09/15/2024 – 11:02
A combination of more intense El Niño events and global warming fueled a vicious cycle of climate extremes and destruction unfavorable to life on the planet 252 million years ago, a study finds. El Niño, a cyclical phenomenon of warming of the waters of the equatorial Pacific Ocean and causing intense meteorological episodes, was decisive for the greatest mass extinction on Earth, 252 million years ago, when it is believed that the planet lost about 90% of its species.
That’s the conclusion of scientists who have presented new evidence on why rapid climate change in the Permian-Triassic period was so devastating to marine and terrestrial life.
The results of the study, led by researchers from the University of Bristol in the UK and the Chinese University of Geosciences in Wuhan, were published in the journal Science.
Science has long linked the mass extinction of that period to massive volcanic eruptions in what is now Siberia. The resulting carbon dioxide emissions rapidly accelerated climate warming, causing the collapse of marine and terrestrial ecosystems.
But why terrestrial life – including usually resilient plants and insects – also met this fate was still a mystery.
Co-lead author of the study and research associate at the University of Bristol, Alexander Farnsworth says that climate warming alone cannot cause such devastating extinctions “because, as we are seeing today, when the tropics get too warm, species migrate to higher, cooler latitudes”.
A hostile and wild climate
“Our research has revealed that rising greenhouse gases are not only warming most of the planet, but are also increasing weather and climate variability, making it even wilder and more hostile to life,” explains Farnsworth.
The Permian-Triassic catastrophe demonstrates that the problem of global warming is not just unbearable heat, but also the extreme fluctuation in living conditions over decades.
Most beings were unable to adapt to these conditions. “But fortunately, some things survived, without which we wouldn’t be here today. It was almost, but not quite, the end of life on Earth,” says Professor Yadong Sun of the Chinese University of Geosciences in Wuhan and co-author of the study.
Study of oxygen isotopes in fossilized teeth
To figure out the magnitude of the Permian-Triassic warming, scientists studied oxygen isotopes in fossilized teeth of conodonts (tiny swimming creatures) and analyzed the temperature record of these organisms around the world, finding a remarkable collapse of temperature gradients at low and mid-latitudes.
Farnsworth, whose team used pioneering climate models to assess the results, concluded that “essentially, it got too warm everywhere.” “The changes responsible for the climate patterns identified were profound because there were much more intense and prolonged El Niño episodes than today, and species were simply not equipped to adapt or evolve quickly enough.”
Permian-Triassic El Niño lasted much longer than one or two years in a row
In recent years, El Niño phenomena have caused major changes in precipitation and temperature patterns, such as the weather extremes that caused the June 2024 heat wave in North America, when recorded temperatures were about 15 degrees above normal.
The 2023-2024 period was also one of the warmest on record globally due to El Niño, which was exacerbated by human carbon emissions, causing catastrophic droughts and fires around the world, the study authors note in the paper.
They point out that, “fortunately”, so far these phenomena have only lasted one or two years in a row, but during the Permian-Triassic crisis El Niño persisted for much longer, causing a decade of widespread drought followed by years of flooding.
At that time, however, there was no Pacific Ocean, but rather the colossal Panthalassa, whose area was 30% larger at the equator – which means that the area of anomalous heating of the waters was much larger and, therefore, had a greater impact on the global climate.
“There was nowhere to hide”
The study’s findings also help explain the abundance of charcoal in rock layers from that period. David Bond, a paleontologist at the University of Hull in the United Kingdom, says that wildfires become very common in drought-prone climates, and the Earth ended up in a state of crisis in which the continents burned and the oceans stagnated, becoming oxygen-depleted. “There was nowhere to hide.”
These mega El Niños ended up feeding back into rising global temperatures, leading to the loss of plant cover. Without plants, which are essential for capturing carbon from the atmosphere and the survival of other beings, the Earth lost one of its defenses against the accumulation of greenhouse gases, which in turn made El Niños even more intense.
According to the researchers, the Earth has recorded, throughout its history, many volcanic phenomena similar to those in Siberia, and many have caused extinctions – but they argue that none have caused a crisis like the Permian-Triassic.
This also helps to understand why the Permian-Triassic mass extinction on the continent happened tens of thousands of years before the extinction in the oceans.
“While the oceans were initially protected from rising temperatures, the mega El Niño caused land temperatures to exceed the thermal tolerance of most species at such a rapid rate that they could not adapt in time,” Sun explains. “Only species that could migrate quickly were able to survive, and there were not many plants or animals that could do that.”
The mass extinction that occurred at that time, although devastating, ended up making dinosaurs the dominant species, until the mass extinction of the Cretaceous period led to the emergence of mammals and, eventually, humans.
ra (EFE, ots)
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