'The Greenhouse Conspiracy' (Transcript) from Channel 4 (UK) programme broadcast in 1990.

"It has all the hallmarks of a good disaster movie: an impending crisis that threatens to engulf the world. From an almost benign start a hardly perceptible change in global temperature the earth's climate could suddenly topple into crisis, reducing large tracts of land to desert, and wreaking havoc on our culture.

For the proponents of the greenhouse effect it heralds something akin to an apocalypse: an earth scorched and burnt by the sun, a climate in chaos. Nor is it a theory supported by a few cranks it has been endorsed by the great and the good, by politicians and academics alike. Nonetheless, there is mounting evidence that it is not true.

Certainly, when it comes to the weather, our impression of what is going on is often wrong:

An Earth Day conference was held at the University of Missouri in the heart of the United States. One of the speakers at the conference was Pat Michaels, a professor of environmental science from the University of Virginia. He began his lecture by asking the predominantly scientific audience how far the summer of1988 differed from the normal in Missouri.

PROF. PAT MICHAELS (Head of Department of Environmental Sciences, University of Virginia, Charlottesville, USA) : The group estimate is that Missouri averaged 2.2 degrees Fahrenheit above normal for the calendar year 1988.

In fact it was below average.

PROF. PAT MICHAELS: You not only got the magnitude wrong, you got the plus or minus sign wrong. I've given this talk about 120 times in places that were colder than normal in 1988 which was much of the United States every crowd has estimated that it has been warmer than normal. I believe you are all very intelligent individuals that's why you are here so where did you get that perception? I would like to know.

PROF. RICHARD LINDZEN (Professor of Dynamic Meteorology, Massachusetts Institute of Technology, Boston, USA): The notion that a warming is catastrophic is drilled into people, to the point where it seems surprising that anyone would question it, and yet underlying it is very little evidence at all. In fact, there is ample evidence to the contrary.

NBC NEWS (23rd June 1988):

Some experts are saying now that the whole world is heating up because of a global 'greenhouse effect' that is, heat caught in the atmosphere by air pollution that prevents its escape.

NBC REPORTER: In Washington a senate committee heard some scientists say the phenomenon called the greenhouse effect is here:

UNIDENTIFIED SCIENTIST. The problems, if not addressed, have the potential for causing a form of chaos not greatly different from that produced by global war.

ITN NEWS AT TEN (11th April 1989):

Information from satellites has convinced most scientists that average temperatures will rise by two to five degrees Celsius over the next one hundred years.

But is there any real evidence of a forthcoming disaster?

PROF. REGINALD NEWELL (Professor of Meteorology, MIT, Boston, USA): No. I would not think there is any evidence for a catastrophic change in our climate at the present time.

INTERVIEWER:No evidence at all?

PROF. REGINALD NEWELL There is no evidence at all.

The case for the greenhouse theory rests on four pillars. On the one hand there's the factual evidence: firstly, that the Earth's climate record shows temperature has increased and sea levels have risen. Secondly, that carbon dioxide has been the primary cause of these changes.

Then there is the third pillar which is not based on evidence from the past or the present but on predictions of climate models that the doubling of carbon dioxide will result in increases in global temperature of between two and five degrees.

And finally, there is the underlying physics which it is widely assumed proves that carbon dioxide is a greenhouse gas and that further increases will result in increases in global temperature.

So let's start with pillar one and the facts about the Earth's climate record.

It's far from easy to get an accurate picture of what's happening to the world's weather. Our evidence is dependent on thousands of individual measurements taken every hour of every day at weather stations throughout the world. It may be Basildon or Phoenix, Calcutta or Buenos Aires, but the techniques are the same. In addition to temperature measurements, each weather station collects data recording the hours of sunshine and the amount of rain. From these measurements, sixty thousand every day, twenty-two million a year, meteorologists try to discern what's happening to the Earth's climate.

Analysis of temperature change over the last one hundred years carried out by the team at East Anglia University in England has played an important role in support of the greenhouse case.

PROF TOM WIGLEY (Head of Climatic Research Unit, University of East Anglia, Norwich, UK): In the recent past the last century or so global mean temperature has increased by about half a degree Celsius. That doesn't 8Ound like a large amount, but it is a very significant and important change.

