SkepticLance

Swansont. Both graphs vary by no more than 0.2C from 1000 AD to 1890. The Mann graph then shows a surge of 0.7C. Again, you are avoiding the main point. And that is that the Mann graph shows a major change in results 'coinciding' with a change in measurement technique, while the other graph, which keeps the same measurement method, shows no significant change at that point. I know you get the point, and are just raising quibbles to deny it to yourself. I have thought about the significance of these results. I have to regard both graphs with scepticism, since the change in temperature shown from (say) 1200 to 1600 AD is minimal. Yet we know from historical data that there was a relatively massive drop in temperature over those years. In the 13th Century in Europe, there was widespread crop failure and deaths by starvation due to temperature drop. Neither graph shows this, which makes me think the tree ring method probably understates temperature change. Thus my interpretation is that the results prior to 1890 for the Mann graph, and all results for the other, are understating temperature change. I would suspect that the Medieval Warm Period of 900 AD to 1200 AD was substantially warmer than the graphs show, and the Little Ice Age of 1600 AD to 1800 AD was substantially colder. If the graphs showed this, then the 'hockey stick' surge in the Mann graph of 1910 to 1998 would appear to be within normal variation. Let me show you a further graph. http://putfile.com/pic.php?pic=6/16504483939.jpg&s=f5 This shows the average results for 169 glaciers shrinking over the last several hundred years (since the Little Ice Age) thus representing global warming. You will note that there is little change in shrinkage rate from 1810 to 2000 AD. This implies that, on average, the trend in temperature rise over that time was almost linear. This ties in with my interpretation of the Mann graph - indicating that the 'hockey stick' surge was an artifact of the change in measurement method.

Daks. Your comment about extinction rate not being constant over the 50 years really does not make much difference. My point was that the rate of extinction was wildly exaggerated, as expressed by Greenpeace. This is true regardless of whether extinction rate is constant or not. Dak said : Are you implying that that's acceptable? There was no value judgement in anything I said. The loss of even one species is a tragedy. I was just trying to knock the exaggerations. Azure Phoenix. You are falling into the 'noble savage' trap. There is nothing special about people being primitive in their technology. They still cause extinctions. The greatest extinction event in the history of humankind was that caused by polynesians crossing and colonising the Pacific. From the sub-fossil record (small bones still remaining) ornithologists know that no fewer than 2,000 species of birds became extinct in Pacific Islands following the arrival of humans. And these were stone age folk. I believe a similar but smaller event occurred with the Carib people colonising Caribbean Islands. Ditto 60,000 years ago following the arrival of humans in Australia, when over 100 species of megafauna died out. In my own country, humans (stone age polynesians) arrived 900 years ago. Within 200 years 36 species of native birds were extinct. My own belief is that we are getting less destructive, not more. Today people actually work to prevent extinctions. The worst areas of the globe in terms of extinctions are not in the developed world, but those in less developed nations, such as Africa, where hunting is wiping out chimps, gorillas and bonobos; or in partly developed nations such as Indonesia where the orangutan is severely at risk.

Allow me to live up to my name and be really sceptical on this one. The media love bad news and putting the worst twist on everything. Many, many media stories are the result of selective perception, in order to get this twist. I think the most probable cause for this story is selectively perceiving that a lizard that has probably been there for who knows how long, is now 'discovered' to be further north than anyone knew. Nothing new about this. I remember a case in Australia, where a large lizard thought to be extinct, was 'found' in a new region of the interior. When the scientists finally got around to asking the aboriginal people, they were told : "You should have simply asked us. These lizards have been here forever, and we have been hunting and eating them all that time." Let me give another example of selective reporting. Most westerners believe that the Sahara Desert is expanding and swallowing more and more of Africa each year. The truth is different. According to New Scientist (21 September 2002, page 4), what happens is that there are a few years of drought, during which the desert expands, followed by a few years of good rain, during which the desert shrinks. In the former, the media go nuts, and report all kinds of alarmist nonsense. Latterly, the media are silent. Net result ; everyone thinks the desert is expanding whereas, on average, it is about the same size as it was 200 years ago when first surveyed. Moral of the story : do not believe everything you read in the news media.

Swansont. You quibble. You wriggle like a fish on a hook. All this is irrelevent. My sole point is that changing the method of measurement changes the results. That point stands out like the Taj Mahal.

