narrator: on this episode of "earth focus," two cities-- freetown, sierra leone, and san francisco, california continen apart, vastly different culturally and economically, yet facing the same struggle to adapt to rapid urbanization, all set against the backdrop of a dramatically changing climate. changing climate.

man: oh, no! woman: the red cross says more than 600 people are now missing and that more than 200 have been killedafter heavy rain caused a severe mudslide

in test african nation of sierra leone.

[car horns honking]

[insects chirping] amarasekaren: oo oo oo! wht's happening? what's happening? no big problem, huh? ok. when we get problem...

man: whoa! [men shouting] [indistinct conversation]

narrator: while freetown residents fight for accountability, in san francisco, climate change isn'ta d as much as it's mitigated. billions of dollars are pourininto the bay area, but prepared for a sea level that's rising? scholl: san francisco is experiencing a tremendous building boom and has be for the last 5 years. tam: we have ucsf hospital. we have the warriors coming. we have a bunch of new apartment buildings.

scholl: you have corporate headquarters of facebook, google, microsoft. christensen: we realize we live in such an amazing place with so much creativi and innovation. i'm excited when i see the young people in the tech industry all over town,ll over the bay area commuting back and forth. there's an energy here. renteria: in mission bay, everyone pretty much works in tech, working on the next start-up. woman: i have 3 cappuccinos for here. renteria: i'll do a coffee. ok. thanks.

i'm considered a millennial. we kind of are free spirits, and we don't believe souch in just full-time gigs. i work in social media marketing, so it's definitely a new industry. a lot of people don't quite understand t i run social for a living. the really cool thg about a job in social media or just tec ithat you can work remotely. coffee shops are free. yes, san francisco is really expensive. there is no other place like san francisco where y're going to have access to the technology, to the communities, to just the people working in the industry. it's just one of a kind, and it's totally worth it. i sold car, and i pretty much walk everywhere now, and i got rid lot of stuff, and i live in a very small apartment , but it's totally worth it just to have access to everything. >> cheers. renteria: i just learned about the sea level rising, and i didn't know about that

before we moved here. does it concern me? yes, because i eventually want to buy property here and have a family here, but i didn't know about that, and i'm not too informed, so it's not something that i'm really too concerned about rht now. i am scared now, though, learning that that's a possility. christensen: people under 40 living here in the bay ea today are very, very likely to see unprecedented annual flooding around the bay in their lifetimes. jacob: it's going to be fantastic in a city that is so vital and known for its' innovation that're going to be able to build this great venue here. christensen: a lot of these new buildings by the end of the century, including the golden state warriors' new arena, would

ve the ground floors at least potentially flooded or basement parking flooded. contemplating maybday putting in flood gates so that their garages don't flood. they're thinking of raising pedestrian access so that it would be out of the water. san francisco itself, you know, built a seawall in the late new land that had been created.s you know, right now, san francisco is looking at spending $5 billion to repair and rce that seawall for another century. scholl: the areas that have been the least developed historically are the marginal lands around the bay, some of which are salt flats. others are abandoned pis,

and they're being rehabilitated because there's basically no place else in the bay area to build, and they're being built upon as quickly as possible by mostly megacorporations that a trying to maximize their value by building very expensive developments. me, it feels like sort of climate denial light. we found in 2015 that $21 billion's worth of development was happening rightst in that c zone. there is a tremendous amount of money to be made t to develop iose areas. by the year 2100, we found, there's a threat that sea level rise couldon a really bad day, a flood land all around the bay exactly where most of the waterfront development is happening, and then 're going to have to figure out how to invest public dollars toect what we're building right now. tam: mission bay was once a bay.

it was an of the bay. it was marshy and brackish and kind of shallow. mission bay is finally getting built after many, many years of planning andgreements around infrastructure. there are some really importantt instns that are there now, new commercial buildings, as well. it's an area that is rapidly becoming a part of the urban fabric of san francisco where it really was once seen as, like, a strange and unoccupied place, but, because we planned it ina era before we were thinking of sea level rise, it's also very low-lying, and it's one of the city's more vulnerable places to future sea level rise. scholl: the problem is that the land is so valuable because it's now nd. development companies couldn't not build there. therrswere billions of dol in real estate to be had, but they built it in obably one of the worst places they could have. it was a bay in the past, andik it mosty will be a bay in the future. tam: we picked this part of

the shoreline for a study aroung deconcepts for future sea level rise because it's the lowest lying area on the eastern waterfront. it's the place that's going to flood first, and so we thought it was the right place to spark a conversation around what are design alternatives or choices that can make in the future at the mouth of mission reek near at&t park. we'll have a really beautifulfu public ace that people might not even realize is designed for flood protection. aneally, we would have we habitat and parks and a place bhere people can access t. we want to have a lot of commercial activity in our city. we definitely need more affordable housing to solve some of the bay area's biggestch llenges, but alongside that, we have to do something about fute sea level rise. ideally, we'll have a lot of people enjoying the waterfront, have some kind of way of protecting people through some kind of barrier or just because we have shallowed the channel in some way that makes it no longer

super thing when there's a super high tide. herrera: the science is undeniable. climate change is altering our planet, placing many of our communities at risk. we must prepare for a future that directly confronts these cnges. the defendants are chevron, exxon, bp, shell, and conoco phillips. these funds will be used to pay for seawalls and other infrastructure needed to we have some real risk that's going to require some billions and billions of dollars of investment byan francisco on infrastructure if we're going to stop catastrophic loss, so that's what we're looking at. a lot of our developments are occurring along the waterfront. our lawsuit is a part of that. i want to have this abatement fund that has been created now to ensu that we can fund the infrastructure improvements that we're going to need to ensure that those developments go forward without the

threat of sea level rise. scholl: politics in san francisco is funny. there are a lot of really on the other hand's probably not enough to prevent the business community from making things even worse right on the ront. christensen: we're going to have to adapt. it's going to take that creativity and enrgy and capital. e question of how do we balance that economic development, the investment in protecting it, with the needs of people and the environment is one that, you know, we're going to find ourselves asking over and or again here in the bay area and around the world.

sheila: wewe haven't made a burger in years. u yoys haven't cooked a burger since the 1960s? yes. you weren't born then, i know. we've been hearing that burgers have really evolve we're not in kansas anymore' that's a big burger. i' a big girl. marilynn: what did you think of the barber brotrs?r. ha ha! ohh, they were so cute! you know, "cute" is your favorite word yay! man: there we go. sheila: bruce, where have you taken us today? bruce: have you ever heard of a dosa? is there any chance that we could see how dosa are made in your tchen? i'm doing it! on be ht with me. yeah? how did i do on my first try? first try is ok, good. at the restaurant,er: the way he probably thinks he'sthat chef part of the family now. well, in my heart, he is. he marilynn: we' brass sisters. we have over 130 years...