But such claims are not universally accepted.

PROF. RICHARD LINDZEN: I think most scientists I know would find it difficult to say anything about this record as it stands. I'm reasonably confident that, given that record alone, few people would plausibly say that this indicates that man has created warming.

There are a number problems with the data, the first of which is that the weather stations are not evenly distributed around the globe.

PROF. RICHARD LINDZEN: Land is only about 32 per cent of the Earth's surface. If you want to take a global average, you're already hoping that this 32 per cent will be representative of the whole. For instance, St Helena Island represents one third of the Atlantic Ocean, which is a bit questionable.

The weather stations may not be uniformly spread over the Earth but in addition often tend to be situated in towns. In Phoenix, for example, not only is the weather station in the middle of the city, it is also next to the airport runways surrounded by acres of tarmac. where overnight temperature can be ten degrees hotter than the surrounding area because the asphalt retains heat.

Phoenix is like every other city: as it has grown, the temperatures have gone up. Because many of the world's weather stations are situated in towns, the temperature record is potentially threatened by the urban heat island phenomenon.

DR ROBERT BALLING (Director of the Laboratory of Climatology, Arizona State University, Phoenix, USA): We've been able to detect heat islands in cities with populations as small as three hundred people. As soon as you begin to replace natural vegetation with concrete you create something of a distortion in the temperature pattern.

It' s an effect that can add up to two or three degrees. If we look at the issue of global warming and we ask, how much warming do we think we should see in the future, it' s also something in the region of one or two or three degrees.

Dr Balling has studied urban heat island effects in hundreds of cities throughout the United States.

DR ROBERT BALLING: We have to be careful when we look at people who say they have detected global warming because what they may have detected is urban warming.

Professor Wigley defends his data and plays down the urban heat island effect.

PROF.TOM WIGLEY: You can estimate what that residual effect might be. We believe that it's quite small.

PROF. ROBERT BALLING: I agree it is a small effect in terms of the total area of the globe that' s being affected by urbanisation. The problem is that most of our measurements come from these areas.

INTERVIEWER:An awful lot of weather stations are in towns, aren't they?

PROF. TOM WIGLEY: A number of them are. There are a number of ways of accounting for the problem: the obvious way is to eliminate those stations from the data set you use to calculate the large area temperature values.

INTERVIEWER: But presumably there must be lots of towns where you don't have data from around them, so it's very difficult to tell whether there' s been an urban effect or not.

PROF. TOM WIGLEY: Oh yes. This is an area of on-going research and still of some concern.

Dr Balling's results would seem to justify that concern.

DR ROBERT BALLING: We looked at a thousand stations in the United States that came from very small towns averaging no more than about 5,800 people. We looked at the temperature patterns over this century and found that most of the United States has cooled this century, not warmed.

Furthermore, new data from space has made the land record more doubtful. Until recently we have had no alternative but to rely on thermometers and weather balloons, but now, for the first time, satellites are giving us another source of information.

Dr Spencer at the N ASA space centre has been able to analyse the satellite data to produce snapshots of global temperature, each one equivalent to tens of thousands of separate thermometer readings taken by hand.

DR ROY SPENCER (Physicist, NASA Marshall Space Flight Centre, University of Alabama, Huntsville): We've found that we can monitor globally averaged atmosphere temperatures with a high level of precision even on a monthly basis. We estimate the precision at about one hundredth of a degree per month.

Unlike the thermometer data, the satellite information is evenly spread and does not suffer from the urban heat island effect.

Over the last ten years, the thermometer record has shown an . underlying upward trend but according to the satellite information the Earth was rather warmer in the first half of the 1980s and rather cooler in the second half.

DR ROY SPENCER: The trend of the thermometer data is only about one to two tenths of a degree, which doesn't sound like much, but it's enough to be significantly different from the satellite indication of no trend.

Over the entire ten year period there was no net warming or cooling.

For the first time, satellites have given us an alternative to the land-based data and they show no increase.

So there is a flaw in the first pillar that supports the greenhouse theory - the urban heat island effect and the satellite information point to question marks over the data on which claims of warming have been based.

But even if we accept the thermometer data as accurate, whether or not there has been a temperature increase depends on the time scale you choose.

INTERVIEWER: Would you accept that over the past ten years there has been no overall increase in global temperature?

