Why these species are on the verge of extinction

In May, Deborah Tabart, chairman of the Australian Koala Foundation, a non-profit based in Brisbane, issued a press release that said koalas "may be functionally extinct in the entire landscape of Australia". A spate of news reports in

November reiterated Tabart's claims. The devastating bushfires in Australia in November saw researchers and wildlife charities fearing hundreds of the marsupials might have perished across Australia—reports suggest the toll could be around 1,000. Visuals of a woman rescuing a wailing koala from the flames in New South Wales went viral.

A species can be declared "functionally extinct" in different situations: if it disappears from the fossil records, if its dwindling population can no longer play an important role in the ecosystem, and when the population is no longer viable to reproduce and sustain itself. In an undisturbed habitat, koalas can live up to 10 years, but there has been a steady decline in the number of mature individuals in the species. The reasons vary: urban development, bushfires and habitat destruction.

The marsupial does face threats. However, according to a Guardian report in November, claims that "koalas are functionally extinct were overstated". The National Geographic too said in the same month that koalas are not "functionally extinct—yet".

Koalas are classified as "vulnerable" in the IUCN (International Union for Conservation of Nature) Red List, with the number of mature individuals pegged at around 300,000 in 2014.

But they are not the only species on the brink. The Sumatran rhino, the smallest living rhinoceros, was declared extinct in Malaysia in November. In Kenya, only two female members of the northern white rhinoceros survive, after Sudan, the last male, died in 2018. But scientists are working towards using frozen sperm samples to repopulate the species. The vaquita, a critically endangered marine animal whose name translates to "little cow" in Spanish, is found only in

Mexico's Gulf of California—their population declined from 567 in 1997 to less than 20 in 2019. A subspecies of the giant tortoise native to Ecuador's Pinta Island was classified as extinct in 2012, while the last known male northern white rhino died in Kenya in 2018. In India, less than 10,000 mature individuals of the critically endangered white-rumped vulture remain—they play a key role in the ecosystem.

A report from the UN noted in May that "nature is declining globally" and "the rate of species extinctions is accelerating". The report found that around one million animal and plant species are now threatened with extinction, "many within decades". For instance, more than 40% of amphibian species are facing the threat of extinction. One such species was the Golden Toad, endemic to Costa Rica, which was declared extinct in 2005.

In her 2014 book, The Sixth Extinction, journalist and author Elizabeth Kolbert describes how humans spread to every corner of the globe. Having discovered subterranean reserves of energy, they began to "change the composition of the atmosphere" and this altered "the climate and the chemistry of the oceans". "Some plants and animals adjust by moving. They climb mountains and migrate toward the Poles. But a great many—at first hundreds, then thousands, and finally perhaps millions—find themselves marooned. Extinction rates soar, and the texture of life changes."