Are We Heading Towards a Sixth Mass Extinction? – AZoCleantech

We use cookies to enhance your experience. By continuing to browse this site you agree to our use of cookies. More info.
AZoCleantech speaks to Robert Cowie from the Pacific Biosciences Research Center at the University of Hawaii about his team's research on the Sixth Mass Extinction. 
As a child, I was aware of the drastic declines of many well-known species of African wildlife, so I was aware of the need for the conservation of biodiversity from an early age. But it was not until I came to Hawaii in 1990 that I was faced with extinction on a massive scale – of native Hawaiian biodiversity, with the vast majority of species unique to Hawaii.
Although I published on conservation and extinction (of Pacific island snails) early on, I only became heavily involved in research specifically on the Sixth Mass Extinction, once I  began collaborating with my colleagues in the Muséum national d’Histoire naturelle in Paris a little over a decade ago, initially as a member of a graduate student’s PhD committee. We published two papers in 2015, a third in 2017, a couple of book chapters, and now the paper that prompted this interview.
End of the Ordovician period (450 Million years ago [Mya], 85% extinct), end of the Devonian (365 Mya, 75% extinct), end of the Permian (250 Mya, 96% marine, 70% terrestrial extinct), end of the Triassic (200 Mya, 80% extinct), and end of the Cretaceous (66 Mya, 75% extinct).
The Red List is a list of all species for which the International Union for Conservation of Nature (IUCN) has evaluated a threat status – from Critically Endangered, Endangered, Vulnerable (the “Threatened” categories), to Near Threatened, Least Concern, and Data Deficient (species for which there is insufficient data for their status to be evaluated).
As a byproduct of this process, species that are evaluated but found to be extinct, are also listed. However, the Red List has only evaluated a tiny fraction of all known species. It has evaluated all known birds and almost all mammals, but these are not a random sample of overall biodiversity.
Larger species tend to have larger ranges and are therefore less likely to be vulnerable to local habitat destruction than smaller species (most invertebrates).
Many rare invertebrates inhabit remote tropical regions, which is why they are so little studied and poorly understood. Given their likely small ranges, they may well be very prone to extinction, yet there is insufficient knowledge to evaluate them. Therefore, Red List evaluations are heavily biased to better-known species. They may also be biased towards threatened species, groups benefitting from being the target of IUCN “Specialist Groups”, or in some cases regions with higher species richness.
All species go extinct eventually – so there is what we call a background rate of natural extinction. This has been interrupted by five previous events of greatly increased extinction rates over relatively short periods of time – which we refer to as mass extinctions – all resulting from natural phenomena.
What we are now seeing is another period of a much-increased rate of extinction, perhaps 100 times the background rate, this time caused entirely by humans. If this continues, and there is no reason to think that it will not, then we are at the start of the Sixth Mass Extinction.
There are approximately 2 million species known to us – though there are estimated to be many more that we have yet to discover, so probably around 10 million in total. We estimate that in the last 500 years, between 7 and 13 percent of those 2 million species that we know have gone extinct – that is, between 150,000 and 260,000 species, so perhaps roughly 10% of known species, and therefore a much higher number of all (known and unknown) species.
Oceanic islands are isolated by the surrounding ocean. Once a plant or animal has by accident reached such an island – which is a very rare event – it is free to evolve in the absence of many of the threats it would have faced in its original habitat. It becomes a new, different species, or even radiates into a number of different species – and all these are only found on this one island.
If humans destroy the habitat where they live, for instance by deforestation – or if humans introduce an invasive species that prey on them – the range of these species is so small that they are easily and completely extinguished, and go extinct. Species in continental habitats, in contrast, may have larger ranges and are therefore less susceptible to such impacts.
Yes, humans are causing what may well turn out to be the Sixth Mass Extinction. The primary driver of this process is habitat destruction. This is intertwined with the impacts of invasive species. Of course, for certain species, killing them for monetary profit (think rhinos) is driving them to extinction.
Climate change is probably going to drive some species to extinction in due course; for instance, species adapted to the tops of high mountains, where it is cold, will have nowhere to go as the climate warms.
We cannot bring back species that are extinct – they are gone forever – so there is no reversing what has already happened. Ideally, however, we should attempt to stop further extinctions, and if that is not possible right now, to at least slow the rate of extinctions. I do not believe that there is a political or economic will to do either, except for a few charismatic species, and even then we are failing – think about rhinos and gorillas, for example.
I’m not sure we have or had a ‘hypothesis’ regarding the Sixth Mass Extinction – rather, we looked at available data and extrapolated from those data to estimate the number of species that have gone extinct since around the year 1500, trying to avoid the biases I mentioned under question 3.
It is an opinion, held by some people, who argue that as humans are just animals going about their business in an evolutionary context, and that although we are demonstrably the cause of the current increased rate of extinction, this is simply an evolutionary phenomenon – humans will do what we do and we should just not worry about increased rates of extinction caused by us because that is a natural evolutionary phenomenon, so just go with the flow. In contrast, my opinion is that humans are not just another species but are the only species that has the capability of causing such dramatic impacts on Earth’s biodiversity, but that we also are the only species that has the conscious choice to continue to let it happen or try to stop or slow it. Since we have this choice, my opinion is that we should try to stop the destruction. This is not science, it is a moral choice.
Conservationists have suggested several approaches to help establish priorities for action, including, among many others:
I doubt much of this will have much widespread and long-term success in staving off increasing extinctions. This is why we advocate a major effort to collect representative specimens of as many species as possible, especially those as yet undescribed and scientifically unnamed invertebrate species before they vanish and are lost and gone forever. In this way, in 200, 300, 500, or whatever years, our descendants would still be able to know and marvel at the biodiversity that the Earth once supported and that humans have destroyed.

