Our cities are growing. According to a page from Our World in Data, four billion people around the world live in urban areas and that number is expected to rise. But cities are not the best places when it comes to sustainability and health on an environmental level. According to the World Health Organization when it comes to urban areas, 91% of people living in urban areas breathe polluted air, are more dependent on fossil fuels for energy polluting the air and are 3-5° C hotter due to concrete buildings and asphalt roads. On top of the fact that some cities are being designed to accommodate high earning individuals are often putting high density living on the bottom of their to-do lists really makes for a bad combination for the environment and us. That is already a big problem, but there is another one that is not nearly as talked about but might be a problem as big or even bigger than this. The fact that there is less biodiversity in our cities.  
  
          Biodiversity is a problem that really needs to be addressed. There are lots of species of plants and animals that are disappearing forever to continue with this urban sprawl. In many places natural predators are being wiped out due to them hunting domestic animals like pets or livestock. This is good for the animals that do not bother domestic ones, but other animals and their habitats, not so much. This is a huge problem in cities. There is little to no wildlife in cities, and that is a problem. It has been shown repeatedly that wildlife and biodiversity help with mental health and supporting a good environmental balance, so why don’t we implement it into cities, specifically high-density cities? So, what solutions can we come up with for this problem?  
      
          Before we delve into practical solutions, we must know what these things are and how to implement them. Let us start with high-density cities. You might have heard this term being tossed around in conversations about sustainability. A high-density city can be compared with normal density. High density cities are cities that have a higher concentration of people in small areas. Think of it this way. You can fit more people in an apartment building than four single-family homes, even though they might take the same amount of land. The apartment building has a higher density than the single-family homes. And because of this saved space, there is better public transportation, so many of these people that do not have cars are always 20 minutes away from anywhere they need to go in the city. This is also a scalable way of building because there is not really anything new, it is just building more apartments and expanding transport systems. What is happening in cities now is a combination of poor public transport with the fact that less dense luxury apartment buildings are popping up with the prices of more dense apartments going up, which means that our cities are getting less dense. To make our cities more sustainable, we need to increase the density of the cities, while making more efficient transport systems.  
  
          The second issue is biodiversity. This is more of an environmental issue, but it can help with urban pollution and mental health problems. Biodiversity is a measure of how many distinct species of plants and animals there are in a place. A place like rainforests with their thousands of animals and plant species is more biodiverse than a city with weeds. What is happening with cities is that the concept of biodiversity does not even exist. The only wild animals are rats and pigeons. The only wild plants are mosses and grass. There is really nothing. The benefits of biodiversity are immense. There will be a lot more color to contrast against the gray background of the city improving mental health. More plants will mean better air quality. More animals will combat the bad noise pollution usually associated with cities. And humans will be connected to nature more, which is good mentally in the long and short term. So, what’s better than biologically diverse cities? Sustainable biologically diverse cities. Combining the benefits of high-density cities with biodiversity is a recipe for happier, sustainable, and scalable cities that people will prefer living in. The only question is how will we do that?  
  
          When thinking of solutions like this, we cannot think of some 2050 technological utopia that will never happen and only be reduced to sleek animation and professional PowerPoints. We need solutions that we can implement right now, without cities coming together to create overly ambitious goals that will never go anywhere (at least with biodiversity). Let us focus on population density. Making roads smaller is not necessary when we are on this step. The solution is not to get rid of roads, but to manage them better. The lanes closest to the curb will be for walking, go further one more lane and you have the bike path, go further one last lane, and you have a bus path. There can be sidewalk bridges to get to the bus stations at the bus path over the rest of the road for easy access. The buses would also run-on electric power. We could implement guerilla gardening in between the sidewalk and road to plant visual and edible plants and to add a splash of color to our roads. We could even create a barrier between roads with these guerilla gardening tactics. The design for a block, block in this case meaning living quarters and basic amenities, could be a block center in the middle, with apartment buildings on the outside. Able bodied people can just walk, while others can take the bus. Sidewalks as always will be lined with several types of vegetation and small ponds or creeks to invite aquatic life into our cities.  
  
