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Friday, November 13, 1998 Published at 13:59 GMT

Global warming: Your questions answered

Global warming
The world's governments have been trying to work out in Buenos Aires what can be done about the threat we face from climate change.

But how real is that danger? Is the world really getting hotter and if so does it matter and can we do anything about it?

Environment Correspondent Alex Kirby answered the following questions sent in by BBC News Online's users - on climate change, global warming and what it all means.

Alex's answers to your questions:

Q: Dear Alex Kirby,
A few years ago the award-winning "The Good Chemistry Guide" was published. (I can't remember the author's name). In that book it was stated that Carbon Dioxide only traps light and heat of a certain wavelengths. Other wave-lengths pass through Carbon Dioxide unhindered. Since this is the case, it was stated, the Greenhouse effect is not the problem that we imagine it to be. I've never read whether this statement is wrong or not. I would like to hear an expert's assessment of this. Many thanks.
Gary Ross

A: Dear Gary
Thank you for writing. A disclaimer first -- I'm afraid I am emphatically not an expert (I am not a scientist of any description). But I have followed the climate change debate for ten years or more, and on the basis of what I have learnt I would say it is certainly not a myth. What convinces me is the consensus view of the Intergovernmental Panel on Climate Change, around 2,000 scientists who include most of the world's best climatologists. Their view is that climate change is serious, and that human activity is playing a discernible part in it. That's good enough for me, though I respect those who sincerely differ. But many of the policies we need to adopt to tackle climate change are "no-regrets" options anyway -- energy conservation, for example, will mean saving money and cutting pollution. So I think it makes prudent good sense to accept the very strong probability of climate change, while we await conclusive proof.
Regards, Alex

Q: Dear Alex
My question to you is, what are we going to do about the American problem? What I mean is, the amount of resources that they consume is ridiculous, the figure "5% of the worlds population yet consume 40% of world resources" says it all. I went to America this summer and I cannot believe that they still drive around in gas guzzling 5-6 litre cars, with no regard for the environment whatsoever. It seems to me that the American Government is not to bothered about the problem either. Fuel in America has no value, for example in June 1998 a gallon costs $1 19c - about 80p. It is ridiculously cheap, and according to my cousins the cost drops in winter, and prices usually stay the same. The Americans need to be educated about these issues, because their current understanding of the problem is that it is somebody else's problem. I read on the BBC news that the Americans seem to think that the South American tropical forests will absorb all of their emissions hence they don't have to make cuts. That is absolutely scandalous. They just have no regard for the environment at all. Trade-offs are a bad Idea because that means countries like the US can just have their emissions quota increased, which means that the problem really is not being solved. However, I feel that it is not all the American people's fault, for example when in California, I saw no evidence of public transport, whether it being buses or trains. Maybe the American Government can take a leaf out of the British Governments book and take a positive stand on these issues, instead of leaving it to somebody else. Another way that I feel the UK can help curb emissions would be to reduce the national speed limit from 70-65mph. This would make the roads a lot safer whilst curbing emissions.
Thanks for your time
Rajen Ladwa

A: Dear Raj
Well, you've said it all, haven't you ? There's not much I can add. But let's not be too rude to the Americans -- there are some who do take the climate change threat seriously, and who are trying to get their fellow citizens to share their concern.
Yes, they need public transport -- and we in Britain have a long way to go there, further perhaps than you suggest: I think you're being very generous to us. And yes, bringing the speed limit down (to 55 mph/90 kmh ?) would be a great advance, if it was enforced.
One the role of the forests, a British Government report earlier this month had disturbing news. The researchers said it was likely that the Amazon forests, which at the moment are absorbing huge amounts of CO2 (2 gigatonnes annually) will in 50 years from now be so weakened by global warming that they will be emitting the same amount of CO2 to the atmosphere -- in other words, they will be worsening the climate change that will have led to their destruction. So neither the Americans nor anyone else should rely on the forests to soak up CO2.
Thank you for writing.
Regards, Alex