The purpose of preventive archaeology is to discover and undertake the scientific study and preservation of archaeological remains that might otherwise be destroyed by land development, thereby safeguarding the archaeological heritage of a site. We are advocating something analogous in terms of preserving our biodiversity heritage in the face of its ongoing destruction.

The paper that prompted this discussion:
The IUCN Red List of Threatened Species:
The Sixth Extinction: an Unnatural History:
Evolution, Extinction and Conservation of Native Pacific Island Land Snails:

Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.
Written by
Laura Thomson graduated from Manchester Metropolitan University with an English and Sociology degree. During her studies, Laura worked as a Proofreader and went on to do this full time until moving on to work as a Website Editor for a leading analytics and media company. In her spare time, Laura enjoys reading a range of books and writing historical fiction. She also loves to see new places in the world and spends many weekends looking after dogs as part of
Please use one of the following formats to cite this article in your essay, paper or report:
Thomson, Laura. (2022, March 07). Are We Heading Towards a Sixth Mass Extinction?. AZoCleantech. Retrieved on March 07, 2022 from
Thomson, Laura. "Are We Heading Towards a Sixth Mass Extinction?". AZoCleantech. 07 March 2022. <>.
Thomson, Laura. "Are We Heading Towards a Sixth Mass Extinction?". AZoCleantech. (accessed March 07, 2022).
Thomson, Laura. 2022. Are We Heading Towards a Sixth Mass Extinction?. AZoCleantech, viewed 07 March 2022,
Do you have a review, update or anything you would like to add to this article?
Cancel reply to comment
The Hiden LAS provides leak analysis of sealed packages.
Lightweight, recycled thermoset-plastic fillers produced and supplied by Composition Materials are made from 100% recycled materials.
Learn more about the service and calibration of Kipp & Zonen instruments.
Robert Cowie
AZoCleantech speaks to Robert Cowie from the Pacific Biosciences Research Center at the University of Hawaii about his team's research on the Sixth Mass Extinction.
Dr. Francois Lapointe
AZoCleantech speaks to Francois Lapointe from the University of Massachusetts about his team's research into the Little Ice Age.
Dr. Laura Christianson P.E.
AZoCleantech spoke to Dr. Laura Christianson P.E. about current water quality conservation practices and how they may not go far enough in providing environmental benefits. Christianson goes into detail about her unique study in this interview. – An AZoNetwork Site
Owned and operated by AZoNetwork, © 2000-2022