this is bbc world news, the headlines: the latest scientific data on climate change says the signs and impacts of global heating are speeding up. the warning comes ahead of the un climate summit in new york. tens of thousands of indian—americans have given a rapturous welcome to the indian prime minister narendra modi and the us president donald trump. the two leaders held a rarejoint rally called howdy modi in houston, texas. the british government says it's ready to fly holiday—makers back to the uk if the troubled tour operator thomas cook goes into administration. it's feared the company's collapse could leave about 150,000 british tourists stranded. liverpool have maintained

their searing pace at the top of the premier league. they beat chelsea at stamford bridge 2—1 in their sixth consecutive premiere league win. just after ten o'clock, mishal husain will be here with a full round—up of the day's news, first our world. safa and marwa are identical twins joined at the head. their family, from pakistan, want doctors to separate them. great 0rmond street in london is one of the few hospitals in the world with the expertise to do it. this is safa's brain, that's marwa's brain. what we need to achieve is effectively untwist the brains, and that is difficult, pretty difficult to do just in your head. but it is perilous. the bbc was given unique access to chart the complex medical and ethical choices made...

this is the day, the moment of truth, and everything hasjust got to be perfect. ..in the hope of giving the girls independent lives. safa and marwa are 21 months old and were born in pakistan. they have come to london's great 0rmond street hospital with their mother zainab, grandfather and uncle, and are under the care of neurosurgeon 0wasejeelani. it is clearly very difficult to go through life when you are joined together like that, so it does make a very persuasive case in favour of doing the surgery. the family are very clear on that. clearly, life being separate is very much better than life together. if we felt there was not a very, very high chance that we could do it

safely, we would be thinking about whether we should do it or not. i think the whole team feel that there is an excellent chance of a successful separation here. the twins‘ father died just before they were born, and then it took more than a year of fundraising before a donor stepped in to cover the medical costs. safa and marwa are what's known as craniopagus twins, which meansjoined at the head. their skull is one long tube. the twins share many key blood vessels. separating these will be a major challenge. both twins‘ brains have a distorted appearance.

one half is pointing up into the other girl's skull cavity. every last detail of the twins‘ extraordinary anatomy has been recreated digitally. plastic surgeon david dunaway will be in charge of rebuilding the girls‘ skulls after neurosurgeon 0wasejeelani has separated the twins‘ brains. they showed me how 3d modelling has helped them to prepare. this hemisphere, which is the right hemisphere of the brain, is standing up, so this is actually projecting into the other child‘s skull. what we need to achieve is to effectively untwist the brains, and that‘s difficult, pretty difficult to do just in your head. for surgeons it is massively helpful, actually being able to touch and hold things makes so much difference to understanding how things are. we spent a long time looking at these models and going through the what—ifs.

numerous models of the twins‘ brains and shared skull have been created using this 3d printer. the whole process takes two days. this one will help surgeons plan how best to divide the layer of skin on the girls‘ skull once they are separated. and they‘re not only using physical models. this is surgery without scalpels. absolutely incredible. this is exactly what we wanted. virtual reality has helped the team plan how to divide the twins‘ shared arteries and veins. it works, it really works. and so now we can see a whole lot more information, a level of detail we‘ve not been able to access previously. this is clearly the way of the future. we‘re using this technology for a highly complex case, but many other routine

operations that we do, brain tumours, blood malformations, so on and so forth, the rest of those malformations, this would be hugely, hugely beneficial for those cases as well. 0k, have we got everyone here? yeah? so we have one case for the list today, safa and marwa, two kids, one case. the surgery is so complex it will happen in three stages over several months. and the twins won‘t be physically separate until the final operation. the aim of the first operation is to separate

the twins‘ shared arteries. at present, each child is supplying the other‘s brain with blood. one, two, and three. what we‘re doing now is, the two arteries that are going from one twin to the other, so we can see the artery, but to do anything to it we‘ll use the microscope. so the artery from safa going to supply marwa‘s brain has been clamped. but every time this is done, there‘s a risk of brain damage. ok, so the brain‘s looking good. the twins have been in theatre now for more than seven hours. and there are still several hours

of this operation to go. so far, everything is going to plan, and both girls are doing well. while one team works on the twins, another, led by david dunaway, constructs a frame made from pieces of the girls‘ skull which can be detached in subsequent operations. this central segment will be our rigid keel to hold the head together. what we need to do is make sure that the twins are rigidly together. being older, they‘re pretty active, and so whatever we do really has to be strong enough to resist the twisting and bending forces that they‘ll be putting on their heads. the first operation lasts 15 hours.

zainab has seven more children back in pakistan, aged five to 16. all of them were born at home, but with this pregnancy she was advised to deliver in hospital. it was not until five days after delivery by caesarean section that zainab was introduced to her daughters, initially by photo. zainab says the twins have distinct personalities.

