down in south # i'm leaving today... down in south america, cheers on copacabana beach, a carnival of colour, new year brazilian style. big ben strikes the hour meanwhile, in london, big ben welcomed in the new decade, with the iconic london eye sparkling on the south bank. in france, saluts and salutations. parisians partied along the champs—elysees. the arc de triomphe triumphantly hailing 2020 had arrived. and in dubai, the world's tallest building, the burj khalifa, was transformed into a tower

of lights and pyrotechnics. as parts of australia are ablaze amid relentless wildfires, the political firestorm focused on syd ney‘s political firestorm focused on sydney's display but the fireworks did go for the city's harbour bridge. bright lights amid dark days. and in scotland, an alternative take on new year's celebrations. a flaming, spinning spectacular, you shouldn't try at home. gareth barlow, bbc news. let's see what the weather prospects are. a little duller for us, let's see what the weather prospects are. a little dullerfor us, but never dull with carol kirkwood. happy new year to you, and you are

still remembered at barometer world in north devon. i was there last week and they said to say hello. how lovely! happy new year to them, to you and to you at home. it is a dull start of the day to day. we have had some fog and frost this morning and if you are out and about, there is a lot of cloud around. some of the cloud is thick enough to produce spots of drizzle. sunny intervals gci’oss spots of drizzle. sunny intervals across parts of east anglia. overnight, the wind is strengthening and we have a band of wind coming oui’ and we have a band of wind coming our way. the isobars

tell you show you then expand when this coming our way. hello, this is bbc news. the headlines: at least eight people have died and hundreds of homes have been destroyed in fires that ripped through australia on new year's eve. the mother of the british teenager found guilty of lying about being raped in cyprus says she believes the resort of ayia napa is unsafe. celebrations around the uk have taken place to mark the start of a new decade, with fireworks displays in london, edinburgh and other major cities. next, in weather world, nick miller and sarah keith lucas reflect on the most significant meteorological events of 2019. this time on weather world, we're in cambridge, where right here during 2019's record—setting european heatwave, the temperature was the highest the uk's ever recorded. at the uk's hottest weather station, i'll discover how you go

about accurately recording temperature, and i'll be finding out what's behind another year of record heatwaves. the science is overwhelmingly clear that the cause of this climate change is our activities as humans putting more and more carbon dioxide and other greenhouse gases into the atmosphere. and i'm at cambridge university, where a new look at pioneering data collected in the 1970s is revealing the real impact climate change is having on our melting ice sheets today. also on weather world, 2019's biggest storms, from devastation in the bahamas, hit by its most powerful hurricane, to the fire ravaging parts of our world. and climate in crisis, as a swedish teenager becomes the face of public protest. how the 2010s became a decade like no other for our climate.

cambridge, famous for its university, its scientists, its punting on the river, and now its heat — because of this. this weather station, which onjuly 25th, 2019 recorded a new national high temperature for the uk of 38.7 degrees celsius. now, in a year when climate change has become increasingly labelled a climate crisis, that may be an unwanted accolade, but nonetheless it's a record that now cambridge holds. but how do you go about verifying a temperature like that, accepting it in the national record? well, philjohnson from the met office was involved in that process on that day. phil, tell me what you did. well, hi, nick. well, first of all, we had a good indication that record temperatures would be broken. so from there we could actually start monitoring temperatures in real time. however, part of our network is done by volunteers, such as at cambridge university botanic

garden. and so it wasn't until the following day where we heard that the temperature had been broken. we needed to come in here and first of all check that the actual instrument had been read correctly. then we performed a comparison or verification with a precision thermometer to make sure the instrument was actually performing correctly. and in addition, we need to check the environment, the surroundings where the screen is. and is the instrument actually deployed correctly? is it exposed correctly? and there is a thermometer inside this box. but tell me why it's enclosed like this. we want to measure the air temperature. if the thermometer was actually outside, then we'll be heating the thermometer directly from the sun, and so that would give a false reading, the same as if you put a thermometer on the wall, you're actually measuring the temperature of the wall and not the air temperature. and there's a very good reason you don't want to open this box today to show us the thermometer inside. it's a very, very sensitive piece of equipment. as soon as we open the door, we actually may get a little spike in the temperature, which we can't accept

