Relief is on the way but for many in the midwest it cant come soon enough. For yet another day millions were plunged into arctic temperatures which closed schools, grounded flights and proved downright dangerous. The polar vortex has already been blamed for multiple deaths, even breathing outside is difficult. The bbcs Chris Buckler is in chicago with this report. Chicago stands surrounded by ice and snow. People here are used to cold weather but these are temperatures seen only once in a generation. To try to keep the citys trains running, the tracks have had to be set on fire and boats have been attempting to break through the solid sheets of ice that cover the chicago river. The windy city has become the wind chill city. My fingertips have been frozen twice and had to take a pit stop twice. Toes frozen twice. So i made two stops. Its brutally cold, bitterly cold. You can actually see frost on your eyelashes. What does it feel like . Its a little cold. They froze and closed a couple of times. Across americas midwest, temperatures have dropped far below freezing. A huge part of the us caught in whats known as the polar vortex. Its pushed arctic air down from the north pole and left many places colder than the antarctic. From the air, Lake Michigan now looks more like land than water. People have been doing their own small science experiments to see for themselves just how cold it is, including this. Ive got boiling water in this flask and youll see, as soon as i throw it into the cold air, it just simply freezes. Further north, even parts of the mighty Niagara Falls have been frozen. This is a deadly cold and people have been killed in accidents on the icy roads and in some cases from just being exposed to these extreme elements. For another evening, centres have been opened to keep the homeless warm and safe. There is no shelter on the streets from these kind of conditions and the frozen beauty of this weather cant be allowed to distract from its dangers. Chris buckler, bbc news, chicago. And just a short time ago we checked back in with Chris Buckler for the latest in chicago. People are getting layered up with as much clothing as possible and trying to keep others off the streets. Here in chicago it has been pretty quiet in what is normally a bustling city. That is because so many businesses, so many schools and colleges have simply been closed. That is true right throughout the midwest. Because these conditions are frankly painful. Ive got my hood down at the moment and im close to shelter, but the truth is we are trying to keep as warm as possible, because your extremities, yourfingers, your toes, my ears, in particular, are really painful today standing out in this. That is true for everyone else. Of course, some people have died as a result of these cold, cold temperatures. Some of them have just been exposed to it. The truth is, you talk to some meteorologists and they tell you about ten minutes in the temperatures chicago has experienced in the past 2a hours could give you frostbite. The hospitals here have been dealing with people who have been suffering from frostbite. We have been doing our best to give people an idea of how cold it is. One of the things we have been doing is by using a t shirt. We wet this t shirt and brought it out of our hotel a short time ago. Within 60 seconds it froze completely. That is a t shirt that was just wet, and a cotton piece of clothing that has frozen in around 60 seconds as a result of the cold there is still here in chicago. At the moment it is around 20 celsius. That feels even colder with the wind chill. Something around 27 celsius. Chris, with a couple of polar party tricks and the team very much earning their money. The second and final day of high stakes trade talks between the us and china have concluded, in the oval office. Chinas leader xi jinping wrote to President Trump to say he hopes they will be able to Reach Agreement before a march 1st deadline, when new tariffs could take effect. This was mr trumps take on a possible deal. I think the relationship that we have right now with china has never been so advanced. I dont think its ever been better. But i can tell you for a fact its never been so advanced. And certainly a deal has never been so advanced. Because essentially we dont have a deal. We never had a trade deal. Were gonna have a great trade deal. But we never really had a trade deal with china and now were gonna have a great trade deal with china if it all works out. And we look forward to it. Its going to be great for both countries. Lets get some of the days other news. The us envoy for north korea has said pyongyang has promised to dismantle and destroy all its uranium and plutonium enrichment facilities, a commitment apparently made to the us secretary of state and to south korean leaders. North korea has made such promises before, and the us is seeking expert access to verify any removal or destruction. A court in the us has found the Syrian Government liable for killing the american war correspondent, marie colvin, and french photographer remi ochlik in an airstrike in homs in 2012. The Court Ordered syria to pay more than 300 million in damages. Its the first time the Assad Government has been found guilty of a war crime. A court in france has sentenced two policemen to seven years in jail for raping a canadian tourist at what was then the headquarters of the parisian judicial police. The case had been rejected in an earlier trial, but the victim waived her right to anonymity to pursue the case. A third man, whos not been identified, is also suspected of raping her. Venezuelas self declared interim president juan guaido has said his family has been threatened, amid the countrys political and economic crisis. In a speech at the central university, he said police had visited his family home looking for his wife. Eliza philippidis reports. Standing outside his apartment block with his wife and daughter, juan guaido said he wont be intimidated by agents of venezuelas special action forces. He has the backing of the United States, and they have warned of serious consequences if Nicolas Maduros government harms them. So the tussle