Some studies have theorized that human activity has killed off around 1,430 bird species and up to 260,000 invertebrate species.
Extinction is an inevitable part of the process of natural selection. Even without the help of humans, it has been estimated that the world would lose roughly 0.1 organisms per million species every year, which is known as the background extinction rate.
However, human-induced climate change has significantly increased the rate, causing species to die off much faster.
For instance, the Atlantic Forest in Brazil once stretched across 463,000 square miles, but it has now been reduced to patches.
Dark extinctions raise questions of how to conserve species and reduce the effects of climate change.
Perhaps by restoring habitats, large numbers of species can be brought back from the brink and help ease the dark extinction crisis.
