captioning sponsored by wnet >> thompson: on this edition for sunday, september 17: the florida keys re-open to residents forced from the their homes by hurricane irma. and later, big business and climate change. american companies change their ways, without government mandates. next on "pbs newshour weekend." >> pbs newshour weekend is made possible by: bernard and irene schwartz. the cheryl and philip milstein family. dr. p. roy vagelos and diana t. vagelos. sue and edgar wachenheim, iii. the j.b.p. foundation. the anderson family fund. rosalind p. walter, in memory of abby m. o'neill. barbara hope zuckerberg.

corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we're your retirement company. additional support has been provided by: and by the corporation for public broadcasting, and by contributions to your pbs station from viewers like you. thank you. from the tisch wnet studios at lincoln center in new york, megan thompson. >> thompson: good evening and thank you for joining us. the 80-thousand residents of florida's southernmost point-- the keys-- were allowed to go home today. for the first time since forced evacuations before hurricane irma. police let cars with residential stickers pass through checkpoints on route 1, the main road through the keys. when irma made landfall here as a category four hurricane seven days ago, it damaged or destroyed 90% of the homes in the area. >> the keys are not what you left several days ago, when you evacuated.

>> thompson: officials are warning residents to bring their own food and water and be prepared to camp out for weeks. >> bring your supplies, bring your medications. bring your water. bring your bug spray. bugs now are about to start coming out. mosquitoes, they are starting to come out. it is going to get worst in the next few days. >> thompson: today, sheriff's deputies went door to door encouraging thousands of residents of hernando county, north of tampa, to evacuate, due to the overflowing withlacoochee river. water has filled the streets and is as high as mailboxes in some places. and florida governor rick scott has announced new rules requiring nursing homes and assisted living facilities to have backup power generators. this, after eight residents of a nursing home that lost power died after the storm due to heat-related causes from the lack of air conditioning. 585-thousand florida homes and businesses remain without power. in the caribbean islands that bore the brunt of irma's wrath, cuba today deployed soldiers to clean up debris and downed trees.

all ready devastated st. maarten and st. barts received new hurricane warnings as "maria" is projected to become a major hurricane on tuesday. st. louis saw a third day of protests today over the acquittal of a white former police officer in the fatal shooting of a black driver back in 2011. generally peaceful protests yesterday turned violent last night, when a small group of protesters refused orders to disperse and smashed store and restaurant windows in a suburb near washington university. police arrested nine people, and missouri governor eric greitens says they could face felony charges. protests started friday, following the acquittal of jason stockley, who shot and killed anthony smith, after a high speed chase. an encounter recorded on police dash cam video. the judge ruled prosecutors failed to prove stockley did not act in self defense. he testified he felt he was in danger, because he thought smith was holding a gun, which turned out to be wrong. in britain, officials today

lowered the terrorist threat level from the highest, of" critical," to "severe." this after police made a second arrest related to friday's bombing on a london train. a 21-year-old man was taken into custody last night. police searched a home in a london suburb linked to the suspect, and britain's interior minister said his arrest suggests the bombing was not a lone wolf attack. the bomb, hidden in a plastic bucket inside a shopping bag, only partially exploded and sent flames through the train car, injuring 30 people. the united nations general assembly, the annual meeting of the leaders of the un's 193 member states, begins tomorrow in new york. on tuesday, president trump will deliver his first speech at the un, and in the past, he's accused it of "weakness and incompetence" and threatened to cut u.s. funding. to discuss what to expect, i'm joined by "washington post" white house correspondent david nakamura. so president trump, this is his debut at the u.n. and as we

mentioned he has never been a huge fan.can you talk about what his administration has been doing to kind of approach this meeting and what he might say often tuesday? >> sure, megan. i was at the white house, when his top advisors, including nikki haley, gave him abriefing. he has not been a fan, saying they have not lived up to their billing and costing u.s. too much on resources and relying on too much the u.s. to lead the way. but they expect the administration to show a leadership role ranging from things range being from north korea's nuclear threat and human rights which president trump has not talked about a lot. but what i think is interesting is if you look back to last year, president obama in his farewell address the u.s. had a

place to make a choice, marking the postworld war ii area or tribalism and building walls. we had president trump who campaigned on building a wall, the question is still whether he'll get that done or the dark world in the way he has talked about it in the past or will he reach out and talk about the merits of this world body. nikki haley has seen the speech, he session the president -- she says he stlaps slaps the right people and hugs the right people. >> despite tougher u.n. sanctions how do you think the ra north korean issue may play out? >> nikki haley said they were worried about dotting the i's and crossing the t's in resolutions at a were toothless

