Not volcanoes, but changes in Earth’s orbit causing the climate to warm rapidly?

Researchers at the University of Pennsylvania looked at PETM cores taken off the coast of Maryland. They dated them using the astronomy technique of calibration against a time scale related to astronomical phenomena, such as Milankovitch cycles. These cycles are cyclical changes in three parameters of the Earth’s orbit: eccentricity, precession, and ecliptic inclination. The timing of these changes varies, but they converge occasionally and are thought to be the dominant paleoclimatic mechanism. Their confluence may have been responsible for the ice ages.

From a recent study by Penn State, we learned that changes in the eccentricity and orbit of Earth’s orbit led to the onset of higher temperatures. This orbital trigger could release carbon, which in turn led to the greenhouse effect known as PETM. We make this hypothesis, says Professor Lee Combe, in opposition to the more commonly held interpretation that the Pytem period was caused by violent volcanism.

The analyzes also showed that the initial phase of the Betem period, which is the phase in which temperatures rose, lasted about 6,000 years. Years. This value is within current estimates from several hundred to tens of thousands of years. It is important to identify this so that we can understand how fast global warming is occurring at that time. During those 6,000 years, 10,000 were released into the atmosphere. gigatonnes of carbon in the form of carbon dioxide and methane, which means annual emissions of 1.5 gigatonnes. The global average temperature has increased by about 6 degrees.

“At that time, the rate of carbon emissions into the atmosphere was about 5 to 10 times less than the current amount. We emit 5 to 10 times more carbon each year compared to the event that left a permanent imprint on our planet 56 million years ago,” Coombe adds.

source:

https://www.nature.com/articles/s41467-022-33390-x