the prime minister's scientific advisers are briefing him today on the spread of coronavirus over christmas as he decides whether to impose more restrictions in england before the new year. in scotland and northern ireland, further measures have come into force today for pubs, bars and cafes. there are warnings that the government isn't doing enough to help people deal with sharp increases in the price of gas and electricity. the national trust warn that some landscapes in the uk could be altered for ever due to extreme weather conditions. and england's hopes of an ashes comeback are fading rapidly after a dramatic second day of the third test in melbourne. now on bbc news, it's time for weather world. sarah keith—lucas and nick miller report on how climate change is affecting the scottish ski industry and look back at 2021's biggest storms. this time on weather world, i'm in scotland, the country that hosted the 2021 cop climate summit. and even though i've come to one of the coldest and snowiest parts of the country, the cairngorms ski area, it faces its own challenges as our world warms. i'll be talking to the people whose livelihoods depend on winter snow here, even if sometimes they have to make it themselves. the factory produces four tonnes an hour, so injust under a month that's about 3,000 tonnes. and i'm in london, where, like many major cities around the world, mass transport systems are facing up to the threat of flash flooding. and i'll be asking what can be done to keep travellers safe in extreme rainfall. also on weather world, sudden and savage — disaster in the usa, hit by one of its largest tornado outbreaks in history. how one canadian province found itself at the epicentre of 2021's climate change—fuelled extremes. it is the effects of these extreme events that can be devastating and lead to loss of life, loss of livelihoods. this is why we are concerned about climate change, exactly. and melting in the tropics, the ice that's disappearing from some of africa's highest mountains. i've come to cairngorm mountain in the heart of the scottish highlands. the ski resort here has been growing since the 19605 and whilst the weather can vary significantly from one season to the next, a recent report on the effect of climate change here predicts fewer snow—covered days and an increasing chance of more days with the temperature above the threshold needed for snow to fall. so, jim, you're the land manager here at cairngorm mountain. you've been doing it about 25 years, working here. what are the changes you've noticed in terms of weather systems and snow conditions? that's right. i think the baseline temperature has changed, less than one degree, but the maximum and minimum temperature we are seeing have changed. we are getting more extremes, so we might be getting warmer summers or warmer temperatures and bigger snowfalls as well. so in any given year there can be big anomalies as it goes through. so, it's adapting to these storm cycles that seem to be getting stronger these days. the irony is last winter you had huge amounts of snow but of course due to lockdown nobody could use it. that's right. phenomenal amounts at this level. what was different about last year, it was really stable. we had cold weather patterns with long periods with no wind at all, which is ideal conditions for skiing. every year is different but itjust shows that any year you can get a standout season and then the next year might be more variable. it's notjust about how much snow falls, but do you sometimes see too much snow falling in quite a short space of time? it's about capturing that snow and using it through snow farming and capturing it in the fences, so we do a lot of work on pushing it out and trying to maximise how we use the snow, creating that base layer that sets you up for a good season. you've had to make quite a lot of adaptions since you've been working here. what are some of the major changes you have made? i think technology is really having a positive effect. snowmaking is becoming a bigger part of it. we can make snow through our fan guns in —2 temperatures so that guarantees local ski schools and that business, it's a busy time coming up. then combined with natural snow and temperatures we can get snow guns going and we can snow farm and start building a base and really the base is key to trying to maintain the snow throughout the season. thank you so much, jim, for explaining how snow production and all your adaptations are so vital to the industry here. i'm going to head now and find out a little bit more aboutjust how you make snow at the top of a mountain. i'm here at the snow factory now, where the man—made snow is produced. mikey, you're head of engineering here at cairngorm mountain, so you're very much in charge of running this machine and producing the snow. talk me through, how does it work? it's an ammonia plant, pretty similar to some fridges and freezers. this cools an ice—maker. the ice—maker has water sprayed in a thin layer on the inside, which is then peeled off with a reamer and falls to a lower part where it's blown out through the pipe onto the slope. that's how it all works. shall we take a look at what it's like on the slopes? let's go see. so, mikey, this is the result, then, these huge mounds of snow here. just how much snow has been made? they've been going about a month or so. the factory produces four tonnes an hour, so injust under a month that's about 3,000 tonnes. once they are in these big piles here, what do you do with it? it's a big mountain to cover. very much so. we spread it out using specialised piece machines which push the snow around. when it gets mixed up it's a lot easier to push. are you predicting you'll be making snow throughout the season, or are you hopeful you might be able to turn it off at some point? we make snow up until our opening day. from then on we proceed untiljanuary and then it depends on the scottish climate. and when you feel some of this snow, if we pick it up here, it looks exactly like natural snow. how does it feel to ski on? when it comes out of the snow factory it's essentially an ice flake, which doesn't have a lot of cohesion. by the time you get to ski on it, it's been mixed with other man—made snow from snow guns and hopefully some natural