According to a new study published in Historical Biology, An International Journal of Paleobiology, mass extinctions of life on Earth appear to follow regular cycles which coincide with major asteroid impacts and devastating volcanic outpourings of lava1. The cycles follow a pattern of about every 27.5 million years for widespread die-offs of land-dwelling animals.
Similarly, paleontologists previously discovered that marine life mass extinction events, where up to 90% of species disappeared, were not random events, but happened in approximately a 26-million-year-cycle. One hypothesis to explain the overlapping of these astronomical and geological events is that Earth passes through the crowded part of our Milky Way galaxy every 30 million years, and during those times, comet showers are more likely to occur, leading to large impacts on earth.
The most infamous asteroid strike we know of is the Cretaceous-Paleogen, which took place 66 million years ago, and wiped out 70% of the species on Earth including the dinosaurs. In the last 500 million years, life has had to recover from five catastrophic blows and an overwhelming amount of scientific research suggests that the sixth one is already underway.
For reference, here is a brief timeline chronicling all 6 extinction events:
- 440 million years ago – Ordovician-Silurian Extinction
- 365 million years ago – Late Devonian Extinction
- 252 million years ago – Permian-Triassic Extinction
- 201.3 million years ago – Triassic-Jurassic Extinction
- 66 million years ago – Cretaceous-Paleogene Extinction
- 11,700 YEARS AGO TO PRESENT – Holocene Extinction
While we wait another 20 million years or so for the next predicted mass extinction that’s caused by a comet strike or volcanic activity, studies show that the current extinction rate is already one thousand times higher than the standard rate, which poses the question whether or not life on Earth will even make it that far2. Furthermore, why is the rate so much higher than ever before? One reason is crystal clear and it’s a result of many factors coming together to create a rapid loss of biodiversity. The first major pressure threatening the survival of our planet’s species is from habitat loss due to human development. Only 20% of the wild remains before we started taking over the Earth. Each year, 130 thousand square kilometers of rainforests are cleared every minute, approximately the size of 50 football fields. Rainforests are estimated to be completely cleared in the next 100 years.
The second factor contributing to the current rapid loss of biodiversity are invasive species. We go exploring and bring things back with us, transporting them into places they’ve never been before. Sometimes, we have done so intentionally and other times, completely unintentionally. For example, the Cuban Tree Frog is very invasive in Florida and in havoc with the native species. They were accidentally brought to Florida in the 1920’s and can now be found in natural and urban areas alike. They have learned to thrive in human-modified environments and populations can be dense enough to be a nuisance not only to humans, but to lizards and native tree frogs as well, both of which they eat.
The third major threat to our planet is a result of exploitation or otherwise called globalization. Goods such as palm oil are especially a double edged sword in countries such as Indonesia and Malaysia because sales help farmers make a sustainable income, provide economic benefits, and contribute to the global value chain. However, palm oil is banned in some places such as the European Union because it causes extensive deforestation, significantly endangering Orangutans.
The fourth major contributing factor indicative of our current mass extinction status is none other than climate change. Examples span far and wide, one being the migration pattern of sharks. They’re migrating to areas they’ve never been before because the earth is getting warmer and they are forced into feeding in areas where there are still fish. A huge misconception that permeates about the fishing industry, especially in Japan, is the myth that sharks and dolphins are eating all the fish and causing the depletion of our fisheries. In fact, the biggest threat to the world’s fish is a direct result of overfishing, and it is predicted that they will be completely extinct by 2050. A new documentary on Netflix called Seaspiracy goes much further in depth about overfishing as the biggest current threat to marine biodiversity.
We can go around the planet and find so many species that are struggling for survival. This article is not meant to be exhaustive as there are other major causes of extinction fueling the problem such as pollution, population growth, and overconsumption. The first Earth Day in 1970 was first founded by these types of concerns, but now the most threatening trend, bar none, is global warming. Although many people assume that the impacts of global warming will unfold gradually, as the earth’s temperature slowly rises, the buildup of greenhouse gases may in fact lead to abrupt and sudden, not gradual, changes. Whether or not climate change/global warming itself will take out inhabitants of our earth, or a giant rock from outer space colliding with us and causing ripples of effects leading to mass extinction, it remains unknown. What is known is that there is a synergy in nature in which all living things depend on each other, and we are seeing cataclysmic shifts pointing in the direction of a dark abyss should we not take appropriate action, and quite frankly, that was long overdue. And while we may see the human race colonize other planets such as Mars before the future is history, right now there is no Plan(et) B.
- A 27.5-My underlying periodicity detected in extinction episodes of non-marine tetrapods
- Has the Earth’s sixth mass extinction already arrived?
- The Bridge at the Edge of the World; Capitalism, the Environment, and Crossing from Crisis to Sustainability. A book by James Gustave Speth