Anton Petrov, discusses the complex history of Earth's glaciation cycles, known as Quaternary glaciation, which include repeated periods of growth and disappearance of ice sheets. The author analyzes these cycles in the context of the current stable climate, which enabled the development of human civilization after the last interglacial. A key theme is the recent and unexplained increase in atmospheric methane levels that scientists have observed since 2007, despite the stabilization of human-caused emissions. The material suggests that this increase in methane is disturbingly reminiscent of "termination" events of the past, i.e., rapid temperature spikes that marked the end of ice ages, which could mean that the Earth has entered another episode of rapid warming.