Warm ice age forever changed Earth’s climate cycles - study

More moisture was produced due to warmer ocean temperatures and more powerful monsoons. This moisture helped the ice sheets to expand.

A new study suggests that the Earth's transition into a whole new glacial cycle, which occurred between 670,000 and 800,000 years ago, was caused by warming.

The study was released in May in Nature, a renowned publication of peer review in science.

The late Middle Pleistocene Transition (MPT) is when the ice age warming took place. Global glacial cycles, which are periods of time throughout ice ages when glaciers advance across the Earth's surface, underwent a permanent change during the MPT.

A drill core taken from South-West Iberia was examined by a team of European experts for data on upper ocean temperatures and Mediterranean vegetation cover.

Drill cores are cylindrical samples collected from the earth's crust or from an ice sheet, and they reveal chronologically arranged layers of silt or ice. These data serve as gauges for current precipitation and westerlies (westerly winds).

These records were coupled with new data on West Pacific Ocean surface temperatures and East Asia Summer Monsoon (EASM) intensity by the researchers.

The researchers were able to develop models to replicate the late MPT climate using this data.

The statistics revealed that throughout this time, both the severity of the summer monsoon in East Asia and the amount of winter precipitation in southwest Europe both increased.

What led to the harsh weather conditions?

According to the study, these unusually severe weather conditions were caused by a "nearly continuous moisture supply from both oceans" that was transported northward by the westerlies.

Researchers hypothesized that this in turn contributed to the ice sheets' expansion during the late MPT.

The MPT heralds the start of a long-lasting, worldwide change in glacial eras. Previously, the climate on Earth was defined by shorter, weaker glacial periods that occurred on 40,000-year cycles, according to a SciTechDaily story on the research paper.

But after the MPT, Earth's climate underwent a drastic change and transitioned to 100,000-year cycles of glacial periods, where the glacial periods, albeit less frequent, lasted longer and were more severe.

The glaciers had to have expanded in size from their pre-MPT levels to produce this transformation, which, as previously established, was fueled by the increased moisture brought on by warmer ocean temperatures.

The "warm" ice age was a major contributor to the shift in the 40,000–100,000–year glacial cycle, even if the exact causes of this transformation are still unknown.

According to Dr. André Bahr, an associate professor of earth sciences at Heidelberg University, "such expansion of the continental glaciers was necessary to trigger the shift from the 40,000-year cycles to the 100,000-year cycles we experience today, which was critical for the Earth's later climate evolution."