Q: Dear Sir/Madam,
After studying for a PhD for 5 years in Solar Physics, I have read many journals and attended several conferences where other solar physicists have discussed a mechanism that could have a considerable impact on the causes of global warming.
Over the past 400 years or so, there are sufficient, and accurate records of Sun spot activity recorded by European and Asian, astronomers, showing a strong and distinct correlation between the number of Sun spots and the average temperature of the Earth for that particular 11 year cycle. The most striking example, is when London suffered the 'Little Ice Age' in the mid 1700's when the Thames froze over and allowed people to skate on it (for probably the only time in modern history). This coincided exactly with the time when there was not one recorded Sun spot, in that 11 year period.
Conversely at the moment, we have been experiencing an unprecedented active Sun spot cycle, to the point where there is normally several years between the disappearance and reappearance of Sun spots to a period of just several months now.
After a scientific education, I am little reluctant to send this as I do not have reference to hand to back this up, but if you were to contact any solar physicist in this country, I am sure they will be able to put more detail around this.
I am just a little surprised that having seen people talk about global warming, I don't think that I have ever heard anyone even consider this possibility outside of Astronomy departments.
Yours sincerely,
Barry Lapthorn

A: Dear Barry
Sunspots probably have some effect, though I don't know what. I think though that there is compelling evidence that something else is happening, and that that something else is climate change caused at least in part by human activity. It does appear to be of a kind and on a scale which makes comparisons with the little ice age largely irrelevant, or at least inconclusive. There's so much we don't know about the climate and the way it works that I certainly wouldn't dismiss what you say. But I don't think it can be more than a fairly small part of the equation. The Intergovernmental Panel on Climate Change thinks that change is taking place, and its analyses go a long way back. And the University of East Anglia disclosed last week that 1998 will be the warmest in Britain for 1,000 years. The trends seem far longer than you are positing.
Thank you for writing.
Regards, Alex

Q: The earth may very well be warming but is this due primarily to man's activity or normal cyclic change related to sunspot activity or some other phenomenon? Why are scientists and others that suggest other possible explanations for global warming being ignored?
Randal White, USA

A: Dear Randal They aren't being ignored. But most reputable climatologists, by which I mean those involved in the work of the Intergovernmental Panel on Climate Change, think that there is discernible human influence at work in the earth's warming. It seems to me that the IPCC guys deserve a hearing, as do their critics. We try to reflect both sides, but my money is on the IPCC.
Thank you for writing.
Regards, Alex

Q: How fair is it to expect developing countries to agree on the same measures as have most developed nations, in the aim of limiting their contribution to climate change? Besides technology transfer, what can be done to assist them in controlling greenhouse gas emissions?
If the US does not ratify the agreement signed in Buenos Aires, what happens then to their part, as a 'developed nation', in the global pursuit against climate change?
Kenny Tai, Malaysia

A: Dear Kenny
Good question! I don't myself think it is fair -- yet -- to expect developing countries to agree the same emissions cuts as the rich world which caused most of the problem in the first place. I think all the developed countries need not only to sign the Kyoto Protocol, not only to ratify it, but to be seen to be taking serious steps to implement it -- and then to go far beyond it (you may remember it requires CO2 cuts of 5.2% on 1990 levels by 2010, while the IPCC called eight years ago for 60% cuts in order to have a manageable climate).
That said, I think developing countries, once they are persuaded that the developed world is serious about tackling climate change, will need to make -- and implement -- serious commitments themselves, to avoid making the same mistakes. What else besides clean technology? Well, for the poorest countries, debt remission would make an immense difference, and for most of the developing world reform of world trade would help as much here as in so many other ways.
If the US doesn't sign up to whatever Buenos Aires agrees . . . ? Then the rest of us will have to go on trying to drag the US kicking and screaming towards reality. Here in Europe several countries, notably Germany, have found that implementing climate change policies can be very lucrative. Shhhh . . . please don't tell the Americans, or they might want to get in on the act as well.
Thanks for writing to us.
Regards, Alex

