How does the rate of extinction today compare with historic extinction rates?

Question

help me on this please!

Answer 1

i read stuff for a course last year that showed current extinction rate as between x100 to x1000 background rate. quick boogle confirms this;

http://www.google.co.uk/search?q=extinct...

it is already being referred to as the Anthropocene Extinction.

Answer 2

how far back do you want to go you have the mass dinosaur extinction,mass extinction from glaciation,the earth has gone through mass heating and cooling stages over the millennium need to specify time lines the earth has been around for a few billion years.

Answer 3

We do not know, and anyone who claims otherwise is simply making it up.  In order to know what the extinction rate is, you will have to know the total number of species on Earth, the total number of extinctions per year, and the number of new species evolving each year.  We do not know any of those figures, so anyone such as Al Gore who says that extinctions are happening at a faster rate now than in the past are simply making it up.  

Further: I challenge anyone to find only one of those variables.  How many species are there on the planet?  If you don't know that answer you cannot know the "natural background rate".

Answer 4

It is impossible to know for sure. To state otherwise is a lie!!!

The truth is we have no idea how many species there are now. So we can not even try and guess how many are dying off.

Answer 5

there have been five major extensions of life on earth, other than that it has stayed relatively the same in the past, and the present

however in the present if you don't include human live, the extinction rate is about double of what it was 10 000 years ago

Answer 6

its a WAG   no one can know...but get this during the last ice age almost all life was killed off...