SkepticLance

As others have said, these polls mean very little, because they never ask the right questions. I am a GW sceptic, but accept that the world is warming and human activity is a prime cause. However, I believe that the computer models are dubious, and a lot of the conclusions drawn by GW enthusiasts are plain wrong. There is no category in the poll for my kind of sceptic.

The rules of basic ecology are often somewhat bent by humans. We are able to increase food production beyond what any 'natural' omnivore could hope to access. We do not even need soil. Hydroponics is startlingly efficient. Even in obtaining animal protein, we are capable of massive production. A Tilapia pond in Asia produces more animal protein per acre than could ever possibly be done in nature. For these reasons, we need to be a bit cautious in applying ecological rules to human society. We are not immune to those rules, but can bend them often to a surprising degree.

Paralith said : However you put it, habitat loss is bad. It's one step closer to extinction, with the next or previous steps involving predation, or pollution, or disease. I don't think one factor should get precedence over the other when it comes to conservation. However, I also understand that resources are limited, but at the rate habitat loss is going, I don't think it's one that can be forced to the backburner. I don't think anyone will disgree with you on the importance of conserving habitat. Apart from anything else, climax tropical rainforest is magnificent - a treasure to be protected. However, while habitat loss is clearly a contributor to extinction, it appears to be rare that it is the sole factor. My own reading suggests that the biggest cause of extinction is the introduction of alien predators, diseases etc. Probably followed by over hunting and fishing. If resources are limited (which they always are) then it makes sense to address the major cause rather than a minor one. For example : Tigers in Asia are rapidly heading into extinction in the wild. The primary cause is clearly poaching. To save the tiger, authorities need to direct their efforts against poaching, and avoid side issues.

To Paralith. Thank you for your research. A very nice list of possible examples. You have done a very good job of searching out and reporting possible examples of species rendered extinct by habitat loss. It appears that most of your examples is an extinction that is a combination of habitat loss with an other cause. Layson Crake includes alien predators. Columbian Grebe includes alien predators (rainbow trout) plus over hunting. Cuban kite includes killings by farmers. Imperial woodpecker includes over hunting as folk medicine Bachmann's warbler. Possibly a clear cut case of extinction by habitat loss, but not known for sure to be extinct, since some habitat remains, so far unsearched. Clearly loss of habitat plays a role in these extinctions, but appears not to be the sole cause.

By sheer coincidence, the latest edition of New Scientist has an article exactly on this topic. It is in the Australian printed edition, 12 May 07, page 43. It begins : "cutting down the rainforest is a disaster for biodiversity. Or is it?" It quotes work by two rainforest ecologists - Wright and Muller-Landau, published in Biotropica vol. 38, page 287. They claim that cutting down tropical rainforest is followed nearly always by substantial regrowth of secondary forest, and the secondary forest becomes a repository for biodiversity. The whole New Scientist article gives no clear answers - treating this as a controversy with arguments on both sides. There are clear cut examples to support the hypothesis. For example : "Torben Larsen, an internationally recognised authority on tropical butterflies. West Africa, he reports, has less than 3% of its original forest cover but appears not to have lost a single species of forest butterfly." As I said, this article does not, overall, give clear cut answers, and describes counter arguments, but nevertheless provides some extra ammunition to support Lomborg's hypothesis.

To CDarwin I had a read of your mongabay reference. It reads as a description of the principles that E.O.Wilson used to derive his extinction rates, which Lomborg says does not happen. With all due respect to the people involved, a description of theory is not settling the question. I was hoping for some real world data to show how valid or otherwise, the Lomborg idea is. To tell you the truth, the feed-back I have seen so far on this thread has just led me to think that Lomborg was right. Habitat loss no doubt does cause some extinctions, but no-where near as many as introducing alien predators and diseases, or direct over hunting/fishing by humans. This principle is important. If we are to act to reduce loss of biodiversity, we must know what to act upon. If it is mainly predator/disease introduction, the best place to divert resources is biosecurity. etc.

A note on biofuels. I am sure that everyone on this forum already knows that corn grain to ethanol is a terribly wasteful process, using lots of fossil fuels, and requiring enormous acreage. A better approach is to use the grain for food, and treat the rest of the corn plant with enzymes to digest cellulose to make sugars, which are fermented to ethanol. The enzymes for this are expensive and come from bacteria in a fermenter vessel. It is worth noting that in the last month, a scientific team has announced that they have genetically modified a corn plant to make its own cellulose digesting enzymes. These enzymes are inactive till the plant gets processed. They did not say how they activated the enzymes. However, if this idea gets off the ground, it could be vital.

