Climate change is a driving force behind the so-called sixth mass extinction in which species are declining at rates 100 to 1,000 times faster than background extinction
Wilson now estimates that the rate will reach 10,000 times higher than background extinction
To determine the background extinction
rate, scientists look to the fossil record and to genetic material, or DNA, which accumulates small changes in its sequence as it is copied and passed down from generation to generation.
The few species that seem to disappear in the uppermost Maastrichtian can be interpreted to constitute background extinction
pattern, or can also be interpreted as the remaining Signor-Lipps effect.
Ranging further, the dispute is carried into questions about the background extinction
rate--reflected in the number of species lost before humans arrived.
Even this five-fold increase in background extinction
rates, however, vastly understates the magnitude of the current extinction event because it is derived only from extinction of species known to science.
According to David Jablonski at the University of Chicago, adaptive traits that enhance survival and diversification of species during times of background extinction
tend to have little in common with those traits that increase the chances of survival during mass extinctions.