We need to, they will give you. This is our planet. It contains an astonishing variety of landscapes and climates. Since life began around 4,000 million years ago, it has gone through extraordinary changes and its climate and in the space that their on it. But no, it seems that our planet is being transformed not by natural events the by the actions of. One species mankind. You know I belong to the most they spared and dominant species and I more or less. We live on 27 years ago I presented life on Earth. A series of traces the evolution of life from its very beginnings. I set out to find them film representative species of the whole animal kingdom in all it's marvelous and wonderful for us. In the final program I dealt with the arrival of human beings. Still a recent event in the history of our planet. There is no scientific evidence whatsoever. The suppose indeed that man will stay on earth should be any longer than that of the dinosaurs, but although denying a special place in the world, maybe becoming a modest. The fact remains that man has an unprecedented control over the world and everything in it. And so whether he likes it or not. What happens next. It is very largely up to him. Up to us. Indeed, at the time I spoke those words. I had no idea that we have been the might have unleashed forces that in the hotel in the climate of fear. Good. The destruction of towns and cities in the southern United States be linked to the collapse of glasses in green. If going people but is the stuff floating around if out there. Might drought in the Amazon that killed thousands of fish be connected to the intensity of forest fires in Australia. And are these events related to one of Europe's hottest ever farmers. Which led to the death of 27,000 people. In every part of the world. New climatic extremes are now being the court. Our weather is in turmoil. During the last 50 years I've been lucky enough to spend my time traveling around the world looking at its wonders and its spenders during a time of course, I've seen many changes some good many bad but it's only in the last decade that I've come to think about the question as to whether or not what I or anybody else has been doing could have contributed to the change in the climate of the planet. It is undoubtedly taking place. In recent years, scientists have been collaborating on one of the most urgent and ambitious endeavors in our history. They're trying to understand the unprecedented changes in our time . And they're linking those changes to the rising temperatures that they're measuring had thousands of weather stations around the world. So, how much have global temperatures well by just over nought-point 6 of one degree Celsius. Since 1900 how can such a seemingly small rise create so much havoc with the planet's climate. Well, that figure nought-point 6 degrees is only an average while some places have cooled a little some like the Arctic has warmed by up to 3 degrees. The frozen surface of the sea creates a highly specialized environment. And an extraordinary range of animals have evolved to live both above and below the ice. But the Arctic is now melting so fast that the whole intricate web of wildlife is under 3. And no species is more at risk than the animals at the top of the food chain, the polar bears. The turn of the year, that is when females give birth to raise their cut. By this time mothers will not have eaten for many months, and yet they now have extra mouths to feed. Their main prey are seals but they can only hunt before the ice melts, but it does that they must come ashore with all the reserves only to raise their cubs. And on land. There are no to hunt. Now because the ice is melting earlier each year mothers are going hungry and the less able to provide for their Cup. In Hudson's Bay Dr. Nick to London sets out each spring to track down the polar bears and check on their health. They been there. I've been working on that all of us here in the Churchill area since the early 1980s over the last 25 years and we're looking at the population ecology of polar bears in relation to tie not of change is population is the most studied population anywhere in the world. By tracking the Bears with such regularity Miquelon and his team have discovered that their numbers have declined by nearly a quarter since he first started stuck. First he needs to find the best. He then tranquilized system so that he can check their body weight to assess their health. The team has to work quickly to make their checks on their family before the mother wakes up. 24 and a half pounds for Cobb one fun on larger bears we take the weight and their length and weak calculate what we call a body-body condition index. It's essentially the weight of the bear divided by its length Square and it gives us a means to compare bears between years over years what condition there and when the come ashore and we found that over the past 25 years or so low that the condition of these bears us declining. Cobb 2 straight line leg zero 6-9. Here we've got a female with a trip letter. It's a very rare sight to find triplets. In the fall time one of the Cubs is a runt of the litter and it's not likely to survive. 