Here's a personal (and true) story. Some years ago, NZ had no laws stopping smokers in public places. However, it was a custom for restaurants to set aside smoking and non smoking areas. I was having a meal with some friends, deep within the non smoking part of the restaurant. Some people sat down in the table next to us (also non smoking) and a patron asked the waiter for an ash tray. I expected the waiter to say no, but the pusillanimous bastard trotted off and came back with an ash tray. After a minute that man lit up. I had, by then, a significant amount of liquid courage in my veins, and I was not about to put up with this. I stood up, and stepped to his table (only one step). I stood there looking him in the eye until he started fidgeting. He obviously thought I was about to hit him. (I am over 6 feet tall and 240 pounds). I reached out and plucked his cigarette from his fingers; and broke it in half, extinguishing it in his ash tray. I then told him in firm (if slurred) terms that this was a non smoking area. The response of the restuarant management was somewhat interesting. They obviously also thought a fight was in the offing. I was apologised to most obsequeously (as was proper) and given several free drinks. The offender was also apologised to and told that, sadly, he could not smoke. Is there a moral to this story?

Actually KLB, It would probably have the opposite effect. The only real substitute for oil at the moment is liquid fuels from coal, which is exactly the opposite direction to which we should be going. Bush junior has already commissioned the first US coal to diesel manufacturing plant (5000 barrels per day) which is exactly the opposite trend to what we need. We should use the 30 to 60 year 'grace period' oil and gas give us to develop better alternatives.

To CDarwin The question is not whether loss of habitat can cause harm. Obviously it can. The question is how much? Lomborg suggests that loss of habitat as a cause of extinction is over-rated. A couple of examples of not-quite-extinct does not really answer the question. I am sure lots of us could come up with similar answers. The question is whether the emphasis on habitat loss as a cause of extinction is valid. I am not suggesting it is unimportant. Just asking about how much it contributes to extinctions. Being from New Zealand, I am very aware of extinctions. Since people have been here only 800 years, we are very close to the subject. In other places, the mass extinctions caused by humans may have occurred a long time ago. Australia, for example, had over 100 species of megafauna go extinct at about the same time as humans arrived - 50,000 to 60,000 years ago. Something similar in North America and in Europe. Here, it is recent. When the first humans arrived in NZ, there was a rapid loss of 36 species of native bird. Large birds to hunting. Smaller birds to the polynesian rat. There were undoubtedly many other species lost, such as insects and lizards. One sub-species of fur seal was lost. Most of these extinctions were within 200 years of the first humans. At the same time, about one third of the native rainforest habitat was lost. Insufficient to be a cause of extinctions. We can be pretty sure that all those extinctions were due to humans hunting prey, or the introduction of the polynesian rat.

To KLB As I have said before, cutting down on the burning of oil and natural gas products will not do much. These are limited resources which will be extracted and burned whatever anyone does. In 30 to 60 years, all the easily exploited oil and natural gas will be gone; converted to CO2. However, the extra CO2 from this source will be only about 20 ppm . The real long term contributor to CO2 will be coal. There is enough in the ground to add at least 1000 ppm CO2. This is substantial. Cutting down on oil and gas is a bit 'cutting off your nose to spite your face', but working to develop technologies that will leave coal in the ground is really worthwhile. Solid coal is by far the best carbon sequestration available. This means that we have a medium term target. We will have to replace oil and gas anyway, with novel liquid and gaseous fuels, when it runs out. This gives us 30 to 60 years. However, replacing coal is something that we can begin working on immediately. Nuclear power instead of coal burning stations is the obvious first step. There should be a plan to close all coal burning stations and replace them. Similarly, there should be a ban on using coal to make liquid fuel.

To Paralith. I disagree. I think that clear cut examples are not by any means an unreasonable ask. I gave a very clear cut example of a clear cut case of extinction by introduced predator (the Stephens Island Rock wren and the lighthouse keeper's cat). I can give lots more examples. Clear cut examples of extinctions by habitat loss should be readily available. There are heaps of examples of habitats totally destroyed. We should be able to point to these and say : "Here is a habitat destroyed, and this is a list of the species that once lived there that are now extinct."

To KLB I doubt that too many people on this forum would disagree with the idea that we should be moving to lower CO2 emission technologies. I agree with that myself. However, I do not agree that we should be taking panic measures. The world should be developing new ways of doing things that result in less air pollution (all kinds). We need research into biofuels, hydrogen technologies, new nuclear technologies etc. We need to introduce these technologies in a properly managed and sane way. Over exaggeration of global warming, and stressing urgency can lead to ill managed introductions of political and economic systems that harm human beings.

To Paralith. The whole point of asking about Lomborg's conclusions is due to the uncertainty. He supplies some statistics that indicate, at the least, that some of the estimates of the importance of habitat loss are exaggerated. However, we need clear cut examples of extinctions caused by habitat loss in order to show its importance.

Paralith. You may be correct in saying that a reduction in habitat may be all that it takes to lead to extinction. However, in spite of lots of replies in this thread, we have no clear cut examples. So far, Lomborg is proving correct.

