Gulf of Mexico escaped climate change 56 million years ago

Today oil drilling poses a major environmental threat to the Gulf with a hypoxic dead zone alarmingly increasing in size

By Kiran N. Kumar

Recently researchers from the University of Texas Institute for Geophysics (UTIG) chronicled how an ancient bout of global warming 56 million years ago that acidified oceans and wiped-out marine life had surprisingly left the Gulf of Mexico with a milder effect.

They found that a steady supply of river sediments and circulating ocean waters had helped radiolarians and other microorganisms survive even while Earth’s warming climate elsewhere eroded life forms, including dinosaurs.

Attributing it to the basin’s unique geology, the UTIG team traced the geological changes which took place about 20 million years before the ancient global warming occurred.

Read: COP26: US and India must collaborate to achieve climate change goals (November 5, 2021)

The rise of the Rocky Mountains had redirected rivers into the northwest Gulf of Mexico due to a tectonic shift known as the Laramide uplift.

Much of the continent’s rivers were directed through what is now Texas and Louisiana into the Gulf’s deeper waters. The rivers fire-hosed nutrients and sediments into the basin.

No wonder, when global warming hit the region, the nutrients underneath provided plenty of nutrients for phytoplankton and other food sources for the radiolarians – which only thrive in nutrient-rich water that’s no saltier than seawater. It confirmed that the Gulf’s waters did not become too salty.

The study 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.

Current Scenario

Interestingly, the above findings were based on samples collected in efforts to find deposits of oil and gas along the Gulf coast. And the Gulf of Mexico is very different today with the Deepwater Horizon oil spill in April 2010 to many more minor accidents hitting the headlines daily.

Now, the Gulf of Mexico is one of the most important offshore petroleum-production regions in the world, making up one-sixth of the United States’ total production.

Oil drilling remains the major environmental threat to the Gulf. There are 27,000 abandoned oil and gas wells beneath the Gulf, which have not been checked for potential environmental problems.

Read: 500 global young change makers to discuss water and climate change (March 17, 2021)

Then there are frequent “red tide” algae blooms that kill fish and other marine life, while may cause respiratory problems in humans and domestic animals close to shore. This has been recorded especially in the southwest and southern Florida coast, from the Florida Keys to north of Pasco County in Florida.

The Gulf contains a hypoxic dead zone that runs east-west along the Texas-Louisiana coastline and is alarmingly increasing in size.

Between 1985 and 2008, the area roughly doubled in size and by 2017, it reached about 8,776 square miles, the largest ever recorded, as per NOAA figures, showed a study published in the National Geographic.

Even poor agricultural practices in the northern portion of the Gulf of Mexico have been attributed for the current imbalance in the marine ecosystem of the Gulf.

The scientists found a tremendous increase of nitrogen and phosphorus in neighboring marine resources, which has resulted in algae blooms and a lack of available oxygen.

In a 2007 study, researchers found occurrences of masculinization and estrogen suppression among the fish populations resulting in sex disproportion.

They found the Atlantic croaker’s sex ratio of 61% males to 39% females in hypoxic Gulf sites very alarming, compared with a 52% to 48% male-female ratio found in reference sites.

Read: Research shows how the Gulf of Mexico escaped ancient mass extinction (June 1, 2022)

Of late, microplastics within semi-enclosed seas like the Gulf have been reported in high concentrations and one study estimated concentrations as one among the highest globally reported.

UTIG geochemist Bob Cunningham, who led the current research, is confident that valuable lessons can be drawn about climate change from how the Gulf was impacted in the past to now.

“This event known as the Paleocene-Eocene Thermal Maximum or PETM is very important to understand because it’s pointing towards a very powerful, albeit brief, injection of carbon into the atmosphere that’s akin to what’s happening now,” he said.

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