sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, hari sreenivasan. >> sreenivasan: good evening, and thanks for joining us. the united states and china today formally ratified a climate-change agreement that came from the u.n. climate conference in paris last december. it has already been adopted by more than 175 countries. in a ceremony today ahead of the "group of 20" economic summit in hangzhou, china, president obama and china's president xi jinping committed the world's two biggest economies to a course of reducing the carbon dioxide emissions that cause global warming. combined, the two nations generate almost 40% of the world's emissions. according to

sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, hari sreenivasan. this is pbs newshour weekend. good evening and thanks for joining us. president obama and leaders of the world's leading economic powers, have wound up the first day of the "group of 20" summit in china. this will be obama's last as president. before a banquet hosted by china's president xi jinping, obama had a full schedule of discussions on issues of vital interest to the united states. in his first meeting with turkey's president, recep erdogan, since a failed july military coup, the president alluded to turkey's demand that the u.s. extradite a pennsylvania-based cleric erdogan accuses of

sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, alison stewart. >> stewart: good evening and thanks for joining us. it happened 15 years ago today- the worst attack on american soil since pearl harbor- when terrorists hijacked four commercial passenger jets and used them as weapons against symbols of the u.s. economy and military. today, on this landmark anniversary, at three memorial sites, america remembered. >> reporter: the ceremony in new york marked the moment when the first plane hit the trade center's north tower. jerry d'amadeo's father, vincent, worked on the 103rd floor for the brokerage firm cantor fitzgerald, which lost 658 people that day. >>

sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, alison strewart. >> stewart: good evening, and thanks for joining us. the united states and russia are promoting a new plan to end syria's civil war, now in its sixth year, having caused half a million deaths and forced millions to flee as refugees. in talks in geneva, switzerland u.s. secretary of state john kerry and russian foreign minister sergei lavrov said a countrywide cease fire is scheduled to take effect at sundown on monday. it calls for government forces of president bashar al-assad backed by russia and rebels backed by the u.s. to stop shooting while humanitarian aid is delivered where needed. >>

sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, hari sreenivasan. >> sreenivasan: good evening, and thanks for joining us. we're coming to you tonight from the studios of ketc, our pbs affiliate in st louis, missouri. for the second time in this year's race for the white house, republican presidential candidate donald trump has publicly raised the specter of violence against his democratic opponent, hillary clinton. campaigning in houston, texas, today, trump was silent on the subject. but last night, at his rally in miami, trump stated incorrectly that clinton favors abolishing the second amendment right to bear arms. and then he said this: >> i think that

sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, hari sreenivasan. >> sreenivasan: good evening, and thanks for joining us. >> police in charlotte, north carolina, said this afternoon they would release their own dash-cam videos of tuesday's fatal shooting of a brack man, keith scott, this as people took part in a fifth day of protests. police chief kerr putney said it had been decided releasing the the videos would not adversely impact the investigation. he said he was in possession of a hand gun, in possession of marijuana, and had committed a crime. police shot and killed scott tuesday after in the parking lot of an apartment complex where he parked to wa

sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, hari sreenivasan. this is pbs newshour weekend. >> sreenivasan: good evening and thanks for joining us. hillary clinton and donald trump are preparing for a super-bowl- sized audience in their first one on one debate since becoming the major party nominees for president of the united states. the tv audience for tomorrow night's showdown at hofstra university on new york's long island is expected to top 100 million, with the candidates focused on the small percentage of voters who have not made up their minds. in an "abc news-washington pos"" poll of likely voters published today, clinton held a slight advantag

sue and edgar wachenheim, iii. barbara hope zuckerberg. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are 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, allison stewart. good evening and thanks for joining us. new york governor andrew cuomo says new york city was "lucky" there were no fatalities caused by last night's explosion in or near a dumpster on a manhattan street. a second, unexploded device found in a plastic bag four blocks away was "similar in design" and is being examined at f-b-i headquarters in quantico, virginia, along with remnants of the first device. >> stewart: shrapnel and flying debris from the explosion hurt more than two dozen people, all treated and released from local hospitals. evidence recovery teams worked the scene all day today. t