stuff, which makes it bind and makes a good skiable surface. and so what do you hope about the future proofing of the industry, where you are able to make snow at higher temperatures like this? snowmaking is key to the future of snow sports here in scotland. we have a variable climate on some of the lower slopes where we operate, it provides a good run down to the base station. thank you so much for showing us your operations here. have you ever wondered how easy it is to measure the depth of snow? it's not quite as simple as you might think. i take a look at that later in the programme. now to the part of the world where weather extremes reached a new level in 2021. british columbia in western canada. in november, record rain as an atmospheric river of moisture from the pacific brought flash flooding to the same areas that only a few months earlier were in the grip of an historic heatwave. it's coming this way fast. let's get out of here. the fires that followed that heatwave had catastrophic consequences for lytton, the town that set a new canada temperature record of 49.6 celsius. speaking at the cop 26 climate conference in november, canadian prime ministerjustin trudeau said this should be an example to the world. in canada, there was a town called lytton. i say was, because onjune 30th it burned to the ground. canada is warming on average twice as quickly as the rest of the world. and in our north it's three times quicker. the science is clear. we must do more and faster. there's certainly an element of, you know, british columbia got very unlucky this year with the number of extreme events that have happened. but for me, these extremes are exactly what climate scientists have been warning us about. exactly as you said, hot extremes are going to become hotter. and wet extremes are going to become wetter. so, this is what climate change looks like. and so, yeah, i think this is a really important message to the world. this is why climate change is important. it's not because each average day becomes a little bit warmer. that's not so much of a problem. it is the effect of these extreme events that can be devastating and lead to loss of life, loss of livelihoods. this is why we're concerned about climate change, exactly. flash flooding reached even greater heights of severity in 2021. in europe injuly, more than 200 people were killed, the greatest number here in germany, where entire villages were wiped out after a stalled weather system produced phenomenal amounts of rain. and also injuly, frightening scenes from zhengzhou in china, where the floods that followed a year's worth of rain in just three days trapped people in an underground metro system and on flooded trains. thankfully, on a far less extreme scale, the transport network here in london was hit with flash flooding in summer. and with climate scientists warning of more frequent bouts of intense rainfall, in a moment i'll be asking transport for london what they are doing to keep travellers safe. water cascades into london's covent garden underground station injuly, just one of a number of flood—related incidents last summer. it's a problem which transport for london says has the potential to be catastrophic, and as one scientist told me, it's a problem compounded by increasing population, building, and an ageing drainage system. we're putting down concrete, tarmac, all those new houses, all those roofs. that surface water is going to increase anything between eight and 18% per small development. and you've got to think about where it's going to go. the drains are already at well over capacity and just can't deal with it. joining me now here at london's southwark station is lilli matson from tfl. lilli, how concerned is tfl about the forecast of more frequent extreme rainfall in a warming world? we're very aware that london's climate is changing. we're seeing warmer weather winters, drier, hottersummers. this all puts a lot of stress on our transport network and it's something we're really planning for now and taking account of so that we're ready as the climate becomes more extreme in future. there was some significant flash flooding in london in the summer. of course we saw those horrific scenes on the metro system in china. how much has this been an alarm call for tfl? we looked with real serious concern at what happened, notjust in china, but also closer to home in countries like germany, where we saw really extreme flooding. and i think that is a real wake—up call. we know that we can have extreme rain of the kind we had in germany here in london now. and we do need to make sure that our assets, our transport system, but all of london's infrastructure, is ready to cope. in terms of infrastructure, though, everything is so built up, both above and underground, close to the tfl system. you must be limited to what you can do? there are real constraints in london. so much of the land is paved and we're losing more land to paving as people pave over their front driveways and all of that. so we're trying to work against that by putting in place what we call sustainable drainage. that means that when we introduce new shrubs, new trees into our paving, that actually helps slow down the rainfall, so, there are things we can do. we are also enhancing our pumps and drainage systems so that we can get water away more quickly and keep the infrastructure working. lilli matson, thank you forjoining us on this edition of weather world. one of the biggest storms to hit the uk in 2021 came at the end of november, as storm arwen brought damaging winds of up to 98mph. falling trees caused widespread disruption, with this one narrowly missing a drinker as it crashed into the back of a pub in wales. tens of thousands of trees came down in the worst affected parts of scotland and north—east england and power was lost to more than 200,000 homes. now to some of your weather watcher pictures, showing the snow that followed storm arwen, which was unusually heavy and widespread for the time of year, particularly across northern england, and compounded the problem for those people that had lost power and heat to their homes. but despite the cold end to the season, overall the uk had its third warmest autumn on record, and the warmest in northern ireland, in a year that northern