but oil exports to north korea and cuts on north korea exports is really going to pinch pyongyang but nobody expects that to change the cals cal includes for kim jong-un. he doesn't know how much the sanctions will help. but what you'll hear from the president is tough talk. he talked about military options being often the table and nikki haley said that as well, the question is what will that mean, what else would it take for there to be direct engagement with the regime in the north. >> what else should we be looking at this week? >> on iran, the president's meeting on monday with benjamin netanyahu from l israel, they don't think that the iranian regime is complying with the spirit of that deal and suggested maybe that they would seek to maybe potentially enact

more sanctions which would unravel that deal. there is a lot at stake for president. >> david nakamura. thank you very much. >> sure. >> thompson: this summer, when president trump withdrew the u.s. from the 2015 paris climate accord-- a voluntary pact to cut emissions of gases that cause global warming-- some opposition came from what is perhaps a surprising place: big business. in response, hundreds of large u.s. companies publicly pledged to reduce their reliance on fossil fuels and increase energy efficiency. in tonight's signature segment, newshour weekend special correspondent stephanie sy reports on some big companies leading the way. this story is part of our ongoing series, "peril and promise: the challenge of climate change." >> reporter: with sprawling

supercenters and close to twelve thousand stores worldwide, wal- mart, may be best known for low prices that local stores can't match. now, the planet's number one company by revenue, wants to be known as a leader in the fight against climate change. >> at wal-mart, sustainability really is core to our mission. >> reporter: kathleen mclaughlin is wal-mart's chief sustainability officer, she's charged with selling walmart's climate vision to shareholders. >> it's critical for business. it's important for customers and for communities. we're seeing effects already in things like supply security of different food commodities. >> reporter: wal-mart's response to climate change began more than a decade ago. in 2005, then c.e.o. lee scott pledged to curb wal-mart's emissions of greenhouse gases like carbon dioxide, which cause the atmosphere to trap heat and warm the earth. scott started moving the company toward clean power sources like wind and solar, with a goal of eventually getting 100% of its energy from renewables.

>> it was a realization about capability and about scale and about how we can use that for good. wal-mart has unique assets as a retailer, just given the reach that we have across categories, the reach we have across countries and across suppliers, and the recognition that we could bring those capabilities to bear on the most pressing social and environmental issues that our customers face in ways that are really relevant for business. >> reporter: wal-mart, headquartered in bentonville, arkansas, began by improving the fuel efficiency of its vast fleet of trucks that deliver goods to its stores. >> so mike, when you're ready, we'll crank it up. >> reporter: using a simulator, wal-mart retrains its truck drivers on gear-shifting to increase their fuel savings. operators can have up to a 30% impact on fuel efficiency based on how they drive, and their job performance is judged accordingly. the company says, improved driving and upgraded trucks have saved the retailer nearly $1

billion since 2005. >> wal-mart has been the driver of a lot of new technologies in the energy efficiency space. >> reporter: mark vanderhelm is wal-mart's vice president of energy. wal-mart has saved energy and money in its store operations by demanding more efficient equipment from vendors that provide its lighting, refrigeration, and heating and cooling systems. in its push for more renewable energy, the company has installed solar panels on the rooftops of 364 wal-mart and sam's clubs. that's only about 8% of all its stores in the u.s., but the panels make wal-mart the nation's second biggest commercial generator of solar power. >> the biggest challenge in the u.s. is making it economic. we would love to see more availability of renewable energy sources that is at price parity with other sources. >> reporter: in other words, wal-mart's ambitious energy goals aim also to save money. so, in its home base of arkansas, where a lack of state

government incentives for renewables make conventional fossil fuel power cheaper, you won't see any solar panels on the local wal-mart stores. while the company has pledged to be 100% powered by renewables, it hasn't said when, and right now only 17% of walmart's domestic power comes from renewable sources. to provide guidance in achieving its climate change goals, wal- mart has partnered with the environmental defense fund, or edf. fred krupp is the group's president. is wal-mart doing enough? >> the scale of wal-mart is hard to wrap your head around. they have 220 million people shopping there every week. in the united states, they sell about a third of all the food that we buy at retail stores. they can always do more. but what they have shown so far is a serious commitment, and the journey is an ongoing one of improvement.