for control of venezuela goes on. Translation we continue and will continue in the street on saturday to support and accompany the ultimatum that the European Union gave Nicolas Maduro and Start Talking very clearly to the armed forces and give some precise orders. We will order humanitarian aid to into the country. The eu have announced the creation of an International Contact group to include european and latin american countries. The aim to help chart a peaceful end to venezuelas political crisis and theyre hoping to do it within 90 days. The purpose of the International Contact group is clear. As i said, it is enabling venezuelans to express themselves, freely and democratically, through the holding of new elections. On thursday, the government of venezuelan president Nicolas Maduro announced that three air force generals have been arrested, accused of plotting an uprising against his government. Translation according to information obtained by our intelligence bodies, there was an arrival from colombia of a group of hired killers, hired by the venezuelan ultra rights to commit selective assassinations against politicians and military leaders. Workers from the state oil company held an anti imperialist march after the us slapped sanctions on the firm on monday in an attempt to cut off a vital source of funding propping up Nicolas Maduros government. Millions of people remain in poverty. Many have left the country looking for a brighterfuture. The United Nations said it is willing to step up humanitarian aid, but requires consent from the government led by Nicolas Maduro and, as yet, there is no indication that that is forthcoming. Eliza philippidis, bbc news. Earlier, i spoke with brian fonseca, director of the Jack D Gordon institute for Public Policy at Florida International university. Right now you have a stand off between legitimacy and power. Ultimately, you have many in the west who have rallied behind guaido. I think the eu today made an important announcement doubling down behind guaido. And, of course, on the other side you have power. You have maduro who still has a lot of control of the military institution. This where you will really see the showdown. This is where youve seen fights and other types paramilitary, ah, militia groups out on the streets in an effort to keep things under control. Given the pretty inglorious history of American Intervention in latin america, i guess that backing from other countries but particularly the us can be a poisoned chalice, it can make you look like a stooge if youre not careful. Absolutely. It is important that most of the hemisphere is a part of this. The United States are certainly launched this last week, followed by canada, quickly, and much of the rest of the hemisphere came online in terms of supporting guaido. They reached out hard to double down behind guaido. And the countries on the other side supporting maduro are quite few. Those you would expect cuba, nicaragua, bolivia. In this hemisphere, of course, russia, turkey, china, globally. But still far more limited than the western coalition that seems to be backing guaido at the moment. How effective do you think mr guaido can be . He says his family has been threatened. We know that he has been stopped from leaving the country and there has been a move to freeze his assets. On the other hand, he has been telling the New York Times that his team has been speaking to the military and the security services. Its an Interesting Development for him to mention that. Again, right now, all signs seem to point to the fact that the military seems to be behind maduro. For how long we dont know. But certainly there have been calls by the opposition to the military to essentially break with maduro. This is part of the amnesty provisions that were launched last week in an effort to try to compel many in the military to put down their weapons or back off from supporting maduro. Either in favour of the opposition or some form of transition that might see the exit of maduro. Knowing what you know about mr maduro, how do you expect him to play it from you . I dont know. Whether or not his time is limited will be dependent on military institutions. I think the military, right now, has been, remains, will remain a key to transition or continuity, change or continuity in venezuela. We will see how long the military stays behind him. There are certainly incentives to stay behind maduro. History tells us that the longer maduro is able to weather the storm, the more likely he is to survive. On the other hand, its imperative for the opposition in this case to stay on the streets and put pressure on both maduro and the military institutions, as well as the International Community to continue to rally behind his legitimacy as the interim president. Brian fonseca there. Stay with us on bbc news. Still to come a real case of poachers turned gamekeepers. We find out how former wildlife smugglers are helping to save russias endangered Snow Leopards. This is the moment that millions in iran had been waiting for. After his long years in exile, the first hesitant steps of Ayatollah Khomeini on iranian soil. South africas white government has offered its black opponents concessions unparalleled in the history of apartheid. And the anc leader, nelson mandela, is to be set free unconditionally. Four, three, two, one. A countdown to a critical moment. The worlds most powerful rocket ignited all 27 of its engines at once. And, apart from its power, its this recycling of the rocket, slashing the cost of a launch, that makes this a breakthrough in the business of space travel. Two americans have become the first humans to walk in space without any lifeline to their spaceship. One of them called it a piece of cake. Thousands of people have given the yachtswoman Ellen Macarthur a spectacular homecoming in the cornish port of falmouth, after she smashed the world record for sailing solo around the world non stop. The latest headlines for you now from bbc news millions of people in the american midwest have been trapped in their homes by an extreme polar vortex, with temperatures below minus thirty celsius. President trump has