A study warns that impacts of modern-day climate change are similar to the scenarios that had taken place before a mass extinction happened million years ago.
An event called Permian-Triassic mass extinction killed 90 percent of all animals on Earth some 252 million years ago. It took about another five million years for the ecosystems to recover from what happened.
Scientists from the Arizona State University describe the episode as the "greatest catastrophe in the history of life on Earth." It seems, however, that worse is yet to come as the events that led to the mass extinction are also happening at present as brought by climate change.
Rapid Oceanic Environmental Changes
In the years leading to the mass extinction, the Earth's oceans showed severe loss of dissolved oxygen. This occurrence is called marine anoxia.
Initially, the team from the university wanted to determine the exact time when the anoxia occurred, its scope of the damage, and if it took place even after the Permian-Triassic. The latter should explain why it took another five million years for the ecosystem to recuperate.
To conduct the study, the scientists chose a marine ecosystem that was destroyed during the Permian-Triassic mass extinction. They found their perfect sample of sediments collected in modern-day Iran.
These sediments were deposited 246-252 million years ago in a shallow tropical ocean near the equator. Specifically, the team analyzed the variations of the uranium isotopes found in these sedimentary deposits.
The team's analysis published in full in the journal Science Advances has revealed that the episodes of mass extinction coincided with episodes of ocean anoxia, which resulted from changes in ocean circulation and nutrient levels in the Early Triassic.
"This finding provides important insights into patterns of oceanic environmental change and their underlying causes, which were ultimately linked to intense climate warming during the Early Triassic," wrote Feifei Zhang, lead author of the study.
The most interesting and worrying result of the analysis, according to co-author Stephen Romaniello, is how similar the marine anoxia of the period to the oceanic changes observed at present. The similarity is particularly striking in terms of the rapid climate warming and nutrient fluctuations seen in the oceans today.
Modern Climate Change
The consequences of modern-day climate change include loss of sea ice, accelerated and longer sea level rising, and more intense heat waves, according to NASA. Furthermore, past environmental reports highlighted that glaciers have shrunk, ice on rivers and lakes are prematurely breaking apart, and trees are either flowering or die sooner.
Most recently, two new studies stated that the Atlantic Ocean current has drastically slowed down and at its slowest pace in 1,600 years. Researchers said that global warming has caused this incidence. If this occurrence persists, the African region bordering the Sahara Desert could experience severe dryness.
