now on bbc news, reporting from the climate frontlines. for the past two decades, the bbc�*s science editor david shukman has been a witness on the frontlines of global warming. in this programme, he explores how we got here and what it means for the future. it's now beyond doubt that the arctic is changing dramatically. i've had a unique position for nearly 20 years as a witness for the bbc to the greatest challenge of our time. how we're damaging the planet so profoundly that we're turning the climate against us. it's a job that has taken me to the farthest corners of the world. i've felt despair as extreme weather strikes people least able to resist it. i've been attacked for highlighting the risks of global warming. and i've also experienced hope that clever ideas and a rising generation will help us to find a way through. so, this is my story, reporting from the climate front lines. the thames barrier in london, a giant defence against the sea. it was built long before anyone worried about global warming, but things are very different now. the job of the barrier is to keep london safe from flooding, and right now, it's coming up to high tide, and the great steel gates are holding back a phenomenal volume of sea water that would otherwise enter the city and potentially cause disaster, which is why climate change matters so much here. they're constantly watching the projections for how much the sea is going to rise. it's also why we'll probably need a bigger barrier by 2070. and this was what first hit me about climate change. while some countries can afford gleaming steel structures like this, most others can't. 0n the coast of bangladesh back in 2009, we saw sea water pouring into this village. the flood was so deep, a boat was the only way for us to get around. and the only defence was a wall of mud that was broken. people were struggling to repair it. a human chain passing handfuls of mud to fill the gaps to try to hold back the sea. the big worry here, of course, is if the forecasts of climate scientists are right and the sea rises even more, maybe by a metre by the end of the century, well, how on earth are these millions of people going to cope? while london is secure, the only refuge here was a narrow ridge. the people who've done least to cause climate change were suffering most from it. life was far more precarious than i'd ever expected, and it was getting worse. all over the world, i was seeing that children were feeling the impact. remembering this school in vietnam always brings a lump to my throat. the class was drawing pictures of flooding, and it was like seeing into nightmares of drowning, homes destroyed, disasters that these young minds are dreading. the people scream out, "help." whether it's too much water or too little, i was finding that the climate risks are similar. it doesn't take much of a change in temperature or rainfall or sea level to make life almost impossible. a drought in kenya in 2006 really brought this home. many of the cattle were dying. they're important to the maasai people. so at a school, i asked how many families had lost animals. almost all of them. my family were very frightened that all our cattle would be cleared off by the drought, and we were very sad. more than a century ago, scientists first started warning that we're heading for trouble. the more we burn fossil fuels, the more heat is trapped in the atmosphere. and despite knowing all this, we're still living in ways that put us on course for dangerously high temperatures. ok, so we're on our way down. i'm starting to feel the air pressure in my ears now. over the years, i've filmed at the heart of the fossil fuel industry. this coal mine is in poland. when the business is digging up carbon, it's like visiting a different planet. no—one seems to worry about climate change. even shifts in the rock don't bother the miners. this is a way of life and a mainstay of the economy. coal is the dirtiest fuel, but there's still demand for it. this is a reality of life for thousands of miners in poland, and because the coal—mining industry is so important to the economy here, it looks set to last for decades, whatever climate scientists and environmental activists want to see happen. oil is also driving up global temperatures and it's also booming. global demand keeps rising. the company running these pumps in california refused to let us in, so we took to the air. this field has been producing for more than a century, and whenever anyone thinks it might run dry, someone comes along and eitherfinds more oil or comes up with a new way of getting at it. the result, as in many parts of the world, there's more oil than previously thought. and if oil's in your blood, you're not going to like global warming. in fact, the oil industry knew about the risks from its own research, but deliberately created doubt. when i visited this well in texas 12 years ago, the owner used a classic line from climate deniers — that any change is natural. the question is — how much difference does c02 really make in our atmosphere? and that question should be debated. there are a lot of climate drivers. you can see the sun shining on my face right now. the sun, obviously, is one of the biggest climate drivers, it goes through many cycles. that view, that climate change is perfectly natural, that fossil fuels have nothing to do with it, has been very strongly held, and it's led to some vicious attacks on scientists and onjournalists like me. i felt pretty exposed at times, accused of being a lobbyist for green industries, of being a hypocrite for using fossilfuels. but i've also watched how the research has evolved, how the scientists have become more confidence as they've gained new knowledge to answer their critics. but it's been quite a job to get to that point. all