Comm: "Is there concrete evidence that the greenhouse effect is changing our climate? This week we travel to Africa, Asia and North America to find out if the long predicated change is already having an impact on society and the economy.

"As the winter ice breaks, in small villages along the banks of the Yukon river delta in Alaska on the edge of the arctic circle, fishermen prepare for the annual salmon run when the fish go up the river to spawn.

"In a good year 200,000 salmon are caught in Alaska's Yukon River. It's the spawning ground of what is believed to be the largest population of wild chinook salmon in the world.

"Native alaskans rely on the salmon not only for income, but for food for both people and their animals.

"Fresh salmon is dried in the sun and stored for the winter months.

"But the times of plenty seem to be over. An age-old way of life maybe coming to an end. "

Native Fisherman: "In my time the salmon were very big and fat, you know when you see a fat man he's very big, round, and large, some of them are real fighters. Hardly we see any of that now, some salmon they don't even taste good to eat."

Comm: "Tom Kron manages the Yukon river area for the Alaska Department of Fisheries and Game."

Tom Kron, Department of Fisheries and Game, Alaska: "Both the state and federal government last year declared the Chum and Chinook return on the Yukon river a disaster and the red salmon return to Bristol Bay a disaster. But we're talking tens, hundreds of millions of dollars of impact from a commercial standpoint, subsistence fisheries you can't quantify the value because it's something that's important to peoples cultures and lifestyles and family."

Comm: "The North Pacific is one of the richest seas in the world and provides almost half of the fish and shellfish caught in the United States, with salmon accounting for 95% of the surface fish found in these waters.

"Scientists working for the Canadian department of Fisheries and Oceans have been monitoring the North Pacific in an attempt to understand the causes of the declining salmon catch. They have found survival rates are down to as little as 1/10th of the levels of just a decade ago. It's feared that species, such as the sockeye salmon, may be driven to commercial extinction."

Comm: "David Welch is the senior scientist in the ocean salmon research project. He has suggested a link between falling salmon stocks and a sharp rise in sea temperature and consequent drop in surface food supply."

David Welch: "Ocean is much warmer and much fresher, more freshwater coming from rain and glaciers and that's sealing off the surface of the ocean from the deep ocean. The deep ocean has lots of nutrient but no light, the surface lots of light but no nutrients. So, as we loose the ability of the ocean to pump nutrients up to where the plants are we are seeing the productivity of the ocean reduced."

Comm: "The cold nutrient-rich waters of the North Pacific are particularly sensitive to rises in sea temperature."

David Welch: "They were very stable until the turn of the century and they've now increased by point 6 (0.6), point 7 (0.7) degrees Celsius, it doesn't sound like a lot but it's a huge increase over what's been seen for the last thousand years. What's even more concern to many of us is that the projections are that because of increased CO2 we're looking at that much change every decade, continuously for the next hundred years because of increased greenhouse gasses."

Comm: "At the University of Alaska, Fairbanks, scientists have been studying the recent warming found in the North Pacific and Bering Sea."

Gunter Weller: "All the changes we see in the Bering Sea and the Arctic are very likely related to global climate change and a man made influence on that by the burning of fossil fuels"

Comm: "Warmer temperatures not only affect the sea life around Alaska. 1.2 million hectares of this Alaskan spruce pine forest are diseased. In some areas more than 90% of the trees are already dead.

"Forest entomologist Ed Holsten has been studying the devastation. He has found it's the Spruce Beetle that's the culprit. It's a pest common in warmer southerly latitudes - but until recently, unknown here."

Ed Holsten, US Forestry Dept: "This area here, this tree was killed a couple of years ago by beetles but by removing the bark we can see this gallery right here which is about 3-4 inches long, there's only one insect up here that makes an egg gallery like that and that is the Spruce Beetle."

Comm: "No longer limited by colder temperatures, the spruce beetle now completes its life cycle three times faster than in cooler years."

Ed Holsten: "In the last ten years we have lost more trees than we have in the previous 60 years, a factor of 10 times more, and if you relate that tree mortality then you plot out temperature, you can see in the last 10 years where we had a real significant increase in mean annual temperature that corresponded to this explosive epidemic of Bark Beetle occurring in Alaska. We have not seen such a long length of favourable weather like this for hundreds if not thousands of years."

Comm: "The state of Montana is home to one of the largest areas of undisturbed wilderness in the United States and the most southerly glaciers to be found on the continent. Glacier National Park makes up the majority of this area."

