Quaternary

The Quaternary period includes all recent glaciations--originally 41,000 year cycles and then about 100,000 year cycles. Research published in Science Advances aims to explain that change.

We show that a gradual lowering of atmospheric CO2 and regolith removal are essential to reproduce the evolution of climate variability over the Quaternary. The long-term CO2 decrease leads to the initiation of Northern Hemisphere glaciation and an increase in the amplitude of glacial-interglacial variations, while the combined effect of CO2 decline and regolith removal controls the timing of the transition from a 41,000- to 100,000-year world. Our results suggest that the current CO2 concentration is unprecedented over the past 3 million years and that global temperature never exceeded the preindustrial value by more than 2°C during the Quaternary.

Stephanie Pappas explains that the modeling used shows global temperatures at a maximum of 1.5 degrees Celsius abover preindustrial values around 2.5 million years ago and the carbon dioxide concentration was never above 400 ppm. Anthropogenic climate change is happening very fast.

Already, the globe is 2.1 degrees F (1.2 degrees C) warmer than the preindustrial average [while carbon dioxide concentration is 405 ppm and rising]. The 2016 Paris Agreement would limit warming to 2.7 F (1.5 C), matching the climate of 2.5 million years ago. If the world can't manage that limit and heads toward 3.6 degrees F (2 degrees C), the previous international goal, it will be the hottest global average seen in this geological period.

Meanwhile, Alaska and Australia saw record-breaking heat last month. Australia is 2.2 degrees Celsius above normal for the first quarter of this year. And Robert Hunziker reports that places in Siberia no longer freeze in the winter.