Q: Your page on the global warming summit, including the links, appears to cover only one side of the issue. For an alternative voice, you may want to like to visit the Global Warming Information Center . We have a wealth of information challenging the notion that global warming is underway and playing havoc with the climate (floods, fires, droughts, etc.) Please feel free to contact me if you need further information.
David Ridenour, Vice President The National Center for Public Policy Research

A: Dear David
Thank you for your very good suggestion. You won't be surprised when I say that, on the basis of the evidence I have found, I believe that global warming is a serious threat, and is in fact beginning to kick in. But I know there are many, like yourselves, who disagree, and we do try to reflect your views. I'll keep your URL handy and hope to link to it soon.
Regards, Alex Kirby

Q: How does the role of sun cycles that naturally make the earth hotter every x amount of years influence global warming? Do they serve to extenuate the global warming phenomenon or could global warming be a result of these and not of the greenhouse effect?
Mark Corbin

A: Dear Mark
Thank you for your question. It's certainly possible that the sun's cycles are somehow affecting the climate in ways we don't understand, and it is possible that the sun is what we should be holding responsible for the collection of phenomena we call the greenhouse effect. But I doubt it. A report earlier this month from the Met Office's Hadley Centre for Climate Prediction and Research said: "Comparisons of model simulations and observations indicate that human-made greenhouse gases have contributed substantially to global warming over the past 50 years". It's not a racing certainty, but if I could afford a bet my money would certainly be on global warming, not the sun.
Regards, Alex Kirby

Q: Mr. Alex Kirby,
What is your personal view of whether "global warming" even exists? What have you done to negate the phoney expert reports that Algore touts?
Jeff Lehmann, USA

A: Dear Jeff
I guess I don't need to ask your personal view of whether global warming "even exists". That's a robustly sceptical question if ever I heard one! And so you deserve an equally robust answer: my personal view is that global warming, if it does not exist yet, very soon will, and will change the earth significantly (that does not mean that I think all or even most of the change will necessarily be for the worse. If we learn to adapt to what I think lies ahead, we will benefit in a number of ways.)
So you won't be surprised when I say that, even if I had any idea what you meant by "the phoney expert reports that Algore (sic) touts", I would have done nothing to negate them, but everything I could to publicise them.
I wonder what makes you so certain that the reports are phoney?
Stay cool, Alex

Q: The evidence of human induced enhanced green house effect is mounting. Will the modest level of green house gases reduction target be an adequate response to this environmental challenge? If not what has to be done and how will the cost of these remedies be shared?

A: Thank you very much for your question. I think you're right, and that the evidence certainly is mounting, and is now pretty compelling, though there are many people who do not accept it. Perhaps that is why the emission reduction targets are, as you say, "modest". In 1990 the Intergovernmental Panel on Climate Change said the world needed to cut its emissions of the main greenhouse gas, carbon dioxide, by 60% (that's right, SIXTY per cent !) in order to stabilise the climate at manageable levels. The Kyoto Protocol, agreed last year, binds developed (but not developing) countries to cuts of 5.2% on 1990 levels by 2010. This week's conference in Buenos Aires heard a call from scientists for that 5% to become 15%, which would take us a quarter of the way to what the IPCC called for eight years ago. The more delay, the higher the likely eventual cost. And I'm afraid the people likely to pay are the poor-not only those in places like Bangladesh and Egypt whose homes are submerged, but others in places like central America affected increasingly by "extreme weather events", as they are benignly called.