20 years ago. It wasn't all that uncommon to find triplets. In the fall. About 5% of the bears. We caught more females with cubs had triplets. We're seeing triplets born in the spring, but we're not one or more of those cubs is not making it through the fall. We're seeing reductions in Cup survival, things of that nature, all related to climb out of form. The ice is now melting 3 weeks earlier each year. That means that there is 3 weeks less feeding time for pregnant mother. Once they come ashore in the sea ice melts the bears are forced to fast for anywhere from 4 months for most parents up to 8 months for a female such this here. Who would have come ashore last summer and it's not hard to see all meal since last July. If the current warming trend continues the future looks bleak for polar bears. It's not just that sea level. Is melting at Sutton alarming rate. The global temperature rise is also being felt much higher up. Mountain glasses all over the planet also now. The mountain ranges of Patagonia rundown towards a sudden tip of South America. This is the, in the northern Patagonian Ice Field it starts almost 2.5 thousand meters above sea level. This remote part of Patagonia is one of the coldest places on earth outside the poll nobody. JC allergist Dr. Stephen Harmison has been working in locations like the meth for 20 years he's been studying how they've changed over that time. The Patagonian Ice Field, the most dynamic ice fields on Earth. To understand climate change in the southern hemisphere. We need to go to places like this. He gives a very good record of climate change over the whole range of time to go. The ground I'm standing on that last year, the net glass. It was here in about the 1870s and by about 19 the 1930s it will be treated to this shoreline the lake shoreline and since then, since 1930s of courses retreated another 2.5 to 3 kilometers perhaps 2 miles back up this valley. We were hearing Martin 88 is this the whole night was completely covered with icebergs. All. Some fake MySpace we hardly get our boats in the ice front and yet that's will go on that landscape is completely changed now . Russia's give us a very visual record of climate change and and the they should be no doubt the climate change is happening. If we look at what glasses and doing all around the world, not just these ones on the north Patagonian Ice Field but glasses everywhere. They're all in recession pretty well and and that gives us a very visual record what exactly is going on in most one. The rate of that class Immelt is now accelerating. In southern Greenland. The amount of ice flowing into the sea has doubled in the last 10 years. This is slowly but steadily causing sea levels to rise. 8,000 miles away. The inhabitants of the tiny Pacific islands of Tuvalu are already facing the realities of an invading sea. As temperatures rise so do those of the sea, causing oceans to expand and that coupled with the dresser melt means that sea levels will rise even higher. Earlier this year tides rose to their highest level ever known flooding the homes of the islanders. They have been troubled by this problem for the last few decades, but according to Diana semi it's getting progressively worse. Most of the people now experiencing this high tide is much higher than it hasn't won and. If next year is going to happen like this and much higher than this year then I don't think there's any future for him to. Through Mario Silva is now 2 values disaster coordinator. The prediction for tomorrow. The highest, but now looking at this time. Boats he flooded. And so, so it's them all their properties is they have been cowed tour guide binning in all those would be damaged by this. See what I. You can see that our rubbish everywhere and you're you seeing that the kids swimming and those waste area, I think a big health problem for kids and especially his people thing these houses and. Very worried flood they have at door climbing outside inside, but the flow this company here. Yes. All my really. PC fear well you here only here and at times, calling them but now this year as they really high time inside the house. This is the first time I think to to move out because and freight. I don't know placed move. But on the islands where the highest point is less than 5 meters above sea level. There is nowhere else to go. There are already plans for some of the population to be evacuated to New Zealand. But warming seas don't only mean rising seas. They have other implications, too. In August 2005 Hurricane Katrina struck the coastline of Louisiana, Mississippi. Wasn't the high sea temperatures that many Katrina so intense. A typical hurricane, an atmospheric disturbance over Africa but it's here in the Gulf of Mexico that they grow to their full destructive power. How you can expert Greg Holland has been investigating what fueled Katrina's force. The process requires that the oceans be warmer than about 26 degrees Celsius. The tropical to get the hurricane started and Jordanian from the surface high up into the atmosphere and what this means the ocean heat energy is used to fuel the development of the immensely powerful winds and it is so powerful, he could run the entire electric grid of the United States for several weeks. Really destructive winds are in the region. Just outside the eye of the hurricane and this is how strong they shred the surface of the ocean into a morass of sea and spray to become so think that the Mitchell becomes impossible to tell a difference between air and water. And the one the tropical oceans, the more destructive the hurricane can out. When Harry can Katrina breached the levees of New Orleans sea temperatures in the Gulf of Mexico and the Atlantic were the highest ever recorded. In the United States. The intensity and sheer destructiveness of the Heineken became the turning point in the debate about global warming. Although scientists will not say that one particular had can is caused by climate change. Many are now making the connection between global warming rising sea temperatures and the increasing strength of Vatican. 