Earth’s extinction history could be repeating

 

During the 4.54 billion years Earth has existed, five mass extinction events have occurred. According to scientists, a sixth mass extinction may possibly begin in fewer than 100 years.

Massachusetts Institute of Technology’s Daniel Rothman, after studying the carbon cycle and 31 extinction events from the previous 542 million yeas for some time, has noticed alarming parallels between the present and the Permian-Triassic extinction event that took place about 252 million years ago. This event is nicknamed “The Great Dying” due to a loss of 96 percent of the species on Earth. Per World Atlas, this catastrophic happening was triggered by a volcanic eruption that emitted so much carbon dioxide that it triggered extreme global warming and causing the acidity level of the oceans to rise.

The next mass extinction will be called the Holocene extinction if and when it occurs. This would be the first time carbon will once again be a factor in the extinction process.

The Ordovician-Silurian extinction occurred 439 million years ago and caused an 86 percent loss of life. The event was triggered by falling sea levels and the formation of glaciers. The extensive vegetation caused an extreme lack of carbon dioxide in the atmosphere, creating the glaciers. The Late Devonian extinction wiped out around 75 percent of the species on Earth about 364 million years ago. Plants on Earth during this time littered the oceans with nutrients, creating massive algal blooms and causing a lack of oxygen in the oceans. The next mass extinction has been mentioned previously; the Permian-Triassic extinction from 251 million years ago. The Triassic-Jurassic extinction from 214 million years ago was caused by asteroid impacts and global climate change. The Cretaceous-Paleogene extinction from 65 million years ago was caused by volcanic eruptions and asteroid impact – all according to World Atlas.

Scientists started wondering how soon it could happen again since these mass extinctions are relatively common in Earth’s history.

The critical level for carbon in the oceans is 310 gigatons and, according to Rothman, humans have the possibility of adding anywhere from 300 to 500 gigatons of carbon to the oceans by the beginning of the next century. By the time the year 2100 rolls around, the carbon cycle will have bypassed the critical threshold. Despite this, it could take up to 10,000 years for an actual extinction level event to happen. The number of years is determined by the time it takes for the carbon cycle to reset after it has been imbalanced. At current rates, this process usually takes around 10,000 years. According to Rothman and MIT, “the critical threshold is no longer tied to the rate at which carbon is added to the oceans but instead to the carbon’s total mass. Both scenarios would leave an excess of carbon circulating through the oceans and atmosphere, likely resulting in global warming and ocean acidification.”

As The Sun reporter Jasper Hamill states, humans have created 1,540 billion tons of carbon dioxide into the atmosphere since the Industrial Revolution.

“This is not saying disaster occurs the next day. It’s saying, if left unchecked, the carbon cycle would move into a realm which would be no longer stable and would behave in a way that would be difficult to predict. In the past this type of behavior is associated with mass extinction,” Rothman said to Hamill.

According to IFLScience, biodiversity on Earth is the highest it has ever been and the next event will bring about unknown consequences.

Melting of permafrost awakens fears of ancient diseases

As the Earth’s temperature begins to rise, not only are the ice caps melting, but the permafrost is melting as well. As this thick, usually frozen layer of soil begins to melt, rumors start to surface regarding ancient and, in some cases, unknown diseases resurfacing and posing potential threats to mankind. However, many of these rumors are false.

As Jasmine Fox-Skelly reports in BBC Earth, “scientists have discovered fragments of RNA from the 1918 Spanish flu virus in corpses buried in mass graves in Alaska’s tundra. Smallpox and the bubonic plague are also likely buried in Siberia.” They suspect that black plague and smallpox DNA fragments are also frozen in the permafrost. These disease fragments have been discovered in buried, frozen bodies of humans and animals alike.

In addition to these fragments, NASA scientists discovered and revived Carnobacterium pleistocene, a lactic acid bacteria, frozen since the era of woolly mammoths over 32,000 years ago.

While scientists are not too concerned, the possibility that dormant plague and small pox viruses could reawaken and spread across the globe has caught their attention.

“Permafrost is a very good preserver of microbes and viruses, because it is cold, there is no oxygen, and it is dark,” Jean-Michel Claverie, microbiologist at the Aix-Marseille University in France said, per Jasmin Fox-Skelly at BBC. Yes, these viruses are concerning, but with modern medicine, including penicillin, they can be easily eradicated.

According to an article by Stephanie Pappas on Live Science, strains of the Zika virus — which has been of recent concern due to mosquitoes — have been discovered in the melting ponds and permafrost. Pappas also reviewed a 2014 study from the American Geophysical Union, which stated warmer climates could also cause outbreaks of Cholera, a deadly diarrheal disease, more so in areas with poor sanitation than others. Additionally, The Indiana Times suggests diseases like malaria and dengue fever will become more common with warmer climates; although, it is not made clear if these specific diseases are coming from the melting permafrost.

Business Insider adds to the list with the discovery of Mollivirus sibericum, from the Siberian permafrost. While it is unclear exactly how this virus affects humans, it is a massive virus, containing 500 genes, causing it to be placed in a category known as Megaviridae, according to Ancient Origins website. The website further reports the discovery of Pithovirus sibericum and Pandoravirus (more large, ancient viruses discovered in 2003), also from Siberia’s permafrost. Erin Brodwin and Lydia Ramsey of Business Insider report a 2005 discovery of Mimivirus in the melting Russian permafrost, which is a virus with 1,200 genes that is twice the length of the viruses infecting the population today. Fox-Skelly notes that tetnaus and pathogens that cause botulism can survive in the frozen ground as well.

These viruses seem intimidating and will require further studying to determine their threat to humans and animals, but they are not the main concern. A reindeer with anthrax died over 75 years ago, became frozen under the soil, and released the disease in 2016 when it thawed and infected about 20 people and killed a young boy in the Yamal Peninsula in the Arctic Circle. Bacteria and viruses are normally not able to survive away from a host for too long; however, the dark, frozen, oxygen deprived permafrost creates the perfect environment for these bacteria to survive.

As the ice continues to thaw, it is possible for more ancient viruses and bacteria to be rediscovered; scientists fear that this will only be the beginning. It is entirely possible for many ancient diseases to “rise from the dead” and infect the living.