By Casey Frye, CCNN Writer
Throughout Earth’s history, there have been five mass extinction events, when a large percentage of living creatures were wiped out in a short span of time due to natural causes. Scientists believe we’re in the midst of the planet’s sixth mass extinction, only this time it’s the result of human pollution. Sadly, the World Wildlife Fund (WWF) recently revealed that mankind’s actions have claimed half of Earth’s wild animals in just the past 4 decades alone.
About 252 million years ago, climate changing microbes (microscopic organisms) evolved to consume new food sources, releasing massive quantities of chemicals that disrupted weather patterns. While this event likely created the oxygen-rich environments required for more complex animals to evolve, it resulted in the “Great Dying”, where 90% of Earth’s species died. Then, about 66 million years ago, dinosaurs and ¾ of all species on Earth died from climate change caused by volcanic activity, as well as the destructive power of an asteroid collision.
As you can see, the common theme here is climate change, where extreme shifts in temperatures throw off weather and radically imbalance natural environments. Humans have been triggering major species deaths in the past five centuries, not only by hunting and consuming animals into extinction, but also by causing global warming with pollution. Machines spew greenhouse gases that trap the Sun’s warmth in the Earth’s atmosphere, which cause dramatic cold and hot temperatures around the world. We have also chopped down countless forests, dug up huge tracts of land, and introduced foreign species into new environments.
While the human population has doubled in the past 35 years with medical advances and better living conditions for mankind, the number of invertebrate (spineless) animals like beetles, spiders, and worms has dropped by 45% in that same time period. Scientists have also concluded that plants and animals are going extinct 1,000 times faster than they did before humans evolved about 200,000 years ago.
Featured image courtesy of Medeis on Wikipedia. Image of Earth courtesy of NASA.