Biodiversity Loss 2025

An article by Dr John Wamsley OAM

Every hectare on earth evolved as a unique community of living organisms, each dependent  on the community and with the community dependent on each organism. A community is  made up of sub-communities and collections of communities make larger communities. Each  one is unique, like fingerprints. Sometimes this is called the ‘web of life’. 

We have somewhere between 3 million and 100 million species of living organisms living  within these communities. About 3 million are described and named while the rest are neither  described nor named. The collection of all these communities, the organisms within them and  the links between the different organisms, all together give us this amazing thing we call  biodiversity (biological diversity). 

We do not have a measure of biodiversity as such, but we can measure Biodiversity Loss. As the links binding these organisms together are broken, some species lose their place and reduce in numbers. When this occurs, for a species, across many communities, the number of this species decreases dramatically. It loses the niche it evolved to fill, and we class it as threatened with extinction.

We define biodiversity loss, for a class of organisms, as the percentage of species, within the class, threatened with extinction. Whereas we may not know the total number of species threatened with extinction within a class, we can get a fair estimate of the percentage threatened simply by taking a sample and looking at the percentage of the class that is threatened with extinction, as we do with polling to guess who is going to win an election.

Under Australia’s Environment Protection and Biodiversity Conservation Act, a list is published, and kept up to date, of Australia’s species which have been classed as Threatened with Extinction. This gives us a complete list of Australian land vertebrates that were threatened with extinction each year from JDDD to JDJK. Table C gives the number of species threatened with extinction during JDDD-JDCK.

Using EXCEL to compute a trendline describing the relationship between the years and the  number of threatened species, you get the following mathematical formula: Number of threatened vertebrates = 1.0325^(t-1832), where t denotes the year.

Several important estimates come from this. Firstly, it tells us that the year that the first vertebrate became threatened with extinction was in 1832, just 44 years after colonisation of Australia. Secondly, it tells us that the number of vertebrates threatened with extinction steadily increased from 1832 to 2025, by doubling each 21 years and 8 months. This, in turn, tells us that nothing that we have done, since 1832, has done anything to slow this steady increase. Thirdly, it tells us that in 50 years, all our vertebrates will be threatened with extinction.

There are three elephants in the room. Firstly, over 60% of Australia’s land is used for  agriculture. Therefore, how it is managed plays the biggest role in the loss of biodiversity, but  this need not be the case. At present regenerative agriculture, organic agriculture and  natural farming are the exception. They need to become the rule. Secondly, climate change must be addressed and finally invasive species must be controlled. 

With the present 20% of vertebrates threatened, the CSIRO tells us that ‘to undo all the human-induced damage and bring nature roaring back across their viable continental range would come with a staggering cost – A$583 billion per year, every year, for at least 30 years. That’s 25% of our GDP. If we wait 50 years until 100% of vertebrates are threatened, it will cost 125% of our GDP.

Dr John Wamsley 

FEBRUARY 2025