Dan Fagre: "Big natural parks like this are extremely unique. We have 5,000 sq kms or 1600 sq miles here and it's relatively pristine. Very few effects of people are here so in this way we are able to use a very unique situation in this grand national park to be able to learn about how systems really operate."

Comm: "Across the globe at extreme latitudes and elevations there has been a consistent and measurable amount of ice melt and glacial retreat in recent years. It has been estimated that over the last 150 years, half the world's glaciers have melted. In Montana, Glacier National Park may have to be renamed."

Dan Fagre: "Glaciers used to be much more dominant here and in 1850 there were about 150 glaciers here and now there are less than 37 of them that are named and we suspect that there is probably some of them that don't even qualify as glaciers anymore because they've become so small."

Comm: "The apparent speed of the retreat of the normally slow moving glaciers has spurred Dr. Fagre into mapping just how fast and how serious the glacial loss is, and to find the extent this could be related to climate."

Dan Fagre: "One of the activities that we've had here at the glacier field station with the US Geological Survey is to look at how this eco system has already responded to climate change. As part of that effort we've been looking at many of the glaciers and they way they have receded over the past 150 years. To demonstrate some of this we've been looking at repeat photography in this case we go to the historic archives and we take a photo like this one from 1932 of the Boulder Glacier, note the small figures here, these are people standing next to this huge ice cave, and then you go to the exact same photo point and 56 years later you see there is absolutely no ice left whatsoever in the landscape. The entire glacier has disappeared and that was quite a large one. You can see historically here from this graph too that the area of the glaciers from 1850 into the early part of this century and you can that they go down dramatically as this lower line which is the average summer temperature goes up. And so this clearly demonstrates that the glaciers are responding to warming temperatures in this particular area this century."

Comm: "Scientists predict the impact of ice melt and glacier loss will not be restricted to the colder regions, but will be felt across the globe."

Gunter Weller: "As glaciers continue to melt, this will have a major impact on the global sea level rise and sea level rise is a problem in many parts of the world - low lying areas, that is why the Pacific island nations are so concerned.

"You know various studies have shown that the sea level rise which is estimated to be about 20cm over the last century - 2mm per year has been mostly due to, half of it has been due to melting of mountain glaciers. Also as you have more open water instead of ice, climate patterns begin to change, storm tracks which are affected by the presence or absence of ice will change and therefore the weather as well as the climate in certain parts will be affected, the ocean is extremely important in all of this and any changes that occur in the oceans system will affect everything else."

Comm: "But in the United States it's not just the wilderness that's at risk. There are also warning signs that climate change threatens the densely populated Eastern Seaboard.

"On the barrier islands of Chesapeake Bay, Maryland, scientists have monitored a ten-fold increase in the rate of sea level rise over the last ten years."

Court Stevenson, Professor, Environmental Science, Maryland University: "In the 1940s it was split into two islands, each about 200 acres but now its less than 60 acres.

"If the trees are lost and the island disappears the waves will be dissipated onto a number of homeowners' beaches and we'll start to see the erosion of the mainland itself."

Joe Coin, resident homeowner: "Many many homes have been lost many many homes have been moved from islands that are sinking into the Chesapeake bay onto firmer ground on the mainland and now even some of those homes are now in jeopardy, having been moved once they find themselves in jeopardy once again."

Comm: "Further south in the state of Florida increased intensity of storms and floods exacerbates coastal erosion."

Dr. Leatherman, Florida International University: "Well at high tide I'd be under water and the waves would be bashing into me, this area is a critically eroding area, like much of the coastline of Florida that's eroding, in fact in the United States 80% to 90% of sandy beaches are presently eroding, it's a national problem."

Comm: "During Hurricane Irene, a relatively minor Force 1 hurricane, much of downtown Miami was under water. The loss to business and soaring insurance rates may have long term economic repercussions.

"Tracked by the National Hurricane Centre in Miami, the largest hurricane in the 1999 season was Floyd. At one time it was predicted that it too would hit Florida, in the panic to escape major freeways were blocked solid for 24 hours trapping some 6 million people. At the eleventh hour it veered northwards, dissipated somewhat as it hit cooler water, and made landfall in North Carolina.

"The greater percentage of damage that stems from Hurricane winds is not usually from the wind itself but from the accompanying surge in tides and excessive rainfall."

