Question

Scientists argue that we are now in the 6th major extinction period, yet very few global extinctions have been documented in the past few hundred years. Explain a) two reasons for this apparent contradiction (2 points), and b) why this might not be a contradiction (2 points).

Answer 1

The 6th major extinction period is also known as the Holocene or the Anthropocene extinction period since it is caused by the activities of man.

a) The reason very few global extinctions have been documented is that most of the species which have become extinct haven't been documented either. The actual rate of extinction of species is estimated to be 100 or 1000 times the rate that is recorded. Some common and even rare species had local populations which no longer exist. According to a study published in the Guardian, scientists found that a third of the thousands of species losing populations are not currently considered endangered and that up to 50% of all individual animals have been lost in recent decades. Detailed data is available for land mammals, and almost half of these have lost 80% of their range in the last century. The scientists found billions of populations of mammals, birds, reptiles and amphibians have been lost all over the planet, leading them to say a sixth mass extinction has already progressed further than was thought.

b) The statement "We have entered the 6th major extinction period, yet very few extinctions have been documented in the past 100 years" has a big loophole: the word 'documented'. Since all the species lost hadn't been documented either, documented extinct species are not a correct indicator of real loss of species. Also, many species still survive with serious losses in their population and varieties. That is also a loss of biodiversity but it is cloaked as gradual, instead of outright extinct.