A global team of experts has hypothesized that the abrupt global warming event that occurred 56 million years ago may have been caused by changes in the Earth’s orbit that led to hotter circumstances. This occurrence, known as the Paleocene-Eocene Thermal Maximum (PETM), is comparable to current climate change. The experts used astrochronology, a technique for dating sedimentary layers based on orbital patterns that occur over long periods of time, known as Milankovitch cycles, to examine core samples from a well-preserved record of the PETM close to the Maryland shore.
They discovered that the eccentricity-a measure of the curvature of Earth’s orbit-and the precession-a measure of its rotation-favored hotter circumstances during the start of the PETM and that both orbital configurations may have had a role in setting off the event. According to Lee Kump, professor of geosciences at Penn State University, an orbital trigger may have led to the carbon release that caused several degrees of global warming during the PETM. The scientific team estimated that the event released around 10,000 gigatons of carbon into the atmosphere as the greenhouse gases carbon dioxide or methane over the course of 6,000 years, which is almost an order of magnitude slower than the current pace of carbon emissions.
The researchers utilized data from a time series examination of the magnetic susceptibility and calcium content in the cores, which are indicators of changes in orbital cycles and may be used to infer the pace of the PETM. Because of gravitational interactions with the sun and other planets in the solar system, Earth’s orbit fluctuates in predictable, calculable ways. These orbital variations impact the climate, and ultimately the amount of sediment transported into the ocean.