Julie Lee-Rose: "You can see the line here where it got into my house, and this is not a pretty sight, everything we had on the porch washed, and this is where I did most of my living because it's cool out here, everything's gone. I had an old player piano over there and its washed away.

"Here I had five dead cows floating, the water was all the way up and they were floating right out here and the stench is better, but it's still bad. And every time I come I look for my kitty cat and I can't find my cat so..."

Edward Jackson: "When I opened the door, pulled the door open, the refrigerator floated right to me, the refrigerator, oh everything, table, stove, it just floated right to you, Everything wanted to float right on down the street with you - that's how high it was."

Comm: "Although hurricane Floyd caused far less damage than it would had it hit Florida the week before, it was never the less highly destructive."

Jay Eaker, Federal Emergency Management Agency: "Fema has 600 people working 7 days a week on this disaster, we have 57,000 requests for assistance Fema will end up reimbursing the state of North Carolina for all this in the high single billions of dollars."

Comm: "The combination of increased storms and floods with sea level rise could well make disasters like Floyd a regular occurrence for people living in coastal zones."

Dr. Leatherman: "Some of our most valuable real estate is packed along the coastline, in fact along the US eastern gulf coast it's estimated that there are 3.1 trillion - with a T - trillion dollars in real estate vulnerable to beach erosion and hurricane impacts."

Comm: "In the developing world a changing climate is a matter of life and death.

"Poor, densely populated low lying countries such as Bangladesh are particularly susceptible to climate extremes. Large scale defences such as those employed by in the Netherlands are simply too expensive. In Bangladesh 110 million people already live in flood prone areas - most of them are farmers with nowhere to escape to. Even a brief flood can be devastating, a large one such as that seen in 1970, drowned 1/4 of a million people."

James Titus, US Environment Protection Agency: "In principal one can protect nations such as Bangladesh just as the Dutch have protected their country, however the situations are really very different, Bangladesh has no money, perhaps more importantly they get a lot more rainfall in a single storm. If you want to build a wall around a country to protect it you not only have to build the wall you have to put in pumps to pump out all the rain water and when the monsoon hits Bangladesh how are they going to pump all that water out?"

Comm: "Several Island communities fear a worse fate than Bangladesh. The Maldives in the Indian Ocean is an archipelago nation, with most of the islands less than a metre above sea level.

"These communities of a few hundred thousand people living far from industrialised countries, face total annihilation from sea level rise.

Saskia Jelgersma, Geological Survey of the Netherlands: "You mentioned the Maldives, that is only coral reefs, very low lying coral reefs, and if there is a metre of sea level rise then the whole Maldives will disappear. It is not possible to make dikes on top of these reefs like the Dutch people like to do, because the reefs themselves have a permeability, they let water through them, so they seep, if they make dykes the water will seep underneath through the corals and flood the land."

Comm: "Climate change not only affects our environment, it can affect our health too."

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Comm: "Concern over the impacts of climate change have led Physicians for Social Responsibility, a Nobel prize winning group of doctors, to call public attention to the impacts a changing climate can have on our health. They have launched a multi-million dollar national TV campaign focusing on the startling increase in asthma cases."

Dr. Robert Musil, Physicians for Social Responsibility - speaking at a conference: "Asthma is clearly related to the kinds of pollution that are formed with increasing temperatures, and we have seen in just the last 20 years a tripling of the death rate from asthma in this nation, we are undergoing an asthma epidemic."

Comm: "There is an increasing body of evidence that links a rise in asthma cases to the combination of higher temperatures and air pollution from increasing amounts of ground level ozone, better known as smog."

Dr. Jon Samet, John Hopkins School of Medicine: "Ozone is a real problem of our modern cities and largely comes from too many vehicles and too much vehicle exhaust which is acted on by sunlight and forms ozone and other what we call oxidants and basically these are sort of molecular bad guys. They're breathed into the lung and they cause inflammation and irritation."

Comm: "Hospitals and Health clinics in major urban conurbations are reporting increasing numbers of asthma cases, particularly among the young, but as Dr Patz explains it's thought ozone or smog does not cause asthma directly."

Dr. Jonathon Patz, John Hopkins School of Medicine: "Ozone itself is not an allergen but people that do have asthma and are allergic to pollen or other allergens in the air if they're also breathing ozone or had been exposed to ozone in the previous day they're allergic response tends to be heightened and that's one concern of course with asthma levels going up if concomitantly with that if ozone levels are increasing as well that can be a fairly important public health problem."