Since this is the science forum, and scientists are supposed to be keen on accurate numbers, let me spout a couple. Environmental organisations are prone to wild exaggeration. For example : Greenpeace once declared that 50% of all plants and animals will be extinct in 50 years. No-one knows how many such species exist, but an average kind of estimate is about 20 million. 50% extinct in 50 years means we are wiping out 200,000 species per year. Hey, let's get a reality check. The actual number of species that are KNOWN to go extinct are 2 per year on average. That is : species that were known to exist a decade or two back and are now gone. Sure, there will be lots of extinctions that we do not know about. But to go from 2 per year to 200,000?? Pull my other leg. It plays Yankee Doodle. Now for a calculation based on a couple of admitedly shaky assumptions. If we assume that 2 million species are known, and 20 million exist, then the ratio of known to unknown extinctions is 1 to 10. If that is true, then the total number of extinctions will be 20 per year. Question those assumptions and extend the limits, and we are still going to get less than 100 per year, even including the insects and 'icky' creatures.

Swansont. Take another look at the two graphs. You and I have both seen numerous graphs of temperature change over the last 500 to 1000 years. We have seen that they are all different to each other, but in relatively minor ways, as are the two graphs I presented. However, the differences after 1890 are not minor. This is a dramatic change. This represents an extra factor in the equation.

Swansont said : Why are they different pre-1890, if they used the same method to that point? Swansont. You are being deliberately difficult. You know enough about this subject so that 5 seconds thought would have given you the answer to this question. For other people who may know less, I will answer your question. There are literally dozens of studies that claim to measure temperature change over the last 500 to 1000 years. Each and every one of them comes up with different values, which makes the two studies I gave quite normal in their differences. The reason for different values is simply a result of the nature of what they are studying. They try to derive global average temperature. To do that, they would need an unlimited number of samples from an unlimited number of sites to get a statistically perfect average. Of course they do not do that. Each study uses a 'small' number of samples from a limited number of sites. Local conditions then skew the results. For example : an ice core sample from Greenland in the year 1750 may give a different result to a tree ring sample in the year 1750 from Britain. The summer/winter temperatures from the two sites will not be the same. While each study attempts to get enough samples to overcome this source of error, no-one actually succeeds. However, these are smaller difference - one study to another. The point I was making is that the difference between the two studies I presented was very dramatic after the year 1890. That is when they changed measurement technique in the Mann study, while the second study kept a consistent measurement method. My suspicion is that the Mann study introduced a major source of error by changing technique. I suspect the error was actually pre-1890, with temperature changes as inferred being somewhat less than reality. As evidence for this, I would point out the small difference as shown for the Medieval warm period, versus the Little Ice Age. Historical data shows that these were dramatic warmings and coolings. However, they are shown as minimal in the Tree Ring studies. This is always a possible problem in masurements that are indirect.

Atheist I am not an expert on dendrochronology, so cannot answer your first question. Your second question is the crux. I do not believe you can directly compare studies using two different measuring techniques. The top graph uses tree rings (as does the bottom graph) until about the year 1890, then switches to direct thermometer measurements. I do not believe that the fact the graph suddenly changes at that point is coincidence.

I would word the problem a little differently. There are lots of ways of reading fossil records of temperature. I would be more concerned about the comparability of those results with modern thermometers. Changing measuring technique in the middle of a study can distort the results. If you can easily download the following reference (I have an old fashioned slow system), you will see two graphs. Above graph changes measurement method mid study. Bottom graph carries the same method right through (tree rings). http://putfile.com/pic.php?pic=6/16504473590.jpg&s=f5 You may care to comment on how the two sets of results differ.

bascule. It is time you dumped that ridiculous link you have invented between climate scepticism and anti-evolution. The first is a science debate. The second is a religion versus science debate. There are many sceptical climate scientists, and their scepticism is based on their honest evaluations as scientists, particularly an appreciation of the doubts and uncertainties of certain current climate dogmas. There are, as you have said, a small number of Ph.D. biologists who resist belief in evolution. However, they take this position out of religious conviction. I challenge you to name even one atheist or agnostic Ph.D. biologist who takes an anti-evolution stance. Indeed, there are more religious biologists who support evolution than those who oppose it.

bascule Your 'Science' reference talks about consensus on the twin ideas that the world is warming and that humans have some effect. We do not dispute that. Where consensus is lacking is on the degree to which humans affect climate, what the future will hold, and whether we should take drastic action.

reor Did you ever onsider a slow acclimation treatment? This is now being tried for recalcitrant cases of peanut allergy. The patient is fed peanut meal at a dose equivalent to one 300th of a peanut. This dose is continued and slowly increased till that person is acclimated. It seems to work, and there is no reason why it should not work for you also, if you have the patience.

Swansont said : But consensus happens because of the evidence, and the direction it points. Dr. Dalek pointed out that there is no consensus. This is something I have stated earlier, also. I am aware of a number of climate scientists who do not fall in behind the IPCC position. Swansont's quote above demonstrates the reason for this lack of consensus. It is simply because the evidence as yet is not sufficient to obtain consensus.