PROF. TOM WIGLEY: No, I wouldn't accept that but that is a question that may be irrelevant in the greenhouse context. The greenhouse effect is a warming over a period of a century .

The warming Professor Wigley is referring to comes from a graph of temperature over the last one hundred years which shows an underlying increase of half a degree Celsius. The problem is that the trend depends on the period you choose to examine.

PROF. RICHARD LINDZEN: If you started or ended it some place else the trend changes. It' s clearly not a record you draw a straight line through and say, 'This is warming'.

INTERVIEWER:

You mean if we took the last fifty years then it would tell a different story.

PROFESSOR RICHARD LINDZEN: Yes, absolutely. In the last fifty years it did nothing it went down and then up.

And if we choose the years from 1930 to 1970 the average temperature actually falls fairly sharply.

We don't have the data to extend the graph back much beyond the last one hundred years but there is evidence that there have been periods in the past when it has been warmer than it is today. Medieval records show that vines were grown throughout Britain, and remains of a beetle, a species of neetle bug, have been found in York, one thousand miles north of its current habitat in the Mediterranean.

So, if we had thermometer records going back for a thousand fears they could well show a fall in temperature.

Doubts over the data and problems with the time base have lead Dr Idso, who has studied the effects of carbon dioxide on the climate for the past twenty years, to be dismissive of claims that the world is warming.

DR SHERWOOD IDSO (Scientist, United States Water Conservation Laboratories, Phoenix, Arizona, USA): Some people claim that there may have been a half a degree Celsius warming over the last one hundred years. This is really tenuous.

If we look at the real world, let's say over the last 100- 150 years, you find no significant warming.

But perhaps, more than global temperature rise, it has been predictions of increases in sea level that have encouraged impressions of impending catastrophe.

Entire cultures are apparently faced with disaster.

CHANNEL 4 NEWS (4th April 1990):

(Scene of children playing on the beaches of a small island in the Maldives). As the children play, year by year the waters are rising around them. They will be adults by the time the Pacific swamps the nine sandy stubs that are the Islands of Tuvalu. If forecasts are correct the seas around here will rise by about two feet over the next fifty years.

It is not only the media, the scientists themselves are not averse to making the situation appear dramatic. Steve Schneider is one of the United States' leading global warming theorists.

DR STEPHEN SCHNEIDER (Greenhouse theorist and modeller National Centre for Atmospheric Research, Boulder, Colorado, USA): If the sea level rises (the predictions range from a few tens of centimetres to maybe a metre or so over the next one hundred years), that by itself is not that serious, except to places that are low-lying such as the Maldives, Venice and probably London. What really is serious is of the warming of the ocean causes an increase in the energy source for severe storms. Then you get a higher probability if more intense hurricanes or other severe storms driven by ocean evaporation.

PROF.TOM WIGLEY: That's particularly important in countries like Bangladesh where there are tropical cyclones that, even today, kill many thousands of people. In some parts of the world I think there is every reason to believe that consequences would be severe.

But as with the temperature changes, the facts about sea level rise tell a different story.

The Oceanographic Institute near Cape Cod, 250 miles north of Manhattan, is one of the most influential organisations studying the sea. For many years Dr Aubrey, who beads coastal research at the Institute, bas travelled the globe investigating changes in sea level.

INTERVIEWER: Can you tell whether the sea level bas gone up or not over the last one hundred years?

DR DAVE AUBREY (Director of the Coastal Research Centre, Woods Hole Oceanographic Institute, Massachusetts, USA) : No, you can't say unambiguously say exactly bow much the ocean has risen over the entire globe. Some tide gauge stations show sea level rising over long periods of time, others show sea level falling.

The problem is that the land is also moving up and down - in some places it subsides fairly fast. You are therefore measuring sea level against another level which is also moving up and down so you are left with a lot of uncertainty.

If you look at the British Isles you see the same thing in a small portion: in the northern part of the British Isles the sea level is falling, in the southern part the sea level is rising.

People have taken the average from different stations and different periods and come up with different answers. In effect, you can come up with any answer you want.

No useful conclusions about the future can be drawn from the record.

We may not be able to predict what will happen in the future but Aubrey bas no doubts about the evidence so far.

