Earth Science: Geology, the Environment, and the UniverseChapter 24:
The Mesozoic and Cenozoic ErasProblem of the WeekTo Be or Not to Be: The Sixth Extinction
The Key information in the problem was taken from information in the reference websites below. Reference Websites:
- Mass Extinctions of the Phanerozoic
*Good short explanations of most widely accepted of mass extinctions and mass extinctions in general.
- The Sixth Extinction
(National Geographic)
- The Hall of Biodiversity: The Sixth Extinction
(American Museum of Natural History)
- The Sixth Extinction....
by Richard Leakey and Roger Lewin (Doubleday, 1995)
- Timing and Rate of the KT Extinction; What Else Died Out?
By Pete Goddard
Answers:
- To find the amount of time it will take for 85% of the known, named species to become extinct at the rate currently believed to be occurring, you can use the following train of thought
- If you are losing 30,000 and gaining 10,000 each year, then you are losing 20,000 species each year.
- 85% of 1.7 million is found by multiplying 0.85 times 1.7 million which is 1.445 million. The remaining amount is 0.255 million (15%) – this is the amount that needs to be remaining.
- Let y be the number of years that it takes to get to lose this many species.
-20y = 1.4445 million
-Divide both sides of the equation by 20
-y = 72.25 years
- In this amount of time, the number of named species will be 0.255 million so 85% of the species will be extinct.
If you want a more specific time, you could change the 0.25 years to months. 1/4 of a year is 3 months.
72 years and 3 months. - The Cenozoic, or current extinction, is occurring at a much faster rate than the Cretaceous extinction did (thousands of years). Scientists estimate that in 100 years 50% of the currently known species will be extinct. Our estimate above, has it occurring even faster.
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