It is a little hard to give you a clear answer without an idea of the background to your story. However, if a bunch of humans were thrown onto a planet, essentially naked with no resources, and if that planet had no easily refined ores, then it is hard to see how they could advance too much. There are some things they could do. Fire, of course, is a major first advance. This leads to manufacture of pottery, assuming clay may be found. Assuming suitable vegetation, then wood and fibre products can be made. If the vegetation contained tannin chemicals, then animal skins could be tanned to leather. An advanced neolithic culture could develop very quickly. With the wheel and writing, that culture could do well. Even glass and soap could be made. However, to advance much past advanced neolithic would be difficult indeed, without suitable metal ores. Extracting metals from low quality ores can be done, but not from a neolithic base. It requires advanced materials. Our heroes could make gunpowder, and use it as a weapon by making wooden or paper rockets, and by making the medieval equivalent of hand grenades. But without good metal, they could not make guns.

herpguy, A typical alpine lake might, despite its beauty, be described as a biological desert. There is usually little life, and only so much diversity. When such a lake is polluted with nutrients, the amount of life increases dramatically. If you count microscopic life, the diversity of life in such a lake also increases. I do not think this could be called simplification. However, it is still a form of pollution, and still results in a drastic ecological change for the lake. I just do not think that the definitions given so far would encompass this change as ecological damage.

bascule, Your version of 'logic' is flawed. For example, you seem to think that climate scientists all agree with you. Sorry. There are lots that accept that there are no certainties. And these are highly qualified, and very experienced true scientists. Your 'certainty' about anthropogenic forcings is just your delusion. Plenty of climate scientists admit to uncertainty about that point. I am not sufficiently arrogant myself to try to say what must be. I know that any argument I might present might be wrong. Sadly, you do not.

In My Memory.I am delighted that you have found a system for maintaining good health. My point was the need to keep up iron and vitamin B12 intake. Clearly you have found such a way. Fortified foods are a good means. However, I will still use my own method, and that is to maintain a wide variety of food intake, including animal protein. Not a good thing to use third world obligate-vegetarians (obligate due to poverty) as a reference. Their health is anything but good.

Aardvaark. How would your definition fit the case of eutrophication of an alpine lake? Alpine lakes are generally very simple, with little life. They are, however, clean, and utterly gorgeous. If someone allows new nutrients to enter, you get a lot more weed growth, organic matter sinking to the bottom, phytoplankton etc. More biomass and more biodiversity. However, the lake become dirty, smelly and ugly.

bascule The funny thing is that it seems the protagonists and antagonists in this discussion have actually come quite close to agreement. You say you accept that climate models are uncertain, and that the degree to which natural/anthropogenic forcings operate are also uncertain, though you believe that anthropogenic dominate. We say that climate models are uncertain and that relative strength of forcings natural vs anthropogenic are uncertain, though some think natural dominates, and I personally think we just don't know. I really do not see a great difference in our positions, and that difference is literally a matter of opinion, not science. I think you would agree with me??? ..that science is not a democracy and (like the earlier non-belief in plate tectonics) whichever theory is accepted by the most people at any point in history does not determine the final scientific outcome. My own opinion is that the whole global warming debate has been utterly distorted by politics, and by media reports that look for the most dramatic story, rather than the most scientific. I suspect that the majority of scientists working for the IPCC would agree with the level of uncertainty which we sceptics have expressed.

It strikes me that we are now descending to arguing semantics. What is hypothesis and what is theory and what are facts? However, it appears that bascule now accepts that there is significant uncertainty in climate models. That is progress of a kind, I guess. This whole thing reminds me of the "Limits to Growth" debacle of 1973. The Club of Rome assembled some of the world's best scientists and economists to try to predict the future. At that stage, they set resource limitations as the big problem. They carried out extensive modelling to work out what would be likely to happen. Of course, the modelling was by numerous calculations using the human brain rather than super-computers, but the principle was the same. One conclusion they reached was that, by the year 2000, the world would have run out of oil. They called for drastic action to limit consumption of various resources, or else there would be disaster. No-one, of course, took any notice. And of course there was no disaster. Does this sound familiar? The Club of Rome would have achieved much more accurate predictions by simply taking existing trends and extending them into the future. eg. the trend to discovering new oil fields. The trend to reduced cost of metals etc. That is precisely what I am saying. The more complex a model has to be, the more the scope for error. And there is nothing more complex than climate models. Again, I repeat. For temperature to increase beyond what we are seeing now as the existing trend, carbon dioxide emissions have to increase exponentially. Why is this? 1. Solar forcings are likely to stop increasing. 2. The theoretical carbon dioxide to temperature curve reduces slope with increasing carbon dioxide. All else being equal, just to keep the temperature increase linear, greenhouse gas emissions have to keep the rate of increase increasing. This might happen, but to get temperature to increase to the high levels some models predict, greenhouse gas increases must be drastic indeed.