>> reporter: jenny ahlen is an edf supply chain specialist based in bentonville, arkansas. >> the things that we buy and consume and how they are made and used and disposed of have a huge impact on the planet. so, grocery is contributing half of all greenhouse gas emissions in the u.s. retail sector. and that's due to both the volume, but also the high level of greenhouse gas impacts embedded in that food. >> reporter: and wal-mart is the largest grocer in the world? >> they are. >> reporter: so this is a hot spot. wal-mart's mission has grown to not only reduce its own stores' impact on climate change, but to compel its tens of thousands of suppliers to transform their practices. at wal-mart's urging, edf helped pork producer smithfield to optimize fertilizer use on crops used to feed its pigs, reducing the amount of the greenhouse gas nitrous oxide released into the atmosphere. the reductions by smithfield and other suppliers contributed to wal-mart taking credit for meeting a goal, in 2015, of

reducing emissions by 20 million metric tons, the equivalent of taking nearly four million cars off the road for a year. wal-mart's newest initiative is called "project gigaton," which aims to persuade suppliers to remove 50 times more greenhouse gases, or one billion metric tons, by 2030, about the same amount of pollution as germany emits in a year. wal-mart, known for squeezing suppliers to keep prices low, is putting a green squeeze on them now, though one that's voluntary. >> it sends a message to their 100,000 suppliers all around the world: if you want your products on our shelves, cut your pollution. >> reporter: 90% of wal-mart's overall greenhouse gas impact comes from its supply chain, and dozens of its major suppliers have already signed on to project gigaton. wal-mart hopes that encouraging its suppliers to cut emissions will have a multiplier effect. one of those participating suppliers was already forging

its own path to sustainability. the candy maker mars, inc, best known for m&m's and snickers bars, has set an aggressive target of using "zero carbon" in its operations by 2040, eliminating all greenhouse gas emissions. >> field is actually 18 acres, so it's pretty big. >> reporter: barry parkin, mars's chief sustainability officer, showed us the vast solar farm in new jersey the company built eight years ago. it now provides about 5% of the power used by the mars chocolate factory in nearby hackettstown, which churns out half of the m&m's sold in the u.s. parkin says the falling price of renewable energy technology, like solar, makes the investments pay off. >> we've done this at cost parity or better. in some cases, our costs are now lower as a result of using renewable energy. >> reporter: so, we're not going to see the price of m&m's skyrocketing because mars has made commitments to the environment? >> no, absolutely not. so, this is not just good for the environment. it's good for mars.

it's good for consumers, and it's also good for the landowners that we're working with. >> reporter: mars has a long- term contract to buy the power produced by this massive wind farm in west texas-- enough to offset the electricity used in its entire u.s. operation. parkin believes that global efforts to curb climate change will eventually lead to fossil fuels becoming more expensive. >> we believe there will at some point be a price on carbon. we're thinking long term, we're thinking that if we are ahead of the curve here and we're reducing our carbon footprint in line with the science faster than our competitors, then we can have a competitive advantage. >> reporter: food companies like >> reporter: this month, mars announced it is investing a billion dollars over the next three years, in part, to help its suppliers reduce carbon emissions, including hundreds of thousands of small farmers around the world. mars hopes the effort will help the company's supply chain reduce emissions by 67% by 2050. the risks of climate change to

>> 70% of the world's cocoa comes from a small region in west africa and all of the climate models say at a that region is going to become drier and that is not good for cocoa. so those millions of farmers there all the predictions there say they are going to start to struggle. >> the risks to climate change to business, goals, the report released this april by several environmental researchers found energy efficiency projects saved these companies nearly $4 billion last year. in addition, after president trump pulled the united states government out of the paris climate accords, wal-mart and mars were among the companies that signed a letter pledging to continue to meet their voluntary targets. but wal-mart's growing business may be in conflict with its

sustainability mission. wal-mart's total retail square- footage has expanded by 43% in the past decade, and along with it, its self-reported carbon emissions went up 9%, even as the pace of its emissions slowed. wal-mart is still building new stores. it is still increasing its carbon footprint. how do you answer the broader question of whether wal-mart can ever be truly earth-friendly? >> we're expanding our footprint, but we believe that our model, so the way we manage our own store operations, the way we work with suppliers, actually optimizes and lowers the footprint to deliver the same amount of product to people. if you look at the scale and ambition of our efforts and what we've actually achieved, i'm actually quite excited about it. >> reporter: by 2025, wal-mart says it plans to reduce its carbon emissions by 18% from its 2015 levels. as ever, the company that has

transformed communities and consumers is striking a path, and expecting others to follow. >> a growing number of political activists are protesting with projection art. read more on our website, pbs.org/newshour. >> thompson: the special counsel investigating russian meddling in last year's presidential election has obtained, though a search warrant, records of russia-linked ads posted on facebook. some by inauthentic profiles. that disclosure, first reported by the "wall street journal" and cnn this weekend, follows a story published thursday by" propublica" that revealed how facebook advertisers could target ads specifically at anti- semitic users. yesterday, newshour weekend's hari sreenivasan spoke with one of the authors of that article"" propublica" reporter julia angwin. >> motion people don't buy ads. how does ad buying work on