       Workspaces and entertainment areas are going to be different. Or at least different in the way they are constructed and connected. Instead of being shoehorned into existing areas, they will have their own districts reachable by train. These districts will be based off the radius of blocks. For example, 20 blocks would be in a district, and that district would have its own business and entertainment places. The train system would work in a way where in every district center, there would be a train station. Then with the public transport network, you could make your way to these business and entertainment places. Office buildings will be built in a way where multiple small businesses can be in the same building. These buildings will be optimized for high-density living, which means mostly cubicles. The public transport network will also be optimized. Since the city will be in different districts, you would have a few metro lines going through clusters of districts, so the bus/bike transportation systems will take you elsewhere in the city.  
  
       Waste management will be a critical issue surrounding the sustainability of the city. This problem cannot be dealt with by pushing all of it inside of a landfill. That will hurt us and the planet, so it is not a promising idea. An idea that might work though is controlled burning. We could bring a bunch of trash to a closed facility and burn it. The fumes will be used to spin a turbine to produce power. Another idea is to compact it. We could use giant compactors like the ones used to compact cars to compact our garbage. This will allow us to harvest methane gas from it to produce electricity. In fact, if we combine both ideas, we could compact a month's worth of trash, collect the methane passively, and when it comes time to burn, we could make power from that, while increasing available space for the facility.  
  
      A lot of emphasis so far, has been placed on plants, but not much on animals. We could implement pre-built nests to attract birds of prey to deal with rodent populations. On the city perimeter, we can dedicate hundreds of acres of land to nature. We can reintroduce natural predators. We can fence off the city and stop them from killing our domestic animals, while keeping populations of deer and other animals in check. We can also introduce non-harmful snakes and educate people on how to coexist with them. As mentioned before, we can introduce mini ponds filled with decorative and edible fish for aesthetics, and to support plants. These are just some of the many things we can do to invite animals into our cities.  
  
      My solution is by no means perfect. This does not even hit every problem of modern cities. There are a lot of things that must happen to make this possible. For example, better access to foot powered travel, and mass reeducation about animals and safety, but I think this is possible. Just imagine a world where this exists. You wake up and look outside to see a majestic falcon flying across your window. The obesity rate is lower because everyone is getting a healthy amount of exercise from walking everywhere. Rats and other pests are not an issue because there are natural predators keeping their populations in check. No one minds these predators because they have all been taught how to coexist with them. People are happier and more connected to nature, meaning rates of suicide, depression, anxiety, and other mental health issues are lower. It is a city where you can go anywhere within 30 minutes. It is a city that breathes with nature and welcomes it instead of pushing it away. It is a different city. It is a sustainable city. This city will undoubtedly have people living happier lives and will lead them to better health. But imagine if we could go further with this. Imagine if we could make these cities self-sufficient. Imagine if the city was taken care of by the people generation after generation. Imagine if all those plans for “green cities” were not cited from eco-modernism with innovative technologies but used some pages from the past to print the future. What if we can blend an eco-conscious way of living with the high-density goodness of cities? This is a real concept, and in many parts of the world it is either already a thing or being adapted into the future. This is what I and lots of people are starting to call: Solarpunk.  
  
      Now there is another sector that we need to look at when planning our eco-friendly city. And that is permaculture. Permaculture is a way of using land that is in line with natural cycles and processes. Permaculture can be used for centuries to make sure that humans will always be taken care of by nature and vice versa. Keep in mind, these solutions are more a part of a Solarpunk level city, but their solutions already work in other places. When you look at examples of permaculture, you will wonder if this can be adapted to a first-world concept. Well, it can! Take a fridge for example, you might think that they can run only on electricity, but there is another way to keep your food cool. A bunch of people have figured out how to make a pot-in-pot fridge. You pour sand into the bottom of the bigger pot, put the smaller pot in, add sand all around the smaller pot, pour water into the sand, dip a cloth in water and cover up the small pot. The small pot will get cooler, then you can store food in it. This can be done on a larger scale with full or mini fridges. But the magic of permaculture really comes in with community solutions. Take food forests for example. It is a forest with a lot of diverse plants and (sometimes) animals that work together in harmony and humans can harvest from it. It functions like a real forest, meaning it requires little to no maintenance. But you might think, this is good for food and all, but that can be sourced from other places, so what good does this do for the city? And I answer that question with wastewater treatment. The whole food forest can be a giant biofilter. There is going to be a lot of water used, because humans use a lot of water, but plants clean water. We can use the food forest to turn our waste into food. We could do it by rerouting wastewater to the roots of the plants in the forest. All the bacteria on roots and in the roots, themselves will take all the pollutants out of the water and reuse them for nutrients in the food.  
  