ireland also recorded its highest temperature on record back injuly. hearing no objections, it is so decided. applause. still to come on weather world, cop fallout — was the applause justified ? we hear from some of those who were in glasgow, as world leaders haggled over plans to fight global warming. this time on weather world, i'm in scotland, where i've been finding out how our warming world is affecting life here at the cairngorm mountains ski area. but of course it's notjust the winters that are changing, but the summers, too. we're high in the mountains and snow is disappearing completely more frequently. patches of snow that can survive in the mountains from one winter to the next are now melting away more often. what is historically the uk's longest lasting patch of snow disappeared in 2021 for what is said to be only the eighth time in 300 years, with the majority of these meltings happening since 2000. iain cameron has been documenting scotland's snow patches for 25 years. i asked him why he does it and what he's discovered tells us about the impact of climate change in these highlands. the snow that i look at is a relic, or they are relics, of previous winters' falls and they persist on the varied gullies and cliffs on the shaded gullies and cliffs of the scottish highlands well into summer and often beyond. in fact, some persist right through the year. so, in summer and autumn, you can often find me with my boots on trudging around the highlands of scotland, looking for the last vestiges of the winter snow. the amount of times that all snow�*s vanishing is increasing. the sphinx patch of snow — britain's most durable — has disappeared really quite a lot in the last couple of decades. so, it disappeared first of all in 1933 for the first time in known history, then in 1959. again in 1996, 2003, 2006, 2017, 2018 and finally this year, 2021. so, you can see the direction of travel. the snows are disappearing earlier and they're disappearing more often. it seems inconceivable that climate change hasn't had a significant impact on this. whether it can be wholly attributed to that, i don't know — it's not my competence. however, it seems absolutely logical to ascribe the increasing disappearance, at least in significant part, to climate change. i think that's a safe assumption. now, more of 2021's extreme weather, starting with disaster in the usa — hit by its deadliest december tornado outbreak on record. the worst—hit state was kentucky, where the utter devastation is hard to comprehend. 0ne tornado is thought to have stayed on the ground for more than 200 miles, crossing multiple states. meteorologists say climate change could be altering traditional tornado patterns in the usa. it's certainly true that climate change is making it more likely to have intense tornados outside of the usual season we think of. the march throuthune period, where you get most of the violent tornados. because now it's warmer longer and you can have these favourable conditions for tornados at different times of the year. august, and ida became one of the strongest hurricanes on record to hit the usa, making landfall in louisiana with 150mph winds. the 2021 atlantic hurricane season was the third most active, with 21 named storms. these scenes of record cold winter weather in texas in february may have made world news but 2021 overall is ranked in the top ten warmest years for the usa after a summer which was its hottest on record. during it, california suffered one of its worst fire seasons. the biggest fire almost completely destroyed the town of greenville in august. summer heat in europe. 0n the italian island of sicily in august, the temperature hit 48.8 celsius — if verified, a new record high for europe, which came during its hottest summer. the indian state of kerala in october, as a house is swept away in a flood. overall, the 2021 monsoon produced near average rainfall, but there are fears the rains during the season are becoming increasingly intense. flooding in australia during its wettest november, in records going back to 1900. under the influence of a la nina weather pattern, forecasts point to a second consecutive wet summer for the country. but in the horn of africa, consecutive poor rainfall seasons have left 26 million people struggling for food, with drought conditions forecast to persist until at least mid—2022. in november, a powerful wind storm hit turkey, toppling buildings and ripping off roofs with a gust of 81mph in istanbul. and we can't forget this — the containership that blocked the suez canal for nearly a week in march, holding up the 12% of global trade that passes through it each day, all because it was apparently blown off course by a gust of wind. now back to africa, and the snowcapped rwenzori mountains on the border between uganda and the democratic republic of the congo. their appearance is changing dramatically as the glacial ice that marks their summit melts away, all within the lifetime of the people who live in their shadow. we used to wake up in the morning and time that specific hour in the morning where you would be able to see the glacier in its shining form. but now you can just wake up and see it. that is one visible change, one actual change that you can see. instead of seeing the snow, you see that the mountain has gone grey like that. there is no glacier any more. you only have to go to specific places now to be able to view it, and at particular times. hydrogeologist richard taylor, who has co—led expeditions to the rwenzori, says because temperatures show little seasonal variability here, the disappearing glaciers are a clear sign of climate change. ice fields in the tropics have a generally stable ice mass in the absence of changing climate, just because of that, if you will call it, seasonal stability and temperature. and so, departures from that, such as climate change, you can see very distinct changes or recessions in those in the areal extent, or the terminal position, or ideally in the total mass of the glacier itself, indicates a change in climate. and so, perhaps the most definitive markers of climate change are the recession of tropical alpine ice fields, which you find in the andes and east africa as well. also in irianjaya, in papua new guinea. as well as the