for our readings. and the principles of recording heat like this are the same anywhere in the world. indeed. the world meteorological organization, they provide standards where we should measure temperatures. for the met office, our standard is 125 centimetres above ground level, normally above grass. some countries are a little bit higher, but generally we are within their guidelines. phil, really good to talk to you. thank you. and it wasn'tjust in the uk that heat was hitting the headlines in 2019. far from it. australia in november, and its largest city, sydney, is almost lost in smoke as multiple fires burn in dry, hot, windy conditions, producing catastrophic fire danger. firefighters face near—impossible conditions as temperatures soar. and worse is to come in december, as the country endures its hottest day on record. in august, the world watched as a record number of wildfires burned in the amazon

amid a political storm about blame. in the usa in october, california's largest fire of the season so far rages north of san francisco. earlier injune, the city had its hottest three days ever recorded in summer. and it was a series of astonishing summer heatwaves in europe that shattered records across multiple countries, including here in france injune, as the temperature reached nearly 46 celsius. then injuly, new national records were set in germany, belgium, the netherlands and the uk. and as the year came to a close, the world meteorological organization said the last decade was set to be the planet's hottest on record. joining me now to talk about all things heat here at cambridge university botanic garden is dr emily shuckburgh, cambridge university's chief climate scientist. so, what stands out for you from what's been happening heatwise around the world in 2019? well, i think obviously what stands out for me beyond all else

is the record temperatures that were recorded here in these gardens back in the summer. 38.7 degrees celsius. and the really significant thing about heat of that level, though, is the effect that it has on people's lives and particularly on vulnerable people — either the very young or the very old. and we've seen spikes in death rates particularly amongst the elderly in the heatwaves that we've seen in recent years. and that's a significant concern. and in terms of those record temperatures and how they fit into the heatwaves, is that something which is going to happen more frequently, or is already happening more frequently? we are seeing it already. so heatwaves in some parts of the world that used to happen maybe a couple of times a century before any climate change, we're now seeing it occurring every few years. and as the temperatures increase globally, those frequencies will increase still further. what's driving the heat and the increasing heat that we're getting? the science is overwhelmingly clear

that the cause of this climate change is our activities as humans putting more and more carbon dioxide and other greenhouse gases into the atmosphere. so today our carbon dioxide levels are coming close to being 50% higher than they were before the start of the industrial revolution. and that has driven globally temperatures to be more than one degree celsius warmer than that time. and that might sound like quite a small number, but the implications of that are really significant increase in the risk of extreme weather events. good to talk to you. we'll be back with you again later in the programme. now it's time to cross to sarah, who's looking at what's going on with temperatures at the other end of the extreme. a warming world is still capable of extreme cold and back injanuary 2019 in the usa, chicago recorded its lowest temperature in 3a years, with minus 30 degrees celsius. you see this on my glasses? this is notjust fog, but frost. it's ridiculous out here, and it's going to get worse.

where you expect it to be cold, temperatures are on the rise. in fact, the arctic is warming twice as fast as the rest of the planet, and in 2019 recorded its second—smallest sea ice extent in the satellite era. but the arctic hit the headlines for something else in 2019 — fire. millions of hectares of forest burned within the arctic circle in scenes described by experts as unprecedented. higher temperatures and a greater frequency of lightning are partly to blame. in order to better understand what's been happening in our polar regions during 2019, i've come here to the scott polar research institute at the university of cambridge. it's the oldest dedicated polar research institute in the world. and professorjulian dowdeswell is the director. so, julian, tell me a little bit about the work that goes on here. our main expertise, i suppose, where we put most of our resource is what we call the icy world and in particular, ice

and environmental change. and, of course, a huge amount has changed since captain scott, shackleton and edward wilson first went into the interior of antarctica. scott's first expedition collected over 20 volumes of data concerning the antarctic at that time, which provides arguably the earliest baseline against which we can judge contemporary change in that part of the polar regions. and over that hundred years, how has our perception of and our relationship with the polar regions changed, because they're very much at the forefront of our minds these days? when i started in the field as a doctoral student a0 years 01’ so ago now, people thought that the polar regions were interesting, but a little bit divorced from the rest of the world, indeed from the rest of the global climate system. and now, of course, we know that absolutely is not the case. and indeed both the arctic and the antarctic are major drivers of the global climate system.