said us china trade talks made tremendous progress but there is still no agreement on ending the two sides dispute. And staying with that story, Marshall Meyer is tsai wan tsai professor of management and sociology at the univesity of pennsylvania. He explained why the whole trade issue is such a complicated one. I dont know entirely what to make of it. Partly because i have been aloft for the past 2a hours. I have picked up some interesting ideas in china. What we are seeing exposes the strength and maybe the weaknesses of both sides. China, i think, is more dependent on global trade than most of us imagined. We see everything is made in china. Goods that go from the us to china dont say made in the us because it is energy, it is agricultural commodities, and i think, quite frankly, chinas concerned that especially on the agricultural side, we saw, i believe, an offer to buy 500 tons of soy beans a day, why is that . No soy beans, no pigs. China has a heck of a time maintaining this. That is without importing soy beans. Theyjust dont have the space to grow it. This indicates one dependency they have got. Despite the advances in solar and wind energy, china is still very much dependent on hydrocarbons and their domestic supplies hardly meet their needs. Still, professor, their Manufacturing Sector is very strong and there is a lot of government subsidisation, how does that factor in . Well, i describe the Manufacturing Sector in china as just awesome. Most americans dont want to accept the fact that technology there is first rate, the supply chains are first rate, and the work ethic is very different from, perhaps our work ethic. I did see something very telling in china. It is called the 9 9 6 plan. This is largely in the technology sector. What does it mean . It means you work 9am to 9pm, six days a week. That is literally the job requirement today. Someone complains it interferes with your family life, the boss will say get a divorce. You can check this out, if you look at taxi records in beijing, shanghai, other cities the hardest time to get a taxi now is 9pm. Ajury in brooklyn has been hearing closing arguments in the trial ofjoaquin el chapo guzman. For weeks witnesses have provided testimony sounding more like a movie script than a real life court case. He faces life in prison if convicted on ten counts of trafficking massive quantities of cocaine, heroin and other drugs into the United States, as leader of the sinaloa cartel. Nick bryant reports. For the past three months the score in brooklyn has been the venue for a legal block buster people looking to the trial ofjoaquin guzman. This muted video showing Mexican Marines tried to ram their way of through the door in one of el chapo hideaways. He managed to escape with his mistress down an underground tunnel. He was then captured and imprisoned. He then managed another audacious escape, this time down a tunnel connected to his shower under which a motorbike was waiting. But the Mexican Marines soon came calling again. This captures the start of his expedition to the United States. He was flown to america. Us prosecutors have accused him of drug trafficking, murder conspiracy and money laundering. He isa conspiracy and money laundering. He is a huge prize simply because he is the Worlds Largest trafficker. When you compare him to pablo, he makes it look like a choirboy. The court has heard some jawdropping allegations. One saying the former mexican president accepted 100 million bribe from el chapo, claimed the politician has strongly denied. The trial is also a History Lesson on americans war on drugs. El chapo smuggling narcotics in plastic bananas. The defence is trying to betray el chapo as escape goat. And that the real leaders are still at charge. But there is an avalanche of evidence and say el chapo should not be allowed to escape justice. More than 50 people have testified during what has been called the drug of the century but not the star witness, el chapo himself. The number confirmed dead from the dam burst at a mine in brazil, last week, has risen to a 110, but more than 300 people are still missing. In the state of minas gerais, where the collapse happened, at least 200 dams are classified by the government as having a high potential for damage, if there was a collapse. The bbcsjulia carneiro has been visiting one in the city of congonhas. Devastation as far as the eye can see. This is waste from Iron Ore Mining engulfing houses, trees, trucks, and hundreds of people believed to be buried under the mud. The dam, owned by mining giant vale, collapsed in the brazilian state of minas gerais in the city of brumadinho. Just over three years ago, another dam failed in mariana, only 120km away. Now attention turns to neighbouring cities like congonhas, home to one of the biggest urban dams in latin america. This is the Casa De Pedra dam, owned by csn. Its right next to the city and holds five times more mining waste than the dam that collapsed in brumadinho. When this neighbourhood here was built here, the dam was a lot smaller but it was expanded over the years, growing closer and closer to the houses. Its just 250m from some of the constructions, and after what happened in brumadinho, residents here say its either them or the dam they dont feel safe here anymore. Translation im terrified, i wake up scared, i have nightmares. I feel this could happen here too. We live right under the dam im scared for everyone here. This activist says theres no dialogue with csn. The company did not want to comment on this report. Translation the lesson comes at a huge cost, with all the lives we lost, but it has to be applied to prevent other collapses. People here want a solution they dont want in doubt. People here want a solution they dont want to live in doubt. Structural problems were detected twice in the dam in the past six years, according to this prosecutor, and were repaired following judicial orders. At the time, csn said the demands had been followed, and the dam presented no risks for workers and residents. Translation its a huge structure, very close to the city. If it breaks, it is going to be one of the worst accidents ever. Mining