over the world, i've joined expeditions as scientists have investigated the climate. counting individual grains of sand to see how faster winds will expand the deserts. needing an armoured vehicle in siberia to reach remote corners of permafrost. enduring the toughest conditions. watch what happens to this weather balloon in a polar storm. understanding how the world is changing is a complicated challenge. for me, it began with a descent into antarctica. i'm climbing down into a crevasse, and it's by getting down into the ice and drilling into it that scientists are able to build up a picture of the greenhouse gases that have been building up in our atmosphere. they find bubbles like this trapped in the ice and analyse the air inside them. the ice holds a record of the climate, trapping carbon dioxide year after year, so we can see how it's risen and fallen. but the next step is working out our role in that, the human fingerprint on global warming, and that involves more recent data. getting to it took a long journey to hawaii and up an old volcano. at the summit lies a forest of instruments. one of them has measured carbon dioxide since 1958. by coincidence, that's the year i was born. so, during my lifetime, levels of this key gas have just kept rising. the most striking thing that i see in the c02 records since 1958 is that the concentration in the atmosphere has gone up every single year. so, where would this lead us? the early computer models couldn't be sure. there were lots of uncertainties, but the scenarios were already looking scary. the arctic was the hot spot, heating up much faster than the rest of the planet, and i was to return to it many times. it was greenland that really unnerved me. it may be remote, but there's enough ice here to raise the global sea level by 7 metres. i could see for myself a frightening pace of change. 0ur helicopter seemed tiny against the edge of the vast ice sheet. this massive wall of ice behind me... and since i first filmed there, temperatures have just kept rising. and ice that had seemed permanent has retreated. back in 2004, it would have been 100 metres thicker than it is now. that's like having a 30—storey building sitting on top. it's alljust going at an incredible speed. the ice was vanishing beneath my feet faster than anyone believed possible, and i immediately thought of bangladesh, and the fact that millions of people on coastlines around the world threatened by streams of meltwater heading for the oceans. gradually, the projections for the future climate were becoming more reliable. the models were more accurate. supercomputers were handling vast amounts of data, so the un's climate science panel has now overcome years of doubt and denial to reach its most definitive conclusion — that it's us forcing up temperatures. there are natural features that are on our side. the great tropical forests. they're home to abundant and diverse wildlife, and they store carbon that would otherwise be heating the air. so, the habitats these animals depend on act as a buffer against climate change. but we're hacking those trees down. we caught this moment in ghana. so, another massive tree taken away to be used for timber. this process is going on notjust in ghana, but in tropical rainforests right around the world. the worst devastation is in the amazon. it's heartbreaking, like walking through a graveyard, a once thriving habitat suddenly silent. and for scientists like erika berenguer, dedicated to researching the trees, the losses are profoundly depressing, and they affect them personally. for me, it's really important, because the amazon cannot speak up, the trees cannot speak up, they cannot say that they are worth it. and they have a value, they are really important, so i have made this my life. the deforestation happens for a reason — it's big business. the trees are cleared to grow soya for animal feed and to raise cattle for beef. the products are then traded all over the world to consumers who may never realise where they're from. so, there's a good chance that i've eaten food that originated in the amazon. as with a lot of people, i'm finding that the penny is now dropping about the impact of the choices we all make. for example, with food, where it's grown, how the ingredients are transported, and in particular, what happened to the packaging after we've finished with it. and i get the sense that people are becoming more aware of climate change partly because of other environmental problems. plastic provokes the biggest reaction because it's right in your face. i filmed this mess in turkey. and it forces us to ask what we do with our own waste, because the plastic items are so recognisable... ..like the plastic hook in the beak of this albatross chick. we were on midway atoll in the pacific, and ifelt real shame at the harm we're causing. a wildlife expert tried to save the young bird. any idea yet what it might be? yeah. i just want to make sure there's nothing sharp. there could be a hook on the end of something? yeah, it looks like we're going to be able to get it out, there we go. and now, we can release the chick. it was a small net for fruit or nuts, used just once and then thrown out without any thought of the consequences. the scale of the damage is so staggering that the tide may now be turning. in indonesia, we filmed these soldiers trying to clear a river jammed with plastic. that seemed pretty futile. butjust up the road, a village was trying to be more positive, using plastic waste to create artistic products. a sign that people are resisting environmental damage. there's the same kind of public resistance to filthy air. when we filmed in china, we wore masks, long before anyone had heard of covid. this family were careful to protect themselves, not against a virus, but against