The scientific community remains significantly divided over whether Earth has entered a period of the sixth mass extinction. A new study, based on the International Union for Conservation of Nature (IUCN) database, conducted a systematic analysis of extinction data for more than 163,000 species and 22,000 genera in the past five centuries. The results show that the genus-level extinction rate of mammals is less than 2%, and the genus-level extinction rate of all species groups does not exceed 0.5%, which is far lower than the threshold recognized by the scientific community as a "mass extinction" event that requires 75% of species to disappear.
The research was recently published in the journal PLOS Biology.
The study pointed out that the species extinction events that have occurred have strong classification and geographical concentration: most of the extinct genera are concentrated in mammals and birds, and about 75% are endemic to islands. Since the beginning of the 20th century, the global extinction rate has shown a significant downward trend, indicating that the impact of early human development activities (such as island colonization) on endemic species has constituted the main cause of historical extinction, but does not necessarily predict future large-scale extinctions.
However, several previous studies raise objections. Relevant teams from Stanford University in the United States and the National Autonomous University of Mexico believe that solely using the final extinction of a species as a criterion may seriously underestimate the actual extent of the ecological crisis. The rapid collapse of population size (such as the sharp decline in global insect numbers) also has catastrophic ecological consequences, and more directly affects ecosystem functions and the survival of human civilization. Researchers at Arizona State University in the United States emphasize that when communicating about biodiversity loss, scientific accuracy and public trust must be balanced.
The consensus of the scientific community is: Whether it is called a "mass extinction" or not, the loss of global biodiversity is accelerating, and cross-scale and cross-category conservation intervention and policy responses are urgently needed.
