Archives par mot-clé : Extinction

When the dinosaurs died, so did forests — and tree-dwelling birds

By Field Museum, May 24, 2018 in ScienceDaily (CurrentBiology)

Sixty-six million years ago, the world burned. An asteroid crashed to Earth with a force one million times larger than the largest atomic bomb, causing the extinction of the dinosaurs. But dinosaurs weren’t the only ones that got hit hard — in a new study, scientists learned that the planet’s forests were decimated, leading to the extinction of tree-dwelling birds.

Invisible Scientific Debates Accomplish Nothing

by Donna Laframboise, April 23, 2018 in ClimateChangeDispatch

SPOTLIGHT: After the Intergovernmental Panel on Climate Change (IPCC) report was released in 2007, its dramatic findings of species extinction were repeatedly emphasized by chairman Rajendra Pachauri.

BIG PICTURE: When it examined the question of species extinction, the 2007 IPCC report relied heavily on a single piece of research – a Nature cover storypublished early in 2004. Written by Chris Thomas and 18 others, this was the source of Pachauri’s claim that climate change threatened 20 to 30% of the world’s species.

Studying oxygen, scientists discover clues to recovery from mass extinction

by Arizona State University, April  17, 2018 in ScienceDaily

About 252 million years ago, more than 90 percent of all animal life on Earth went extinct. This event, called the “Permian-Triassic mass extinction,” represents the greatest catastrophe in the history of life on Earth. Ecosystems took nearly five million years to recover and many aspects of the event remain a mystery.

A research team, led by scientists from Arizona State University and funded by NASA and the National Science Foundation, is helping to understand why this extinction event happened and why it took life so long to recover. The study, published in Science Advances, was led by ASU School of Earth and Space Exploration graduate student Feifei Zhang, with direction from school faculty member Ariel Anbar.

Extinction and global warming 250 million years ago

by U. of Bristol, January 10, 2018 in A Watts, WUWT

One of the key effects of the end-Permian mass extinction, 252 million years ago, was rapid heating of tropical waters and atmospheres.

How this affected life on land has been uncertain until now.

In a new study published today, Dr Massimo Bernardi and Professor Mike Benton from the School of Earth Sciences at the University of Bristol show how early reptiles were expelled from the tropics.

Volcanic eruptions drove ancient global warming event

by Marcus Gutjah et al., August 30,  2017 in PhysOrg

A natural global warming event that took place 56 million years ago was triggered almost entirely by volcanic eruptions that occurred as Greenland separated from Europe during the opening of the North Atlantic Ocean,

The amount of carbon released during this time was vast—more than 30 times larger than all the fossil fuels burned to date and equivalent to all the current conventional and unconventional fossil fuel reserves we could feasibly ever extract.” Ridgwell said.

An unexpected finding was that enhanced organic matter burial was important in ultimately sequestering the released carbon and accelerating the recovery of the Earth’s ecosystem without massive extinctions.

See also here

Dino-killing asteroid could have thrust Earth into two years of darkness

by National Center for Atmospheric Research/University Corporation for Atmospheric Research, August 21, 2017 in ScienceDaily

Tremendous amounts of soot, lofted into the air from global wildfires following a massive asteroid strike 66 million years ago, would have plunged Earth into darkness for nearly two years, new research finds. This would have shut down photosynthesis, drastically cooled the planet, and contributed to the mass extinction that marked the end of the age of dinosaurs.

Underground magma triggered Earth’s worst mass extinction with greenhouse gases

by Howard Lee, geologist, August 9, 2017 in WUWT

Earth’s most severe mass extinction, the “Great Dying,” began 251.94 million years ago at the end of the Permian period, with the loss of more than 90% of marine species. Precise rock dates published in 2014 and 2015 proved that the extinction coincided with the Siberian Traps LIP, an epic outpouring of lava and intrusions of underground magma covering an area of northern Asia the size of Europe.

But those rock dates presented science with a new puzzle: why was the mass extinction event much shorter than the eruptions? And why did the extinction happen some 300,000 years after the lava began to flow?

Flourishing ocean drives the end-Permian marine mass extinction

by Martin Schobben et al., July 2014,

The Permian geologic period that ended the Paleozoic era climaxed around 252 million years ago with a sweeping global mass extinction event in which 90 to 95 percent of marine life became extinct. It would take 30 million years for planetary biodiversity to recover. Understanding the contributing factors of the end-Permian mass extinction is critical to understanding and perhaps mitigating the current anthropogenic climate change.

Earth Is Not in the Midst of a Sixth Mass Extinction

by Peter Brannen, June 14, 2017

“It is absolutely critical to recognize that I am NOT claiming that humans haven’t done great damage to marine and terrestrial [ecosystems], nor that many extinctions have not occurred and more will certainly occur in the near future. But I do think that as scientists we have a responsibility to be accurate about such comparisons.”

Many popular science articles take this as a given, and indeed, there’s something emotionally satisfying about the idea that humans’ hubris and shortsightedness are so profound that we’re bringing down the whole planet with us.

Battered Earth revived by mineral weathering after mass extinction

by University of Tromso, May 5, 2017 in ScienceDaily

Bedrock of Earth got severely beaten up by hothouse climate conditions during one of planet’s mass extinctions some 200 million years ago. But the process also allowed life to bounce back.

The hothouse conditions of this mass extinction caused oceans to eventually become depleted of oxygen, and thus become unbearable to live in. But weathering of silicate in the bedrock of Pangea, and subsequent formation of carbonate, tied up the CO2 into the minerals, slowly removing the greenhouse gas from the atmosphere.

Megafaunal extinctions driven by too much moisture

by University of Adelaide, April 18, 2017 in ScienceDaily

Studies of bones from Ice Age megafaunal animals across Eurasia and the Americas have revealed that major increases in environmental moisture occurred just before many species suddenly became extinct around 11-15,000 years ago. The persistent moisture resulting from melting permafrost and glaciers caused widespread glacial-age grasslands to be rapidly replaced by peatlands and bogs, fragmenting populations of large herbivore grazers.

The idea of moisture-driven extinctions is really exciting because it can also explain why Africa is so different, with a much lower rate of megafaunal extinctions and many species surviving to this day, says Professor Cooper.

Timing of global regression and microbial bloom linked with the Permian-Triassic boundary mass extinction: implications for driving mechanisms

by Björn Baresel et al., March 6, 2017, Nature

Since the early days of stratigraphy, mass extinctions were noticed to coincide with major and global sea-level changes1,2 that significantly alter extinction patterns and time-series of geochemical proxies. In the case of the Permian-Triassic boundary mass extinction (PTBME), the system boundary itself has been initially placed during a global eustatic regression3, but was subsequently placed during a global transgression4 …

Shock finding : P-T mass extinction was due to an ice age, and not to warming