Lomborg appears to be mainly talking about rainforest, and rainforest rarely totally disappears. Even those people in Brazil who assiduously remove the forest to create farm land have a hell of a job trying to stop the forest growing back. It is more difficult than we think to totally destroy that kind of habitat. The howler monkey example is a good one, except for the fact that they are spread over an enormous expanse of tropical rainforest, meaning that there is no real danger of extinction even if a few outlying populations suffer.

ofgreenstar said : I've decided to quit on many occasions due to health risk involved with smoking. But then i don't. I don't even make it a day. I smoke about 7 to 10 a day Face it. You are addicted. Mark Twain said that giving up smoking was easy. "I've done it a thousand times." The real problem with smoking is the starting. Once started, as ofgreenstar has found, it is very, very difficult to give up, and only a few with real strength can do it. What I am going to harp on is the need to discourage people from starting. Lots of teenagers start smoking in their blithe belief that they are immortal and nothing harmful will ever happen to them! The tobacco companies certainly encourage this illusion. If we do not do everything we can to disillusion those idiotic teenagers, then the carnage will continue. Deaths from tobacco outnumber deaths from car accidents in my country by about 20 to 1. Beyond the deaths, there is illness of sufficient severity to massively reduce enjoyment of life sooner or later to pretty much all serious smokers. If people cannot see the need to discourage kids from starting, then those people are not able to think rationally. The whole business of second hand smoke pales into insignificance against this much more important principle.

To Paralith. I am not pushing Lomborg's barrow. However, his quotes at least carried numerical data. The concept you presented of extinction debt may have validity. However, the degree of such validity cannot be ascertained by your data. We need proper studies and the numerical results of those studies. It should not be too difficult to quantify that extinction debt in a number of situations. After all, there has been numerous cases of habitat loss in various parts of the world throughout human history. A simple study should be able to look at extinctions that occurred at various times following various losses of habitat. Can you quote any such data?

To Pangloss. Where do you draw the line? There have been literally dozens of studies on the health effects of second hand smoke. The end result is pretty much known. More research is a large waste of $$$$$$. Let me nail it down for you. Second hand smoke is a trivial, but still harmful health influence. Not sufficiently bad to be of real concern to most of us. Short term exposure to second hand smoke, by the results of studies to date, is essentially so close to harmless we might as well call it harmless. Smoke is harmful, to a significant degree to : 1. Those who smoke. For them, there is more than a 50% chance that their eventual death will be early, and caused to some degree by their smoking. 2. Probably, babies and toddlers are harmed by second hand smoke. They should be given total protection from inhaling the noxious substance. For adults, second hand smoke is probably a trivial detrement to their health. Carrying out more studies is highly unlikely to change this picture.

In response to your requests for more of Lomborg's thinking, some selected quotes. Obviously this is a tiny part of the whole. If you need more, you will have to go to your public library and get out the book. Page 252. "Lovejoy constructed a model to back up Myers controversial figure of 40,000 (species lost to extinction each year). Lovejoy's model is in reality attractively simple. A large part of all species are found in the tropical rainforests. If we simply allow the rainforests to remain in place, nothing happens. If we cut down all the rainforest, practically all the species will disappear. Lovejoy then assumes that if half the forest is cut down, a third of the species will disappear. And there you have it. With an estimated 50% to 67% reduction in rainforest in 20 years, we get a localised reduction in the number of species of 33 to 50%. Lovejoy estimates this will lead to an overall reduction in the number of species in the world of approx. 20%." On page 253 "Wilson formulated a rule of thumb. If the area is reduced by 90%, then the number of species will be halved." Page 254 " In the US, the eastern forests were reduced over two centuries to fragments totalling just 1 to 2% of their original area, but nevertheless this resulted in the extinction of only one forest bird." Page 254 about Puerto Rico. " the primary forest had been reduced by 99% over a period of 400 years. 'Only' 7 out of 60 species of birds had become extinct although the island today is home to 97 species of birds. This indicates a serious problem with Wilsons rule of thumb." "We get to understand the situation when we are told that the overall forest area of Puerto Rico never fell below 10 to 15%." "In fact, FAO figures show that about half of all tropical forest that is cut down is converted to secondary forest." Lomborg then spends half a page describing the problem of lack of data. "Heywood and Stuart (referring to a book) point out that the recorded extinction figures for mammals and birdsare 'very small'. If the extinctions rates are similar for all other species, and if we assume 30 million species, we get an annual extinction rate of 2300 0r 0.08% per decade. Since the area of rainforest has been reduced by approx. 20% since the 1830's, it must be assumed that during this contraction, very large numbers of species have been lost in some areas. Yet surprisingly, there is no clear cut evidence of this." Page 255 about Brazil's Atlantic rainforest. "almost entirely cleared in the 19th Century, with only 12% extremely fragmented forest left. According to Wilson's rule of thumb, one ought to expect half of all the species to become extinct........the group could not find a single known animal species which could properly be declared to be extinct..." Lomborg concludes a new extinction rate of 0.7% in 50% years globally. I think you can see from these quotes, that Lomborg claims estimates of extinction rates from habitat loss are substantially exaggerated. Does anyone on this forum have data to the opposite?