DR DAVE AUBREY: There is no evidence that sea level rise has accelerated due to global warming.

We may not be able to confirm that the sea level is rising by direct measurements, but in 1989 there appeared to be evidence of sea ice melt when submarines passing under the pole reported that the ice at specific points was less deep than it had been ten years earlier. But Julian Paren at the British Antarctic Survey is sceptical :

DR JULIAN PAREN (Scientist, British Antarctic Survey, Cambridge, UK): Just two snapshots ten years apart, even if they did show a thinning, would not be significant compared with long-term monitoring of sea ice extent.

The submarine observations are contradicted by the only reliable evidence, coming once again from satellites, which for the last twelve years have given a daily picture of sea ice extent in the Arctic and Antarctic

DR JULIAN PAREN: It shows no change. There have been changes from year to year but taken as a whole you cannot say, statistically speaking, that there has been any significant change in sea ice concentration around the Antarctic.

The satellite data has only been with us since the late 1970s, but recently analysis of the amount of salt in samples of ice created from snow that has fallen over the last few hundred years, taken from the edge of the Antarctic, has indicated that the present levels of sea ice extent are far from exceptional.

DR JULIAN PAREN: The closer the open water comes to where you take measurements, the more contaminated with sea s alt the ice cores become.

It is quite clear that there have been periods of five to ten years at a time when the sea ice level has been less than it is today.

So, changes in the amount of sea ice do not support the idea that the world is getting warmer.

It' s not surprising therefore that supporters of the greenhouse effect back off from the actual data under scrutiny.

PROF. TOM WIGLEY: What we know about the greenhouse effect is not just based on the data. The data is the ultimate way of proving whether the models are right or wrong but because of the natural variability of the system we cannot say yes or no.

DR STEPHEN SCHEINDER: Looking at every bump and wiggle of the record is a waste of time it's like trying to figure out the probability of a pair of dice by looking at the individual rolls. You've got to look at averages. So, I don't set very much store by looking at the direct evidence.

So, from the actual climate record of the earth, from the thermometer measurements on land and changes in sea level and ice extent, there is no convincing evidence of an increase in temperature or of a rise in sea level.

The first pillar of the greenhouse theory proof of global warming from the climate record turns out to have no substance.

Like the first pillar, the second pillar relies on our past evidence of the climate, but this time to support the claim that carbon dioxide causes an increase in temperature.

DR STEPHEN SCHEINDER: We know that when the earth Was colder, 20,000 years ago in the last ice age, there was 25 per cent less carbon dioxide than during the present warm period, since the industrial revolution. We also know there was 50 per cent less methane. So we know cold times tend to be associated with less greenhouse gases, warm times with more.

But that's only part of the story. Our knowledge of ice age temperature and levels of carbon dioxide come once again from ice buried within the Antarctic plateau.

Ice cores taken two thousand metres below the surface have enabled us to look at the last 160,000 years.

There is no doubt from the record that for the last couple of hundred thousand years temperature and carbon dioxide levels do appear to follow each other. But it is far from clear that carbon dioxide causes temperature to change.

DR JULIAN PAREN: We certainly know that the temperature falls long before the carbon dioxide levels.

It's clear that declining temperature causes a decline in carbon dioxide in the end. It's quite a straightforward effect.

So, if the record from the distant past tells us that, if anything, it's temperature that causes carbon dioxide levels to change and not the other way round, what does the recent past tell us?

One matter over which there is no dispute is that levels of carbon dioxide in the atmosphere have increased substantially. But it has not been a steady increase.

Carbon dioxide levels rose slowly from the middle of the last century but it was only in the 1950s that levels started to increase rapidly.

But, even if we accept the thermometer data, the temperature change which is supposed to have been caused by carbon dioxide does not coincide with the increases in carbon dioxide.

PROF. PAT MICHAELS: It's pretty apparent that the lion's share of the warming occurred before the lion' s share of the trace gases went in.

PROF. TOM WIGLEY: Yes that's a remarkable puzzle.

So how does he solve it?

PROF. TOM WIGLEY: In the first part of the century you see a large natural warming. Natural variability has to go both ways, so why is it strange that in the next forty years or so there was a large natural cooling which was large enough to offset the greenhouse effect?