air pollution. the chinese people themselves forced the authorities to shut down or move the dirtiest industries. we're starting to get a little lost. and there's now a similar impatience with climate change. year after year, i've seen the lack of progress in international negotiations. it's why greta thunberg has made a stand, gathering the support of millions, fed up with endless talk. "build back better, blah blah blah. "green economy, blah blah blah. "net zero by 2050, blah blah blah." when i met greta, i was struck by her determination. she was getting ready to protest at the next climate summit. by going there with many other young activists, i hope that, together, we can help spread the message, and to make people listen to the united science. so, how do we get out of this crisis? i've had a front—row seat at the emergence of forms of new clean power. the biggest investments are in china. we filmed this team throwing up one or even two wind turbines every day, a breakneck pace that was driving down prices. at this solar power station in spain, giant mirrors focus the sun's rays on a boiler. i can feel the temperature rising just in the metal of this ladder. and all of the sunlight is reflected up here to the top of this tower. it's incredibly bright and hot. the temperature here can reach more than 400 centigrade, enough to power a boiler here, which goes on to generate huge amounts of electricity. the project looks incredible, but since our visit, it has struggled financially. not every new technology will succeed. instead, a concept that once seemed impossible — planting wind farms out at sea — is now taking off. and the turbines are getting bigger, far bigger. this is the next one to be lifted. hoisting this huge structure up off the quayside and onto a ship is an incredibly painstaking and difficult task. it has to be repeated thousands of times, if the government's energy targets are to be fulfilled. and since we filmed, offshore wind has gone from strength to strength. the costs are far lower than predicted. it's a green technology that's booming. whatever we do, we are going to have to adapt to a hotter planet. in namibia, amid a dusty landscape baked by drought, there's a vivid patch of green where a class is being taught how to cope without rain. we know now, maybe in the next two to three years to come, we don't know if we will get even a single drop of rain. and therefore, we have to come up with something, which is going to help the children. other ideas seem obvious — shades over the windows to keep the sun off, planting more trees to soak up carbon dioxide — billions will be needed. and maybe our food will come in new low—carbon ways. i was stunned to enter this vertical farm. there are fields in layers. a young researcher here, beth campbell, was bursting with enthusiasm. this is the future. if you can grow stuff that's supposed to grow in italy here in the uk, you can grow it anywhere in the world, you can grow it in the middle east, in africa, and then you cut out all of the transportation, so you're saving money, time and resources. and carbon, i reckon. and carbon, a lot of carbon. you're not flying basil all over the world. so, what lies ahead? well, i've turned repeatedly to everyone's favourite guide, david attenborough. the warnings have been proved true, he tells me. what climate scientists have been saying for 20 years, and that we have been reporting upon, you and i both, is the case. we were not causing false alarm. it is the case, and every day that goes by in which we don't do something about it is a day wasted, and things are being made worse. i'm now preparing to leave the bbc, but for the sake of my children and their future children, i want to keep explaining what's in store for us, and how there's so much we can do about it. covid has shown us that, when governments have the will and get behind the science, it can make a difference. and, as with the pandemic, everyone's at risk, and everyone can help, which means that we're all on the climate front lines. hello, most of us did not see a white christmas. some places to. most will have a white boxing day. heavy snow across northern parts of england and southern scotland. through the rest of today we will keep that mix of rain and sleet snow. some sunshine. stilla scattered showers here. eastern england will keep cloud. the hill snow is easing from northern england. four or5 snow is easing from northern england. four or 5 degrees. snow is easing from northern england. four or5 degrees. much milderfurther england. four or5 degrees. much milder further sell. england. four or5 degrees. much milderfurther sell. to england. four or5 degrees. much milder further sell. to this evening and tonight, it will become drier. still a little bit of showers across northern part. extensive mist and fog developing. perhaps across northern england and scotland a bit of frost. a murky day for many of us on monday. wet and windy for the southern half of england and for a time. drierfurther north. top temperatures somewhere between six and 12 degrees on monday. goodbye. this is bbc news broadcasting in the uk and around the globe. our top stories... tributes pour in for archbisop desmond tutu — nobel laureate and veteran of south africa's struggle against apartheid, who has died at the age of 90. there was a sense in him that life was to be celebrated, even when he was in the troubles of soweto where he was a priest, that actually when you look at reality, every human being is a stand—in for god. new coronavirus restrictions come into force in scotland, wales and northern ireland, as the uk's devolved administrations try to limit the spread of the omicron variant. omicron causes chaos for travellers — 7,000 flights cancelled around the world over the christmas weekend.