Stretching of the continents 56 million years ago is likely to have caused one of the most extreme episodes of global warming in Earth’s history, new research suggests.
During this time, the planet experienced an increase 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 studied the effects of global tectonic forces and volcanic eruptions during the period of environmental change almost 60 million years ago.
They believe that the extensive stretching of the continental plates in the northern hemisphere – rather like the pulling of a toffee bar that thins and eventually separates – massively reduced the pressures in the Earth’s deep interior.
This then drove 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 PETM warming.
‘Stretching’ of the continents 56 million years ago is likely to have caused one of the most extreme episodes of global warming in Earth’s history, new research suggests. Pictured is a false colour satellite image of the Faroe Islands – one of the locations studied by scientists
The team studied volcanic ash layers and lavas in the laboratories of the Integrated Ocean Drilling Program’s (IODP) Bremen Core Repository, Germany
Scientists found that intense episodes of volcanism were likely responsible for 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 lead global temperatures to spike by 5 to 8 degrees Celsius (9 to 14 degrees Fahrenheit), bringing the average as high as 23 degrees Celsius (73 degrees Fahrenheit).
It lead to dramatic changes in Earth’s climate, driving major organisms to extinction and forcing others to migrate.
Dr Tom Gernon, an associate professor of Earth science at the University of Southampton and lead author of the study, said: ‘Despite the importance and wider relevance of the PETM to global change today, the underlying cause is highly debated.
‘It’s generally agreed that a sudden and massive release of the greenhouse gas, carbon, from the Earth’s interior must have driven this event, yet the scale and pace of warming is very hard to explain by conventional volcanic processes.’
The scientists found evidence from rock drilled from the seafloor for a widespread episode volcanic activity lasting 200,000 years, which coincided with the PETM.
Using archives of rock drilled beneath the seafloor near the edge of the Atlantic Ocean, the team found evidence of an abrupt and widespread episode of volcanic activity across the North Atlantic Ocean that lasted just over 200,000 years, strikingly similar to the duration of the PETM.
This finding prompted the researchers to investigate a broader expanse of the North Atlantic region, including Greenland and the Faroe Islands.
Here, they found that kilometre-thick piles of lava that started to erupt just before the PETM show unusual compositions that point to a significant increase in the amount of melting of the uppermost solid part of Earth’s mantle beneath the continent.
Dr Gernon said this would have led to a rapid increase of carbon being released, which would have led to the global warming.
Fragments of lava from the Atlantic are pictured here under a microscope
The volcanism occurred as the North Atlantic region was in the final stages of rifting, or breaking apart, in some ways similar to the geological processes occurring today in the East African Rift Valley, pictured
The intense volcanic activity occurred just as the continental landmass that united Greenland and Europe was most intensely stretched by plate tectonic forces.
Eventually, North America and Greenland finally separated from Europe, leading to the birth of the North Atlantic Ocean.
Scientists believe it was this final phase of stretching that brought about substantial melting in the Earth’s mantle, leading to massive carbon release, and in-turn, global warming.
Dr Thea Hincks, senior research fellow at the University of Southampton and co-author on the study, said: ‘Using physically realistic estimates of the key characteristics of these volcanic systems, we show that the amount of carbon needed to drive warming could have been attained by enhanced melting.’
Dr Gernon added: ‘Such rapid events cause a fundamental reorganisation of Earth’s surface environment, altering vast ecosystems.’
The study has been published in the journal Nature Geoscience.
WHEN WAS THE PALEOCENE AND HOW DID IT IMPACT BRITAIN’S CLIMATE?
The Paleoscene (‘old recent’) is a geological period that stretched from 66 to 56 million years ago.
During this period, the Earth’s climate was up to 15°C (27°F) warmer than it is today.
As a result, tropical and sub tropical forests extended further north and would have been widespread in the UK.
At the time there had not been an ice age for 100 million years.
The distance between Europe and Greenland was a tenth of what it is today.
There was massive volcanic activity between Baffin Island and northwest Europe that extended as far south as Bristol Channel.
The shape of the continents were similar to those today except they were arranged differently due to tectonic plates. Britain, Ireland and Norway were all landlocked and the Arctic sea was almost completely surrounded by land
Britain, Ireland and Norway were all landlocked and the Arctic sea was almost completely surrounded by land.
The shape of the continents were similar to those today except they were arranged differently due to tectonic plates, according to a website dedicated to the Paleocene.
Most of the world’s most famous geological features would not have been recognisable, including mountain ranges like the Alps and Himalayas which formed during the Tertiary period.
Prior to the Paleocene-Eocene Thermal Maximum (PETM) – which occurred around 55 million years ago – non-avian dinosaurs had been extinct for around ten million years.
Early mammals, amphibians, reptiles, insects and flowering plants were the dominant forms of life.
Mammals were generally small, had short legs and five toes on each foot.
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