Dr Samet: "Certainly we have been surprised by recent scientific evidence showing that levels of air pollution both ozone and particles that we once might have thought had little or no risk are showing up as affecting public health and this comes from studies showing even numbers of deaths on a day are affected by levels of air pollution with data worldwide showing this."

Comm: "Rising temperatures not only increase smog levels, large and sudden jumps in temperature place extra burdens on already weakened bodies. Again most at risk are those in large urban areas."

Dr. Samet: "We've known for quite a while about so called urban heat islands and you we have these urban cores with large blocks of concrete and materials in the streets and in the buildings and of course these retain the heat and typically during the summer there may be as much as in Fahrenheit perhaps 8 - 10 degrees differences between temperatures in urban core areas and outlying suburbs and this is often been called the urban heat island effect so what happens under such circumstances with sustained heat is that even at night they may be very little relief from the heat and this may go on day after day after day."

Comm: "The Urban Heat island effect was thought to be largely responsible for the deaths of over 700 hundred people in Chicago, during a heat wave in the early 90's. Dr Falvo sees the impact of urban summer heat as a serious health threat, particularly when extra demand on power for air conditioning leads to an overload and then power cuts."

Dr. Cathy Falvo, Physicians for Social Responsibility: "Summer heat kills and when you get power outage, you know, yes I know I should stay in air conditioning if I'm elderly particularly if I have respiratory problems but if there is no electricity there is nothing I can do about it. I shouldn't stay indoors if there's no air conditioning and no fans, but on the streets of Manhattan were all this heat sits and bakes you from the concrete that's all around, there are not a lot of options, when all of a sudden all the power fails you don't even know where the people who need to be moved out of buildings and cannot move themselves because they are too frail are, much less have the means to move them."

Dr. Robert Musil, Physicians for Social Responsibility: "Climate Change is one of the largest human health risk that we face. We originally won a Nobel Peace Prize with concern for nuclear weapons. This is like Nuclear War in slow motion. Climate Change will affect every nation, all citizenry, and as I said, the human health affects from disease, from drought, from floods, and other things will be disastrous."

Comm: "Global warming can also encourage pests, some have a serious affect on human health. For many nations across Africa malaria takes its toll all year round, killing up to a million people a year. But in the highland regions it was a different story. At 2000 metres, Bole-Sebeta village in Ethiopia has a cool climate, too cold for the malarial parasite to thrive. Then in 1998, Bole was hit by an epidemic."

Bedada Boka, Bole-Sebeta village: "There were about 100 people who died last year...We were surprised and frustrated during the epidemic episode because we know malaria usually occurs in lowland areas...it's only last year that people have died due to malaria here"

Comm: "In 1998 severe epidemics struck across East Africa, attacking highland populations who had never been exposed to the disease and had no immunity. In one highland village of 2000 people, over 900 became sick and 100 were reported dead. Some blamed these epidemics on the migration of people, or drug resistance of the parasite. But other researchers say there's a different culprit."

Dr. Andrew Githeko, Kenya Medical Research Institute: "Over a wide area of Western Kenya and Eastern Uganda there has been an increase of about 1 to 2 degrees over the past 10 years since 1988, and this has tended to be consistent with the observed transmission of malaria. So we think there is a correlation between the increase in temperature and the cases of malaria epidemics we're seeing in these areas."

Dr. Tesfaye Mengesha, Ethiopian Health and Nutrition Institute: "In some areas like Bure, that is a highland misty area, you never expect to see a mosquito, you are shivering from cold usually. That's where it attacked. It's just unbelievable. Before 1997, it had never happened."

Comm: "The villagers of Bole have no idea why this disease suddenly descended on them, but many scientists are convinced it's due to climate change."

Abebe Tadege, Ethiopian Meteorological Service: "More than 90% of the stations, are showing an upward trend in temperature. So one possible explanation is the warming trend that we are observing in our recordds as well."

Comm: "And the phenomenon of 'highland malaria' is not confined to Africa."

Dr. Andrew Githeko, Kenya Medical Research Institute: "In a global context we think this is a general phenomenon because we've had epidemics in Pakistan, in Peru, in Madagascar and in east Africa from Ethiopia to Rwanda"

Comm: "All around the world, global warming and the resulting changes to our climate - caused by pollution of the atmosphere - is making an ever greater impact. Next week we look at some solutions to rising greenhouse gas emissions. Wind farms, wave power and harnessing the massive potential of the suns energy."