How many humans can planet Earth support? The answer depends on assumptions you make about human diet, waste production, resource use, what constitutes a 'reasonable' standard of human living, and about the need to protect planetary ecosystems and biodiversity for their intrinsic values and for future generations. Many studies (both scientific and non-scientific) have looked at this issue. There are different answers. In my view, planet Earth over-shot its carrying capacity for humans towards the close of last century; probably some time between 1970 and 1990.

If you wish to think about this issue, and form your own opinion, I believe it's essential to consider the following:

Attenborough, David (2020) "A life on our planet: my witness statement"   Video documentary

Attenborough, David (2020) "Extinction: the facts"   Video documentary

Attenborough, David (2021) "Breaking boundaries: the science of our planet"   Video documentary

Attenborough, David (2021) "A perfect planet"   Video documentary.

Andersen, K and Kuhn, K (2014) "Cowspiracy: the sustainability secret"  Video documentary
               Editor's note: controversy exists about exactly how much global meat production
               contributes to greenhouse gas emissions, water use and waste disposal problems.
               However, there is no controversy amongst scientists working in the field that the 
               industry is a major contributor in these areas. In my view, there's no question now
               that the full or partial removal of commercial meat from an individual's diet is an extremely 
               important way to address the Earth's environmental crisis. 
               Note that an updated version of the documentary, supported by Leonardo DiCaprio, 
               premiered globally on Netflix in September 2015. The same authors produced the 2017
               documentary What the Health.

Andersen, K and Tabrizi, A (2021) "Seaspiracy"  Video documentary
                Editor's note: Like Andersen's previous documentary on meat in diet, this documentary 
                sparked controversy. This is no surprise, noting that, globally, many fisheries scientists
                derive substantial income for the fishing industry. My own work, available on the web, 
                documents dishonesty and incompetency within Australian fisheries management agencies. 
                Without doubt, corruption also exists within fisheries management agencies across the globe. 
                It is interesting to note that my own critiques on fisheries management received praise from 
                marine conservation scientists and commercial fishers, but were substantially ignored by 
                Australian conservation groups.

Home

Who hears the fishes when they cry? It will not be forgotten by some memory that we were contemporaries.  Henry David Thoreau, 1849.

We must place biodiversity conservation at the center of ocean governance.
Sylvia Earle & Dan Laffoley, 2006.