Michaels has a more straightforward explanation:

PROF. PAT MICHAELS: Only so m any things can go against a simplistic theory before you have to admit that the theory is simplistic and needs revision.

So, not only does the climate record fail to prove that carbon dioxide causes temperature change : if anything, it suggests the reverse may be true. The second pillar supporting the greenhouse theory turns out to be as insubstantial as the first.

The third pillar supporting the theory is constructed from the climate models - perhaps more than anything else it is the predictions of the models that doubling of carbon dioxide will lead to increases in temperature of between three and five degrees by the end of the next century that have sustained fears of an impending crisis.

But can we rely on these predictions?

Although superficially similar, the climate models are radically different in character from the models used to provide daily weather forecasts, which start from information about the current situation and try to calculate what will be happening over the next few hours and days. The complexity of the mathematics involved means that the models cannot predict with any accuracy beyond five days. Changes in climate take place over decades and centuries so these weather forecasting models are of no use for estimating climate change. So, instead of starting from current weather information, the climate models try to simulate the entire climate of the Earth from first principles.

The computer is given the amount of heat arriving from the sun, the laws of physics which describe how heat radiates, and the radiation properties of the atmosphere. With these starting points the computer then calculates the temperature of the earth, the wind speeds, the rainfall and so forth. The models then simulate the Earth's climate over a number of years and produce an average annual temperature cycle.

With a doubling of carbon dioxide large areas become hotter than the current average.

Schneider's model, produced at the US National Centre for Atmospheric Research, is one of about five influential current models of the world's climate. But if we are to believe the predictions we must first be convinced they can accurately simulate our current climate. Dr Mitchell heads the team at the Met Office in Britain that has developed another of the world' s major climate models.

DR JOHN MITCHELL (Modeller, Meteorological Office, Bracknell, UK): We get a picture of not just the north-south distribution of temperature but also of large-scale variation across the continents. And this is very much as observed.

DR STEPHEN SCHNEIDER: We do very well: we let the sun go up and it gets hotter; take the sun away and it gets colder. I remember talking to a US Congressional hearing and one of the senators said to me: 'you mean to tell me you've spent a billion dollars of our money to tell us it gets hotter in summer and colder in winter? ' My answer was: 'yes sir and we are very proud of that.'

Some scientists however are less impressed.

PROF. RICHARD LINDZEN: I don't think we can speak of these models as being accurate at this point. They are experimental tools. We're trying to forge these tools. To use them to forecast delicate things like warming is calling for an accuracy these models simply do not have.

PROF. REGINALD NEWELL: We certainly don't understand the models well enough to take the predictions seriously.

One criticism of the models is that they fail to take account of all the so-called feedback effects. Some of the most important of these are related to clouds.

Professor Jonas is a world expert on how clouds affect climate. His experiments are designed to find out how different types of cloud reflect the sun's rays.

PROF.PETER JONAS (Head of Atmospheric Physics Group, UMIST, Manchester, UK): The climate models are treating clouds in a very simplistic manner and this makes it very difficult to include the true magnitude of the feedback effects within those models.

As the temperature rises evaporation increases and more clouds are created. But in turn the clouds then reflect the sun's radiation away.

PROF. PETER JONAS: This causes less warming at the Earth's surface so that the increase in temperature produces by carbon dioxide is reduced by the presence of clouds.

These effects are not small.

PROF. PAT MICHAELS: The energy balance equation tells us that everything else being equal, if you change the reflectivity of the globe a mere two per cent or so, you compensate for the doubling of carbon dioxide because you reflect away more solar radiation.

Slight changes in cloudiness can drastically influence how the world responds to trace gases.

So, given the simplified character of the models, we should be wise to treat their results cautiously.

PROF. TOMWIGLEY. They give roughly the right seasonal cycle of temperature, they show it's warmer at the Equator than at the Poles.

INTERVIEWER: These are pretty gross descriptions aren't they? If they didn't show it WAS warmer at the Equator there' d be something seriously the matter!

PROF. TOM WIGLEY. Yes, but it's more important that a model used for climate studies predicts storm tracts over the North Atlantic or shows you that the Sahara ought to be a desert.

But showing that the Sahara is a desert was precisely what the Met Office model had failed to do according to its published findings. If you look at the predictions for current rainfall they show that as much rain falls on Central Sahara in summer as on Ireland or Scotland.