2005 it was the worst season ever recorded. And Greg Holland is one of those who believes that worse is yet to come. As you can see there's a massive rebuilding program underway, but unfortunately this stretch of coast song will certainly be revisited by hurricanes, like a trainer and because of global climate change we going to be more intense more destructive and possibly more frequent. It's a grim warning but is global warming of the changes we're now seeing really a new phenomenon in the Earth's history. These days, when we talk of climate change, we tend to mean changes that we ourselves have brought about, but of course the climate of the Earth has always been changing, either because of some great, cosmic event like a collision with a meteorite or else because of some more slower gradual change in the amount of energy that the Earth receives from the sun. The reborn rearguard. It's the sun that provides our planet with warmth and light. Why when you know. Not the amount amenities that the Earth receives from the sun there. You know. In cycles of tense and often hundreds of thousands of years the earth tilts and changes it orbits around the sun and with each cycle the patterns of light energy playing on the changes. These natural changes have contributed to dramatic shift in my client in the time of the dinosaurs. It was much warmer than it is now. He would have found dinosaurs roaming in forests, close to the north and south poles. 70 million years after that much of our Paris was freezing. It's become locked in a cycle of success if ice ages. If the city of New York had existed 160. Thousand years ago it would have. Been on the edge of an ice pack some 2 kilometers high and yet global temperatures were only 4 degrees lower than they are today. 30 thousand years later, the same city would have been under 5 meters of water yet global temperatures were less than 2 degrees warmer. This see-sawing in the Earth's climate was driven by natural forces long before mankind appear. But there's another powerful influence on our climate. If we have to take into account among the many glasses that make up the air we breathe, there is one that is particularly important carbon dioxide it traps the sun's energy and so keeps a panic. Greenhouse gases like carbon dioxide act as a blanket around the earth prevent in the sun's energy from reflecting back into space. Left. It's called the greenhouse effect and it prevented the planet from freezing since the earth began without the global temperature would be minus 19 subsidies. On the face fit carbon dioxide seems to be a good thing it stops our planet from freezing and so sustains life on Earth and without it, no plant could grow because they need carbon to build their tissues. Leaves absorb the gas from the atmosphere through their pores. They then break down on the carbon dioxide molecules released the oxygen and retain the Cup. Over hundreds of millions of years the great forests so much carbon dioxide. Out of the atmosphere that they reduce the greenhouse effect and cool the planet down. When the trees died. They were buried and overtime crushed and compressed with the carbon still within in the ages that followed. These layers are slowly buried beneath the earth's surface. At this open cast coal mine in China, you can descend for 500m through layer upon layer of rock representing 10s of millions of years. Right at the bottom, a layer of what was once would and leaves and is now coal and. It's an ideal place for Professor Bob Spicer to studies appliances influence the climate. All that time ago. These leaves blast saw the light of day. Some 50 million years ago when they were on the trees taking in carbon dioxide and using the energy of the sun the fix that carbon into their tissues and leaves and twigs and the like. Now the original had a cooling effect on the atmosphere because they were taking carbon dioxide out and where we Burnley the call on the carbon. That's nice one, and put it back into the atmosphere. Today we have the opposite effect we warm up the atmosphere. Now all the coal is being carried up to the surface to be burned in the power station, which provides electricity for hundreds of thousands of people. Oil and gas Nicol also fossil fuel. When such fuels averting the carbon re combines with oxygen and is released back into the atmosphere as carbon dioxide. The carbon dioxide spreads evenly through the Earth's atmosphere. Sickening. The greenhouse blanket the the world and further warming the planet. That blanket extends for miles above the earth's as you climb up away from the Earth the. Is become thinner. The temperature. As a result, becomes colder. It was while I was making the living planet in the mid 1980s the tide began to appreciate the crucial role of the atmosphere in shaping our climate. We are very close to the top of our environment for all the goes on within the 5 brief Miles this envelope of atmosphere that wrapped around the world, it's here, but the weather is manufactured. When I spoke those words scientists were already detecting crucial changes in the composition of the atmosphere. In particular, changes in the level of carbon dioxide. All over the planet they were recording rising levels of that particular gas in there . The first regular measurements were started 48 years ago, from the top of the extinct volcano of money on lower in Hawaii. And it is the rate at which the carbon dioxide blanket is thickening that is causing so much concern. When I was