In this video, we're going to talk about estimating Earth's human carrying capacity, which turns out to be extremely difficult as estimates have varied widely from about 13,000,000,000 humans up to over 1 trillion humans in some cases. There are many different methods that can be used to help us estimate Earth's carrying capacity for humans, including this concept of ecological footprint. What's important for you to realize is that all of our human activities consume resources and produce wastes, and nature needs to have the capacity to handle these demands. The ecological footprint is really just a way for us to measure if nature is capable of meeting the demands of our human activities or not.
Another important thing for you to realize is that every single individual has an ecological footprint, including me and you. This ecological footprint can be scaled up from individuals to a household, to a city, to a country, and ultimately to a global human ecological footprint. Ecological footprint can be defined as the amount of land and water that's needed to support current human activities, and it's often measured in GHAs or global hectares. To understand a global hectare, we first need to define a hectare, which is simply a unit of area that's equivalent to 10,000 meters squared and is approximately equal to 2.47 acres.
For you football fans out there, this is an area that's just a little bit less than 2 American football fields, including the end zones. A global hectare, abbreviated as GHA, is a hypothetical hectare of land or water with world average biological activity. GHAs only include hectares that are capable of supporting human activities, and those not capable are disregarded from the calculation of global hectares. As an average, global hectares are a standardized measurement, allowing us to compare ecological footprints of individuals and countries in completely different parts of the world. Let's take a look at the image down below where on the left-hand side, we're showing you the entire earth.
It's estimated that the Earth's entire surface has about 51,000,000,000 total hectares. However, not all of those hectares are capable of supporting human activities, and not all hectares are equivalent in terms of their biological activity or productivity. It's estimated that there are only about 12,000,000,000 globally productive hectares. With a human population size today of about 8,100,000,000 humans, if we were to evenly distribute these 12,000,000,000 global hectares to each of these 8,100,000,000 humans, we get the maximum sustainable ecological footprint. This is a kind of carrying capacity. By dividing 1 2 , 000 , 000 , 000 by 8 , 100 , 000 , 000 , we get an answer of about 1.5 global hectares per person.
Unfortunately, it's believed that humans currently have an unsustainably large ecological footprint greater than the maximum sustainable one, estimated at 2.7 global hectares per person. This is larger than 1.5 and signifies that, if maximum sustainable ecological footprint represents the carrying capacity, we are somewhat already beyond the carrying capacity in some ecologists' eyes. Notice the image on the right-hand side where we've got some interesting features on the shoes, showing different human activities. In the shoe with the actual ecological footprint, we're depicting human activities that are more environmentally demanding, such as using individual cars for transportation, coal-burning factories for energy, deforesting areas, using animals as a primary food source, and cargo ships with oil spills which can be devastating to aquatic biomes.
Ultimately, it's important for us to be aware that the actual ecological footprint on average per person is estimated to be greater than the maximum sustainable ecological footprint. By being aware, we can each do our part to reduce our ecological footprints and help others around us reduce theirs so that we are less demanding on nature and can ensure a sustainable and happy human population over time. This concludes our lesson, and we'll be able to apply these concepts moving forward. See you all in our next video.
