A new ice age will begin within the next 11,000 years.

According to the Milankovitch cycles theory, glacial periods are influenced by the Earth's position and the tilt of its axis in space, which in turn affects the flow of solar radiation. Subtle fluctuations in the orientation of the Earth's axis give rise to climate cycles lasting 41,000 and 21,000 years. Meanwhile, cycles of 100,000 and 400,000 years are linked to the geometry of the Earth's orbit around the Sun, known as eccentricity. Despite geological data from the Quaternary period supporting this theory, it is challenging to distinguish the roles of axial tilt, precession, and eccentricity, primarily due to the need for absolute dating of paleoclimate records. In a recent study, researchers approached the problem differently by analyzing the patterns of glacial advance and retreat.

2025-02-28 10:00:51https://naked-science.ru/article/climate/novyj-lednikovyj-period

The most enigmatic aspect of the problem is linked to the 100,000-year glacial cycles that have influenced the climate over the past million years. Experts have yet to determine what causes the shift in glacial regimes — precession, axial tilt, or both factors.

Scientists from various countries, led by Stephen Barker from Cardiff University (UK), employed a different approach to tackle the “100,000-year problem.” They posited that precession and tilt of the Earth's axis play distinct roles in glacial retreat. In this scenario, the phase shifts relative to one another would be reflected in the graphs of glaciations and interglacial periods. An article on this subject has been published in the journal Science.

Information about ocean temperatures during prehistoric periods is derived from the shells of tiny organisms called foraminifera. These shells accumulate and store the heavy oxygen isotope — ¹⁸O — for millions of years. The warmer the ocean, the more of this isotope is found in the shells. The authors tracked fluctuations of oxygen-18 across three independent datasets over the last 800,000 years. They overlaid these graphs with the graphs of the phases of axial tilt and precession.

The peaks in the ¹⁸O graphs indicated pivotal moments in glacial periods — when glaciers were retreating confidently. This coincided with the peaks of precession phases (minima) and axial tilt. Notably, the first factor is the primary driver for the onset of glacial retreat, while the second plays a more significant role in the climate of interglacial periods and the initiation of new glaciation. It was also discovered that the end of a glacial period occurs following a decrease in the eccentricity of the Earth's orbit.

Thus, the researchers demonstrated that the onset and conclusion of glacial periods in the Pleistocene are not random, but depend on three orbital factors. They were able to separate the contributions of each factor.

The new model enabled the researchers to estimate the onset of the next glacial epoch. Analysis of the dynamics of the ¹⁸O isotope level indicated that it continues to decrease, suggesting that a cooling trend is underway. However, it remains uncertain whether a minimum will be reached. According to predictions, the next glaciation (following the phase of axial tilt decrease to its minimum) is expected within the next 11,000 years. The authors of the study noted in comments to the media that all these patterns could only trigger the next ice age under natural conditions, meaning in the absence of anthropogenic global warming.