after a month, the twins are back in theatre. this is safa‘s brain, it looks happy... this time the surgeons will separate the shared network of veins that drain blood from each twin‘s brain. but disturbing this equilibrium could also do permanent damage. a portion of each twin‘s brain is being supplied by the other twin. so there is a real risk of causing a stroke at the time of the surgery, that is something that is weighing heavily on us. there could be something down there that i can‘t see at the moment. the more the surgeons try to divide the vessels that link and nourish them, the more unstable the twins become. we're going to have to take ventilation down. 0k? down?

marwa‘s heart begins to fail. we are not stable, but we are less unstable. good enough for me. the anaesthetists manage to stabilise the girls so the operation can continue. because marwa is clearly the weaker twin, the surgeons decide to give her a key shared vein. the operation lasts 20 hours. so i‘m relieved, i‘m relieved. i mean there was a chance we were going to... ..potentially lose marwa during the surgery. it‘s been a big operation, but hopefully if they wake up as we hope they will, it‘s gone well. yeah. but shortly after surgery, safa suffers a stroke.

there was a period on tuesday evening where... we felt that we were very close to losing safa and that she stayed in that critical state for... for 48—72 hours after the surgery. it was a very difficult time for the girls, their families and the entire team looking after them. in a break from their work at great 0rmond street, the two lead surgeons are in ireland to meet another set of twins.

it‘s eight years since they last saw ritaj and rital. it‘s hard to believe that these sisters, born in sudan, were once joined at the head. thank you! you are very welcome. back then the surgeons feared the girls might die unless separated. and this was rital and ritaj just one month after surgery. each parent able to hold a child in their arms. i hope that they will get a normal life and be treated as normal human beings. their father is now a doctor in ireland. we are now sitting here with two healthy twins, just like what i hoped at that time. so it‘s a great moment in my life as well. so the dream came true? exactly, yeah. i‘m a very proud dad now. that was a very hard time.

and at the same time it was a happy time because of the conclusion. rital has some learning difficulties. by the long—term outcome of the twins‘ separation has been hailed as a major success. the surgeons believe it‘s because it was done in the first year of life. what we put the two kids through and the brains through is a lot. and the younger brains and the younger circulations are better adapted. everything is easier. a one—year—old's regenerative capacities are so much better. the skin heals better, it stretches better, the bone grows in better. they‘re setting up a charity so that funds are available to pay for early intervention in future cases and for research into the best way to separate conjoined twins.

it‘s january 2019. i think the last two months after their last operation on the brain has been a little bit of a stormy time for safa and marwa. they‘ve had ups and downs with infections and temperatures, and marwa‘s heart is having to work quite hard for both of them, and that‘s causing her a few challenges. but they‘re hanging in there. and they‘re both reasonably well. the next challenge for the surgeons is to ensure each twin will have enough skin to cover their skull when they‘re eventually separated. they do this by encouraging the skin to expand. the tissue expanders are balloons that sit underneath the skin, and they have a tiny little port attached to them through which we can inject saline. so the idea now is that we will

gradually inject the tissue expanders, and they will blow up like a balloon, and the skin over the top of them will stretch. and it‘s a very, very effective technique of making more skin out of the skin we have available, so that when we come to separate safa and marwa, there‘s enough skin to cover both of their heads. these rare cases leave a lasting impact on the surgeons. if i may, i haven‘t asked david‘s permission to say this, but the last separation that we did, when the kids were finally separated, and everyone was overjoyed and so on and so forth, and people were happy, and i looked at david and he had tears in his eyes. and he denies it to this day, but he did at that time. yeah. ithink... everybody has been so invested in this for so long. it is a surprisingly emotional thing, i think, when they finally come apart.

and when that experience of them actually leaving the operating theatre as two separate people is quite indescribable. at last, four months since the first surgery, the day of separation. two forceps. two brains laid out. so this is safa‘s brain, that‘s marwa‘s brain. if you do, give me a seven. little by little, the bone and the tissue which joins them is cut. so they are separate apart from that piece ofjewellery. and then, after seven hours,

the final connection is severed. fantastic. 0k. done. it's a very emotional moment. we've been working a long time to get them here. they've been through so many operations, and now it's worked. you still have four, five hours to do? yeah, we have to put them together now. so we've taken them apart, and now we have to reconstruct their heads. marwa is still in the operating theatre through here, while safa has been moved just next door. for the first time, the survival of each of the twins is not dependent on the other. and that‘ll make it easier

for the two surgical teams to regulate their heart rate, blood pressure, and other vital signs. safa and marwa‘s brains used to have a distorted shape. but four months ago a plastic sheet was inserted between them, and by gradually tightening the pressure, it has largely corrected their appearance, essential before their skulls can be rebuilt. this means both teams can begin reconstruction. the patchwork of skull pieces are shared between theatres. so a piece for me, a piece for you. to have enough to cover their heads, each fragment must be divided in two. the skull is very usefully designed in three layers. so there is an inner layer of very thick, tough bone, an outer layer of thick, tough bone, and in between it the bone is like a honeycomb, so you can split the bone, it‘s half the thickness, but it means we should be able to cover nearly all of the head

with bone afterwards. this shows the jigsaw of bone fragments that were pieced together to form the skull of marwa on the left and safa on the right. the gaps have been seeded with bone cells. and in the months to come, these should slowly close up. the final task of the 17—hour operation is to stretch the skin over their reconstructed skulls. it‘s a pretty amazing day, isn‘t it? everything is good. thank you. oh, what a day. they have been quite amazing

throughout, actually. they‘re great family, and i think they draw strength from one another. and they seem to be getting through it very well. we asked mum who she would pick up first, whether it was safa or marwa? and the answer was both — with support! so, uh, yeah... the road to recovery for the twins is slow, but four months after separation, safa and marwa are beginning to make progress. # hello, safa # hello, marwa # how are you today? # the twins have daily physiotherapy. it‘s hoped this will help them reach some basic milestones — learning to roll, sit, and hold their heads up. # twinkle, twinkle, little star

