narrator: the challenges facing our world are growing all the time. how do we build stronger economies with equal opportunities for all? how do we build a sustainable world for generations to come? how do we protect our cities and harness the power of technology for our common benefit? in this series, using the latest bloomberg research and analysis, we will make sense of the problems of tomorrow. inequality, sustainability, artificial intelligence, the

gender gap, and the demographic time bomb. and in this film, how we manage our megacities. millions of people every year swell the planet's cities. can we harness economic potential of these hubs, or are we creating centers of poverty, inequality, and violence? ♪ narrator: this is the age of the city. for the first time in human history, more people live in urban than rural settlements. the world's urban population is growing by 70 million people each year. 301 cities account for 50% of global gdp. this will rise to 66% by 2025. so if we don't get things right in our cities than the consequences for humanity are

profound. james hertling: cities are critically important to the global economy and to progress in the global economy. cities can be sources of chaos, as well as development. narrator: this makes them so alluring and so vital. they can be dangerous places. but cities are where fortunes can be made. >> one of the primary factors driving urbanization is opportunity. you live on a farm, and you are growing crops -- you don't have a lot of opportunity. you see a growing, bustling city, your friends are moving there, they are getting jobs in offices, maybe jobs in a manufacturing center, there are restaurants, culture, life. this is attractive, something

you want to be a part of. james hertling: everything is relative. they will have greater access to schools, greater access to employment, greater access to health care and a less vulnerable economic life. ♪ narrator: in 1900, 12 of the world's biggest cities were in north america or europe. 100 years later, this number had fallen to just 2. most of the biggest cities in the future will be in the developing economies of asia and africa. >> most of the growth in cities will be in china, india, and nigeria. those three countries alone will account for 37% of the world's population. staggering numbers. here is an example -- lagos, the biggest city in nigeria. its population every year it is adding the equivalent of boston. >> the urbanization rate in the u.s., japan is over 70%. in china, it is 50%.

so china may have a lot megacities, they may have larger cities, but they are going to get bigger or there is going to be more of them. that is going to be a trend. a lot of emerging markets are going to experience trends like that in the next 50 years, especially with a large population. narrator: this incredible rate of growth makes the challenges of managing a large city more difficult. james hertling: the biggest risks facing cities are the same risks that challenge all of us, politically governing, climate change, economic inequality, productivity, economic growth, employment, education, transportation. those issues that face cities are the same that face everyone, except in a much more concentrated way.

narrator: one city battling with these problems is rio de janeiro in brazil. alessandra orofino is on the front lines, trying to solve them. she believes the world's biggest cities are in danger of sinking under a tide of poverty, decrepit infrastructure, and citizen apathy. and unless we do something about it, billions will suffer the consequences. alessandra orofino: the kind of urbanization we have today can only go so far. if we do not change the way we design our cities and make cities change with us, we will have serious limits to urbanization. they will become impossible to manage, impossible to live in, miserable places to be. if we change that process, those limits could change and possibly be nonexistent.

have to think about the environment and how we can better build them together. ♪

narrator: managing megacities is one of the great challenges facing the world. this is rio de janeiro, brazil. nearly 12 million people crowd into its metro area. it is beautiful and vibrant. but it also has its problems. crime, inequality, and poverty. alessandra orofino is an urban activist and thinker who has lived and worked in megacities on three different continents. she has worked with united nations on sustainable developing goals and founded, meu rio, an ngo that uses data gathered from citizens to raise campaigns and solve issues posed by the rapid growth of the cities. meu rio has 170,000 activists. alessandra hopes it can be a model for other rapidly growing cities around the globe.

alessandra orofino: we build on a rich tradition of activists and try to bring it to the world that make sense to people. i was born in this city. in rio de janeiro. my family has a mixed background. my father comes from a neighborhood in rio that was quite dangerous in the 1990's, quite poor, or lower middle class. and my mom comes from a wealthy background, one of the best neighborhoods in rio. it taught me the city can be amazing, but it can be very rough and unequal. that is not just a characteristic of this city. it is something we are increasingly seeing in cities around the world. narrator: rio de janeiro is similar to many emerging megacities. some neighborhoods are as wealthy as any other on the planet. others remain impoverished and

