The stretching of continents 56 million years ago likely caused one of the most extreme episodes of global warming in Earth’s history, new research suggests.
During this time, the planet experienced a rise in temperature of 5-8°C (9-14°F), culminating in the Paleocene-Eocene Thermal Maximum (PETM), which lasted about 170,000 years.
It caused the extinction of many deep-sea organisms and reshaped the course of evolution of life on Earth.
Scientists have studied the effects of global tectonic forces and volcanic eruptions during the period of environmental change nearly 60 million years ago.
They believe that the extensive stretching of continental plates in the Northern Hemisphere — like pulling on a toffee bar that thins and eventually separates — has massively reduced pressures in the Earth’s deep interior.
This then led to intense but short-lived melting in the mantle – a layer of sticky, molten rock just below the planet’s crust.
The team, including experts from the universities of Southampton, Edinburgh and Leeds, suggests that the resulting volcanic activity coincided with and likely caused a massive burst of carbon release into the atmosphere linked to the PETM heating.
The “stretching” of continents 56 million years ago likely caused one of the most extreme episodes of global warming in Earth’s history, new research suggests. Pictured is a false-color satellite image of the Faroe Islands – one of the sites studied by scientists
The team studied layers of volcanic ash and lava in the laboratories of the Integrated Ocean Drilling Program (IODP) Bremen Core Repository, Germany.
Scientists found that intense episodes of volcanism were likely responsible for the rapid warming during the Paleocene-Eocene Thermal Maximum Warming event. Pictured is a volcano in Montserrat, West Indies
WHAT WAS THE PALEOcene-Eocene THERMAL MAXIMUM?
The Paleocene-Eocene Thermal Maximum (PETM) was a global warming event that occurred about 56 million years ago.
During this time, scientists estimate about 3,000 to 7,000 gigatons of carbon accumulated over a period of 3,000 to 20,000 years.
This has led to global temperatures rising by 5 to 8 degrees Celsius (9 to 14 degrees Fahrenheit), bringing the average to 23 degrees Celsius (73 degrees Fahrenheit).
This has led to dramatic changes in Earth’s climate, driving key organisms to extinction and forcing others to migrate.
Dr Tom Gernon, Associate Professor of Earth Sciences at the University of Southampton and lead author of the study, said: “Despite the importance and greater relevance of PETM to global change today, the underlying cause is highly debated.
“It is generally accepted that a sudden and massive release of the greenhouse gas carbon from the Earth’s interior must have driven this event, but the scale and pace of warming are very difficult to explain by conventional volcanic processes.”
Scientists have found evidence from rock drilled into the seafloor for an episode of widespread volcanic activity lasting 200,000 years that coincided with the PETM.
Using archives of rock drilled into the seafloor near the edge of the Atlantic Ocean, the team found evidence of an abrupt and widespread episode of volcanic activity in the North Atlantic Ocean that lasted just over 200,000 years, surprisingly similar to the duration of the PETM.
This discovery led the researchers to investigate a wider expanse of the North Atlantic region, including Greenland and the Faroe Islands.
Here, they found that kilometer-thick piles of lava that began to erupt shortly before the PETM show unusual compositions that point to a significant increase in the amount of melting of the solid upper part of Earth’s mantle beneath the continent.
Dr. Gernon said this would lead to a rapid increase in carbon release, which would lead to global warming.
Atlantic lava fragments are pictured here under a microscope
Volcanism occurred when the North Atlantic region was in the final stages of rifting, or breaking up, in some ways similar to the geological processes taking place today in the East African Rift Valley, pictured
The intense volcanic activity occurred at a time when the continental mass uniting Greenland and Europe was most intensely stretched by the forces of plate tectonics.
Eventually, North America and Greenland eventually split off from Europe, leading to the birth of the North Atlantic Ocean.
Scientists believe it was this final phase of stretching that caused the Earth’s mantle to melt substantially, leading to massive release of carbon and, in turn, global warming.
Thea Hincks, senior researcher at the University of Southampton and co-author of the study, said: ‘Using physically realistic estimates of key features of these volcanic systems, we show that the amount of carbon needed to drive warming could have been achieved by enhanced fusion.’
Dr. Gernon added: ‘These rapid events cause a fundamental reorganization of the Earth’s surface environment, altering vast ecosystems.’
The study was published in the journal Nature Geoscience.
WHEN WAS THE PALEOcene AND HOW DID IT AFFECT THE CLIMATE IN GREAT BRITAIN?
The Paleoscene (‘early recent’) is a geological period that extended from 66 to 56 million years ago.
During this period, Earth’s climate was up to 15°C (27°F) warmer than it is today.
As a result, tropical and subtropical forests extended further north and would have spread across the UK.
At the time, there was no ice age 100 million years ago.
The distance between Europe and Greenland was one-tenth of what it is today.
There was massive volcanic activity between Baffin Island and northwestern Europe that extended as far south as the Bristol Channel.
The shape of the continents was similar to today’s, except they were arranged differently due to plate tectonics. Great Britain, Ireland and Norway were all landlocked and the Arctic Sea was almost completely surrounded by land.
Great Britain, Ireland and Norway were all landlocked and the Arctic Sea was almost completely surrounded by land.
The shape of the continents was similar to what they are today, except they were organized differently due to plate tectonics, according to a website dedicated to the Paleocene.
Most of the world’s most famous geological features would not be recognizable, including mountain ranges like the Alps and Himalayas that formed during the Tertiary period.
Before the Paleocene-Eocene Thermal Maximum (PETM) – which occurred about 55 million years ago – non-avian dinosaurs had been extinct for about ten million years.
Early mammals, amphibians, reptiles, insects and flowering plants were the dominant life forms.
Mammals were generally small, had short legs and five toes on each foot.