A bout of global warming hit Earth 56 million years ago. The event acidified oceans and wiped out marine life. However, the bout of global warming had a milder effect in the Gulf of Mexico, where life was sheltered by the basin's unique geology, a new study has found.
The paper describing the findings was recently published in the journal Marine and Petroleum Geology. The study, led by researchers at the University of Texas Institute for Geophysics, can help scientists determine how current climate change will affect marine life and aid in efforts to find deposits of oil and gas. The findings shed light on an ancient mass extinction.
Valuable Lessons Can Be Drawn From How Gulf Of Mexico Was Impacted
Despite the fact that the Gulf of Mexico is very difficult today, Bob Cunningham, a geochemist at the University of Texas Institute for Geophysics, said that valuable lessons can be drawn about climate change today from how the Gulf was impacted in the past.
In a statement released by the University of Texas Institute for Geophysics, Cunningham said the event, known as the Paleocene-Eocene Thermal Maximum or PETM, is very important to understand because it is pointing towards a very powerful, albeit brief, injection of carbon into the atmosphere which is akin to what is happening now.
How Researchers Investigated The Ancient Period Of Global Warming
The study researchers investigated the ancient period of global warming and its impact on marine life and chemistry by studying a group of mud, sand, and limestone deposits found across the Gulf.
The scientists sifted through rock chips brought up during oil and gas drilling and found an abundance of microfossils from radiolarians, which are a type of plankton. The radiolarians had surprisingly thrived in the Gulf during the ancient global warming. The researchers concluded that a steady supply of river sediments and circulating ocean waters had helped radiolarians and other microorganisms survive even while Earth's warming climate became more hostile to life.
How Gulf Of Mexico Survived Mass Extinction
Marcie Purkey Phillips, one of the authors on the paper, said that in a lot of places, the ocean was absolutely uninhabitable for anything. However, researchers do not seem to see as severe an effect in the Gulf of Mexico as has been elsewhere, Phillips added.
This can be explained through geologic forces which reshaped North America at that time. The rise of the Rocky Mountains, which took place about 20 million years ago before the ancient global warming, had redirected rivers into the northwest Gulf of Mexico. This was a tectonic shift known as the Laramide uplift, and had sent much of the continent's rivers through what is now Texas and Louisiana into the Gulf's deeper waters.
When global warming hit Earth and North America became hotter and wetter, the rain-filled rivers fire-hosed nutrients and sediments into the basin. This provided plenty of nutrients for phytoplankton and other food sources for the radiolarians, the study said.
The Gulf of Mexico remained connected to the Atlantic Ocean and the salinity of its waters never reached extremes, the findings confirm. The presence of radiolarians alone confirmed that the Gulf's waters did not become too salty, according to Phillips. The radiolarians only thrive in nutrient-rich water that is no saltier than seawater today. According to Cunningham, the organic content of sediments decreased farther from the coast, which is a sign that deep currents driven by the Atlantic Ocean were sweeping the basin floor.
How Is The Study Special?
The researchers have accurately dated closely related geologic layers in the Wilcox Group, which is a set of rock layers that house an important petroleum system. This is a feat that can aid in efforts to find undiscovered oil and gas reserves in formations that are the same age. The findings are important for researchers investigating the effects of today's global warming because they show how the water and ecology of the Gulf changed during a very similar period of climate change long ago, the statement said.
Geologic samples from 36 industry wells were compiled as part of the study. These wells are dotted across the Gulf of Mexico. The researchers also compiled a handful of scientific drilling expeditions including the 2016 University of Texas at Austin-led investigation of the Chicxulub asteroid impact, which led to the extinction of non-avian dinosaurs.
John Snedden, who co-authored the study, believes that the study is a perfect example of industry data being used to address important scientific questions.
He said the Gulf of Mexico is a tremendous natural archive of geologic history that is also very closely conveyed. The researchers used this very robust database to examine one of the highest thermal events in the geologic record, which, Snedden thinks, has given them a very nuanced view of a very important time in Earth's history.