DR JOHN MITCHELL: There's no doubt that on regional scales of 2,000 kilometres or less, one cannot have a lot of confidence in the model predictions.

Others go further.

DR SHERWOOD IDSO: I don't believe there is any good evidence to lead us to believe what the models are telling us. Right now they are predicting that for the carbon dioxide rise we have experienced over the last century or so, there should have been a couple of degrees Celsius warming, but there has been nothing like that. There is the possibility of a half a degree warming but that maybe due to other causes or it may not be a real warming . at all it may Just be a figment. of the data due to problems such as the urban heat island effect.

INTERVIEWER: Overall, are you confident that the models give an outcome for global change that we can rely on?

DR JOHN MITCHELL: I am convinced that models are the best way to determine what the outcome of the increases in trace gases is.

INTERVIEWER: That's a different answer. The question is, can we at the moment believe with any confidence in the predictions they are making?

DR JOHN MITCHELL: Can you be more specific about what you mean by predictions?

INTERVIEWER: The most obvious one is the effect of carbon dioxide on temperature.

DR JOHN MITCHELL: I'm not sure how you quantify confidence.

PROF. PAT MICHAELS: We should caution here that it's not that the modellers are incompetent bumbling people, they are limited by the speed of light. That's why simplifications are made in models.

INTERVIEWER: Why do you think people are taking the models seriously?

PROF. REGINALD NEWELL: I don't know. It's very difficult for me to understand how you could possibly take the aggregate of these models seriously. You look at the differences of predictions for one region at one time.

The third pillar supporting the greenhouse theory turns out to be as flimsy as the first two.

So there is only one remaining support for the theory: the underlying physics.

DR STEPHEN SCHNEIDER: The reason I believe there is a high probability of unprecedented change in the next century is not based on the performance of the planet in the last one hundred years - there are just too many unknown and unknowable factors. It's based on the greenhouse physics.

The greenhouse physics is supposed to show that carbon dioxide is a greenhouse gas : that it absorbs radiation reflected from the Earth's surface and emits that radiation again, causing an increase in radiation, or heat flux, arriving on the surface on the Earth, and a w arming of the planet.

DR JOHN HOUGHTON (Chief Executive of The Meteorological Office, Bracknell, UK): We know how much greenhouse gas has gone into the atmosphere : we know how much more methane there has been over the last one hundred years, we know about CFCs (they're greenhouse gases too). So, we know there will be some warming.

But the assumption that the basic physics necessarily implies a warming is not accepted by some atmospheric physicists.

INTERVIEWER: There are a lot of scientists around, not only members of the public, who are categorically saying that if you increase carbon dioxide in the atmosphere you get heating.

PROF. REGINALD NEWELL: I'm saying that is not at all evident.

Carbon dioxide is not the only greenhouse gas, nor the most important. Water vapour and ozone are the primary greenhouse gases. A number of other trace gases such as methane play a minor role. These gases do not simply absorb radiation, they also emit it - in fact they emit as much as they absorb. Furthermore, the way they absorb and emit radiation changes throughout the atmosphere. The radiative process is therefore highly complex and the effect of any one gas is not the same throughout the atmosphere and is linked to all the other gases.

PROF. REGINALD NEWELL: Additions of carbon dioxide into the atmosphere will certainly cause an increase in the downward flux of energy at the surface but that will not necessarily change the temperature of the lower layers of the atmosphere. I think it will cause more water to evaporate, which will have a lot of ramifications, one of which will be the radiative effects. These will tend to produce more cooling, and also more clouds which will reflect the solar radiation. So it's not at all obvious that increasing the carbon dioxide in the system will make the temperature rise.

Professor Newell is not alone in this view. In a recent paper on the effects of carbon dioxide, Professor Ellsaesser of the Lawrence Livermore Laboratories, a major US research establishment in California, concluded that a doubling of carbon dioxide would have little or no effect on the temperature at the surface and, if anything, might cause the surface to cool'.

The radiation effects of the greenhouse gases are further complicated by convection currents which carry warm air at the surface to higher altitudes.