melting glaciers, weather patterns in the area are changing. in 2020, some of the heaviest rain on record caused destructive flooding, but there are longer spells when the rains people rely on to grow crops don't come at all. now that the weather has been changing, we no longer receive rainfall, the crops are dying in the gardens. last season i planted two full acres of beans, but i did not harvest anything because there was no rain. and many others are facing the same problem. in november, the eyes of the world were here on scotland, when glasgow hosted cop26, the latest major summit to tackle climate change, amid warnings that time is running out to limit global temperature rise. hearing no objections, it is so decided. after two weeks of negotiations, world leaders agreed a plan to reduce the use of coal, which is responsible for 40% of annual co2 emissions. but only a weaker commitment to phase down rather than phase out coal after a late intervention by china and india. and when it comes to reducing co2 emissions, governments will meet again next year to pledge further cuts in a bid to limit global temperature rise to 1.5 celsius. more money will go to help poorer countries cope with the effects of climate change and make the switch to cleaner energy. whilst some describe the glasgow agreement as a breakthrough, others felt it didn't go far enough. we asked some of the delegates what they thought. when i was asked to deliver a speech at the world leaders' summit there was so much going on in my mind. sub—saharan africans are responsible forjust 0.5% of historical emissions. the children are responsible for none. they are waiting for you to act. please open your hearts and then act. when it comes to the outcome of the cop, on one hand i was grieving. grieving because the outcome does not address the impacts of the climate crisis being experienced right now. grieving because people in countries like mine are still facing loss and damage caused by the climate crisis. but i think there was so much energy out of the cop, with the young people and civil society and i think to me this is what true leadership looks like. cops are always about the game of one—upmanship. and that, i think, is the saddest thing about the climate conference. it's all about how you can make sure that you go out as the good boy and that somebody else is made to, you know, be scolded as the errant country. and i do believe india walked into the trap by reading out the statement at the very end. how can anyone expect that developing countries- can make promises i about phasing out coal and fossil fuels subsidies? developing countries have - still to deal with their development agendas and poverty eradication. but i do understand why a country like india is so distrustful of the global system. that it finds that it has to argue for its rights to development because there is no finance coming. there is no technology transfer. there is no support. instead, the global community only lectures and berates countries like india. our time here on cairngorm is almost up, but before we go, the team have lent me a pair of skis so i can feel for myselfjust how good the snow is here. ruari, you're the senior countryside ranger here, so how do you get an accurate reading of snow depth? first of all, down at car park level we have a stevenson screen and we have been recording weather data there since pre—1980, so we have scales, centimetre and metre sticks, to record the snow. but historically, actually, the people on the hill know how deep the snow is. sometimes you can come up and the hill is covered in snow, and then a night of wind and it has been windswept clean. it changes literally every day. so, there is plenty of snow around at the moment. is this a promising situation for the start of the season? well, it's promising. it is promising that we've had a good lot of snow. the ground has started to cool down as well, which makes a big difference for the snow to actually last. and if we get some hard frosts now then the snow we do have should last that wee bit longer. fantastic. well, there's plenty of snow around today. fingers crossed for more of this for the rest of the season. ok, i haven't been on a pair of skis for a few years but i hope it's just like riding a bike. let's see. off i go. woo! well, it's encouraging to see so much snow here so early in the season. long may it last. and that's it for this time on weather world. from the cairngorm ski area... and from me here in london, and whatever the weather, we will be back with more weather world in the year ahead. so, see you then. goodbye. hello, there. we've got some extremely mild weather to come later this week with temperatures not too far away from the december records. today, it's grey and cloudy, murky, with the low clouds making it quite dark at times, with pulses of rain moving across england and wales. further north—west, something a little bit brighter for scotland and northern ireland but here there will be a scattering of showers. temperatures across northern areas are fairly close to the seasonal norm but it is mild in the south, where temperatures could reach between 11—13 celsius for some. 0vernight tonight, mist and fog patches will reform so it will become quite murky again. outbreaks of rain developing later in the night as well. the rain and cloud keeping temperatures well up, 7—9 c. colder in northern scotland, cold enough for a few patches of frost in the countryside. tomorrow, it's a wet day coming up, with this rain very slow to ease away eastwards, so still some rain around across eastern england into the afternoon. the brightest weather again for scotland and for northern ireland as well. that's the latest. this is bbc news broadcasting to viewers in the uk and around the world. are set to be announced today, but uncertainy still remains on whether future measures will be imposed before the new year. in new york, children aged 12 and over need to be fully vaccinated for indoor restaurants and leisure facilities, as the city sees infections rise. warnings the british government isn't doing enough to help people deal with sharp increases in the price of gas and electricity. tributes and reflections for the anti—apartheid hero archbishop desmond tutu, who died at the age of 90.