There is no clear answer to your question. We do not know what progress was made over the 200,000 years. Most of the technology would have been biodegradable, and thus left no records. eg. did they have the ability to tan animal skins? In theory, it is easy. The first use of metals was probably from the odd rare lump of naturally occurring bare metal - eg copper and gold. However, it would not have become widespread until metal could be extracted. Certain copper ores yield copper from reduction under heat with carbon. It is likely that this was discoverd by accident when someone kindled a fire on top of such an ore. When the fire went out, they discovered some very sooty lumps of copper among the ashes. Of course, copper by itself is not as useful as bronze, since it holds an edge only for a short time. Otzi the iceman from about 5000 years ago had an axe head made of copper, so it probably was considered to be of value. The next big step involved someone learning to blend it with tin to make bronze - a much more useful material. Tin ores were abundant in Britain. Perhaps someone smelting copper accidentally mixed the copper ore with tin ore??? The Hittites about 1000 BC were the first to smelt iron ore. The process was similar to copper, but using much hotter furnaces. Perhaps someone found that blowing through the coals of a fire made it much hotter, and accidentally used iron ore??? I personally suspect that each step forward took an accident combined with a primeval genius to observe and take it a step on.

bascule said And I'm still waiting for any recent, peer-reviewed scientific papers arguing that natural forcings are predominant And you will not get them either. No-one has said such papers exist. No-one has claimed proof of either type of forcing being dominant. That is because such proof or even strong evidence does not exist. That is why I argue that we just do not know. Swansont. You claim that I am mis-using statistics. You are correct, of course. It is not possible to say for certain what the correct temperature prediction should be, and my method was very tongue in cheek. The real point is that global warming computer models are dreadfully misleading. There are none that can be called accurate. Personally, I think that a simple linear projection from current trends is more likely to be correct than any current model. The great virtue of such a projection is that, at least, it is beginning from reality. As I pointed out, with the probability that solar forcings will not increase (or not much), and with the temperature/carbon dioxide relationship being a diminishing curve, to see substantial temperature rises beyond current trends would require an enormous increase in carbon dioxide emissions. Unlikely!

Actually caloric restriction is only PROBABLY a means to increasing life-span. It has been tested in a number of mammals but not humans as yet. It appears to have an effect of switching off one key gene, related to insulin activity. There is one chemical substance known to do the same - resveratrol, found in red wine. This has been dosed to mice, and shown to increase their lifespan in a way similar to caloric restriction. The dose used (in human terms) is equivalent to the resveratrol in 70 bottles of red wine per day! Doubtless resveratrol tablets will be available soon. However, it is still unproven whether they work in humans.

bascule. Rather than get into a no-holds barred point by point battle, let me clarify my position. We are in a debate. I read your position as (and correct me if I am wrong) : "Anthropogenic greenhouse gases are the primary driver of global warming." My position is NOT simply the opposite of yours. My position is : "We do not know which of several possible drivers are dominant." In other words, I am not saying you are wrong. Just that we do not know. For this reason, to support my position, I do not need to provide evidence that AGGs are not dominant. I have a second position to argue. I know you are not fighting this point, but others are (or were). My second point is that "we need not view the 21st Century warmings with great alarm. Most predictions are exaggerated." Now back to evidence. As I have said before, I do not demand 100% proof. There is no such thing. I just challenged you to come up with genuine empirical evidence. I know this is possible, since I have seen it. Not enough to persuade me that the story is cut and dried, but enough to persuade me that AGG's are a factor. Whether dominant or not appears to me to be still unproven. Either you are unaware of this evidence, or you are so fixated on non-empirical evidences that you cannot find a true empirical evidence. Yet empirical tests are the foundation of science.

bascule. You misinterpret my logic. It is more : "If the model chosen by the USNA cannot be trusted, then who or what can we trust?" If you look at the temperature increase on your much loved 'hockey stick', you will note that there is a clear trend line that is linear. If we extend that linear trend into the future for 50 years, guess what? We end up with the Hansen 0.75C. To me, the most rational interpretation of all this is to say that we are unlikely to have a temperature increase over 50 years of more than 0.75C. The theoretical response to greenhouse gases is a curve, not a straight line. In other words, if we double the greenhouse gas increase, we get less than double the temperature increase. To maintain a linear increase in temperature, we need a growing increase in greenhouse emissions. Add to that the fact that in the 1990's solar forcings reached an 8000 year high, and are thus unlikely to increase much more, and thus will not contribute to future global warming to any great extent, then it is seriously unlikely that future temperature increases will be more than linear. Put it all together : 50 years = maximum increase 0.75C.