enabling vast ice sheets to engulf the Northern Hemisphere.