John Cuthber said : It's the old idea that "it only takes one cancerous cell to grow into a cancer and it only takes one carcinogenic molecule to turn a cell cancerous because there's only 1 (nuclear) DNA molecule in a cell for it to interact with". I'm not at all sure about the second clause there. Let me return to a wee bit of science. Dr. Bruce Ames (now retired) spent his whole professional life researching carcinogens and their effects. He found that over 50% of ALL chemicals we ingest are carcinogens at high dose. The flip side of this discovery is that 100% of all chemicals are non cancer causing at sufficiently low dose. Cabbage contains more than 20 chemicals that have (so far) been classified as cancer causing. However, at the the low doses found when you eat cabbage, they are harmless. It is rather probable that the nasty chemicals in cigarette smoke are also harmless in the doses we get from short exposure to second hand smoke.

Phil said : Many studies published in serious journals are based on faulty logic, bad methodology and sometime even worst. Perhaps Dr Siegel is right, perhaps Glantz's claim IS ridiculous. However, articles published in equally serious journals should be use to debunk this. For Stossel to present something as a "myth" based only on the opinion of ONE scientist is downright manipulative. Although in the end it'll probably damage the reputation of science more than his ratings. The problem here is that many studies have been done on the health effects of breathing second hand smoke. Overall, very little harm has been proven, but there is probably SOME harm, even if it is a tiny fraction of the harm smokers are doing to themselves. Because there are so many studies looking at something so difficult to demonstrate, there are results on both sides. That is : some results show no harm and some results show harm. People getting into arguments on this can find study results to 'prove' whatever position they choose to stand for. Overall, we should accept that the harm is there but is probably trivial. If there is an exception to this, it is probably to those most vulnerable individuals - babies and toddlers. Smokers should not allow smoke to pass into the lungs of these ones.

DH Congratulations for dumping the habit. I have been told that nicotine is one of the most addictive substances known - as bad as heroine - and to be able to quit is evidence of real strength of character. My biggest hang up on smoking is those who begin. I know that it is really, really tough to quit once addicted. Thus, the best approach is to push the message as hard as possible ; "Don't start!" It irks me to see beautiful young teenagers smoking. You know damn well they have just started, and they are in the process of harming their healthy young bodies. I have lost three friends, my father, and my father-in-law, to illnesses ascribed to their smoking habits. I want everyone who knows, and ESPECIALLY smokers to push the message : "Don't start."

Paralith. Thanks for the reply. I think you are correct. I think we must exclude such factors as new predators (including humans) and new diseases. However, removal of plant cover, or a change to the physical parameters, including pollution, can be included. The other change that is often touted is global warming. Again, I am unaware of any extinction that can, as yet, be laid solely or mainly at the door of global warming. However, I think, for this question, we need to exclude global warming, which is a separate and controversial subject. I still have seen nothing to lead to the conclusion that Lomborg is wrong.

To Sayonara. The reason I called it a small rat is because it is a small rat. The Polynesian rat is a different species to the ship rat or the Norwegian rat, which are both much bigger and both more destructive. We know from current day ecological studies that the Polynesian rat can harm small species of bird, but the larger ones (Kiwi, Takahe, Kakapo) are not affected. I have a friend who is a zoology technician who works with researchers, including some who have been studying the ecology of the Polynesian rat, and I have, whether I wanted to or not, listened to a lot of the findings. Easter Island is an example of an ecological disaster of substantial proportion about which an enormous amount of uninformed garbage has been written. The truth is that there are many conflicting theories unresolved. There is little doubt that the native polynesians presided over a big deforestation event. Their own loss of population afterwards is a bit controversial. Some researchers believe it was due to the terrible practise of 'blackbirding' (a euphemism for taking slaves) combined with the introduction of European diseases. Others claim it was due to their own destruction of the ecology of the island. The polynesian rat was carried right across the Pacific and doubtless caused the extinction of 1000 or more bird species. But only small birds. Sayonara said : If we consider habitat loss to be "any change to the habitat that changed it sufficiently to make it non survivable", then Lomborg is clearly wrong and there is nothing more to discuss. Yet we still have not received any clear cut examples. Unless we can demonstrate that it happens, and frequently, then Lomborg is right. There are about 20 known extinctions per year. That is : species known to have existed a few years ago which are now known to be gone. If habitat loss is a major cause of extinction, we should be able to find a reasonable number of these that are almost totally caused by habitat loss.