a boy in the 1930s . The carbon dioxide back it was still below 300 parts per million. This year the thickness reached 382 the highest figure for hundreds of thousands. But how can we possibly know that carbon dioxide levels are higher now than they were thousands of years ago. In Patagonia is ice fields huge gaps open up in the summer months, giving scientists a chance to investigate far below the glasses. Stephen Harrison is taking the opportunity to descend deep into a pair of us in the . It's risky. You, you know. The glasses a melting so fast. The potentially invaluable records of the past artists. Yes. Ice cap in which his glasses flow from is melting more quickly probably than any other comparable ice mass on Earth. You can see them out of water, which is around us. Stephen has spent the last 20 years studying Latinos and past climates, he knows that ice can preserve valuable evidence. Carbon dioxide is a as an important driver of climate change. In other words, is that important factor in in in changing the global climate. You have to see how come not citing changed with the pattern periods and warm period throughout her history. You can see the ice here is absolutely full of of of bubbles from the bubbles informed when the ice was formed. And of course the bubbles contain atmosphere oxygen and carbon dioxide if we want to understand the the role of carbon dioxide as a sort of as a thermal blanket over the earth. We need to know about how come a dark side has changed the concentrations of change in the atmosphere over hundreds of thousands of years. An analysis of bubbles such as these in places like Antarctica and Greenland gives us that that that's fantastic record. That record is now also preserved thousands of miles away. Not in the ice fields as originally contained it but in Denver, Colorado. In this store room of the United States national ice core laboratory hundreds of thousands of years' worth of ice core records are maintained at minus 36 degrees. These ice cores have been extracted from as much as 3 kilometers beneath the polar ice caps. I mean for Professor marks a rare as each one provides a valuable source of information about a particular moment in the past. Well, this particular chunk of ice was about 16,000 years old come from the Greenland ice sheet. What we see here are layers of fossils snow every year on the top of Greenland, there's an accumulation of snow and this is a good compacted you're through years layer after layer of snow eventually before these layers of ice and it's within these layers of ice that we can tell all kinds of things about deep that the Earth's past what we find today is at the carbonate oxide concentrations in the atmosphere are higher than anything we've seen in the past 600,000 years. It's telling us that human activities are having a strong him. Back on the claim it's, it's. It if we measure this in parts per million of carbon oxides in the atmosphere, what we call the pre-industrial output before he wins were starting to have a team with around 27280 Premier League. What we've seen now. The most recent record today are telling us that it's up to about 380 for the. So you can see that today if levels are far beyond anything that we. If you talk to be 5 years ago I would have been kind of a fence sitter on this whole idea of greenhouse gases involved in climate change no war. The changes that we've seen seem to be much too strong much too radical to be just simply explained by natural climate cycles. What we're seeing now is the impact of humans humans are starting to change the climate itself. Those changes could now be occurring. Even in places which are absorbing huge amounts of cotton dioxide. The Emerson is often referred to as the lungs of the world for here plants taken vast volumes of carbon dioxide and give out oxygen to appreciate the immensity of the greenery where this gaseous exchange takes place. You have to get up into the branches, some 50m about the ground. I'm up in the canopy of the jungle. The tropical rainforest, here there is a greater bulk of life both animal and plant and the greater diversity too and can be found anywhere else at all and this huge proliferation comes from 2 main courses warmth and witness the wetness comes from the abundant Equatorial rains for warmth from the tropical sun and between them. Those 2 factors have created the jungle which stretches in a broken green band Wright round. 20 years later and in spite of intensive logging vast areas of this phone is still survive. Bridgestone Youzhny. But scientists like down next had in covering an even more sinister threat to the health of the John. Go them deforestation he has discovered that many of the largest traders are dying. What I think is for me the most scary part about the future of the Amazon is drought because when a drought comes often with very little warning it affects not just one or 2% of the basin, it's an effect 30% for us in ways that we are just now learning can be quite devastating to the forest. In 2005 the Amazon region suffered its worst drought in 60 years. The lack of rain, led to a catastrophic fall in river levels decimating the fish popular. 