PROF .RICHARD LINDZEN: If you put greenhouse gases near the surface and convection currents short circuit them, they won't contribute to warming. If you put a lot in at the surface and take a little away near the top where the heat is deposited by convection, that could lead to cooling, even if you had a net increase in the amount of greenhouse gas. There is no simple uniform relation between the amount of greenhouse gas in the atmosphere and the temperature at the surface. We just don't understand enough about the behaviour of the atmosphere to predict the effect of a change in the level of carbon dioxide with any certainty.

Even the final pillar supporting the greenhouse theory, the underlying physics, turns out to be as insubstantial as the rest.

Although there is no convincing evidence that increases in carbon dioxide are bad for us, it's still easy to think of it as a pollutant. But carbon dioxide is the equivalent of oxygen for plants : the essential life-giving gas. It may well be that the increase in carbon dioxide levels turns out to be a good thing.

DR SHERWOOD IDSO: The vegetation of this planet developed and acquired its basic characteristics in an atmosphere that had much more carbon dioxide than at present. Logic will therefore tell you that if you have more carbon dioxide in the atmosphere, plants will do better and this is exactly true.

For the past three years Dr Idso has been growing sour orange trees in enclosures containing double the amount of carbon dioxide to normal. The carbon dioxide enriched air is continuously pumped into the chambers and escapes at the top.

At the same time identical trees are kept in exactly the same conditions but are fed normal air. These enriched trees have 180 per cent more volume, have more leaves, more primary branches, more higher-order branches, more blossoms.

DR SHERWOOD IDSO : An interesting question is how much carbon dioxide we can possibly put into the atmosphere if we bum all the fossil fuels the crust of the earth. It has been estimated that the maximum would be ten times the present level, which would do no harm to animal life and would still be beneficial to plant life.

It's very likely we will need the added benefit of carbon dioxide enrichment to feed future the generations.

If there is concrete evidence of the benefits of carbon dioxide, and the detrimental effects are at the very least questionable, how is it that we have been led to take talk of catastrophe seriously? After all, it was only some fifteen years ago when a rather different global climate catastrophe was in vogue.

"THE WEATHER MACHINE" (BBC 1, November 1974):

There's the ever-present threat of a big freeze. Will a new ice age claim our lands and bury our northern cities? It's buried Manhattan Island before when great glaciers half a mile thick filled the valley of New York's Hudson River.

INTERVIEWER: You do accept that ten to fifteen years ago people were talking about global cooling, not warming?

DR STEPHEN SCHNEIDER: Not everybody - I was one who was not sure.

INTERVIEWER: You say you didn't believe in global cooling but in your first book you said, 'I have cited many examples of recent climatic variability and repeated the warnings of several well-known climatologists that a cooling trend has set in, perhaps one akin to the Little Ice Age. Well, that was just fourteen years ago.

DR STEPHEN SCHNEIDER: I said that because at the time it was true. But you've got to be honest, you've got to tell things the way they are. I don't mind people quoting what I said in the 1970s.

INTERVIEWER: Doesn't all of that add up to saying that you're asking governments to spend billions of dollars on a view which is different from one you held a decade ago?

DR STEPHEN SCHNEIDER: I don't see any problem in saying that people learn. I'm not embarrassed about a view I held a decade ago.

PROF. PAT MICHAELS: You should remember, when I was going to graduate school, it was gospel that the ice age was about to start. I had trouble warming up to that one too. This is not the first climatic apocalypse, but it' s certainly the loudest.

There may be many reasons why we might want to believe in a apocalypse but for the scientists involved it's very straightforward.

DR ROY SPENCER: It's easier to get funding if you can show some evidence for impending climate disasters. In the late 1970s it was the coming ice age and now it's the coming global warming. Who knows what it will be ten years from now. Sure, science benefits from scary scenarios.

DR SHERWOOD IDSO: A lot of people are getting very famous and very well funded as a result of promoting the disastrous scenario of greenhouse warming.

PROF. REGINALD NEWELL: My suspicion is that if you have a crisis like this it' s easier to gain funds for the profession as a whole.

PROF. TOMWIGLEY: I don't think funding directly influences the nature of the research or the approach. .

INTERVIEWER: But indirectly?

PROF.TOMWIGLEY. Using my organisation as an example, we have only one permanently-funded university scientist that's me. I have a dozen research workers with Ph.D.s who are working in the climatic research unit and they are all funded on so-called soft money. Their existence requires me, or us jointly, to get external support.