Q: Dear Environmental Correspondent,
I apologise for writing, but I simply cannot let the dreadfully biased and scientifically illiterate reporting on the Buenos Aires Global Warming Summit which characterised the News at 9.00 this evening to go unremarked.
In brief:
(a) CO2 is not the most important greenhouse gas - this is water vapour; (b) CO2 is not a pollutant - it actually fertilizes plants; © In the latest world survey, a large majority of scientists clearly indicated they did not accept a link between CO2 and temperature change.
When will you understand that Buenos Aires is about politics and that organisations such as the WWF are political organisations; they are not arbiters of scientific truth.
So many scientists are quite appalled at your current coverage of the global warming issue (witness e-mail after e-mail to me personally on this subject). But not even some of the protagonists of the global warming thesis make the errors of (a) to (c) above.
Yours exasperatedly,
Professor Philip Stott

A: Dear Professor Stott
Thank you for your message about the Nine O'Clock News' coverage earlier this week of the Buenos Aires conference.
On the specific points you raise:
Yes, water vapour is a more abundant greenhouse gas than CO2, but (correct me if I am wrong) CO2 is the most abundant greenhouse gas that can be linked to human activities.
Yes, CO2 fertilises plants. Salt does the human organism good, so long as you eat it in reasonable amounts. If you eat too much, you poison yourself. In the same way, too much CO2 DOES cause pollution. You can have too much of a good thing.
You say "a large majority of scientists clearly indicated they did not accept a link between CO2 and temperature change". OK. Who are these scientists, and what are their areas of competence? As you know, the Intergovernmental Panel on Climate Change includes in its ranks most of the world's leading climatologists, and they are convinced that climate change is something we should be taking seriously.
I do understand, and have understood for many years, that organisations like WWF are to some degree political. And I think you understand that they also employ some very reputable scientists. I doubt if the individuals or the organisations would claim to be "arbiters of scientific truth". Would you? Truth emerges from people honestly disputing, doesn't it?
You and I have corresponded before. We disagree at a pretty basic level about climate change. Although I think you are mistaken, I respect your views and the sincerity with which you hold them. Although I am not a scientist, may I ask you to extend the same respect to those who sincerely differ from you?
Thank you.
Yours, not exasperatedly but in hope
Alex Kirby
PS I seem to remember a former Prime Minister, name of Thatcher, who was quite convinced that climate change was a serious threat. Like her or loathe her, nobody can argue that she was easily fooled.

Q: Dear BBC: I was surprised not to find our page listed as an external link for this page.
We have fourteen people in Buenos Aires providing content which can be found here.
Langston Goree, International Institute for Sustainable Development, Canada

A: Dear Langston
Thank you very much for your message. I'm sorry we haven't yet listed you as an external link in any of our climate change stories. I'm pretty sure we shall, though, before long-and I think you will remain an important resource long after Buenos Aires. It may be some small comfort to know that you have been listed on my Favourites/Bookmarks for some time. We do love you!
Alex Kirby, Environment Correspondent, BBC News Online

Q: Your news deals with very few facts. Statistics mean nothing without the data. You speak of such things as Global Warming without any scientific proof. only a computer model projection with a lot of assumptions. Our forecasters using a weather model cannot predict the weather even a week ahead better than 50% and that is no better than a guess. Global warming activist claim to predict the temperature for decades ahead. Big farce.
Mr Bill

A: Big farce, huh? OK, Mr Bill, try these for facts-and I mean FACTS. The amount of carbon dioxide in the atmosphere before the industrial revolution was about 280 parts per million by volume (ppmv). It is now more than 350 ppmv. In Britain, 1998 will turn out to have been the hottest year for a thousand years. Alaska is undergoing what one scientist there calls "unprecedented" change . . . glaciers shrinking, sea ice disappearing, permafrost melting. These are FACTS, and they're happening NOW. OK, no scientist will yet say that it is 100% certain that human activity is causing global warming and that this is responsible. But many of them will say that seems increasingly like the only possible explanation. You could be right, Mr Bill. But I shouldn't like to bet on it.

