 In the previous episode of X-10 we saw that empowering women across the world and reducing the mortality rate among children are our best weapons to reduce population growth, because they have a profound impact on the overall fertility rate. Still, for the sake of argument, say that life extension therapies that slowed down or even reverse aging were to cause such a big increase in population that nothing we try actually manages to keep our numbers low. At that point, would we be too many people for this planet? How many is too many? Whatever that number may be, is it set in stone or can we change it? And if so, welcome to X-10, your one stop YouTube show for all things life extension. Do you come here often? If so, maybe you'd like to subscribe by clicking the red button down below. Don't forget to click the little bell icon and select all notifications so that you'll never miss a single episode. Now, back to overpopulation. The maximum number of individuals of a population that an environment can support is called the environment's carrying capacity. This concept is widely used in ecology for non-human species and essentially, it relates the resources available in an environment to the populations of an animal species in that environment. The basic idea is that if a population exceeds its environment's carrying capacity, its members will start dying off until the population shrinks down below the carrying capacity. As long as we're talking about animal populations, the carrying capacity of their environment depends only on things like space, food, water and so on. When it comes to humans, it gets much more complicated as it is reflected in the wild variety of human carrying capacity estimates that have been proposed, which range anywhere from less than a billion people to over a thousand billion people. Most estimates fall somewhere between 8 and 16 billion people, but none of them are set in stone and scientists are aware that they need to be taken with several grains of salt. As a matter of fact, this concept has been criticized over the years, because while it works well for animals, the interaction between humans and the environment is much more complicated and it might simply not be very well captured by the definitions of carrying capacity. The high variability in the different carrying capacity estimates depends in no small part on the method used to calculate them, but the problem is also that our technology can change the way we interact with the environment and thus its human carrying capacity in unpredictable ways. Before the Third Agricultural Revolution of the mid-1900s, feeding a population as large as today's was impossible. Without the changes in production techniques that occurred back then, the earth could not have supported the almost 8 billion people that exist now. That's an example of humans increasing the carrying capacity of the planet. One of the catches is that we rely heavily on fertilizers to grow our food, and fertilizer production requires a lot of natural gas. Natural gas exists in limited supply and producing more and more fertilizer for the needs of a growing population will consume it. So natural gas is an example of a constraint on the human carrying capacity of the planet, at least for as long as our production methods don't change. If we could grow food without fertilizer, the amount of natural gas would no longer be a constraint. That's why carrying capacity estimates aren't final. It's very hard to predict when a new breakthrough will allow us to do more with less, or when disaster might strike and reduce our ability to support ourselves. So, what can we do to make sure that even if life extension significantly increases our population, we will always be able to feed everyone without screwing over the planet in the process. Let's take one step at a time. In terms of space only, could we fit more people on this planet? In principle, yes, absolutely. Estimates of the current total size of urban and built up areas in the world, including infrastructure, vary a little depending on the source, but they range between 0.6 and 1.5 million square kilometers. That's not a lot. It's between 0.5 and 1.4 percent of the total habitable land of the world, which is around 104 million square kilometers. Give or take a few million square kilometers. Estimates of the total land dedicated to agriculture, that is, both livestock and crops, are much more similar to each other and gravitate towards 50 million square kilometers. That's about half of the total habitable land. It's a lot. And it has a number of negative environmental consequences that we're gonna get into in a minute. But, speaking of space, if science and technology could help us reduce the amount of land needed to grow food, even by, say, 10%, that would be a lot of land where all our existing cities, towns, villages and infrastructure would fit several times. So it's not like we don't have space for more people. We do, if only we can figure out a way not to use so much of it to produce our food. That's a challenge, of course, because the implication is that we need a way to grow food for more, maybe many more people than we have today, with less land than we do now. Of course, space isn't the only problem, and in fact it's probably the least of our concerns. The really big problem is that food, energy and water are intertwined in a complex way. For example, in order to produce food