the poles are just about as far away as you can get from the big, industrial, carbon—emitting parts of the world. so why is it that the poles are quite so sensitive to climate change? the arctic is almost inarguably the most sensitive part of the whole global climate system. but in the last 20 or 30 years, there's been an enormous change in the summer sea—ice cover in the arctic. in fact, a change from about eight million square kilometres per year to only about 11.5 or 5. and what you do by removing that ice by the end of the summer, because it's slightly warmer in the arctic, is you change the reflectance of the surface very greatly, and you swap something that's very bright and reflective for something that's much more like my jumper, for something that's really absorbent. that happens year on year. each year, there's a bit less sea ice. each year, the temperature of the water in particular is just a fraction warmer, which makes it more difficult the next year for the sea ice to form,

that's a self—reinforcing process. and that is the reason really that ice reflectance, that feedback, that is the main reason why the arctic is the most sensitive part of the whole global climate system. and 2019 has been another year of extreme weather around the world, from record—breaking heatwaves, floods and also wildfires even to the north of the arctic circle. so what really stands out in 2019 in terms of what's going on at the poles? fires are a big thing throughout the globe. and, of course, they manifest themselves by things like black carbon in ice cores. and we can actually trace how those have changed over the decades. over the past 800,000 years in the longest antarctic ice cores, we can see that co2 levels are very strongly coupled with temperature over successive glacial, interglacial cycles. thank you so much, julian. and thinking about how we use historic ice data to look forward into the future, a little bit later in the programme i'll be back looking at some newly available digitised ice data that is helping climate scientists map what could potentially happen to our climate in the future.

now for some of your weather watcher pictures, starting with these scenes from november, when parts of england suffered severe flooding in a deluge which contributed to south yorkshire, nottinghamshire and lincolnshire seeing their wettest autumn on record. but the autumn rainfall wasn't evenly distributed across the uk. in fact, parts of northern and western scotland were much drier than average in autumn and exceptionally dry in november. become a bbc weather watcher by signing up online at bbc.co.uk/weatherwatchers, and you could be in the running for pic of the season, which in autumn was won by tony's view of the stormy seas in wales. still to come on weather world: underwater — why a warmer world can also mean a wetter world. now on weather world, some of 2019's biggest storms, starting with hurricane dorian, seen approaching the bahamas in september.

the few images taken as the category five storm hit paint a terrifying picture, as a flooding storm surge ploughs across the abaco islands. the aftermath is apocalyptic. the near—complete devastation here at marsh harbour on great abaco is a product of the strongest storm ever to have hit the bahamas and one of the most powerful on record in the atlantic. in the western pacific in october, hagibis is the strongest typhoon in 60 years to hitjapan. the storm leaves behind widespread damage, including to these bullet trains swamped by the floodwaters. earlier in march, cyclone idai is one of the strongest ever to hit africa. this is what it did to the city of beira in mozambique. idai is the southern hemisphere's second deadliest tropical cyclone on record.

and in may, cyclone fani ploughs into the east coast of india. it's the strongest storm here in 20 years. but countless lives were saved thanks to a mass evacuation in advance of the storm. no tropical cyclone in italy, but a storm surge all the same combines with the venice high tide in november to produce the worst flooding here in over 50 years. st mark's basilica was said to have suffered grave damage, with its crypt completely flooded. in the uk, 2019 has brought bouts of severe flooding, most recently in november across parts of yorkshire and the midlands, as record autumn rainfall sent some rivers to their highest levels ever recorded. extinction! rebellion! during 2019, public protest and direct action about climate change reached new levels. chanting.

spain in december, and thousands demonstrate as madrid hosts the united nations climate conference. arriving by train, teenage swedish environmental activist greta thunberg has a police escort, such is the interest in someone who's become the face of the climate protest movement. addressing the conference, she said not enough is being done to combat the climate crisis. to stay below 1.5 degrees, we need to keep the carbon in the ground. only setting up distant dates and saying things which give the impression that action is under way will most likely do more harm than good, because the changes required are still nowhere in sight. well, i'm back here at cambridge university's botanic garden with cambridge university's chief climate scientist, dr emily shuckburgh.