Q: I would like to know if someone can tell me why if most the CFCs are used in the Northern Hemisphere. Why is the Ozone layer hole bigger in the Southern Hemisphere? Regards

A: Hello, Joe. It's a question that used to bother me, and I think many other people continue to wonder about it. The simple answer, I think, is that the CFCs circulate right through the troposphere, and they do their most severe damage over the Antarctic because that's where conditions are most suitable for them to react with the ozone molecules. The circumpolar wind pattern there is more stable than in the Arctic, and temperatures (at the relevant height above the earth) tend to be even lower than in the northern hemisphere. And, as I guess you know, the damage to the ozone layer is going to go on getting worse for some years yet before it starts to improve. I'm sure you, living in Oz, remember to "slip, slop, slap" to protect yourself against possible ultra-violet radiation. It's something we all need to remember nowadays. Regards, Alex

Q: Dear Alex
Could it be possible that the warming effect we are seeing is the result of some kind of very long term cyclical effect? eg the "pulsing"of the sun over millenia. I understand that this has been postulated as a reason for the coming and going of ice ages.
I recollect reading of research which indicated the "albido" (or ability to reflect light and heat) of the planet during the last ice age was so high, because of the extent of white snow and ice, that no other rationale exists to explain why the suns heat was not permanently reflected into space and an ice age settled onto the Earth for all eternity.
Millenia ago England was tropical (as evidenced in our coal and oil deposits ), then afterwards covered by huge ice sheets, then afterwards again temperate, over many cycles.
In Roman times the south of England was warm enough to produce wine, yet in Elizabethean times there were ice fairs held on the Thames, including bonfires on the frozen river, and everyone knows of the Dickonsian Christmas card scenes of snow and ice. The temperature change from Roman to Elizabethean and Victorian times, then to today, cannot be wholly attributed to man made reasons, can it?
Were these changes in climate the result of global warming produced by man, or some more enormous climatic cycle which we have yet to understand, or a combination of both?
Tony Reid, Malaysia

A: Dear Tony
Thank you for your question. The short answer to it is "Yes". You are right: the warming we are seeing now, and that scientists are predicting will increase, COULD be some long term cycle.
That said, I think it is pretty unlikely. The consensus opinion of the Intergovernmental Panel on Climate Change, consisting of around 2,000 international scientists, including the leading climatologists, is that the climate is changing, and that human activities have played a significant part in this already. Earlier this month a report from the UK Met Office's Hadley Centre for Climate Prediction and Research said: " . . . Comparisons of model simulations and observations indicate that human-made greenhouse gases have contributed substantially to global warming over the past 50 years. Initial results also indicate that climate models can simulate reasonably well the climate change of the past 140 years, and this gives us confidence in predictions of the future . . . Although it is still not possible to unambiguously assign recent change to human activity, we are working towards a more robust assessment . . . of the natural variability of climate . . . "
To me, that seems reason enough to take the problem very seriously. And remember that many of the things we need to do to tackle what I would call the very high probability of climate change are so-called "no-regrets" policies, like energy conservation, which will save money and cause less pollution.
Regards, Alex

Q: Anyone who does not admit that the world climate is changing is deluding themselves. The evidence, to me, is undeniable and staring us all in the face. The climate has changed dramatically many times in the past, so whether the current change is natural or man-made is irrelevant; we must all cooporate and adapt if we are to survive. Everything we can do to minimise the effects must be done, so that our descendants can thank us for securing their future.
Why, then, do the US refuse to accept job losses and reductions in economic strength at the expense of everyone in the world? The emissions trading idea proves that many people are unwilling to take responsibility. In this way the ability to pollute will become a very expensive commodity, and a prized possession. This seems rather backwards; surely the most valuable thing should be the ability to live in balance with the world and not emit any pollution?
Joel Laird

A: Joel, THANK YOU for that! I think you are entirely right in saying that climate change is a reality and that we need to adapt to it. But I do part company with you when you say it is irrelevant whether it is natural or man-made -- if we establish beyond argument that human activities are contributing to it, then we shall be able -- at least in theory -- to restrain them. I guess the reason why the US refuses to accept the reality is because it knows there will be some difficult decisions involved (and I think, although you can go a long way with "no-regrets" policies like energey conservation, some of the choices we face will be hard, in terms of giving up some of the things we now take for granted). I also think climate change is very much a matter of justice, within this generation and between it and those to come. Carbon dioxide can kill as surely as a bullet, as the Guardian's environment correspondent pointed out the other day.