Funding may have encouraged support of the greenhouse theory, but if you oppose the theory, life can get difficult.

PROF. REGINALD NEWELL: I was warned when I wrote my first paper which discussed the difference between the climate models and some figures I was looking at for the Tropics that it would be very difficult and my funding would probably be cut. In fact it has been cut.

INTERVIEWER: Did you believe that at the time?

PROF. REGINALD NEWELL: No, I thought that the system was so straightforward and honest - that bringing in a new perspective to the whole thing which I thought I did in 1979 would be considered to be a positive thing: people could hear both sides of the argument and then have a debate.

INTERVIEWER: Perhaps the greenhouse theory has been successful in terms of raising funds : by saying there' s a crisis around the corner, people are talking about putting in more funds.

PROF. REGINALD NEWELL: Perhaps it has worked; perhaps I was wrong but I think it's going to backfire.

DR ROY SPENCER: Richard Lindzen has recently said that this whole area has become a new McCarthyism. If you don't jump on the environmental bandwagon to stop the inevitable warming of the Earth, then you will be ostracised from the scientific community and from everybody else's community , because it's not fashionable to disagree with the environmentalists these days.

PROF. PAT MICHAELS : People who have a point of view which may not be politically acceptable are going to have problems. That's not surprising. I have had experiences with editors of more than one journal who have said that my papers have been rejected because they are held to a higher standard of review than others. I believe this is because what they say is not popular. That's OK: I'm a big boy. I know I would have been more successful if I had said the world is coming to an end, but I can't bring myself to do that.

Of course it's not only been the scientists. The media also benefits from a good disaster story.

'THE BIG HEAT' (Panorama, May 1990):

Storms, cyclones, drought, high winds and floods: a foretaste of global warming, a change in global climate caused by man's pollution of the planet.

To say that the climate is OK does not usually make the headlines. And the best prophets of doom are the ones filmed most. (Shot of Stephen Schneider being interviewed in front of the cameras).

DR STEPHEN SCHNEIDER: The rate of change is so fast that I don't hesitate to call it potentially catastrophic for ecosystems.

PROF RICHARD LINDZEN: There. are statements made of such overt unrealism that I feel embarrassed. I feel it discredits my science. I think problems will arise when one will need to depend On scientific judgement and by ruining our credibility now You leave society with a resource of some importance diminished.

DR STEPHEN SCHNEIDER: Of course you always tell the truth, but how many people get more than a few seconds in the evening news? So you use information selectively.

And if the scientists and the media have connived to make a good story, the politicians have not been slow to see the advantages.

MARGARET THATCHER (BBC News, 25th May 1990):

We would be taking a great risk with future generations if, having received this early warning, we did nothing about it Or took the attitude, Well, it will see me out.'

INTERVIEWER: Why do you think it is that politicians, and indeed Congress, have been convinced that there has been global warming?

PROF.PATMICHAELS: I don't know that they have been convinced, but their business is to be responsive to their constituents and their constituents are convinced. It would certainly not be in their best political interests not to act convinced, would it? So, the people want to believe this and the politicians can't say to their constituents, {You are stupid,' can they?

It may not quite add up to a conspiracy, but certainly a coalition of interests has promoted the greenhouse theory : scientists have needed funds, the media a story, and governments a worthy cause. And beyond that, is it the millennium that encourages notions of an apocalypse, or simply that in a world without belief we need a catastrophe to give us something to believe in; where for once, in a battle between nature and humankind, we can line up on the side of good against the forces of evil.

PROF. PAT MICHAELS: There's a lot of blood in this battle; people hate each other about this issue. Haven't you noticed that? Have you ever seen a nastier scientific issue? I guess it' s because people passionately feel that it' s a battle between good and evil.

If the consequences of the greenhouse theory did not extend beyond a moral crusade it could be left to those of a religious turn. of mind. But it cannot be so lightly ignored.

PROF. PAT MICHAELS: Would you walk down the road towards a policy which people have rightly said requires an economic restructuring of the world, knowing that the world was doing the opposite to what the basis for that policy said? "

Source: http://web.ukonline.co.uk/Members/ad.johnson/text/life.htm