An international team of researchers has discovered that the Paleocene-Eocene Thermal Maximum (PETM), a period of rapid global warming 56 million years ago, may have been triggered by changes in Earth’s orbit that favored hotter conditions.
According to Penn State University geosciences professor Lee Kump,
“The Paleocene-Eocene Thermal Maximum is the closest thing we have in the geologic record to anything like what we are experiencing now and may experience in the future with climate change.” Our work addresses important questions about the event’s trigger and the rate of carbon emissions. There has been a lot of interest in better resolving that history.
Using astrochronology, a technique for dating sedimentary layers based on orbital patterns that occur over long periods of time, also known as Milankovitch cycles, the group of researchers examined core samples from a well-preserved PETM record near the coast of Maryland.
Victoria Fortiz (pictured right), a graduate student at the time at Penn State, and Jean Self-Trail, a research geologist at the U.S. Geological Survey, work on a core sample from the Howards Tract site in Maryland. Credit: Penn State discovered that the shape of Earth’s orbit, or eccentricity, and its wobble in its rotation, or precession, favored hotter conditions at the beginning of the PETM, and that these orbital configurations may have contributed to the event’s onset.
According to Kump, the John Leone Dean in the College of Earth’s and Mineral Sciences,
An orbital trigger may have led to the carbon release that caused several degrees of global warming during the PETM as opposed to what is currently the more popular interpretation that massive volcanism released the carbon and triggered the event.
The scientists stated that the timing is crucial for comprehending the rate of carbon release into the atmosphere.
Mingsong Li, lead author of the study and assistant professor in the School of Earth and Space Sciences at Peking University, stated, “This study allows us to refine our carbon cycle models to better understand how the planet reacts to an injection of carbon over these timescales and to narrow down the possibilities for the source of the carbon that drove the PETM.”
About one and a half gigatons of carbon were released annually,
Kump stated, “That is cause for some concern because those rates are close to an order of magnitude slower than the rate of carbon emissions currently.” We are currently emitting carbon at a rate that is five to ten times higher than our estimates of emissions during this geological event 56 million years ago.
In order to estimate the PETM’s pacing, the researchers used a time series analysis of the calcium content and magnetic susceptibility found in the cores, which are proxies for changes in orbital cycles.
Kump stated, “The reason these orbital changes have an expression in the geologic record is because they affect climate Earth’s.
Additionally, this has an impact on the amount of sediment carried into the ocean, as well as the amount of rainfall, erosion, and productivity of terrestrial and marine organisms.
Kump stated, “Just like you could extract each note from a song, we can develop histories by coring down through the layers of sediment and extracting specific cycles that are creating this story.” Of course, there are gaps and distortions in some of the records, but we can use the same statistical techniques that apps use to figure out what song you’re trying to sing. It is possible to sing a song and still be able to identify the song, even if you forget half the words and skip a chorus. We can use the same method to reconstruct these records.
Public by world news spot live