     You might be wondering: How will we produce electricity? Well, the answer lies in two parts. First, we must reduce the amount of electricity we use using methods that do not require that much electricity, and secondly, we must produce more individual electricity than communal to encourage sustainability. For example, take cooking for example. There are diverse ways you can cook without electricity or natural gas, for instance, solar ovens. They redirect the sun’s rays to heat up food. They require only the sun to work. It is also a low-cost solution to our food problem. You might counter with “What if the sun doesn’t shine? Well remember the food forest waste-water treatment system I was talking about earlier? The system does not include solid waste in the cycle to form clean water, so what happens to it. There could be a system that separates solid waste from liquid waste and stores the solid waste in a vat to harvest the methane gas which could be burned for heat. Or just turn the waste into balls of dung to act as coal blocks. Heating and AC will be checked by the sun using Earthship building techniques. Washing and drying clothes is also something to be addressed. Drying is easy. Just hang up your wet clothes over a water collector to flush it to waste management systems. But washing is a new problem. One that I think I can solve. The basic idea is to take a clay pot and fill it with dirty clothes, water, and soap. Then, stick pieces of wood around the clay pot so it functions as a waterwheel. Put our waterwheel on a fast current (maybe clean water just entering the house), and you got some clean, no energy washing. It is always a clever idea to reduce the amount of electricity we use, but somethings we just cannot. People will always use their personal devices, and you cannot run them on sunlight. So, the answer is just clean energy. Just put some solar roofs on and the extra energy problem is solved.  
      
      All of this is great, but it leans on one principle: Take care of the city for future generations. This might be the hardest challenge to overcome when building this bright future because most people are not even thinking about tomorrow, so how will they think about their descendants? How will we create a culture where it is the norm to think about the future, but it does not weigh down on us so much that we abandon it and go back to our old ways? The answer is education. School can have a lot of effects on the future of the children it teaches, (some of it being bad) and that is what we want to take from it. We need to find a way to educate students so they will remember what we teach them for the rest of their lives. An effective way to learn things is just to do them. Their city has all the things that they need to take care of when they are older, so when it comes to teaching them to take care of it, the subjects are only a walk away. They could teach elementary children how to take care of plants. They could teach middle school children how different wastewater treatment methods work. They could teach high school students how to grow food forests and how to pass down these teachings down to their children. It will be in this education that kids will learn how to care for the place that they live in so descendants of theirs can live and take care of their city and habitat for generations and generations to come.  
       
      Overall, if we want to make our world sustainable, cities are going to be a big part of that effort. We need to investigate ways of making them more densely populated and easier to move around. Making sure that we include nature in it too makes sure these cities are not just preferable to live in, but will help the health of not only the humans living in them but the environment and habitat they live in. Then there is Solarpunk, making waves in city design and living. A solarpunk city is less of a city and more of a living ecosystem built by permaculture and based on the principle to give back to the other generations. Building a city so blatantly different to what it is usually seen as is the spirit behind it. Introducing old ideas combined with new thinking with a little (okay a lot) sprinkle of time can make this a reality, but what I do know is that it is inevitable. Making sure that all these things are in balance while also catering to the first world treatment that cities are expected to have while also redefining what a city should be and look like will be tough, but I know that it is possible. We can build a world that can accept nature and learn to grow (pun intended) with it to make a world that cares about what brought us here. That is the future I am envisioning and what I am trying to make a reality. The question is, will you do too?