facebook? >> you go in and say i want to buy an ad and they offer you all sorts of options, ages, city, zip code. you can 95 thoughts, like i want people who listen to bon jovi or have nose rings. >> sreenivasan: what did you do? >> somebody gave us a category they said there was one jew haters. there are 2200 of them you can target, we thought, really? so we bought an ad, because we thought maybe would be an approval process where it wouldn't go through, but it went up there about one of the other bugs, maybe we bought another one, a third one just to make sure they went through and we decided they did have an ad category called jew hater. >> sreenivasan: there is a part of jury story suggested categories. >> right. when you put in jew space h it

suggests jew hater how to burn jews why jeus are in the world and it suggested other things that are related their top suggestion was the second amendment which was related. >> sreenivasan: are these phrases or categories that people have assigned to themselves? >> yes. it seems as though that these are fields of study and people had put in their profile their field of study was these things. everything you write in your profile where you fill out your interest, your police officers, whatever they turn it into an ad category. >> sreenivasan: they say listen it is not our job to censor. that's not facebook when you confronted them with that. >> they took it down, the categories that we mentioned but they also took down all self identified categories. they said we need to figure out how we can sift through these to make sure there isn't other

stuff in here. >> sreenivasan: how is this even fixable? there is no way that humans can sit there and look at every type of ad that every company across facebook wants to buy. >> it is a big data problem for sure but think about the big data problems facebook has rm caught actually. catching nipples and faces, i just not sure they have tried. >> sreenivasan: let's talk about the money at stake here. even if they shut the spigot off, this is serious money. >> yes, i mean facebook they have the most advertising dollars of anybody online. and that's because of this collection of all these teeny tiny micro-segments. if you add up all the micro-segments it is going to add up whether it is one or two pers of all their advertisers.

>> sreenivasan: julia anguin, thank you forking being here. >> it's good to be >> thompson: for fourteen year"" storycorps" has been recording and sharing real experiences of everyday people who have extraordinary stories to tell. in this animated installment, vietnam veteran tom geerdes talks to his daughter, hannah, about how the war changed him. >> what was the biggest change for you about vietnam? >> i wasn't worried anymore about being socially acceptable. from the day i got out i didn't shave or cut my hair for probably a year. and people that i knew before i left, even some of my cousins, didn't think too much of me after i got back. so i took a long bicycle trip. >> went off and got by yourself? >> yes. i rode straight north up to minnesota cut across and rode

all the way to the west coast. took me about six weeks. >> using that you sort of healed from vietnam on that trip? >> it helped a lot but really, i actually didn't heal from vietnam until quite a number of years later. i had a janitorial business. and i was doing floors at serious. -- at sears and they had a vietnam movie on there. and something just broke. and i cried. i sobbed like a baby for a couple hours. while i was finishing them floors, adjudicat just sobbed l. because it was several friends that i lost. it was just too much devastation that i saw. just too much hurt. and i really didn't plan on coming back. >> i'm glad you came back.

>> yeah, me too. me too. >> thompson: tonight, pbs premieres the ten-part documentary "the vietnam war," from directors ken burns and lynn novick. it features americans who fought in the war, those who opposed it, and vietnamese soldiers and civilians. tomorrow on "the newshour," part two of judy woodruff's interview with hillary clinton. >> one of the biggest problems in wisconsin has been the well- executed effort to suppress voters-- african american voters in milwaukee, young voters particularly in madison and elsewhere. it proved to be very effective. >> thompson: that's it for this edition of "pbs newshour weekend." i'm megan thompson. thanks for watching. good night. captioning sponsored by wnet captioned by media access group at wgbh access.wgbh.org >> pbs newshour weekend is made possible by: bernard and irene schwartz.

the cheryl and philip milstein family. sue and edgar wachenheim, iii. dr. p. roy vagelos and diana t. vagelos. the j.p.b. foundation. the anderson family fund. rosalind p. walter, in memory of abby m. o'neill. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we're your retirement company. additional support has been provided by: and by the corporation for public broadcasting, and by contributions to your pbs station from viewers like you. thank you.

they said, "what do i do with this money?" and i said, "investing is just about assigning yourself the right story." i didn't wanna go to college, but my dad wanted me to go to college. why did you come back to omaha? when i came back i had a about $175,000, and i thought that was all i would need to live the rest of my life. have you ever run into that guy again? no, he needs protection now. when you had your first annual meeting, how many people showed up at that? well, we had 12, but you had to count my aunt katie and my uncle fred. any word of advice you'd give to somebody who's a young investor who would like to emulate you? woman: would you fix your tie please? well, people wouldn't recognize me if my tie was fixed, but okay. just leave it this way. all right. [♪] [david reading onscreen text]