09/23/2021 at 10:03 AM CEST
Scientists have discovered a hitherto unknown factor that caused the Permian mass extinction: the uncontrolled appearance of toxic microbes in fresh and salty waters that disabled them for life. This was possible for three reasons that, as has been proven, occur in every period of global warming: the emission of large amounts of greenhouse gases (formerly by volcanoes, now by man), a sharp rise in temperatures and the excessive contribution of nutrients to the waters from the mainland (as happens, for example, in the Mar Menor).
252 million years ago the so-called end-Permian mass extinction took place, undoubtedly the most catastrophic event of this type in the history of the Earth, since 95% of all marine species and 70% of all land vertebrates disappeared. Scientists continue to investigate the causes of such a shocking episode and are discovering a disturbing truth: the factors that caused this mass extinction are very similar to those that are unleashing the current climate change.
Until now, the great Permian extinction had been attributed to large volcanic emissions of greenhouse gases and a significant rise in temperature. However, a recent study published by the University of Connecticut (USA) has just identified a new cause of extinction during extreme warming events: toxic microbial blooms.
In a healthy ecosystem, microscopic algae and cyanobacteria provide oxygen to aquatic animals. But when their quantity overflows, these microbes deplete available oxygen and even release toxins into the water, creating a toxic soup that kills other living organisms.
This is what these scientists have seen, for example, in Sydney (Australia). The outbreaks of toxic microbial bloom would have occurred shortly after the first volcanic episodes of the Permian mass extinction. Once the animals that fed on the water bottom died, the microbes were free to grow and multiply. Thus, freshwater systems were filled with algae and bacteria, delaying the recovery of animal species for millions of years.
The three main ingredients in that ‘toxic soup’ that aquatic systems have become are accelerated greenhouse gas emissions, high temperatures and an abundance of nutrients.
Volcanic eruptions provided the first of the elements, while sudden deforestation caused the last. When the trees were destroyed, their degraded remains found their way into rivers and lakes, providing all the nutrients the microbes would need.
Scientists analyzed sediments in these types of ecosystems and verified these facts. When they compared the fossil records of different warming-related mass extinctions, the team found extremely similar results. That is in periods of global warming, the proliferation of deadly microbes is common as aggressors of water ecosystems.
Today, humans seem to be following the same recipe and microbial blooms are, in fact, increasing in fresh and salt water. The situation is disturbing.
“We are seeing more and more toxic algal blooms in lakes and shallow marine environments that are linked to temperature increases and changes in plant communities leading to increases in nutrient contributions to freshwater environments,” he notes. Tracy Frank, head of the Department of Geosciences at the University of Connecticut.
“Therefore, there are many parallels with today. Volcanism was a source of CO2 in the past, but we know that the rate of CO2 inflow that was observed back then was similar to the rate of CO2 increases that we are seeing today due to other effects & rdquor ;, he added.
According to the report issued a few weeks ago by the Intergovernmental Panel on Climate Change (IPCC), the influence of humans on climate change is “unequivocal”, creating conditions that favor the spread of these heat-loving microbes.
In combination with the nutrient influx from water pollution, mainly from agriculture and deforestationThis has led to a sharp increase in toxic blooms. The results: massive fish kills, serious effects on human and livestock health, and an annual cost measurable in billions of dollars.
Massive increase in fires
“The end of the Permian is one of the best places to look for parallels with what is happening now,” said Chris Fielding, another of the report’s authors.
“The Another major parallel is that the temperature rise at the end of the Permian coincided with massive increases in wildfires. One of the things that destroyed entire ecosystems was fire, and we’re seeing it right now in places like California. You wonder what the long-term consequences of events like that are as they become more and more widespread, “he added.
In his opinion, these are “clear symptoms & rdquor; of an unbalanced ecosystem, and the present study indicates that the impacts of flowering events can have repercussions for an extremely long time.
However, unlike species that suffered mass extinctions in the past, “we have the opportunity to prevent these toxic blooms. keeping our waterways clean and reducing our gas emissions greenhouse & rdquor ;.
“The scary thing is that we are used to thinking in terms of timescales of years or maybe tens of years, if we get really adventurous. The mass extinction event at the end of the Permian took four million years to recover. That’s sobering, ”Fielding warns.
Reference study: DOI: 10.1038 / s41467-021-25711-3
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