6 months after the drought Dan never stat is finding that the trees have still not recovered. Right now we're measuring how much water stress the tree that this leaf growing on who was under when we cut it. Last year's drought caught assault by surprise they've had devastating effects and the people who live in the Amazon. We're just right now getting a handle on how many hundreds of thousands of square kilometers of forest were severely damaged by a drought killing enormous trees, which are the key organisms in these ecosystems could be the 2006 is it your full of forest fire because of the drought of 2005. The drought was linked to the abnormally warm seas in the Atlantic , which disrupted the rainfall patterns in the forests. It's particularly worrisome because. It's the type of ocean heating and it seems to cause the drought in the Amazon last year that is exactly what is predicted, and their scenario hopeful who worry. Yes. But the Amazon is not the only rich ecosystem now at risk. The world's coral reefs and other marine equivalent of the rainforest teeming with countless different species. That you know. Warming sea temperatures are already putting the oceans and the life within them under increasing strain. The 2000 kilometer long Great Barrier Reef in Australia is one of the wonders of the world. Early in the life on Earth series I examined it for myself. The reason may look like some fantastic multicolored jungle of plants and flowers. But when you touch, one, it has a hard being incongruous crunch the stone. Then 27 years ago the reef seemed won a huge unblemished and healthy world of its own. I described the intimate relationship between the tiny animal coral polyps and the alchemy that shelter inside them. Lately. A relationship established hundreds of millions of years ago that eventually produced Greece so immense that they're visible from space. So it may well be the river passing astronaut came this way, several hundred million years ago, you might have noticed. But at the time I was making the series I was unaware of a new and disturbing phenomenon. Now, in early 2006 the state of the car on the Barrier Reef is worrying marine biologist Ove Hoegh Guldberg. In recent years. He and other scientists have found that the reefs a far more sensitive to see temperatures than they had previously. This year has seen temperatures are abnormally high. Everywhere and up. Well, I can say it isn't blitz Carl's Carlson Adobe proudly Anelka existing a brilliant bike. This is the cost of the out, you have a lot of that this is all that's left of the absolutely reflect the skeletons okay I'm here, I just saved and later after they don't the time glitz golf and silicone struggling, but I think I said it really quite like this before. If you cut off. What is particularly unsettling scientist is that this reaching is becoming more frequent is sea temperatures remain high for too long. Then the out he won't return and the call may die Ove Hoegh is using approved to discover how stressed this Congress. I tells me that you know most of the Algeria, who left in these corals are severely damaged and I've been terrorized by combination of heat and likely. Away. When I come here and see this said it really stressed out rescue a former self getting really concerned it's another reminder that there are a huge changes on the way with climate change in the, this is the 3rd bleaching event in the last 90 years of the Great Barrier anything and everything they had and as predicted if they getting more frequent and and more severe head and I called customer funds that you rather frightening movement in the area. Of of. Devastating thought but if the warming continues. Some of our richest environment. Some species that live in them will be under threat. And it's not just the non-human. We as a species will not be immune either. How can we possibly know what the future holds. Scientists don't pretend that they can predict specific changes to the climate with absolute certainty. But they can do his calculate the likelihood that they will occur. It's here at the Met Office's Hadley Centre in Exeter that we can't find the answer to some of the big questions. This super computer can perform 10 billion calculations per second each one contributing to a model that scientists like Peter Cox can use to protect our future climber. Climate models that essentially come out of weather forecasting models they run for much longer periods around own for hundreds of years rather than days but they contain older complex they contain clouds they contain rainfall patterns they contain winds and Clark models have to contain slower components like how the vegetation on the soil respond to changing how the oceans change. The model is like a virtual world a sort of flight simulator. Where everything from the melting ice in the Arctic to the formation of clouds in the atmosphere and the temperatures of the oceans are represented by solemnly leap, it can give us the probability that future events may happen. For instance, one of the chances of are having another major heatwave like the one of summer 2003 . And as the planet warms up can we expect heatwaves more often. It's impossible to put any particular climatic or weather event down to climate change alone. But what you can do is say that climate change affects the chance of an event occurring and though it to the very extreme 2003 summer we've suffered in Europe. He killed many people in France for example is a case in point. That's something that is a, a rare event now is a one in 200 year type of event, but that is twice as likely as it was before we started to click change the climate and by 20-40 because of future climate change, it will become a one in 2 year event almost the norm by 20-80 will consider that call you. One place where the Hadley model is predicting increasing temperatures is the next year province in northern China. Not good news for a land where the desert is expanding. Over the last 20 years, there's been a marked