for everybody, we need massive amounts of energy and water. More people need more food, which means that more energy and water are used to produce it, and we get more of the side effects caused by their use. The magnitude of these effects varies depending on the food being produced. On average, most meats, dairy and farm seafood require far more land per kilogram than the vast majority of vegetables. They also require more water per kilogram, in the order of thousands of litres, and they cause far more greenhouse gas emissions. Greenhouse gases, or GHGs, are waters causing our planet to abnormally warm up, and food production in general accounts for more than a quarter of the total greenhouse gas emissions in the world. While crops cause lower GHG emissions than livestock and fisheries, it's still a solid 27%. Land use also increases the level of GHGs in the atmosphere. For example, forests are natural carbon sinks, meaning that they capture carbon dioxide, a GHG, as part of their respiration process. But to make room for crops and pastures, we need to cut more trees, so more carbon dioxide stays around. The negative effects of food production are too many to list or discuss all in a single episode. You can find out more in the description below, but the point is these effects are problematic enough now. We don't want to know how much worse they'll be, if and when the population will be much larger, but we would like to know how we can prevent them. Thankfully, there are some promising technologies in the works that may revolutionize the way we grow our food, produce our energy and live our lives. Their potential benefits are so huge that they're well worth embracing regardless of the size of our population. Cultured meat is meat that doesn't come from a slaughtered animal. It's grown in a lab using stem cells from an animal, but there is no killing ball. It used to be the stuff of science fiction, but nowadays it's not even news anymore. And soon it may be on supermarket shelves, it's just a matter of cost and scalability. The first cultured meat burger was created in 2013 by Dr. Mark Post from Maastricht University and his team. It was actually publicly tasted in 2013, and the people who ate it essentially said it passed almost for the real thing. Cultured meat started off expensive. Dr. Post's burger cost nearly 250,000 euros and took over two years to prepare, but in a 2015 interview he said they expected the product to be commercially viable within 10 years and that the cost could be reduced down to 8 euros per burger. Dr. Post is far from being the only one working on this. There are several companies working to bring cultured meat over tables, including Dr. Post's, and they all have an interest in driving the cost down as much as possible. You'll find a list of companies in the description below. Some of them are working on cultured fish too. The benefits of cultured meat could be enormous. A 2011 study estimated that producing 1,000 kilograms of cultured meat could require between 7 and 45% less energy, cause 78 to 96% less greenhouse gas emissions, use 99% less land, and 82 to 96% less water than traditional meat. In addition, lab-grown meat carries far less risk of diseases because it's creating a laboratory environment, and it could be custom-made to be more nutritious or contain less cholesterol, for example, not to mention that it would be cruelty-free. Traditional crops have a smaller environmental impact than meat or fish, but they still have one and vertical farming might help produce it. Vertical farming is the practice of growing crops in vertically stacked layers with no soil involved. A vertical farm can be set up in a city building where it takes far less space than a traditional farm, precisely because it extends upwards, not horizontally. To grow crops without using soil, vertical farms use techniques such as hydroponics, aquaponics, and aeroponics. These techniques are similar to each other, and the basic idea is that the plant roots are submerged in a liquid solution containing all the nutrients the plants need. Hydroponics uses up to about 70% less water than conventional farming methods. An aeroponic farm, where the liquid solution is misted in air chambers where the plants are suspended, uses even less water. Aquaponics farms combine crops with basically fish tanks in order to mimic a natural environment where the wastewater of the fish is continuously recycled. The plants absorb nutrient from it, making it reusable for the fish. Besides lower land and water usage, vertical farms have other advantages. They are not affected by the weather because everything happens indoors, they have little to no pest problems because of the strictly controlled environment, and they're less disruptive to plants or animals because they're built in cities. Vertical farms also produce fewer CO2 emissions than normal farms because there are no large fuel-burning farming machines involved. Heating, cooling and lighting are artificial, so your crop isn't dependent on the geographic location of the farm itself or on the time of the year. All that glitches is not gold though, and while extremely promising, vertical farming isn't going to replace traditional farming just yet. For one, vertical farms have higher startup costs because urban locations are expensive, and because of the temperature control systems. The power source used should also be factored in. If vertical