If you could travel back 65 million years ago, you would be able to witness the fifth mass extinction on Earth. It was at that time that a major event — likely the impact from a comet or giant meteor— wiped out more than half of all life on Earth [source: Choi]. Among the life forms that died out were the dinosaurs.
As enormous as that extinction event was, an event 250 million years ago dwarfed it. The Permian extinction saw 95 percent of all marine life and nearly all land life die out [source: PBS]. The world might look very different today had this extinction not happened. Scientists believe enormous volcanic eruptions in what is now Asia caused this mass extinction.
Today, Earth could be facing its next mass extinction. A global report issued by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and released on May 6, 2019, found that some 1 million species are at risk of extinction — the greatest number in in human history.
Why are so many life forms dying out? Several factors could contribute to extinction, but one seems to dominate all others: human interference. Whether it comes in the form of hunting, destruction of habitat or introducing an alien species to a new environment, humans have made an enormous impact on life on Earth in general. The history of our meddling goes back 100,000 years, when humans first started to migrate out of Africa. And then really picked up around 10,000 years ago when humans developed agriculture. Since that time, human activities have wiped out thousands of species of plants and animals. About 75 percent of the land-based environment and 66 percent of the marine environment have been significantly altered by human actions, according to the report.
Climate change has also accelerated extinction as many animals and plants can't adapt to warming or cooling ecosystems. If the trend continues, we could see a mass extinction that could threaten our own survival. We'll learn more in the next section.
Extinction Warning Signs
It can be difficult to grasp how the extinction of a seemingly insignificant life form could impact the rest of the world. But it's true that one life form's disappearance could cause enormous problems for life in general.
Let's consider a fictional example. Imagine a lake teeming with life. There are fish and amphibians living in the lake, and insects on and around it. Reptiles, birds and mammals live around the lake and depend upon it, too. Now imagine that a species of insect at that lake dies out for some reason. The impact of this event could be catastrophic.
First, any other insects, fish or amphibians that fed upon the now-extinct insect would be affected. These creatures would either have to adapt by eating something else or would die out. Move one step further up the food chain and you'll see that it's a domino effect: The creatures that fed upon the animals lower on the food chain would see a decrease in their food supply.
Now imagine that scenario taking place across the entire world at varying levels of the food chain. According to Richard Leakey and Roger Lewin, authors of "The Sixth Extinction," we could lose half of all species on Earth by 2100. They point out that species extinction can happen even if we stop destructive habits now. Small populations may succumb to sudden events ranging from natural disasters to disease. But if we continue to clear away rainforests the situation will be even worse.
What can we do about it? It'll require humans to make some sacrifices. Decreasing our carbon footprint is a good start. Reducing the amount of meat we eat can also help since raising stock requires ranchers to clear land. Cutting back on destructive habits could save thousands of species over the next several decades. And it might just save us, too. The global report says that the next two years (2019-2021) are a critical window for limiting climate change and the sixth mass extinction. It is asking various countries to commit to changing the way we feed ourselves and protect nature to limit biodiversity loss and climate change.
Learn more about biodiversity, ecology and extinction by following the links on the next page.
Last editorial update on May 6, 2019 04:49:44 pm.
More Great Links
- Ananthaswamy, Anil. "Earth faces sixth mass extinction." New Scientist. March 18, 2004. (May 11, 2010) http://www.newscientist.com/article/dn4797-earth-faces-sixth-mass-extinction.html
- Choi, Charles Q. "Greatest Mysteries: What Causes Mass Extinctions?" LiveScience. Aug. 8, 2007. (May 11, 2010) http://www.livescience.com/strangenews/070808_GM_mass_extinctions.html
- Connor, Steve. "Earth faces 'catastrophic loss of species.' " The Independent. July 20, 2006. (May 11, 2010) http://www.independent.co.uk/news/science/earth-faces-catastrophic-loss-of-species-408605.html
- Eldredge, Niles. "The Sixth Extinction." American Institute of Biological Sciences. June 2001. (May 11, 2010) http://www.actionbioscience.org/newfrontiers/eldredge2.html
- Leakey, Richard and Lewin, Roger. "The Sixth Extinction." Anchor. Oct. 1, 1996.
- PBS. "MASS Extinction." NOVA scienceNOW. November 2006. (May 11, 2010) http://www.pbs.org/wgbh/nova/sciencenow/3318/01.html
- Z., Mickey. "The Sixth Extinction is Underway: Are You Worried Yet?" Planet Green. Dec. 13, 2009. (May 11, 2010) http://planetgreen.discovery.com/travel-outdoors/sixth-extinction-worried.html