Q: Do we really have enough historical data to predict that we have global warming, or just a limited weather cycle? Did people believe that 350 years ago when the Thames froze that we were having another ice age?
Mike Jones

A: Thank you very much for your question. It's one a lot of people are asking. Certainly, there are not many climatologists who will yet say, hand on heart, that climate change is 100% certain to happen. But many that I know say they think the evidence all points that way, and that the early signs are here already. A report earlier this month from the Met Office's Hadley Centre for Climate Prediction and Research had this to say: "Comparisons of model simulations and observations indicate that human-made greenhouse gases have contributed substantially to global warming over the past 50 years. Initial results also indicate that climate models can simulate reasonably well the climate change of the past 140 years, and this gives us confidence in predictions of the future . . . Distinguishing the human-made signal from background natural climate variability is a challenge . . . Although it is still not possible to unambiguously assign recent change to human activity, we are working towards a more robust assessment . . . of the natural variability of climate". Watch this space ! And, unlike the situation 350 years ago, we are affecting the climate -- since the start of the industrial revolution, the amount of CO2 in the atmosphere has increased from about 280 parts per million to about 350 ppm.

Q: Why is CO2 that much important? A combustion reaction releases just as much water H2O, another triatomic molecule whose specific heat coefficient can not be that much different?
Reinaldo Baretti Caguas, Puerto Rico

A: Thank you very much for your question, Reinaldo. The reason why CO2 is important is simply that it is the most abundant greenhouse gas that human activity produces, accounting for about half of all the emissions that are causing concern. You mention H20, and you probably know that water vapour is another of the greenhouse gases. It is more abundant than CO2 -- but most of it is produced by natural processes, and so is beyond our control.

Q: Dear Sir, because of global warming, do the oceans evaporate more? As a consequence of this - will more moisture be swept to the North and South Poles and cause another ice age?
Michael Lawson

A: It's an interesting question, Michael - but I have to admit I've never heard any suggestion that there will be significantly more ocean evaporation. The main concern, as you probably know, is the extent to which they will warm up themselves as a result of climate change, and how much carbon dioxide they will absorb. I recently came across a report which said the oceans are bound to go on heating up for the next five centuries, whatever we do, because so far it is only the near-surface waters that have begun to heat: as the warmth penetrates downwards, their own influence on the climate will become that much more marked. I think is it inevitable that there will be more evaporation, but the regional variations to be expected from climate change are notoriously hard to predict, and while there may be an increase in snowfall nearer the Poles, I do not think climatologists think that means any likelihood of a new ice age.

Q: With more and more scientific evidence pointing to (a) natural cause(s) - try research starting from the New Scientist-for global climate change, and indicating that, in fact, we have just come through a period of extreme climate stability and are returning to a more normative state, why the continued focus on blaming humanity for it? Wouldn't we be wiser to focus our efforts on figuring out how to adapt, fast? Thanks.

A: Thank you for that, Ahasverus - though I have to say I cannot agree with you! It seems to me there is more and more scientific evidence strengthening the belief that global warming is happening, and that human activities are at least partly responsible. But I don't think it's a question of "blaming" humanity, as you say -- let's not get into a guilt trip about this. If climate change is happening, and if we are helping to cause it, then surely it's important to understand that and act on it, so that we can reduce our damaging behaviour to a minimum. Plus -- many of the adaptation measures being suggested would be good in themselves, "no-regrets" policies. Cutting energy use, for example, would save us money and mean less bad health from polluted air. There is a positive side to it, I think.

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