decline in Maine. Powerful winds have driven the thin soil into dues smothering fields and villages. In soup will drink many villages have deserted their homes for the cities. Those who are left behind like one lane must endure a daily battle with the encroaching dealings. Yeah, there wasn't so much sand here before. Okay. Now the wind is blowing. More and more sensitive and. So what do you know she also. I remember when I was a child. The environment was really good. And in 1973 went dry the grass struck growing but dust storms the sand covered everything and began to affect our lives in every way Chi white. If you go, if you go you know and I get home if I don't brush I sand away account gets into my house. Then if you, if there is takes a lot of time so it affects my work. But they require a lot of people have left the village already. There was also sold securities would you might they want to improve their lives. So you know moved to a better place with water and much better conditions you not Georgia. But the group. Those villages that aren't swamped by sand are suffering from severe drought this village ego has not had a harvest for 3 years. Professor Lin that is working for the Chinese government trying to discover how badly affected the local people are. You know, until that can you remember when you were younger. You know what. At the same situation to do and when I was a child who it was also sometimes very trying IVF. But it's become more serious. In recent years. So you know it's not on the radar for troops being on recently from the harvest was very bad why was that there's been a rifle. There's been no rain for 3 years called White out of work well by, we can only depend on the food given by the government and without crops. We have no income we can't buy anything and we have no money to spend. When the winds pick up the dry soil completely create a standstill. Such storms are already afflicting cities like Beijing if the dying continues this will only get worse. The bleak realities of climate change are being felt all over the world. And yet despite so much evidence some people refused to believe that human activity is the cause of the changes we're seeing the climate models at the Hadley Centre, believe that they have put. They sat both natural climate variations and our carbon dioxide emissions into their model to see which best explains the changes in temperature. Over the last 120 years. The key question of course is how can we distinguish between variations due to natural causes and those variations of the climate that are induced by human activity. And the key thing that convinced me it anyway was a graph like this one that we marked out on the floor that have been prepared from climate scientists like Professor Peter Cox now explain to us the significance of this squad. Okay. What we're gonna do is to take a walk through time and the first thing to note, as we walk through its a bit the climate is naturally variable. It's a spiky based occasionally there's a downward trend that's associated a volcano going off the coast of system down because of the dust, it throws up the general it just isolates around and then we get to a period around about 1910 where you can start to see an upward trend a warming of the climate and global warming, if you like, and the issue is what caused that was that humans are was that natural. So what we do to try and work that one hours to take a climate model and to put in the various factors, what we can say with its blinkered here is a car model that includes just these natural factors. So this is when volcanoes go off and the output from the sun and you can see that the curve can reproduce recently well this mid-century warming so up to this point, you could reasonably argue climate variation can be explained by natural factors, but as we move on, we can see that's no longer true. If you get to the latter part of 20th century from about 1970 onwards. Here you can see the red curve. He observed temperatures in the green really begin to diverge. And the question again is what caused this recent woman. So we run the model, again we include human factors particularly include greenhouse effect from mostly from carbon dioxide that comes to fossil and then we get this yellow card and we can see as well as reproducing. The mid-century warming we get this recent rather rapid warming reproduced and that tells us 2 things, one is that the model looks realistic looks like the real world and the second thing, the model tells us but this recent morning is due to human beings. So there you have it. There seems little doubt that this recent rises the steep rise in temperature is due to human activity. If you look at the green line of now. True variability. It's clear that without the action of human beings, they would have been far less temperature change since the 19-7. We are all involved in this, our whole way of life is structured around the Burmese of fossil fuels. I find it sobering to think that while I've been traveling the world trying to record the complexity and beauty of our planet. The night to have been making my own contribution to global warming as I recognized when I presented life on Earth. All those years ago. We are a flexible and innovative species. And we have the capacity to adapt and modify our behavior now we most certainly have to do so, if we are to deal with climate change. It's the biggest challenge we have yet faced. This sea wall was built to keep out what he recognized it was a force of nature something beyond our. We ourselves have become a force of nature.