Mass extinctions are described as events where at least half of the species alive & living on Earth get wiped out in a very short amount of time. A lot of scientists believe that our species is part of a 6th mass extinction today, except this one is entirely caused by humans.
In the 570 million years (roughly) that life has existed on our planet, we have had 5 major mass extinctions, all naturally occurring. They are listed below:
- Ordovician-Silurian Extinction: Small marine organisms went extinct. (440 mya). Scientists estimate that glaciers locked up much of the world's water into ice and caused sea levels to drop.
- Devonian Extinction: A drawn-out mass extinction that depleted 70% of sea animals, some insects, plants & amphibians. (365 mya)
- Permian-Triassic Extinction: This event wiped out tons of species living on planet Earth, including many vertebraes. (250 mya). Scientists estimate this one to be the deadliest, eradicating 90% of the species on Earth at the time.
- Triassic-Jurassic Extinction: The extinction of other vertebrate species on land allowed the dinosaurs to flourish. (210 mya). Scientists believe that volcanic eruptions caused this extinction to wipe out 20% of sea species, mammal-like creatures and large amphibians.
- Cretaceous-Tertiary Extinction: (65.5 mya) - Wiped out a reptile dominated planet and made room for mammals to evolve, diversify & thrive. There is speculation of a crater dated 65 million years ago off of Mexico's Yucatan Peninsula, which may have caused the event to occur.
All of these extinctions were driven by naturally occurring events; volcanic eruptions, asteroids, sea level increase/decrease, etc. Global warming is a byproduct of some of these naturally occurring events and also plays an impact on these extinctions. Scientists estimate that 90% of all species that have ever existed on Planet Earth are now extinct, which shows how small our existence really is in the history of Earth.
People always argue that "Global Warming happens naturally", and they're not wrong. According to NASA, there have been 7 glacial formations and disappearances in the past 650,000,000 years, all of which took place over those past 5 mass extinctions. Massive volcanic eruptions and comets crashing down onto Earth also have the capability of changing the climate almost instantly. The difference between naturally occurring global warming and the climate change we talk about today, is that the speed of which our climate is changing is drastic and the evidence makes it pretty clear that it is mostly caused by us. I don't remember any massive asteroids in the past 50 years hitting our ice caps & started melting them...do you?
Global temperatures are rising, ocean temperatures are rising, ice sheets in the North & South poles are melting at a rapid pace, losing 400 billion tons of ice mass a year combined and that number is increasing every year. Snow coverage and glaciers are disappearing and sea levels are increasing, flooding cities around the world. In fact, sea levels rose 8% in the last 100 years, and rose 16% in the past 20 years. More intense & extreme weather as well as ocean acidification also show the rate to which we are changing our climate.
According to WWF's Living Planet Report, 6 billion tons of fish and other sea creatures have been removed from the world's oceans since 1950 (I would state the value in pounds but it's way too long). Between 1970 and 2014, we have lost 60% of our biodiversity of vertebrate species, with South and Central America experiencing the most dramatic biodiversity loss of 89% in that time frame. This is all due to pollution, overfishing, greenhouse gas emissions & deforestation/land clearing. Other species don't have the time to evolve to these changing climate conditions because not only are we warming the world at record speed, but we are also ruining their habitats, changing their biological patterns, and encouraging the population growth of invasive species (scary). We're not just changing one little factor they can adapt to; we're changing everything.
We won't be able to survive it all either: Recent studies by the World Health Organization show that the air we are breathing is causing extreme health conditions and death in humans. Toxic air has killed 600,000 children in 2017. Not only that, but micro-plastics found in most bottled and tap water are infiltrating human bodies, as studies have recently found micro-plastics in human feces. Biodiversity, which we're losing rapidly, is the foundation of farming, agriculture, and medicine. We are dependant on the withering rainforests and the shrinking aquifers for clean water and air. Nature is the basis of our entire economy, and provides us with $125 trillion of services. Without it, we are nothing.
According to some scientists, we are in the midst of the 6th mass extinction and we are fully responsible for it. Others are on the other side of the playing field, arguing that all of the details are too intertwined to understand fully, stating that if we were in the midst of an extinction, there would be no saving us now.
In a world where everything is interconnected, small changes in one population or species can compound and grow in severity, negatively impacting other areas of nature. Alternatively, small changes made by us and our policy makers have the power to ripple positive change and change the trajectory of our planet.
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If you want to read about WWF's Living Planet Report for 2018, click here.
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