Mass extinction events that span two periods of global warming in Earth's history destroyed huge amounts of ocean life and destroyed reef ecosystems, warns a new study.
It was previously suggested that Late Late Triassic and early Toarcian extinctions, both linked to massive volcanism and resulting climate changes, simply intensified extinction rates that were already underway.
But according to new research, this was not the case.
An analysis of background extinction rates and those experienced during the two events suggests that the extinction patterns changed dramatically each time due to the increase in ocean temperature, acidification and oxygen-free waters.
It was previously suggested that Late Late Triassic and early Toarcian extinctions, both linked to massive volcanism and resulting climate changes, simply intensified extinction rates that were already underway. Artist's impression
"The data show clear differences in the magnitude of extinction and selectivity between hyperthermia [extreme warming events] and background intervals, "the authors write in a new study published in Proceedings of the Royal Society B.
Mass extinction of the Late Triassic (LTE) and the extinction of Early Toarcia (ETOE) occurred approximately 201 million years ago and 187 million years ago, respectively.
The latter is considered the second largest event of loss of marine biodiversity in the history of the Earth.
According to the new research, these past warming periods and resulting extinctions offer a look at the threats posed by human-induced climate change today.
Both events were "responsible for the massive extinction of marine organisms and led to significant ecological agitation," the document said.
Mass extinction of the Late Triassic (LTE) and the extinction of Early Toarcia (ETOE) occurred approximately 201 million years ago and 187 million years ago, respectively. The latter is considered the second largest event of loss of marine biodiversity in the history of the Earth. Artist's impression
The team modeled the extinction through the Late Triassic and the Early Jurassic using a global database of marine organisms.
And, this revealed profound changes that varied between the two extinction events.
Both periods experienced changes in the selectivity of the extinction, or the types of species that became extinct during that time, but the effect was more extreme during the Upper Triassic.
This finding goes against the previous suggestion that there was no difference in the extinction selectivity of background rates.
The team also found some patterns that emerged between the two separate events.
"Despite differences in the conditions of initiation, the species involved and the magnitudes of global warming and environmental change, LTE and EToE show some common patterns of selectivity," the researchers explain in the study.
"Both events show strong extinction selectivity against pelagic predatory guilds and benthic photosynthetic suspension feeding organisms, suggesting that these groups of marine organisms may be particularly vulnerable during episodes of global warming."
WHEN WERE THE & # 39; BIG FIVE & # 39; EVENTS OF EXTINCTION OF THE EARTH?
Traditionally, scientists have referred to the "Big Five" mass extinctions, including perhaps the most famous mass extinction triggered by a meteorite impact that caused the end of the dinosaurs 66 million years ago.
But the other major mass extinctions were caused by phenomena that originated entirely on Earth, and although lesser known, we can learn something from their exploration that could shed light on our current environmental crises.
- The Late Ordovician: This ancient crisis, about 445 million years ago, saw two major waves of extinction, both caused by climate change associated with the advance and withdrawal of ice sheets in the southern hemisphere. This makes it the only major extinction linked to global cooling.
- The Late Devonian: This period is now considered as a series of "pulses" of extinction that extend over 20 million years, beginning 380 million years ago. This extinction has been linked to a major climate change, possibly caused by an eruption of the volcanic area of Viluy Traps in present-day Siberia. A large eruption could have caused rapid fluctuations in sea level and reduced oxygen levels in the oceans.
- The Middle Permian: Scientists have recently discovered another event 262 million years ago that rivals in size with the 'Big Five & # 39; This event coincided with the eruption of Emeishan in what is now China, and it is known to have caused simultaneous extinctions in the tropics and higher latitudes.
- The Late Permian: The massive extinction of the Late Permian, about 252 million years ago, dwarfs all other events, with approximately 96% of the species that become extinct. The extinction was caused by a vast eruption of the Siberian Traps, a gigantic and prolonged volcanic event that covered much of present Siberia, which led to a cascade of environmental effects.
- The Late Triassic: The Late Triassic event, 201 million years ago, shares a series of similarities with the Late Permian event. It was caused by another large-scale eruption, this time from the Central Atlantic Magmatic Province, which announced the division of the supercontinent Pangea and the initial opening of what would later become the Atlantic Ocean.
According to the researchers, both heating events caused rapid increases in temperature, oceanic anoxia (in which oxygen is depleted) and acidification.
This, in turn, led to the collapse of reef ecosystems.
In addition to discovering new clues about Earth's past, researchers say the findings provide a "broad warning" of what might emerge as a result of current trends in climate change.