emily, we talked earlier about how warm the world has become. but in that video, we saw lots of rain and flooding. so how does this warmer, wetter world fit together? yes, it might sound counter—intuitive, mightn‘t it? but, actually, a warmer atmosphere can hold more water in it. that's just simple physics as to how that happens. and that means that there's more — that it's wetter, essentially, to be able to rain down and heavy rainfall events. and that's the essential reason why we've seen more and more flooding here in the uk, but also flooding events around the world as well. and we've seen really powerful hurricanes and typhoons as well. is that something that also fits into climate change science? mm, the way in which climate change interacts with hurricanes and cyclones is quite complex. but in terms of the damage caused by those hurricanes and cyclones, it's very clear that much of that damage is exacerbated by climate change. so we've just talked about how climate change can cause heavier rainfall and a lot of the damage associated with cyclones, this comes from the flooding, the storm surges that we've seen

associated with those. so heavier rainfall, greater storm surges, but also sea level rise across the world. as the seas have been rising, those storms are going to penetrate that much further inland, causing that much more damage. and amidst all of that background of heat, flooding and storms, 2019 has really been a year of political activism, public activism as well, when it comes to climate change, more awareness about that, hasn't it? we've seen young people around the world really rising up and saying "our future is at stake" and their future really is at stake. it's decisions that we all make over the coming decade that will determine not just our children's future, but their grandchildren‘s and their grandchildren‘s future as well. thanks for talking to us in this lovely setting on such a sunny day. thank you! a uk climate scientist and his team at reading university are helping us

to visualise how much the world is warming with these climate stripes, here showing each year's average global temperatures since the 1880s in a coloured stripe, clearly progressing from blue to red over time as temperatures have warmed. bbc weather presenter ben rich takes a look at how you can look for a climate stripe to show the temperature trends where you are. this is the show your stripes website, and on the home page, we're greeted by the same global climate stripes we've just been looking at. but the great thing about this website is we can delve a little deeper. we can look at patterns in different places around the world. and it's quite simple to do. if i click on "region" and then select africa, for example, i can then choose a country. in this case, i'm going to choose ethiopia. and these are the climate stripes for ethiopia. this data goes back to 1901. it comes from berkeley earth.

and you can see this pattern of things getting warmer over the years, and in some parts of the world, we can dig even deeper than that. the usa is a great example. if i click on "region", choose north america, then find the usa, we're able to select different states of the us. if i choose florida, again, here are the climate stripes. this data comes from noaa, the us weather and climate service. this data goes all the way back to 1895. as you'd expect with a smaller area, there is a bit more variability — some warmer years earlier on, some cooler ones later on. but generally speaking, you can see that warming pattern, and that is the striking thing about this website. basically, wherever you look around the world, you will find that trend of accelerated warming in recent years. i'm back at the scott polar research institute at the university of cambridge and, professorjulian dowdswell, you're going to take me back in time to look at some of the research that was done here almost half a century ago and look at why it's so relevant to what's happening today.

after the end of the second world war, the surface of the antarctic ice sheet began to be mapped, but there was no knowledge at that time at all of what the thickness of the antarctic ice sheet was. it was realised by the late ‘50s that ice was semi—transparent to radio waves at certain frequencies. and what that means is if you fly a transmitter and a receiver at that frequency, this is the atmosphere and beneath it is the ice surface, which we can see is a very strong reflector. and then some of the megahertz energy from the transmitter actually penetrates through from the ice surface, through the ice itself to the rather more diffuse bed and that energy is reflected again back to the receiver. and that allows us for the first time to actually map