workers here are concerned after the dam collapse. Vale employees voted to interrupt their shift for two hours to mourn their colleagues in brumadinho. Translation if its so safe, why dont shareholders live undera dam . We have to change the model of mining and governments need to pressure private companies, rather than ease licences for mining. After two disastrous collapses, brazils mining dams are under scrutiny, and People Living under their shadows dont want to be the next victims. Julia carniero, bbc news, congonhas, brazil. The snow leopard is an animal in serious danger. Its native to central and southern asia but its estimated there are fewer than 10,000 still alive. And that figures expected to go down in the coming years. But conservationists are trying to do something about it, as the bbcs tim allman reports. There is a bleak splendour to the altai mountains. Cold and unforgiving, you have to be tough to survive here. Mergen markov has lived here all his life. He is on the hunt for Snow Leopards not to kill, but to photograph, these automatic cameras helping to monitor the snow leopard population. Translation i am really happy i have this job which allows me to spend all this time outside and admire all the animals ive managed to photograph. Is it better than killing them . Yes, they are so beautiful in the photographs. This is the village of argut. After the collapse of the soviet union, the collective farms went bankrupt. Many people took to hunting the local wildlife. The fur of a snow leopard could sell for more than 500. So the World Wildlife fund pays for the purchase, so the World Wildlife fund pays former poachers mergen included, to try to protect them instead. Translation he quickly understood that if he kept on poaching and selling first, he would earn money only once for each animal hed kills. Whereas with us, he earns money regularly. Local volunteers are also paid to go on patrol and monitor this vast area of land. Over time, the hope is the number of Snow Leopards will rise. These animals will return home. Tim allman, bbc news. More for you on the bbc website. And you can get in touch with me and most of the team on twitter. Im bbc mike embley. Thank you for watching. Hello. There is more snow to come in this forecast as we head into friday. The main focus is the zone, say, from south wales across east anglia and anywhere south of here. All driven by this area of low pressure, which stays close by as we go into friday. Now, whilst the earlier amber warning from the met office has expired, we still have yellow warnings in place for both snow and ice. So, slippery surfaces, tricky travelling conditions. Stay up to date with the latest travel news on your bbc local radio station. By friday morning, we are likely to see perhaps 5 10 centimetres of snow across parts of wales, south west england, particularly over the higher ground, up towards the chilterns and the cotswolds. At least a couple of centimetres elsewhere. And we will start to see further sleet and snow showers piling into north east england. Some of those may well get further south and westwards, perhaps down towards the midlands. Should be a fine start to the day across northern ireland, but cold and frosty. And a really cold start again across scotland, although not quite as cold as the nightjust gone. And, once again, frequent snow showers piling into north scotland, the highlands and also the northern ireland. So, as the day wears on on friday, we will keep our zone of snow showers across central and southern england. It will become more fragmented and increasingly sleety through the day. Still further snow showers piling into north east england, across the north york moors. As i mentioned, some of those may just get across the pennines and down towards parts of the midlands. It will be a breezy day in places, particularly the further south you are, so thats just going to exacerbate the cold feel. And, for most, temperatures are not going to get much above three or four celsius. But we should at least see them above freezing across parts of Northern England and scotland, where we struggled through thursday with the fog. As we go through friday night and into saturday, we still keep this feed of showers, mainly down eastern and some western coasts. And we start to lose the sleet and snow from south east england. But a cloudier night here, so temperatures will stay above freezing. Elsewhere, further west, under clear skies, getting down to 1 or minus two celsius. Still 11 5 across the highlands of scotland. Then we start the weekend, and our area of low pressure moves away into france and germany, and for a brief time through the weekend things are looking drier and quieter. Now, with a northerly wind, we are still going to pick up some wintry showers down some eastern coasts. A few mayjust clip some western coast, but for most on saturday its a dry day, with some crisp winter sunshine. After a frosty start, temperatures getting up to between 3 5 celsius, perhaps 6 7 across south west england. So, to sum up the weekend, its going to stay cold, there will be some sunshine, further wintry showers and perhaps we could see some rain later on sunday, with some snow across scotland. Bye bye. The latest headlines for you now from bbc news tens of millions of americans are still enduring temperatures as low as 50 celsius across several midwestern states. The extreme weather is blamed for at least 21 deaths. Its been more than 20 years since a similar polar vortex covered such a large area. Us and chinese negotiators have praised what they say is progress in two days of trade talks in washington. American officials will go to beijing for more talks soon. President xi jinping has said he hopes both sides can meet each other halfway before a march 1st deadline, when new tariffs may kick in. Venezuelas self proclaimed interim president has promised to focus on rebuilding the economy and ending the countrys humanitarian crisis. Juan guaido accused president Nicolas Maduro of trying to intimidate him by sending special police to his house. The organisation of american states has denounced that move. Now on bbc news, hardtalk