Why are species in decline?2022-06-16T13:20:19+00:00

Why are species in decline?

Home-Conserving nature-What is Biodiversity?-Why are species in decline?

Species Loss

Recent scientific analyses estimate the current rate of extinction to be around 1,000 times higher than the natural background rate (Pimm et al., 2014), a reality which sees species go extinct every day. Of the 93,579 species presently assessed by the IUCN Red List, which acts as a barometer for life on Earth, 27 per cent are adjudged to be threatened with extinction (IUCN Red List, 2018): more than one fifth of those are Critically Endangered species. Furthermore, in addition to species extinction, species abundance has been reduced dramatically in the last century. The Living Planet Index (WWF, 2016) estimates the loss of vertebrate abundance between 1970 – 2012 to be around 58 per cent, based on 14,152 populations of 3,176 species monitored. These trends are as dramatic as they are harrowing, and such is the scale of biodiversity loss that scientists have begun to describe the current species extinction as the sixth mass extinction event in the 3.4 billion year history of life on Earth, one driven by homo sapiens.

Endangered species - A Bonobo in tree, image by Christian Ziegler, National Geographic

Whilst conservationists are often warned not to make everything sound too depressing, it is difficult to present the current statistics on species extinction and decline in any other way. Yet as our knowledge grows, so does the realisation that we are actually capable of doing something about this. Earth’s fate is not consigned. Indeed, the present extinction crisis is not blind, in almost all cases we know both how and why biodiversity is decreasing, which brings hope that we can do something about it.

Habitat Loss

The principal driver of biodiversity loss has been the loss of the habitat. Human beings have altered the natural environment over the past few centuries at an unprecedented pace. For example, since the pre-industrial era 32.2% of global forest cover has been lost (Adams, 2012), and if all dams currently planned or under construction are built then natural hydrological flows would be lost from 93% of all river volume (WWF, 2016). Going back to our understanding of biodiversity, that difference between and amongst species reflect organisms’ adaptations to particular environments, it is easy to comprehend how habitat loss drives species to extinction, as where the environment these species are adapted to survive in is suddenly replaced by one in which they are not, they can no longer subsist. It is true that organisms have the ability to adapt to a changing environment, but the evolutionary process is in the main an incremental one, unfolding over thousands of years, and whilst some species show an astonishing ability to quickly adapt to human-altered environments, these species are the exception rather than the rule, as many slip silently towards the precipice of extinction.