not just the surface, but the thickness of the antarctic ice sheet. so thinking back to this data that was gathered almost half a century ago, technology must have come on a long way since then, so how do you get this into a kind of format that we can use and compare to our modern records now? well, technology has changed a lot. and, of course, we're in the digital age. so we, together with colleagues at stanford university in the us, have realised that we can actually redigitise these old film records at very, very high resolution. and this we actually did last year with the help of the hollywood film industry. we remastered, effectively, these films in analogue form into digitalform. we can compare our data from the 1960s and the early 1970s with modern satellite and airborne measurements from just the past decade or so. and then we can compare things such as elevation change and thickness change. so when you're comparing what the ice was like a0 or 50 years ago to what's happening now, have there been any surprises in this data? 0h, always. i mean, in some ways, things haven't changed in some

places, and in other areas, things have changed much more than we expected. for example, there are channels on the underside of some of the floating margins of the ice sheet, we call these floating ice shelves, that in fact have stayed in the same position and about the same size through the whole 40— to 50—year period. and that's interesting because it shows in those cases the lack of change. and there are other areas where we compare modern thickness with the thickness 30 or a0 years ago, and there we see changes of over 100 metres. so what this suggests is that some parts of the antarctic, as one might expect, are actually more sensitive and some are less sensitive to external climatic stimuli. thank you so much forjoining us and for talking us through some of the really fascinating and important work that's going on here. a great pleasure. november 2013, and typhoon haiyan bears down on the philippines, the deadliest in a decade of more powerful tropical cyclones. as we enter the 2020s, we asked university of reading climate scientist dr nicolas bellouin for his personal take on the 2010s,

a remarkable decade of weather and change for our climate. this has been an extraordinary decade in terms of weather and climate, and many records have been broken, many kinds of records all across the planet. it has been a warm decade. indeed, seven out of the ten warmest years have happened since 2010, and 2016 is the warmest year on record ever. that brings heatwaves as they've been recurring in many parts of the globe. and with that comes the risk of fires, which have peaked in brazil and have been very strong in australia, in california and in south—east asia, but also in sweden, which recorded

record fire in 2018. precipitation has also hit records. china had its wettest year in 2016 and the us in 2018. flash flooding is now recurring often in africa and in france, italy and spain. so the question for me as a climate scientist or perhaps more generally for us as a society is whether this is a transition towards an even warmer world or a call to action to avoid further surges? the effects of severe weather can sometimes hit with little warning. in the uk in march, watch this man narrowly escape disaster as strong winds caused part of a building to collapse. and sometimes we can bring near disaster on ourselves. in november, this man and child are lucky to escape with just a soaking as big waves hit the coastline of the isle of wight. and finally, what to some can seem like the worst of weather is, for others, pure joy.

australia in november, and it rains in new south wales. in a state hit by severe heat, drought and fire, the reaction is understandably enthusiastic. and that's it for this time on weather world from cambridge. there's more to see online, including highlights from our previous programmes, at bbc.co.uk/weatherworld. let's see what a new year — a new decade — of weather brings. it will bring more weather world. so until we're back, keep checking the forecast.

good morning and happy new year. we started on a misty and murky note, but there will be a lot of cloud around today. in the west, some of that will be thick enough for spots of drizzle. under clear skies, we will see some sunshine in north—east scotland, north england and at times north wales. windy across the far north of scotland. this evening, more glad to come, the wind strengthening by the end of the night across western scotland, with gusts to gale force and then we have a band of rain arriving in the west of scotla nd a band of rain arriving in the west of scotland and northern ireland first of all. tomorrow, a cloudy note for england and wales. some

heavy rain pushes across scotland and northern ireland into england and northern ireland into england and wales. then it is a lull before the next band of heavy rain comes oui’ the next band of heavy rain comes our way with hail and thunder. it's going to be a windy day. this is bbc news. the headlines at 10am. at least eight people have died and hundreds of homes have been destroyed in the fires that ripped through australian on new year's eve. some communities have been cut off. a couple of isolated communities where we have got reports of injuries and burn injuries to members of the public. we haven't been able to get access via roads or via aircraft. it's tough. it was scary. you don't really know what to do, even if you've thought about it, it's hard to know what you'd do or feel at that moment, for sure. the mother of the british teenager found guilty of lying about being raped in cyprus says she believes the resort of ayia napa is unsafe. in their new year messages, the prime minister says brexit will mark a new chapter for the uk, while the archbishop