cut off. bridging this gap will, alessandra believes, have profound benefits for us all. alessandra orofino: cities bring people closer. they have the density in them. they are the places where most innovation will naturally happen. it's hard to innovate when you are always talking to the same people and hearing the same thoughts. cities are the exact contrary of that. they are natural hubs for innovation, natural hubs for economic growth, and they tend to be the engines of growth in most countries. narrator: but when the growth is rapid and unplanned, the results are gridlocked streets, poisoned air, and an infrastructure that simply cannot cope. alessandra orofino: i come from a city that expanded too rapidly for sure. how do you create sidewalks, schools, mobility systems to cater to a growing population? if that rapid urban expansion is happening in environments where inequality is paramount, the

challenges are even bigger. narrator: in a megacity, one of the biggest challenges can be simply getting from a to b. alessandra orofino: our mobility systems, in general -- very few exceptions -- suck. when you have a poor mobility system, you preclude entire segments of the city from living the city. from actually accessing the opportunity and the beautifulness and the amazingness that city has. because it is hard for them to get around. you also preclude the rich people in the city from getting to know other areas of the city, which can be exciting and fulfilling experience in itself. so you are creating a city in which everyone is living in their own territory, which is terrible. narrator: at the forefront of these infrastructure problems are the city's poor. they can become physically cut off from the economic opportunities living in a city provides.

alessandra orofino: it includes rapid expansion of cities. the fact that in the developing world, one third of the population is living in slums, something none of us should accept as we grow and think about a planet in which we want to live. narrator: slums are a result of rapid, unplanned expansion. today, an estimated 863 million people live in slums. if the slum dwellers in india were a separate nation, they would be the 13th most populous country in the world. but slums are not always hopeless places. alessandra orofino: the poor are not just sitting and waiting for the government to do something for them, they are creating their own environment. in rio, most of that infrastructure was built by them. so there is a level of do-it-yourself that you see in more poor neighborhoods than neighborhoods precisely because

the government wasn't there. narrator: this means slums must be handled delicately by urban planners. alessandra orofino: what do we do with areas that were developed by communities but lack infrastructure? even if we are assuming goodwill, in terms of how we handle them, if the only thing we want to do is provide those areas with quality public services, there are choices that have to be made. which pieces do we leave, which pieces do we change? if we don't handle that process in a way that is human and intelligent and is aimed at protecting the interest of the poorer communities, we can end up with massive rates of dislocation and destroying an urban fabric and social fabric that is so important and so vital.

here in rio, we have santa teresa, a neighborhood with a tram. it is beautiful. most trams in rio were destroyed earlier in the 20th century. this is something that the neighbors organize and kept their trams. it was a forgotten neighborhood for a while. it became a lot poorer. in the past five to six years, it has been gentrifying. the government decided to turn the tram, one of the remaining parts of the city, into a tourist attraction. but the only reason why the tram still exists is because we organized and kept it here. they created the value. narrator: alessandra believes

cities often ignore creativity. the result is a democratic deficit, which erodes faith in the city government and alienates already vulnerable communities. alessandra believes cities must take citizens with them if they are to expand successfully. alessandra orofino: what we definitely have not got right is the process by which we involve citizens. i have not seen one case of a city that has used the collective intelligence of its citizens and distributed power to make it. when we get that right, we see a lot of other issues we see. narrator: but for us to truly harness the power of our cities, we need to heal the divisions within them first. alessandra orofino: if we keep building unequal cities, these cities are not very good to live in for most of their population, i don't think we can hope to be happy in these urban spaces.

the worst-case scenario would be cities that do not have a soul and become less and less attractive to entrepreneurs, for people who want to create new economic activity, and ultimately become less wealthy. narrator: across the ocean from rio, another giant city is growing. lagos is now the most economically important city in africa, but its growing pains that are excruciating. and threatening the futures of 21 million people.

♪ narrator: more people live in cities than ever before. but many of the world's biggest cities are struggling to cope. lagos, on nigeria's atlantic coast, is the largest city in the world without a citywide rail system. meaning everyone has to travel by road.

for workers, like abraham cole, his daily commute takes over his life. >> what time did you wake up? >> this morning, i woke up like 3:00, 3:30. i usually do not do breakfast. narrator: in three years, the population of lagos has nearly doubled from 11 million to 21 million. but this staggering expansion has overwhelmed the city's impoverished infrastructure. >> how long will it take? >> it should take me for five minutes to get to the office. >> in full rush-hour, how long

does it take? >> 6, 7 hours in traffic. three hours going, three hours coming back. it is much worse coming back. coming back is something else. i don't think i want to waste seven hours of my every day time for the rest of my life. narrator: lagos is currently ranked in the top five least livable cities in the world. but although the city's economy is bigger than kenya's, simply getting to their desks is a daily ordeal for millions of workers. >> when do you see your children? >> weekends. weekends only. sometimes i see them during the week, if they really want to see me. and they came to see me. sometimes, they miss me that much. >> it must be quite difficult. >> yes, it is. but it's that we have to do. for now. ♪ narrator: like millions of lagosian workers, abraham's first act after getting to work in the morning is to take a nap. >> welcome to my office.

