I’m going to assume that at some point in your life you have seen one in a multitude of Hollywood disaster movies charting the mass extinction of species on the planet. These range from Deep Impact in 1998, War of The Worlds in 1953 to the extreme environmental changes posed in 2012 and The Day After Tomorrow. These films show what I would call traditional perceptions of mass extinctions as a large scale event takes place very quickly i.e. the Asteroid in Deep Impact or the dramatic climate swing in The Day After Tomorrow, but the so called 6th Mass extinction isn’t anything so flashy. This new potential mass extinction has been going on quietly ever since humanity started spreading across the globe with extinction rates increasing through time as a direct response of human activities. Just by taking a look at the IUCN Species Red List and the number of endangered species it is enough to realise that something big is underway. When I had a look today there were 5919 species on the endangered list most of which are plants (2655) and occur most in Forest biomes (2595).
Dramatic as it sounds species driven extinction isn’t happening for the first time in Earth’s History. There is a theory circulating that cyanobacteria, the first known species to produce Oxygen from photosynthesis, may have caused what it becoming known as the Oxygen Catastrophe. This Catastrophe scrubbed Iron from seas rich in it through oxidation and released pure oxygen into the atmosphere. This was an ecological disaster as many species required iron as a major nutrient and Oxygen was poisonous to many early bacteria. Furthermore, the new pure Oxygen in the atmosphere reacted with the Methane removing this greenhouse gas plunging Earth into an Ice Age which it nearly didn’t come out of and killed the majority of remaining life.
This new human driven mass extinction may follow the same route as our much earlier predecessors through our output of greenhouse gases forcing climate change. However the more likely scenario is through our very spread and our resource heavy lifestyles we as a species have already influenced the planet irreversibly. It is estimated that within 300 years 75% of animal species will be extinct as a result of increasing pressure on habitat, resources, exploitation for food and decreasing genetic diversity amongst other pressures. The natural extinction rate of the planet is estimated at 1 species in a million but after careful examination of the known extinction of species globally the current rate could be as a high as 1,000 – 10,000 species in a million.
Though Brief, I hope this post has done something to raise your curiosity into the how and why scientists are increasingly worried about extinctions and how this has effects on the human species itself. I personally take a hopeful outlook that sees work on extinction rates as the vehicle through which the majority of people can access and come to challenge environmental issues directly.
Interested? See More At:
- http://discover.iucnredlist.org/discover – Red List
- http://www.bbc.co.uk/nature/extinction_events – The 5 Great Mass Extinctions
- New Scientist Article http://www.newscientist.com/article/dn4797-earth-faces-sixth-mass-extinction.html