farms got their power from coal, they wouldn't be all that ecological. At present, only a limited number of different crops are profitable to grow in a vertical farm, and those that require insect pollination need extra work because insects are just not part of the equation in an indoor farm, and pollination needs to be done by hand. Still, as the world moves towards greener energy sources and lander water scarcity drives demand, vertical farms could become a more profitable and viable solution to feed a growing population in a more sustainable way. Genetically modified organisms, or GMOs, are another great tool in science's toolbox that could change the way we grow food. As a matter of fact, people have been manipulating the genome of crops ever since agriculture existed. Only they did it manually through selective breeding and cross-pollination. These techniques allowed to select plants with more desirable traits like resilience to droughts or pests and larger yields, but they were extremely slow and imprecise. Through modern genetic engineering techniques, the same thing can be done with extreme precision and much more quickly. The benefits are many. GMO crops could be engineered to have longer shelf life to resist pests and adverse environmental conditions and produce larger yields. A meta-analysis of the impact of GMO crops published in 2014 showed that they reduced the use of chemical pesticides by 37% while increasing crop yields by 22% and farmer profit by 68%. That's not peanuts. Even though GMOs have long been at the center of a safety controversy, the general scientific consensus is that they're no more dangerous to human health than conventional crops. The debate over this and other concerns is still raging, though. To date, there is no conclusive evidence that GMOs may be generally bad for us or the environment. A growing population means a growing need for energy, particularly clean energy, burning fossil fuels to satisfy the energy needs of our current population or those of a much larger future one would be essentially madness. Better options exist already today, but it would be impossible to talk about them all in a single episode. You'll find more information about them in the description below, but right now we're going to briefly talk about nuclear fusion. Nuclear fusion is the opposite of nuclear fission, which is the process that creates the nuclear energy that everyone knows about. In nuclear fission, atomic nuclei split in an energy-releasing chain reaction. In nuclear fusion, atomic nuclei are fused together, releasing much more energy than fission in a much safer way. Fusion is what powers stars. And in stars, the reaction is kept going by the star's enormous gravity and pressure. Recreating fusion in a lab requires extremely precise and controlled conditions, such as temperature and pressure. And the slightest variation would result in the reaction coming to a halt. That's the abridged version of why fusion reactions can't lead to the same kind of devastating explosions that can occur with fission reactions. Possible fusion fuels are isotopes of hydrogen, variations of it that have a different number of nutrients in their nuclei, of which the primary one, deuterium, is easily accessible and abundant. The only waste products of nuclear fusion are helium, which is completely harmless, and tritium, which can be dangerous, but decays fairly quickly. Because of fuel availability and the high energy yields, fusion is considered to be the energy source of the future, potentially able to satisfy all our foreseeable needs for centuries to come. The catch is that controlled fusion is not easy to achieve, and while several initiatives around the globe have made considerable progress over the past decades, we are not yet at the point of using fusion energy to power the world. However, scientists are confident that it can be done, probably during this century, and many are working on it. You'll find a list of companies and institutions working on nuclear fusion in the description. There are certainly other things that would be worth discussing in terms of managing the needs of a larger population, water scarcity, for example, the employment of other forms of renewable energy production, and last but not least, the economy of the future. Will there be enough jobs for everyone? Will there be jobs as we know them in the first place? These are all very interesting questions, but as we can't possibly discuss everything in a single episode, you'll find further reading material about them in the description and will probably make separate episodes about them in the future. Thank you very much for sitting through this entire episode of X-Ten. If you liked it, please let us know with a like or a comment and share it with your friends. If this is your first time on this channel, consider subscribing by clicking the red button down below. You should also click the little bell icon and then choose all notifications to be sure to be notified every time we release a video. Producing videos like this one is extremely time consuming and requires a lot of work. If you'd like to help us make more, you could do so by becoming a lifespan hero to support us. Find out how on lifespan.io.com. Thanks again for watching. See you soon with the last episode of X-Ten's Overpopulation series where we'll talk about something radically different, ethics. See you then and take care.