# how i wonder what you are... # safa has not fully recovered from her stroke. we made the decision that the bulk of the common vessels go to marwa, the weaker twin. and because of the decision, safa suffered a stroke. so what i really want to see is the weakness safa has at the moment, and she has a weakness in her left arm and left leg, improves. so for me the big moment‘s going to be when she walks and when she uses her left arm properly, because, you know, i have given her that weakness, and for me that‘s a hard thing. nearly a year since they were admitted to hospital, the girls are leaving great 0rmond street.

the family will stay in london until the twins are strong enough to return to pakistan. the donor who paid for the surgery is continuing to support them. they are clearly going to face some challenges. but i think, overall, it‘s a positive outcome for them. they are going to need support, but they have a chance of leading a happy life. whatever hurdles safa and marwa may face in years to come, they will at least do that as a separate, independent girls. twins still, but conjoined no more.

hello once again. thoughts on the week to come injust a moment, but first of all i‘ve been thinking about september‘s rainfall thus far, comparing it to an average month to see how dry it has been across eastern areas and even out towards the west, well, you still haven‘t had 100% worth as we would expect in an average month up to this point. and for that at times, well, we‘ve thanked high pressure. you can fit one in to the jet stream here in the past few days as the jet stream itself has meandered its way right up towards iceland. but now we‘re just dipping it the other way and into that little kink you can fit areas of low pressure and their associated fronts. that‘s how many of us concluded the weekend. and this is how we‘re starting the new week, a new area of low pressure, new weather fronts coming in from the atlantic. the last of sunday‘s weather pushing up towards the northern isles,

then an interlude of drier, finer conditions. but that really won‘t last across these western areas, as the next set of weather fronts work their way in from the atlantic, not cold by any means, both by day and by night, the temperatures pretty close to the seasonal norm. but as i say, these southwesterlies are moisture laden and they will at times force cloud and wind and rain in their wake. here, at the start of tuesday, it may well be that we have notjust one little system to affect the southern parts of the british isles initially, but another one following close on its heels, and they may offer the prospect, as you commute on tuesday particularly across the southern half of the british isles, of some very wet and at times some pretty windy weather as well. so we keep a close eye on developments here, and it won‘t be just the south‘s problem, because with time it will push some really quite heavy rain everfurther north, towards the borders of scotland. i don‘t think the rest of scotland or northern ireland will see the very worst of the conditions, but that wind will be a feature, some of the gusts around 40—45 mph.

and we may well ramp them up later in the day across this southwestern quarter as the next feature works its way ever further towards the east across the southern counties. so that could give quite a wet and windy start to wednesday, but thankfully wednesday offers many of us a bit of a lull in proceedings, a quieter day, less in the way of wind, a little bit more sunshine, helping to get this temperatures well on into the teens, as you see, widely across the british isles and a drier interlude for sure. but it is but an interlude, because as we look towards the west again at the start of thursday, another set of weather fronts,a lot of isobars again on that chart. so it‘s another spell of wet and windy fair initially towards the west, but then as the day goes on, spreading that prospects of that combination of wet and windy fare anywhere really from cumbria through northern ireland into the heart of scotland. the rain at this stage lighter and patchier down towards the south and east,

but that same weather front eventually drags the prospects of some heavy bursts of rain right even into east anglia the south east on friday before that frontal system gradually quits the scene. and then we go into something a little bit more sunshine and showers to finish off the day on friday. the temperature‘s still around the mid or upper teens. here we are as far ahead as next weekend, and we suspect that low pressure is still going to dominate to start off with. but this is just the suggestion of a little bit of a high pressure trying to build in across the southern counties of the british isles, offering perhaps a somewhat drier interlude. and again thatjet stream just beginning to take on that characteristic dome, but that in its own right could be really short lived. lots going on. take care, bye—bye.

in a moment, mishal hussein will be here with the latest headlines, but first, a look at what‘s been happening at the labour conference in brighton. once again, policy has been overshadowed by talk of division within the party. speaking to the shadow home secretary diane abbott earlier, our political correspondent, iain watson, asked her about the decision of labour‘s national executive to back jeremy corbyn‘s brexit plan, not to endorse either leave or remain in any general election campaign. iam i am remainder iam remainderand i am remainder and i iam remainder and i represent a solidly remain constituency and we do need to arrive at a position that everybody can unite behind. and i

think