>> what are you going to do now? >> i think i've -- it is 7:10. so i took a nap for 30 minutes. and get ready for work. narrator: 2000 people migrate permanently to lagos every day. straining the city's infrastructure further and expanding the city from the land to the sea. the result is slums like makoko. a floating settlement on the city's lagoon. ♪ james hertling: infrastructure has not kept pace with the population growth. so basically of quality of life, access clean water, for example, access to electricity are limited. so before you even get to issues related to growth and developing, lagos and nigeria have to sort out more basic issues of infrastructure.

narrator: makoko is the oldest slum in lagos. 80,000 people live here in buildings sitting on stilts connected by a complex system of canals. james hertling: successful cities find ways to deliver services to even the most deprived. that is the challenge, especially in the developing world, where resources are at a premium. narrator: in makoko, residents have developed their own infrastructure, including freshwater and electricity. and this three-story floating school, which doubles at a community center, is the latest addition to this unique environment.

the school was completed in 2013. it is cheap and easy to build. its designers hope it will be a template for future buildings in makoko. james hertling: makoko in nigeria raises interesting questions of government and control. it has been a long ignored area. and the local residents took charge and tried to improve their own lot with schools and their own locally initiated development projects. but also the central government has decided it wants that area for its own development reasons. narrator: only a few kilometers away lies an alternative vision of how lagos may develop. not a grassroots community vision, but a grand project of incredible scale. eko atlantic.

david frame: where we are standing, we are in the alignment of the financial district. what we ll "eko boulevard." this is where all the major financial institutions will establish their headquarters and offices. narrator: eko atlantic is a multibillion-dollar residential and business district built on 10 square kilometers of reclaimed land. it is, in effect, a new city -- or it will be soon. its backers hope a quarter of a million people will one day live here, with 150,000 workers commuting from the old city across the water. david frame: when we initially thought about building eko atlantis, we looked at an area in london, we looked at dubai, and we looked at the heart of london, heart of paris, heart of new york.

obviously, the vast majority are wealthy people. i could not afford to live in the heart of london. but, in creating the residence for these people, you are also creating job opportunities. and it is the norm, here in nigeria, that if you create residential apartments, you also create orders for the domestic staff working for that family. you have to take into context that this is a city development. it is not a low income settlement. it is a business sanctum. primarily. this is the future. the first commercial development of lagos. there is no doubt of that. narrator: david hopes the first residential units will be open by the end of 2016, with the infrastructure of the whole site in place by 2022. >> projects like eko atlantic raise as many questions as they answer. especially from where local residents are aware that they

may be getting the short end of the stick. on the other hand, they really do lend themselves to starting from scratch and being able to build structures where there are schools, hospitals, offices, transportation facilities. and they give gigantic cities like lagos an opportunity to create a model of what can be, presuming they are planned and executed correctly. narrator: the future paths of megacities like lagos remain uncertain. organic, citizen-led growth like makoko, or large-scale planned developments like eko atlantic. what is clear is that left unchecked, growth could destroy city's immense potential. james hertling: i am an optimist

when it comes to cities. i grew up in new york in the time when we were on the edge of bankruptcy. here we are in the 21st century, and new york is booming and thriving. it is a tremendous place. you can see, with proper planning and a diverse and vibrant population, what is possible. alessandra orofino: i hope those little cities will be interconnected, in the sense they will have solidarity networks, there will be brazilian networks, and the citizens will feel like they're cities where they want to be. a project they want to build and they can move, visit each other, learn from each other. ♪

♪ ashlee: one of the basic truths of the human condition is that people love to float, and there's no better place to float than here at the dead sea in israel, where large mammals can achieve buoyancy. there is a ritual to doing it the right way. you need to cover yourself with mud, lather up, and relax with a